This dramatic astronaut photo shows a trio of colorful lakes straddling the border between Nevada and California. The three lakes ‪—‬ which vary in shape, size and salinity ‪—‬ also occupy very different biomes.

The most famous lake in the trio, Lake Tahoe (on the left), is the largest alpine lake in the U.S.. It covers an area of around 192 square miles (497 square kilometers) and sits at about 6,223 feet (1,897 meters) above sea level in the Sierra Nevada, which stretches across the bottom of the image and is covered in snow.

The other two bodies, Walker Lake (upper right) and Mono Lake (lower right), are positioned southeast of Lake Tahoe and each have have a maximum width of around 13 miles (21kilometers). (Another major body of water, Pyramid Lake, is located out of the shot to the northeast of Lake Tahoe, while two much smaller lakes sit between the three larger lakes.)

The border between California and Nevada runs directly through the middle of Lake Tahoe and continues to bisect the space between Walker Lake, which is in Nevada, and Mono Lake, which is in California.

While Tahoe is located in the lofty climbs of the Sierra Nevada and is subsequently exposed to very wet and cold conditions, Walker and Mono are situated within the Great Basin desert. This flatter region — which also covers parts of Utah, Idaho and Oregon — has a drastically different environment because it sits within the mountain range's "rain shadow" and, therefore, receives very little precipitation, according to NASA's Earth Observatory.

The other stark difference between the lakes is their respective colors, which become even more apparent when viewed from above.

Lake Tahoe is the second-deepest lake in the U.S., with a maximum depth of 1,645 feet (501 m). As a result, it has a rich, bright-blue hue. It has constant subsurface currents that prevent it from freezing over in the winter, so it looks the same year-round.

Walker Lake is endorheic, which means it does not have a proper inlet or outlet and instead rises and falls via rainfall and evaporation. Over the past few centuries, the rate of evaporation has outpaced precipitation, which has made the lake extremely salty, or hypersaline. This altered chemistry, combined with the lake's shallower waters and the presence of various microbes, gives the lake a greener hue when viewed from above.

Mono Lake is also endorheic. It has seen an even sharper drop-off in recent years, as evidenced by a series of "bathtub rings" left over from when the lake had much higher water levels. It's home to salt-tolerant photosynthetic algae, which are preyed upon by brine shrimp (Artemia). Drops in the shrimp population in the colder winter months allow the algae to bloom, causing Mono Lake to turn bright green. If you look closely at the image of the lake, you can see a large swirl that represents the blooming algae getting trapped within wind-driven surface currents.

Due to the sharp rises in their salinity, Walker and Mono lakes have almost no remaining fish populations. This has allowed algae to take a greater hold in both lakes, according to the Mono Lake Committee.

Mono Lake also made headlines in 2010 when NASA scientists found a species of bacteria living there that could feed on the high levels of arsenic in its waters — a first in microbe biology, which could "impact the search for evidence of extraterrestrial life," researchers claimed. However, this paper was eventually retracted in 2025 after experts noticed flaws in its data.

Although it is rare to see many visually contrasting lakes in close proximity, similar scenes have been snapped from space. For example, in Africa's Great Rift Valley, there is a striking trio of blue, green and yellow lakes. Colorful collections of lakes can also be found in Crimea's "putrid sea" and around the Etosha Pan in Namibia.

See more Earth from space

Blackwater lakes and rivers in the Congo Basin are releasing ancient carbon into the atmosphere, a new study shows. Previously, scientists thought this carbon was safely stored in the surrounding peatlands, but the research reveals that's not the case.

The finding contradicts the long-held assumption that old peat carbon remains trapped underground, suggesting that some tropical peatlands could switch from being carbon sinks to major carbon sources.

"We are now faced with a 30-million-tonne question: we need to determine if this is just a small, natural leakage of ancient carbon, or the onset of broadscale destabilization," study lead author Travis Drake, a carbon biogeochemist at the Swiss Federal Institute of Technology Zurich (ETH Zurich), told Live Science in an email.

Drake and his colleagues have conducted three research trips to the Congo Basin over the past four years. Specifically, the team traveled to the Cuvette Centrale, a 56,000-square-mile (145,000 square kilometers) region of forests and swamps in the Democratic Republic of the Congo that holds Earth's largest known tropical peatland complex. Situated in the heart and to the south of the Cuvette Centrale are two large blackwater lakes — Lake Mai Ndombe and Lake Tumba — while a major blackwater river, the Ruki River, flows west-northwest across it to meet the Congo River.

Blackwater lakes and rivers contain high levels of decaying plant debris, or dissolved organic carbon, which gives them their black color. This dissolved organic matter, together with direct inputs of carbon dioxide (CO2) from the surrounding swamps and forests, creates supersaturated concentrations of CO2 in lakes Mai Ndombe and Tumba and in the Ruki River. As a result, these waters emit enormous amounts of CO2 into the atmosphere.

Crucially, however, none of the CO2 was previously thought to originate from the Cuvette Centrale's ancient peat, as these deposits, protected from decomposition by their oxygen-depleted, waterlogged environment, were believed to be highly stable.

But in a paper published Feb. 23 in the journal Nature Geoscience, Drake and his colleagues found otherwise. Their results showed that a significant proportion of the CO2 escaping the Cuvette Centrale's blackwater bodies is from peat carbon that is between 2,170 and 3,500 years old.

"We were very surprised because we fully expected the carbon dioxide to be modern," Drake said.

The researchers drew their conclusions from measurements they took at Lake Mai Ndombe in 2022 and 2024, and at Lake Tumba and the Ruki River in 2025. They accessed Lake Mai Ndombe with small boats, which was difficult due to strong winds that almost capsized them, Drake said.

"The ecosystems remain in relatively pristine condition," he said. "There are some small settlements and villages scattered around Lake Mai Ndombe, but they are far and few between."

The team measured sediments, greenhouse gases, dissolved organic carbon and dissolved inorganic carbon, which includes dissolved CO2, bicarbonate ions (HCO3–) and carbonate ions (CO32-). Later, in the lab, the researchers analyzed their samples with high-precision spectrometry to separate modern carbon from plants and older carbon from soils.

"Because the organic carbon in the lake was modern, we assumed the inorganic carbon would be too, so we initially just analyzed a single sample to confirm," Drake said. But when about 40% of the inorganic carbon in that sample turned out to be millennia old, the team decided to test the remaining samples.

The results were consistent across Lake Mai Ndombe, so the researchers returned to the Cuvette Centrale to sample Lake Tumba and the Ruki River. Both contained high levels of inorganic carbon derived from ancient peat, suggesting that microbes in the region are breaking down peat carbon into CO2 and methane, which then seep into lakes and rivers before wafting into the atmosphere.

The Cuvette Centrale is estimated to hold one-third of the carbon stored in tropical peatlands globally, equivalent to about 33 billion tons (30 billion metric tons). It's possible that recent losses of ancient peat carbon are linked to the formation of new peat deposits, in which case the phenomenon might be nature returning to a state of equilibrium, according to the study. But it's also possible that climate change is destabilizing long-buried deposits and that the Congo Basin's peatlands are nearing a tipping point.

"This pathway highlights a critical vulnerability," Drake said. "If the region experiences future drought, this export mechanism could accelerate, potentially tipping these massive carbon reservoirs from a sink into a major source to the atmosphere."

Next, the researchers will analyze water trapped in the Congo Basin's peat to explore if and how microbes are releasing ancient carbon.

"Ultimately, we aim to confirm whether this process is happening across the entire Cuvette Centrale and quantify oxidation rates to determine if this leakage is a natural baseline or a sign of instability in this large carbon reservoir," Drake said.

This intriguing astronaut photo shows a pair of islands in the murky green waters of a major African lake. Both landmasses are home to monasteries that hold important religious relics, including the remains of several ancient emperors.

The two islands, named Dek and Daga, are located within Ethiopia's largest body of water, Lake Tana, which has an average surface area of around 1,200 square miles (3,100 square kilometers) — around the same size as Rhode Island. The lake, which is listed as a UNESCO biosphere reserve, is located in the Ethiopian Highlands, around 5,800 feet (1,770 meters) above sea level, and has a maximum depth of around 50 feet (15 m).

Lake Tana was formed around 5 million years ago when volcanic activity dammed a group of ancient rivers. It is now the major source of the Blue Nile — a 900-mile-long (1,450 kilometers) tributary of the Nile River that flows through Ethiopia and Sudan.

Dek, the larger of the two islands, measures around 4.5 miles (7.5 km) across at its widest point and has a population of around 5,000 people, while Daga has a maximum width of around 1 mile (1.6 km) and is not permanently inhabited.

When viewed from above, the islands stand out against the lake's insipid milky-green coloring, which is the result of algal blooms that thrive off nutrients from agricultural runoff and wastewater, according to NASA's Earth Observatory.

Related: See all the best images of Earth from space

Dek is an agricultural hotspot thanks to its nutrient-rich volcanic soils and high rainfall, which is due to its location in the Intertropical Convergence Zone — a low-pressure belt near the equator that experiences frequent thunderstorms. Most of the island's surface has been transformed into agricultural fields, which appear light brown and red when viewed from above. Their main crops are corn, millet, coffee and mangos.

In the photo, a bright orange lake is situated towards Dek’s southeastern corner. It is unclear exactly what gives this lake its vibrant hues, but it is also likely tied to agricultural runoff, according to the Earth Observatory.

However, the two islands' most interesting sites are probably their monasteries, which cannot be easily seen from space.

Holy relics

Experts believe that there is at least one church or monastery on more than half of the 30 or more islands within Lake Tana (the total number of islands within the lake is disputed because some only appear during the rainy season, when the lake expands). These religious sites were created, in part, to protect Ethiopia's most valuable relics and treasures during times of war, according to the Earth Observatory.

Dek is home to at least five churches, as well as the 18th-century Narga Selassie monastery, which is filled with stunning paintings of Ethiopian history. However, Daga is arguably home to a more important monastery, named Daga Estifanos or "St. Stephen of Daga," which dates to the 13th century.

The mummified remains of at least five Ethiopian emperors — who ruled the country at various points from between 1270 and 1730 — are kept at Daga Estifanos, and are each displayed for tourists in special glass-sided coffins, alongside crowns, scrolls and other artifacts from their reigns, according to the Lake Tana Biosphere Reserve website.

But, due to local customs, only men are allowed to visit Daga and its monastery. In fact, the local "no females" rule is even applied to farm animals.

Other major religious sites in Lake Tana include Tana Cherkos, an island populated exclusively by monks from the Ethiopian Church. The Ark of the Covenant was supposedly kept there for around 800 years, sometime after it was stolen from Jerusalem and before being moved to the Ethiopian mainland, according to the Lake Tana website.

Archaeologists in Saudi Arabia have discovered 12,000-year-old life-sized animal etchings — "monumental rock art" that dates to over 2,000 years before humans were thought to be in the region, a new study finds.

These highly realistic depictions of camels and other creatures were likely culturally meaningful for these hunter-gatherers, and probably served as waymarkers to help people locate oases that popped up when the area became wetter starting from 16,000 to 13,000 years ago, the researchers wrote in the study, which was published Tuesday (Sept. 30) in the journal Nature Communications.

The rock art could have also marked ancient travel routes or even signified the territory of a group and its intergenerational memory, the researchers said. These findings ultimately show that "humans were able to survive in the desert very early on, much earlier than we thought and in much harsher conditions than we thought,"study co-author Maria Guagnin, an archaeologist at the Max Planck Institute of Geoanthropology in Germany, told Live Science.

At the crossroad between Africa and Asia, Arabia was a key migration route for early humans, with research published April 9 in the journal Nature confirming the region underwent various "humid episodes" that enabled these dispersals. Yet there previously was no evidence of human occupation in northern Arabia between the end of the Last Glacial Maximum (around 25,000 to 20,000 years ago), the coldest period during the last ice age, and around 10,000 years ago. Researchers assumed the area had been abandoned because it was too arid to survive.

Now, following a tip from local amateur archaeologists about a giant piece of rock art, researchers have explored three previously unknown sites in the southern Nafud Desert in northern Saudi Arabia that upend that assumption.

When they arrived, one teammate wandered off to explore the area and discovered "the first big excitement," a rock formation with ancient art surrounding a pool of water, Guagnin said. And on the other side of the mountain were the remains of an ancient lake.

The team subsequently found 62 rock art panels with 176 engravings across the three sites, with some etched into huge cliff faces 128 feet (39 meters) up. The engravings were predominantly of life-sized animals, mainly camels.

Importantly, these depictions were commonly of male camels with distinctive bulges around their necks that they form during the mating season and thick winter fur. This suggests that the ancient water sources may have formed in winter, and may have also symbolized the resilience of these animals to the harsh environment, the authors speculated in their study.

Digging up the desert

The archaeologists excavated directly below four camel engravings to try to determine their age. They unearthed over 1,200 stones, 16 animal bone fragments and three hearths. The team dated these using luminescence dating, a technique that measures when sediments were last exposed to heat and sunlight, and radiocarbon dating, which measures the ratio of different versions of carbon.

These methods revealed that the rock art was between 12,800 and 11,400 years old.

At one excavation site, the camels' legs had been obscured by layers of sediment. When they dug down, the team were amazed to find the stone tool likely responsible for creating the masterpiece, which they dated to around 12,200 years ago. This provides "an indirect date for the engraving," the authors wrote in the study.

They also found arrow points, bladelets and stone beads; but "this isn't just a handful of arrowheads," Guagnin said. A community lived in the region and crafted tools and ornaments typical of the Natufian culture in the Levant, many miles away around the eastern Mediterranean. "They were in contact with the Levant somehow across hundreds of kilometers," she said, and learned about the latest tools and accessories.

Crucially, "some things are imported but then some things are unique," study co-author Michael Petraglia, an archaeologist at Griffith University in Australia, told Live Science. These people were also developing their own culture, with the rock art having symbolic meaning as well as being clear ways of marking routes to water sources, he said.

An analysis of the sediments in the dried up water sources revealed the region had become more humid starting around 16,000 to 13,000 years ago, forming seasonal lakes. This discovery represents the earliest evidence of increased humidity in northern Arabia after the Last Glacial Maximum.

"This is a very exciting study revealing a part of Saudi Arabian history that has so far not been readily visible," Hugh Thomas, an archaeologist specializing in Saudi Arabia at the University of Sydney who was not involved in the study, told Live Science in an email. He said that these results show that "the entire region was populated and that even at this time, it was an interconnected landscape."

Stone Age quiz: What do you know about the Paleolithic, Mesolithic and Neolithic?

From above, Antarctica might seem like a cold, flat and desolate landscape — and it certainly is. But beneath the ice sheet lies an entire hidden world: Scientists have discovered diverse biomes, hidden rivers and lakes, mountains and valleys, primordial bacteria, and even the remnants of ancient ecosystems.

Almost 90% of Antarctica's land is covered in a thick layer of ice — around 1.3 miles (2.2 kilometers) deep, on average — and it's been that way for around 34 million years. Yet researchers have only scratched the surface of what lies under the mysterious continent.

"It's so exciting to dive into these past worlds and to understand how this continent evolved over time, and what that means," Johann Klages, a sedimentologist at the Alfred Wegener Institute of Germany who studies climate history in Antarctica, told Live Science. "What does it tell us about our own existence on this planet?"

In his research, for instance, Klages discovered the first amber fossil ever found in Antarctica — a remnant of the ancient temperate rainforest that covered the continent over 90 million years ago. Klages believes there's likely more amber to be found in future expeditions, too.

Antarctica is also home to over 400 subglacial lakes. The largest, Lake Vostok, lies under 2.5 miles (4 km) of ice near Russia's Vostok Station. "And what's in there? Probably microbes," Klages said. "But also," because of the immense pressure of the ice, "probably life that isn't found anywhere else on Earth."

Related: Will Antarctica ever be habitable?

A complex system of rivers funnels water in and out of those lakes, according to research led by Christine Dow, a glaciologist at the University of Waterloo in Canada who has used radar imaging to see what lies beneath the ice's surface.

If you're having a hard time picturing an entire body of water underneath an ice sheet, just think of a river you would see flowing into a lake and toward the ocean — "but then you just add on 4 kilometers [2.5 miles] of ice on top," Dow explained. That ice makes the water behave a bit strangely. "You can actually have water flowing uphill underneath the Antarctic ice," she told Live Science. "It's not as defined by gravity."

A lot of what lies under the ice is not as exciting, however. "The vast majority of what's underneath the ice is just rock," Klages said. "It's just crystalline bedrock, crystalline basement, granite."

One of the most important elements is the very large planes of soggy sediment beneath some parts of the ice, Dow said. "Those are the areas that are flowing really fast into the ocean, because essentially the ice is just floating on top of this slurry of wet sediment," she explained. "It's not as aesthetic-sounding as the mountains and the valleys, but it's very important for understanding how the ice is behaving."

Knowing what's going on underneath the ice sheet is important for predicting what will happen when it melts, according to Dow and Klages.

There are entire areas of the Antarctic, like much of West Antarctica, that are below sea level because of the thickness of the ice sheet. "There's no ocean there right now, because the ice is taking up all of the space," Dow said.

If you imagine that the ice is in a bowl, it's currently right at the rim. But once the ice starts to retreat, it will move back into the bowl. And because ice is less dense than water, it will become more buoyant. At that point, the ice is "floating like a giant ice cube," Dow said.

Once all of the area below sea level becomes filled by the ocean, the ice will become more unstable and will break up, contributing even more to sea-level rise. "So the moment when that ice starts retreating from the rim is really critical," Dow said. "And we're at that point right now.

"It's a pretty unstable place, the Antarctic," she added. "It's beautiful, it's vast, it's mysterious — but it's also really dangerous."

Antarctica quiz: Test your knowledge on Earth's frozen continent

A volcanic crater in Indonesia over 7,700 feet (2,350 meters) above sea level is home to Earth's largest acidic lake, with water like battery acid. In this excerpt from "Beyond The Sea: The Hidden Life in Lakes, Streams, and Wetlands" (Johns Hopkins University Press, 2024), author David Strayer examines the extreme chemistry of some of our planet's natural lakes — and the life they host.

I know people who really like water chemistry. They spend all day thinking about redox reactions and mass balance and valences and solubility indices and spiraling metrics, and when the workday is over, they go out for a beer with their friends and talk about redox reactions and spiraling metrics. (In my experience, water chemistry enthusiasts are often beer connoisseurs as well, which makes sense in a weird way if you think of a glass of beer as a special kind of aqueous solution.)

These are people who when asked to name their favorite chemical element say "ooh, ooh, can I have three?" and then name five. I'm guessing that you're not one of those people.

So instead of going into great detail, element by tedious element, about the enormous variation in the chemical content of inland waters, I'm just going to briefly talk about how much pH varies across inland waters, assume that is sufficient to make my point about the chemical diversity of inland waters, and move on to subjects that you like better than water chemistry.

You may remember from high school chemistry that pH is a measure of whether a substance is acidic or basic (or "alkaline"). Materials that are neutral (neither acidic nor basic) have a pH of 7, acidic materials have a pH less than 7 (household vinegar has a pH of about 2.5), and basic materials have a pH greater than 7 (household ammonia has a pH of about 11.5). The pH scale is logarithmic — a change in pH of one unit represents a 10-fold change in acidity (technically, a 10-fold change in the activity of hydrogen ions). So vinegar at a pH of 2.5 has about a billion times more hydrogen ion activity than does ammonia at a pH of 11.5.

The logarithmic scale allows us to conveniently express enormous differences in chemistry but makes it easy to forget that small differences on the pH scale can mean big differences in chemistry which can have large consequences.

For instance, the ocean today has a pH of around 8.1, which tells us that it is a little basic. Higher concentrations of carbon dioxide in the air resulting from fossil fuel burning have caused the ocean's pH to fall 0.1 units from a preindustrial value of 8.2, and models suggest that it may fall to 7.8 by the year 2100. These sound like small changes hardly worth worrying about. But a change from 8.2 to 8.1 represents an increase in hydrogen ion of 26%, and a change from 8.2 to 7.8 means an increase of 150%.

These changes are enough to cause serious problems for marine life. Organisms like clams and corals that make their shells out of calcium carbonate find it increasingly difficult to build and maintain their shells if the pH drops just a few tenths of a point. Ocean scientists are now scrambling to understand and find ways to prevent or manage these changes before we lose important parts of ocean ecosystems as the pH drops by 0.3 or 0.4 units.

The pH range across inland waters is far greater than the few tenths of a point that are so important in the ocean. This exposes inland water organisms (and chemical processes) to an enormous range of chemical conditions. Most inland waters have a pH between 4 and 9. Again, this range may sound modest, but it represents a 100,000-fold range in hydrogen ion activity. And there are waters that lie outside even this expansive range.

The most acidic natural inland waters are the lakes that lie in the craters of volcanoes, like Kawah Ijen in Indonesia. These lakes are so rich in sulfuric acid that they may have a pH as low as 0.1. To put this in context, fresh battery acid has a pH of about 0.7. The label on battery acid (which remember is about a quarter as strong as this lake water) warns that it causes severe skin burns and eye damage and advises consumers to use personal protective equipment, to immediately call a poison control center if it gets swallowed, and to dispose of it in an approved waste disposal plant. You might feel pretty confident in guessing that nothing lives in this lake.

But when scientists sampled Kawah Ijen (an undertaking that required special gear; as you might imagine, a lot of regular gear like aluminum boats would dissolve in the lake water), they found a green alga and three kinds of archaeans living in the lake.

Apparently, no animals live in the lake. However, the acid water in its outlet stream is gradually neutralized as it flows downstream, and the researchers discovered fly larvae called chironomids living in the stream at the point where the outlet stream reached a pH of about 2.5 (like vinegar, remember?).

Related: 'It looks like smoke': Mysterious chimneys spewing shimmering liquid discovered at the bottom of the Dead Sea

And more remarkably, not only do these species survive in highly acidic waters but some of them even prefer these harsh conditions. One of the archaeans living in volcanic waters can tolerate pH below 0 and grows best at a pH of 0.7. That is, battery acid is its ideal pH and vinegar and lemon juice are far too mild for its taste. (If you’re wondering about how low the pH of nonnatural waters can go, a pH as low as -3.6, yes that’s minus 3.6, has been recorded in some groundwaters in California polluted by mining wastes. It was a major technical problem for scientists to figure out even how to measure such low pH.)

At the other end of the spectrum, alkali lakes often have a pH of 9.5 to 11.5. Alkali lakes typically occur in regions that are so dry that any water that runs into the lake leaves by evaporation rather than through an outlet stream. This allows minerals dissolved in the water to build up to very high concentrations. Depending on the surrounding geology, such lakes may develop into salt lakes (like the Great Salt Lake in Utah) that are filled with sodium chloride (ordinary table salt) or alkali lakes that contain a lot of sodium carbonate (washing soda) and other minerals that give the lakes such high pH and alkalinity.

Alkali lakes and the salt flats that form when the lake dries up altogether have been in the news lately because some alkali lakes and flats are a major source of lithium, which is needed to make batteries for electric cars and which has other uses. Alkali lakes also show up in the old westerns — parched travelers who ran out of water two days ago come across a desert pool, and the greenhorn in the group throws himself into the brackish water, swallowing it in huge gulps. Then he stumbles away from the water, retching, after which the laconic leader of the band remarks: "bad water."

Again, you might think that such bad water wouldn't support life. As is the case of the corrosively acidic volcanic lakes, few species other than microbes can tolerate the harsh conditions in alkali lakes, but these few species can be enormously productive. In fact, alkali lakes can be among the most productive of inland waters in terms of the sheer amount of biomass that is grown each year.

So in contrast to the pH of the ocean, which is very near 8.1, the pH of inland waters spans a range from about 0.1 to 11.5, representing a 250 billion–fold range in hydrogen ion activity. Life exists and even thrives over this enormous range. This huge range in pH presents both a challenge and an opportunity for evolution to produce species whose ecology and physiology are adapted to some specific part of it: different species for strongly acid waters, mildly acid waters, neutral waters, mildly alkaline waters, and strongly alkaline waters.

Excerpted from "Beyond the Sea: The Hidden Life in Lakes, Streams, and Wetlands" by David Strayer. Copyright 2024. Published with permission of Johns Hopkins University Press.

The trio of lakes in this striking image each have a different color thanks to a combination of factors including depth, water chemistry and inhabiting wildlife. This is very strange, not only because of the lakes' proximity but because in the not-too-distant past (geologically speaking), they were once part of the same ancient lake, according to NASA's Earth Observatory.

The three lakes are Lake Shala, which has a deep-blue hue; Lake Abijata, which is green; and Lake Langano, which has a sandy-yellow hue similar to the surrounding landscape. The trio is located in Ethiopia's Great Rift Valley, around 125 miles (200 kilometers) south of the country's capital, Addis Ababa. 

Related: 12 amazing images of Earth from space

Lake Shala is around 7.5 miles (12 km) long and 17 miles (28 km) across at its widest point. It is the deepest of the three lakes, with a maximum depth of 873 feet (266 meters), which is why its waters appear dark blue from above. It is a soda lake, meaning it is highly alkaline (has a very high pH). Despite the extreme conditions, the lake contains a large number of small crustaceans and microorganisms that support large flocks of visiting flamingos and pelicans.

Lake Abijata, which is around 11 miles (17 km) long and 9 miles (15 km) wide, is the shallowest of the three lakes, with a maximum depth of 46 feet (14 m). As a result, it is highly variable and has lost around one-third of its area over the last 50 years. The lake's green color is most likely due to a bloom of phytoplankton on its surface, which also attracts a large number of birds. 

Lake Langano is around 11 miles (18 km) long and 10 miles (16 km) across. It is fed mostly by streams to the east, which dump brown sediment from nearby mountains into the water — giving it its yellow color. Langano is a popular destination for beachgoers because it is the only lake in the area not inhabited by parasitic worms that can transmit a potentially fatal disease known as schistosomiasis.

However, until around 10,000 years ago, the three lakes were part of a single massive body of water, named Lake Galla, which disappeared after changing rainfall patterns and tectonic motion altered the surrounding landscape.

Huge pink flocks of millions of flamingos — flamboyances of flamingos — are one of nature's great spectacles. But colleagues and I have uncovered worrying trends in the salty and highly-alkaline "soda lakes" of east Africa where most of these birds live.

Lesser flamingos are the most numerous of the six species of flamingo found across the world, and more than three quarters are found in the soda lakes of Kenya, Tanzania and Ethiopia. Despite their numbers, with estimates ranging between 2 million and 3 million birds, the species is in decline and officially classified as "near threatened".

The causes of the population decline have been difficult to identify due to the remoteness of many soda lakes and the nomadic nature of the birds. They often fly at night between the soda lakes in search of new feeding sites, in response to the boom and bust nature of the cyanobacteria they feed on, commonly known as blue-green algae.

However, rising water levels at many of the feeding lakes are decimating the cyanobacteria the birds have evolved to eat. In research now published in the journal Current Biology, my colleagues and I found that only half of the lakes that provided high-quality feeding habitat in 2000 were still suitable feeding lakes in 2022.

Lesser flamingos feed by turning their heads upside down, pumping water through fine hair-like structures called lamellae in their beaks and catching only cyanobacteria of a certain size. This highly specialised tactic means the birds are heavily dependent on certain cyanobacteria species such as spirulina.

This is the same vitamin-rich spirulina you might have seen in smoothies or supplements. In nature, the species that flamingos feed on only grows in highly salty and alkine conditions, and in soda lakes it grows in such numbers that these lakes are some of the most productive ecosystems on the planet.

But these lakes are especially sensitive to change because they often have no outflowing rivers. And as their waters rise they are diluted, reducing their salinity and alkalinity and limiting the growth of the cyanobacteria the flamingos depend on.

More water, less food

To assess the threats facing lesser flamingos, we used satellites to monitor 22 key feeding lakes across Ethiopia, Kenya and Tanzania between 1999 and 2022. This is the first time the whole east African range of lesser flamingos has been monitored at this scale.

Water levels have risen the most in recent years in Kenya and Tanzania, particularly at historically important flamingo lakes Bogoria and Nakuru, which supported more than 1 million birds in the recent past.

However Nakuru almost doubled in size between 2009 and 2022, while its mean concentration of chlorophyll a — a photosynthetic pigment measured by satellites that can be used as an estimate of cyanobacteria presence — halved. The number of birds has noticeably declined in response to the losses in their food source.

Lake Natron in Tanzania is also worth highlighting as it is the only regular breeding site for lesser flamingos in east Africa. The rising water levels and declining food sources at Natron therefore threaten not only current populations but the birds' ability to breed in the region, possibly leading to drastic declines in the future.

Rising water levels are likely caused by a combination of increased rainfall in recent decades and deforestation which causes the rainfall to run off directly into the lakes. Rainfall is predicted to increase in east Africa with climate change, driving further lake level rises in the future.

It's not entirely bad news, for the flamingos at least. Six of the 22 lakes provided more suitable flamingo habitats in 2022 compared to 2000. The birds will likely find new feeding lakes in shallow salt pans and seasonal lakes. However, without a history of flamingos living there, many of these lakes do not have the same international protections.

Related: Is Africa splitting into two continents?

It's not only the flamingos that are at risk. Soda lakes contain plants and animals found nowhere else on earth including fish species, invertebrates and phytoplankton. Declines in their most charismatic birds provide an insight into what could be happening beneath the surface.

These lakes can act as early beacons of how climate change can impact inland waters across the world. If we want to protect these highly fragile ecosystems and their iconic pink birds, we'll have to take action to mitigate the increasing rainfall in the region.

We need to know what's happening on the ground and where the flamingos are going, so more regular water quality monitoring and bird counts are required across the soda lakes. We also need to protect forests near the lakes most susceptible to change and restore lake catchments that are already degraded. This will reduce the amount of rain running straight into the lakes and will give the cyanobacteria a fighting chance.

With the right help, spectacular flamboyances of flamingos will continue to grace east African lakes in the future.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

Archaeologists in the Balkans have discovered the likely remains of an 8,000-year-old village built out over an ancient lake — the earliest-known village of any kind in Europe.

The lake, located on the border between Albania and North Macedonia, holds hundreds of tree-trunk stilts that the archaeologists believe formed the foundations of the prehistoric village. The researchers can't yet estimate the settlement's original size — but their discovery of a defensive palisade of tens of thousands of wooden spikes, now underwater, indicates the village was relatively large.

Albert Hafner, an archaeologist at the University of Bern in Switzerland who led the excavations, told Live Science that divers sampled wood from the submerged tree trunks and wooden spikes near the Albanian village of Lin on the western shore of Lake Ohrid a few weeks ago.

The results of dating tests won't be available for months. But Hafner said the submerged wood is probably the same age as wooden foundations unearthed on the shore, which his team determined date from between 5800 B.C. and 5900 B.C.

This would mean it's the oldest settlement archaeologists have found anywhere in Europe, he said.

Related: Back to the Stone Age: 17 key milestones in Paleolithic life

Hafner's team also found evidence of similar "pile dwellings" built over the water at the underwater prehistoric site of Ploča Mičov Grad on the eastern shore of the lake — part of North Macedonia — but those remains date to a few hundred years later.

It now seems both villages were built on opposite sides of the lake in phases over hundreds of years, and that the later building phases had obscured the earliest, he said.

"It seems to be quite typical that we have multiple phases of settlements, with sometimes long gaps in between," he said. "It now looks like Lin dates mostly from the sixth millennium [B.C.] in several phases, starting in about 5900 and ending in 5000."

First farmers

Hafner has led the EXPLO project for several years, examining lakes in the Balkans for traces of settlers from Anatolia — now Turkey — to Europe about 8,000 years ago. They are thought to be the first people to bring farming to Europe from around Mesopotamia.

The early farmers interbred with hunter-gatherers who had already occupied Europe since about 45,000 years ago during the Upper Palaeolithic period, and who probably arrived from Africa via the eastern shores of the Mediterranean.

And both ancestries interbred with nomadic proto-Indo-European peoples like the Yamnaya, who arrived in Europe from the Eurasian Steppe about 5,000 years ago. Most modern Europeans show a genetic mix of all three ancestries. 

Hafner explained that the many large lakes in the Balkans region held clear traces of the early migration from Anatolia. 

Lake dwellers

Hafner's team has so far investigated more than half a dozen sites across the Balkans. 

Research into some of the lake settlements was conducted in the 1960s. But the latest excavations use refined techniques like very accurate radiocarbon dating and dendrochronology, which can determine when logs of wood were felled by looking at tree growth rings, Hafner said. 

Most of the former piles and stilts underwater near Lin are now covered by silt, but a few  protrude from the lake floor. And archaeologists are unsure if the settlement was built in deep water or above mostly marshy ground.

Ancient people were likely drawn to the lakes because of water and plants there. But exactly why prehistoric people chose to build their houses on piles or stilts above a lake or wetland isn't clear — though the practice is seen throughout Europe, from the Balkans to the Baltic.

Hafner thinks that under normal conditions it would have been easy to get between houses with dugout canoes. But the large palisade of wooden spikes indicates the village was sometimes attacked, he said; and houses on the water were more easily defended (although perhaps not always successfully.)

Dozens of eerily perfect circles of slushy ice, known as "ice pancakes," have been floating on the surface of a Scottish river after temperatures in the U.K. unexpectedly plummeted. 

Callum Sinclair, project manager for the Scottish Invasive Species Initiative (SISI), spotted the stunning circular sheets of ice Dec. 9 on the River Bladnoch in Wigtownshire, Scotland. Pictures of the peculiar pancakes taken by Sinclair were shared on the SISI Twitter page on Dec. 13, along with a short video of the icy discs bumping into one another and being washed downstream by fast-moving currents.

"I've seen ice pancakes occasionally before," Sinclair told Live Science in an email. "But these were particularly interesting" because of their perfect shape, he added.

Photos shared in the comments of the SISI post also revealed that ice pancakes have formed on the River Kelvin near Glasgow and the River Esk in the Lake District in northwest England in recent days.

Related: What are the different types of ice formations found on Earth?

Ice pancakes are relatively rare structures that tend to form in very cold oceans, lakes and rivers, according to the U.K. Met Office. 

On rivers, the pancakes form when frozen foam on the water's surface gets trapped in a spiraling current known as an eddy. As other bits of frozen foam and ice hit these forming discs, the debris joins onto the nascent pancakes, which causes them to grow, according to the Met Office.

On open water, the pancakes form when surface ice gets broken up and rounded out as currents and waves cause the icy chunks to bash into one another, according to the Met Office. 

Ice pancakes can grow to between 8 and 79 inches (20 and 200 centimeters) across, and although they look like solid discs, they are often quite slushy and easily break apart when lifted up, according to the Met Office.

Although the icy discs dot the Great Lakes of North America and the oceans surrounding Antarctica, where temperatures often fall well below freezing, ice pancakes are much rarer in U.K. rivers. 

However, an unusually cold snap, caused by an area of low pressure that got trapped by surrounding areas of high pressure over Russia and Greenland, has caused temperatures across the U.K. to fall below freezing for more than a week, according to the BBC.

The lowest temperature recorded during the cold snap so far was 0.8 degrees Fahrenheit (-17.3 degrees Celsius) in Aberdeenshire, Scotland on Dec. 12, according to the BBC.

A  trio of technicolor lakes in Ethiopia, each one a different color from the others, is visible in stunning detail in a satellite image recently released by NASA. The unusual colors are the result of numerous factors, including water chemistry, depth and inhabiting wildlife.

The three lakes are Lake Shala, which has a deep blue hue; Lake Abijatta, which is green in color; and Lake Langano, which has a sandy-yellow hue similar to the surrounding land. The lakes are located in Ethiopia's Great Rift Valley, around 124 miles (200 kilometers) south of the capital, Addis Ababa. 

The Landsat 8 satellite, which is co-owned by NASA and the U.S. Geological Survey, snapped the striking real-color image months ago using the onboard Operational Land Imager. The image was released online Oct. 7 by NASA's Earth Observatory.

Related: Landsat satellites: 12 amazing images of Earth from space 

Lake Shala, which is around 7.5 miles (12 km) long and 17.4 miles (28 km) across at its widest point, is the deepest of the three lakes, with a maximum depth of 873 feet (266 meters), which makes the water appear a deep blue color from above. The lake has numerous vents on its bottom that pump sulfur into the water. As a result, the lake is highly alkaline, meaning it has a very high pH. Despite the extreme conditions, the lake contains a large number of small crustaceans and microorganisms that support large flocks of visiting flamingos and pelicans, according to Earth Observatory. 

Lake Abijatta, which is around 10.6 miles (17 km) long and 9.3 miles (15 km) wide, is the shallowest of the three lakes, with a maximum depth of 46 feet (14 m). As a result, Abijatta is the most variable of the pictured lakes; within the last 50 years, the lake has lost around one-third of its area, according to Earth Observatory. Lake Abijatta's green color is most likely due to a bloom of phytoplankton on its surface.

Lake Langano, which is around 11.2 miles (18 km) long and 9.9 miles (16 km) across, is fed mostly by streams to the east. The lake's yellow color comes from brown sediment that is transported from nearby mountains by the rivers that feed it. Langano is a popular destination for beachgoers because it is the only lake in the region not inhabited by parasitic worms that transmit a potentially fatal disease known as schistosomiasis, according to Earth Observatory.

The contrasting appearance of the lakes is even more surprising considering that all three used to be part of a single ancient body of water known as Lake Galla, which also included the nearby Lake Ziway. The enormous ancient lake was likely connected to the sea via the Awash River (which still flows today) up until around 10,000 years ago. At that point, tectonic plate movements and changes in rainfall patterns caused Lake Galla to begin to dry up. By around 2,000 years ago, the lake had fractured into the different lakes visible today, according to Earth Observatory. 

Giant viruses have been discovered infecting microscopic algae in a rare lake in the Arctic Ocean, a new study finds.

The Milne Fiord epishelf lake is a body of fresh water that sits on top of seawater less than 500 miles (800 kilometers) from the North Pole. Researchers studying the lake found that the fresh water had a richer and more diverse range of viruses than the salt water beneath it. They also found "giant" viruses — several times larger than typical viruses — affecting microscopic algae just below the boundary between fresh water and salt water.

"Just as the freshwater ecosystem of the lake is distinct from the ecosystem of the Arctic Ocean, it also has its own distinct community of viruses," study co-author Mary Thaler, a microbiologist at Laval University in Quebec, told Live Science in an email.

An epishelf lake is held in place by ice but has no physical bottom. The lake's fresh water floats above the seawater because fresh water is less dense than salt water. The top of the lake is covered in ice, protecting the fresh water from waves or wind that would otherwise force the two water types to mix.

Related: Thousands of new viruses discovered in the ocean 

The researchers drilled through the ice and collected water samples from the lake. Then, they sequenced the DNA found in these samples to identify a variety of viruses, including some belonging to a group of giant viruses called Megaviricetes. 

"One of the characteristics of viruses in general is how tiny they are, much smaller than the smallest bacterium, and carrying only a few genes to help them replicate," Thaler said. "However, in the past twenty years, scientists discovered giant viruses that are as big as a bacterium, with genomes that could potentially carry many interesting genes."

The researchers don't know how most of the viruses affect the microscopic algae, or even which viruses infect which organisms, according to a statement released by The American Society for Microbiology. The study authors hope to learn more detailed information about the ecosystem in the future, but they're in a race against time; rising temperatures threaten to destroy the ice dam holding the fresh water in place.

"Epishelf lakes used to be more common in the Arctic, but now they are extremely rare," Thaler said.  "If the ice dam breaks apart — which has happened in other fiords — then Milne Fiord Epishelf Lake will be lost."

The study was published online Aug. 25 in the journal Applied and Environmental Microbiology.

Originally published on Live Science.

First the drought came. Then, the bodies started washing up.

For over a decade, water levels have been plummeting in Nevada's Lake Mead, the biggest reservoir in Clark County, Las Vegas, and one of the largest reservoirs in the United States. On May 1, receding waters due to regional drought led officials to a gruesome discovery on the reservoir's shore: a metal barrel holding a corpse that had been dumped into the water more than 30 years ago, CNN reported. 

Just a few days later, more human remains emerged in Lake Mead's Callville Bay, National Park Service (NPS) representatives said in a statement. A witness reported finding "human skeletal remains" on May 7 at approximately 2 p.m. local time, and NPS rangers responded to the call and recovered the remains. 

They contacted the Clark County Medical Examiner to analyze the bones, but the cause of death has yet to be determined and at the time there is "no evidence to suggest foul play," police officers told KTNV Las Vegas.

Related: Drought helped push the Vikings out of Greenland, new study finds

The clothes and footwear found on the decomposed body in the barrel suggested that the person died "sometime in the mid '70s to early '80s," Las Vegas Metropolitan Police Department (LVMPD) representatives said in a statement. 

"We believe this is a homicide as a result of a gunshot wound," said LVMPD Homicide Section Lt. Ray Spencer. The victim's identity is unknown, but such information "will be released by the Clark County Coroner's Office when it becomes available," LVMPD representatives said. 

Two sisters found the second set of remains — a human jawbone with attached teeth — on an exposed sandbar while they were paddle-boarding on the lake, ABC News reported.

Lake Mead provides water for more than 40 million people across seven states and into northern Mexico; it is formed by the Hoover Dam and fed by the Colorado River, and it lies about 30 miles (48 kilometers) east of Las Vegas, according to the NPS. At maximum capacity, Lake Mead holds 9.3 trillion gallons (36 trillion liters) of water, according to NASA Earth Observatory (NEO). But the last time the reservoir was anywhere near full capacity was in 1999, and water levels have been dropping steadily ever since. Warming temperatures fueled by climate change are worsening persistent drought conditions that may be the region's worst dry spell in more than 1,000 years, NEO reported.

In August 2020, Lake Mead's waters reached only about 35% percent of its capacity. On May 9 of this year, Lake Mead's water level measured about 1,052 feet (321 meters) above sea level — roughly 162 feet (49 m) lower than in 2000, and the lowest level on record since the 1930s, CNN reported. 

And with no end in sight for the punishing regional drought, more of the reservoir's long-hidden and grisly secrets may reappear from the depths, said former Las Vegas Mayor Oscar Goodman.

"There's no telling what we'll find in Lake Mead," Goodman told the Navajo-Hopi Observer. "It's not a bad place to dump a body."

Originally published on Live Science.

Last week, wildlife officials in Utah yeeted thousands of fish out of a plane and into 200 high-elevation lakes across the state.

The Utah Division of Wildlife Resources (DWR) has been dumping fish out of airplanes since 1956, Live Science previously reported. In a video that went viral this week, fish can be seen bursting from the underside of a plane, carried downwards in a plume of water; the shiny animals then careen through the air towards the water's surface. The most common species dropped during these flights are various species of trout, a hybrid trout known as splake (Salvelinus fontinalis) and Arctic grayling (Thymallus arcticus), according to Live Science.

Related: 5 surprising facts about lakes 

Although this method of restocking lakes may seem violent for the young fish, because the creatures are only 1 to 3 inches (2.5 to 7.6 centimeters) long at the time of release, the wind actually carries them down quite gently — like leaves fluttering in a breeze, Phil Tuttle, the outreach manager for the southern region office of the Utah DWR, told Live Science in 2018. About 95% of the fish are expected to survive each release. 

During a single flight, the plane carries hundreds of pounds of water and can drop up to 35,000 fish, Utah DWR officials wrote on Facebook. Pilots fly just above the tree line while dropping the fish, or as low as possible while considering other natural barriers like cliffs and mountains, Live Science previously reported. Before the Utah DWR began using planes, people and horses would carry the fish up to the remote mountain lakes on foot; this journey proved more stressful for fish than being tossed from a zooming plane.

If the Utah DWR didn't restock its high-elevation lakes each year, the popular fishing spots would soon be entirely depleted of fish. The fish used for restocking are raised in hatcheries, and most are bred to be sterile to prevent a sudden population boom and ensure they have a minimal impact on native wildlife species.

Originally published on Live Science.

A mysterious neurodegenerative disease has been killing bald eagles and other animals at lakes across the United States. And after 25 years of sleuthing, researchers have finally figured out its cause.

The disease, known as vacuolar myelinopathy (VM), was first discovered in 1994 when a large number of bald eagle carcasses were found near DeGray Lake in Arkansas. VM attacks the brains of infected animals, causing problems with motor functions and eventually leading to a "gruesome death," according to researchers. 

"When the birds are really sick, they just look really drunk, they stumble around and fall down," co-author Susan Wilde, an aquatic scientist at the University of Georgia who has been studying VM since 2001, told Live Science. "But it gets even worse, they get paralyzed, blinded and can have tremors and seizures before eventually succumbing to the disease."

Initially, scientists had no idea how the eagles acquired the disease. Scientists eventually identified an invasive plant and later a particular species of cyanobacteria that seemed to be responsible, but the exact mechanisms behind VM continued to elude detection.

Related: 10 bizarre diseases you can get outdoors 

Now, a new study has uncovered the culprit: a neurotoxin called aetokthonotoxin that is produced under certain circumstances by the cyanobacteria living on the invasive plants.

"A toxin produced by cyanobacteria that colonize a highly invasive plant, which has the capacity to affect diverse animal phyla, should not be underestimated in its potential impact on our environment," lead author Steffen Breinlinger, a doctoral student at Martin Luther University Halle-Wittenberg in Germany, told Live Science.

 What is VM? 

Since it was first discovered in 1994, VM has spread quickly throughout lakes in the U.S.

"We have found it in nine states from Virginia to Texas," Wilde said. "But I don't think we understand just how many places this might be occurring."

A wide range of lake species also seem to be impacted by the disease — fish, frogs, snails, salamanders, turtles and snakes, as well as smaller birds like, coots, owls and waterfowl.

However, bald eagles (Haliaeetus leucocephalus) are one of the most affected species because they feed on all of these other infected animals, Wilde said.

"We know it's at least 130 eagles that have died testing VM-positive," Wilde said. "But the recovery rate of dead bodies is probably around 10 or 12%, so it's probably at least 10 times that number."

Researchers test for VM by performing a necropsy immediately after the animal's death. Lesions and damage to the brain are the only physical evidence of the disease and can only be properly identified during a short window of time after death. This makes tracking the disease and estimating deaths even harder, Wilde said.

Spreading across the U.S.

Early on, scientists discovered that VM was found only in lakes where an invasive plant species, Hydrilla verticillata, was also found. The Hydrilla, which is native to Central Africa, was first found in the U.S. in 1960 in Florida and has since become one of the most successful invasive plant species in history, according to invasive.org.

It only takes a few fragments of the Hydrilla plant or some of its tubers — structures created by plants to store nutrients that can also be used in asexual reproduction — to be introduced into a lake before it takes over and becomes almost impossible to remove, Wilde said.

However, scientists soon realized that not all lakes where Hydrilla grows were linked to VM, so something else must have been causing the disease.

In 2015, a new study by Wilde and colleagues identified a species of cyanobacteria (Aetokthonos hydrillicola) that was found on Hydrilla in lakes where VM was occurring in animals. But the exact cause of the disease still remained a mystery because the team couldn't explain how the bacteria were causing VM. 

Solving the mystery 

In the new study, Wilde sent samples of the cyanobacteria to Breinlinger and other researchers in Germany, who attempted to grow cultures of the bacteria and see what toxins they produced.

To their surprise, the German team found that cyanobacteria grown in regular cultures did not produce any toxin and seemed to disprove Wilde's theory that they were responsible for VM. However, when grown on cultures that included bromide, the plants produced a toxin that researchers now think causes VM. The toxin is called aetokthonotoxin, which translates to "poison that kills the eagle."

Exactly why the cyanobacteria produce the toxin and why they only do so in the presence of bromide is still unknown.

Bromide does occur naturally in lakes in small doses, but it is also introduced by humans in the form of herbicides (ironically used to control the spread of Hydrilla), as well as chemical run-off from both flame retardants and pollution from coal-powered power stations, Breinlinger said. 

"It was only this discovery that made us aware that VM is also spreading due to anthropogenic influence," Breinlinger said. 

Next steps 

It is highly unlikely that VM will ever be eradicated from U.S. lakes, but now that scientists better understand the toxin responsible for it, they can figure out ways to control the spread and manage the disease, Wilde said. 

Related: 50 of the most endangered species on the planet

"If we control the bromide in the reservoirs, Hydrilla will not accumulate in it and ultimately Aetokthonos [the cyanobacteria] will be stripped of its weapon," Breinlinger said. "Without bromide, it simply cannot produce the toxin in the first place."

However, it is equally important that researchers are able to locate all the places where VM is prevalent, and Wilde believes citizen scientists could play a crucial role.

"Citizens that recognize what Hydrilla looks like and when a bird is acting really strange could be huge," Wilde said. "We've just got to keep an eye out for it and keep it under control."

The researchers are also planning to do further research on how the new toxin affects small mammals, such as mice, to see just how dangerous it could be in humans.

"There is actually some of the toxin in the tissues that waterfowl hunters would consume," Wilde said. "It seems even more important to get to the point where we ask whether or not humans would have some health effects if we consume [the toxin]."

The new study was published online March 25 in the journal Science.

Originally published on Live Science.

Frigid lakes locked beneath the Antarctic ice sheet may be home to more microbial life than scientists ever imagined.

More than 400 subglacial lakes lie beneath the Antarctic ice sheet, completely shut off from sunlight, according to the new paper, published Feb. 17 in the journal Science Advances. These lakes form where the weight of the surface ice bears down on the base of the sheet, generating intense pressure and lowering the melting point of the ice. As the base melts, the remaining ice insulates the meltwater from cold air, while geothermal heat from the bedrock below also helps prevent freezing, according to a statement.

Some of these pitch-black lakes lie near the ice sheet's edge, where water can periodically flow in and out. Scientists have uncovered microbial life in two of these hydrologically active lakes, but it's unknown whether more isolated lakes near the center of the ice sheet can also sustain life. Many of these lakes have been cut off from the surrounding environment for millions of years.

Related: Antarctica: The ice-covered bottom of the world (Photos) 

Past research suggested that microorganisms in these forbidding lakes likely live in the sediment at the lake bottom, which is brimming with nutritious minerals, a 2018 study in the journal Earth and Planetary Science Letters found. But now, the new study hints that microbes may thrive throughout the extreme ecosystem, in both the sediment and the surrounding water.

Geothermal heat flux — the flow of heat from the Earth's interior — essentially stirs the lake water, lifting nutrients from the sediment into the water above, the study suggests.

"The water in lakes isolated under the Antarctic ice sheet for millions of years is not still and motionless; the flow of water is actually quite dynamic," lead author Louis-Alexandre Couston, a physicist at the University of Lyon in France and the British Antarctic Survey, said in the statement. "With dynamic flow of water, the entire body of water may be habitable."

In above-ground lakes, water flows due to wind and heat from the sun. This powers convection currents, where differences in water temperature across the lake drive water flow. Although subglacial lakes can't be warmed by the sun, the team determined that heat from the planet's interior is strong enough to fuel "vigorous" convection currents from below. The heat itself is generated by the decay of radioactive elements, such as thorium and uranium, and also includes heat left over from when Earth first formed, according to a 1990 report in the journal Geophysics.

As heat causes the subglacial water to circulate, this flow not only frees minerals from the sediment, but also distributes oxygen and minerals from higher in the water column; these additional nutrients come from dust trapped in the ice sheet that gets released as the ice melts.

Related: Ocean sounds: The 8 weirdest noises of the Antarctic

"Our calculations demonstrate that mixing of subglacial lake water is highly likely and would encourage dispersion of oxygen-rich water throughout the water column and down to the lake floor sediments, where microbial life is likely to be most abundant," the authors wrote in the new study.

The team based these initial conclusions on modeling studies, but soon, scientists plan to sample water and sediment from a subglacial lake called Lake CECs, named after the Chilean scientific center Centro de Estudios Científicos, according to the statement. This expedition will allow the team to test their predictions and see where microbes actually live in the unique ecosystem.

For now, based on their current modeling, "it should be considered that most — if not all — Antarctic subglacial lakes are dynamic hydrologic environments," the authors wrote. "We expect that the same conclusion holds for isolated subglacial lakes in Greenland and elsewhere in the solar system," in reference to subglacial lakes on the moons of Jupiter and Saturn, they added.

"The physics of subglacial water pockets is similar on Earth and icy moons, but the geophysical setting is quite different," meaning the physical properties of the surrounding environment, study author Martin Siegert, co-director of the Grantham Institute – Climate Change and Environment at Imperial College London, said in the statement. So while both environments are similar, new theories will be needed to understand what additional physical factors might shape subglacial lakes on icy moons, Siegart said.

"With new missions targeting icy moons and increasing computing capabilities, it's a great time for astrobiology and the search for life beyond the Earth," he said.

Originally published on Live Science. 

A teen has died from a rare "brain-eating" amoeba infection after a family vacation in Florida, according to news reports.

The 13-year-old, Tanner Wall, and his family had recently stayed at a campground in North Florida, which has a water park and lake where the boy went swimming, according to local news outlet News4Jax. Several days after swimming in the lake, Tanner developed symptoms, including nausea, vomiting, headaches and a stiff neck, News4Jax reported.

Tanner was initially diagnosed with strep throat, but his parents suspected Tanner could have a more serious condition, and so they drove him to UF Health in Gainesville, Florida, for a second opinion.

There, the teen was placed on a ventilator, and doctors made a devastating discovery. 

"They said, 'We're sorry to tell you this, but your son … has a parasitic amoeba, and there is no cure,'" Tanner's father, Travis Wall, told News4Jax. Tanner died from an infection with Naegleria fowleri on Aug. 2, News4Jax reported.

Related: 5 Key Facts About Brain-Eating Amoebas

Naegleria fowleri is a single-celled organism that's naturally found in warm freshwater, such as lakes and rivers, according to the Centers for Disease Control and Prevention (CDC). In the U.S., most infections occur in southern states, particularly during the summer months after it has been hot for prolonged periods, which raises the water temperature, Live Science previously reported.

Swallowing water contaminated with Naegleria fowleri will not cause an infection, but if contaminated water goes up the nose, the organism can enter the brain and destroy brain tissue. Infections are almost universally fatal, with less than a 3% survival rate, according to the CDC. It's unclear exactly why some people are able to survive the condition, but factors that may contribute to survival include early detection of the infection and treatment with an experimental drug called miltefosine, along with other aggressive treatments to reduce brain swelling, Live Science previously reported. (It's important to note that miltefosine is not a proven treatment for the condition, and some patients who received the drug still did not survive.)

However, N. fowleri infections are very rare, with only 34 infections reported in the U.S. over a recent 10-year period, even though millions of people go swimming each year, the CDC says. But infections may be becoming more common as water temperatures rise due to climate change, according to Business Insider.

Tanner's death is the second reported in Florida this summer from the same infection. The first death was announced by the Florida Department of Health on July 3, although few details were released about the case.

As a precaution, the Florida Department of Health recommends that people avoid swimming in warm freshwater during periods of high water temperature and low water levels, and that they use nose clips or hold their nose during activities in warm freshwater.

Originally published on Live Science.  

The humongous, mysterious "ice rings" that pockmark the world's deepest lake during Siberia's winter and spring months may look like icy crop circles, but they're not due to alien activity, atmospheric conditions or even, as previously thought, methane bubbles percolating from the lake's bottom. 

Rather, it appears that warm, swirling eddies of water under Lake Baikal's thick ice are responsible for these ice rings, some of which are up to 4 miles (7 kilometers) in diameter and can be seen from space, a new study finds.

Solving this mystery, however, wasn't an easy affair. An international team of researchers from France, Russia and Mongolia, who have studied the lake's ice rings since 2010, elected to travel to the lake biannually in 2016 and 2017 for a new study in which they drilled holes in the ice near the rings, and dropped sensors into the water below. One year, they heard that two vans had gotten stuck in the ice rings. One of them sank into the lake, and was never recovered.  

Related: In living color: A gallery of stunning lakes

In Siberia's colder months, Lake Baikal — the largest freshwater lake in the world, by volume — freezes over. The ice is so thick, people routinely drive over it, said study lead researcher Alexei Kouraev, an assistant professor at the Laboratory for Studies in Spatial Geophysics and Oceanography (LEGOS) at the Federal University in Toulouse, France.

"It's a no-brainer," Kouraev told Live Science. "It's a very long lake, and if you want to go from one side to another, either you do 400 kilometers [248 miles] one way and then 400 kilometers on the other coast." But the trip across the ice is just about 25 miles (40 km), "so the choice is evident," he said.

However, while the ice is thick outside of and inside these rings of thin ice, the rings themselves can put vehicles and their occupants at risk, Kouraev said.

The fellowship of the ice rings

Ice rings have formed on Lake Baikal since at least 1969, and can last anywhere from days to months, satellite images show. However, these rings have unpredictable behavior, and show up in different parts of the lake from year to year. Moreover, they tend to appear in late April, but can crop up as early as January or as late as May, Kouraev said.

But scientists couldn't figure out how they formed. One of the more popular theories, indeed one that Live Science reported on in 2009, suggested that the greenhouse gas methane bubbles up from the lake's deep bottom to cause these rings. But Kouraev and his colleagues noticed that some of these ice rings formed in the lake's shallower waters, areas with no known gas emissions.

After analyzing data from the sensors they had dropped into the lake, the scientists found that the lake had warm eddies flowing clockwise under its ice cover. The currents weren't as strong at the center of the eddies, which explained why the centers of these rings still had thick ice, Kouraev said. However, the current at the edge of the eddies was strong, which explained why the ice on top of this edge was thinner, he said. 

The sensors revealed that the water at these eddies was 2 to 4 degrees Fahrenheit (1 to 2 degrees Celsius) warmer than the surrounding water. What's more, the eddies had a lens-like shape, a phenomenon that is common in oceans but rare in lakes. 

Related: In photos: Monster waves

But why did these eddies form in the first place? According to the sensors, which were kept underwater for 1.5 months at a time, as well as thermal-infrared satellite imagery, it appeared that the eddies formed each fall, before the lake froze over. Moreover, strong winds blowing in waters from the nearby Barguzin Bay could help them form, Kouraev said.

He noted that, so far, these ice rings have only been found in Lake Baikal, as well as the nearby Lake Hovsgol in Mongolia and Lake Teletskoye, also in Russia.

As for drivers who cross the frozen lake in their vehicles, Kouraev said that while cracks are easy to spot, the rings themselves can be harder to see at ground level because they're covered with ice. As a public service, Kouraev and his colleagues, who jokingly call themselves the Fellowship of the Ice Rings, have written booklets, given presentations and told Russia's national park service and ministry of emergencies about the rings. They also routinely update their website about the location of newly formed ice rings, which are visible in satellite images.

The study was published online in the journal Limnology and Oceanography in October 2019.

Editor's Note: This story was updated to note that the researchers have been working at the lake since 2010. Moreover, the vans that got stuck in the ice rings did not belong to the researchers.

• Album: Stunning photos of Antarctic ice
• In photos: The vanishing ice of Baffin Island
• In photos: Antarctica's Larsen C Ice Shelf through time 

Originally published on Live Science.

Rare mounds of a crystalline mineral have emerged above the surface of Utah's Great Salt Lake, where they're expected to remain just a few months before disappearing again. 

Scientists think these mounds may be similar to mineral structures on Mars that could preserve traces of  microbes that may have lived in the planet’s  saltwater lakes billions of years ago.

The four white mounds, which measure up to 3 feet (1 meter) high and dozens of feet across, were first seen near the southern shoreline of the Great Salt Lake in October by park ranger Allison Thompson, Utah State Parks representatives wrote in a blog post.

Related: Photos: The World's Weirdest Geological Formations

Thompson noticed that the mounds grew as the winter deepened, and she called in members of the Utah Geological Survey to investigate.

After taking samples for chemical tests, the state geologists determined that the mounds are layered formations of a mineral known as mirabilite, a crystalline sodium sulfate. The scientists think the mounds will remain only as long as the weather stays below freezing; in the spring, the mirabilite will dissolve in the warmer waters, and the mounds will disappear.

Mineral mounds

Mirabilite often forms beneath the salt-rich waters of the Great Salt Lake, but this is the first time the mineral has emerged as mounds above the surface, said Mark Milligan, a geologist with the Utah Geological Survey.

"There are mirabilite deposits every winter, but they are precipitating near the bottom of the lake," Milligan told Live Science. "They wash ashore, and you get these windrows [ridges] of white, slushy mirabilite." 

Layered mounds of the mineral are usually seen only in Arctic regions, he said.

Geologists think the mineral precipitated from the salt water above sulfate-rich hot springs in the lake, which were gradually exposed as the lake level dropped due to the consumption of water elsewhere, Milligan said.

Mirabilite gets its name from the 17th-century German-Dutch chemist Johann Glauber, who discovered it in mineral waters from Austria, according to his own writings. He named the mineral "sal mirabilis" — Latin for "miraculous salt" — and it's since been known as "Glauber's salt." Mirabilite was once widely used in medicine, especially as a laxative. 

Though mirabilite has not been found on Mars, scientists think ancient mound-like deposits of similar sulfate minerals might still contain fossilized traces of any ancient Martian microbes.

NASA reported in 2011 that the Opportunity rover had found sulfates on Mars that appeared to have been deposited by water, and the Curiosity rover recently detected signs of ancient saltwater lakes, Live Science sister site Space.com reported.

The temperatures on Mars, which average minus 80 degrees Fahrenheit (minus 60 degrees Celsius), also would be low enough to keep such minerals stable, Milligan said.

• Gallery: Rainbow of Life in Great Salt Lake
• Photos: The Clearest Lake on Earth
• In Living Color: A Gallery of Stunning Lakes

Originally published on Live Science.

Hidden beneath Greenland's Ice Sheet like an enormous necklace of sparkly blue and oddly shaped beads, scientists have discovered 56 previously unknown and gem-like lakes. This brings the total number of known subglacial lakes there to 60, the researchers said.

Greenland isn't alone in housing hidden lakes; Antarctica also has them, although the southern continent's lakes tend to be larger than the ones in Greenland.

Some of Greenland's subglacial lakes are quite tiny. A few are just 656 feet (200 meters) long, while others stretch 3.6 miles (5.9 kilometers) in length, the researchers found. [Stunning Photos of Greenland's Supraglacial Lakes]

"The lakes we have identified tend to cluster in eastern Greenland, where the bed is rough and can therefore readily trap and store meltwater, and in northern Greenland," study co-researcher Stephen Livingstone, a senior lecturer in physical geography at the University of Sheffield in the United Kingdom, said in a statement.

The lakes are chilling out under the Greenland Ice Sheet, which is about seven times the size of the United Kingdom. The sheet is 1.8 miles (3 km) thick in some places and plays a key role in rising sea levels.

Sometimes giant ice sheets develop subglacial lakes because heat pops up in weird places. For instance, the heat can be generated by the flow of ice, geothermal energy deep in the ground or water from the surface that drains through the sheet's cracks. Then, this meltwater can become trapped in depressions, forming subglacial lakes.

By mapping these lakes, researchers can learn where ice melts and drains under the ice sheet, which influences how the icy block responds to rising temperatures caused by human-made climate change.

Researchers found most of this necklace of lakes by analyzing radio echo sounding data, which creates a snapshot of the bed beneath the Greenland Ice Sheet. Most of the lakes were found under slow-moving ice, they noted.

"This study has for the first time allowed us to start to build up a picture of where lakes form under the Greenland Ice Sheet," study lead researcher Jade Bowling, an associate lecturer at the Lancaster Environment Centre at Lancaster University in the United Kingdom, said in a statement.

However, Greenland's lakes may change as the climate continues to heat up. For example, meltwater on the surface may form lakes and streams at higher elevations on the ice sheet, and these could drain to form more active subglacial lakes that regularly or seasonally fluctuate in size, the researchers said.

The team already saw more active subglacial lakes at a spot where surface water regularly seeps into lakes. At two locations, the scientists saw subglacial lakes drain and then promptly refill.

Whatever happens, the researchers are excited to learn more about these bodies of water.

"These lakes could provide important targets for direct exploration to look for evidence of extreme life," Livingstone said. Sampling sediments from these lakes may also reveal "a record of environmental change," he said.

The study was published online yesterday (June 26) in the journal Nature Communications.

• Photos: Craters Hidden Beneath the Greenland Ice Sheet
• Historic Photos Paint Picture of Greenland Ice Loss | Climate Central
• Images: Greenland's Gorgeous Glaciers

Originally published on Live Science.

A 10-mile-long (16 kilometers) lake just popped up in the middle of the hottest place on Earth.

Last week, a storm blew through Death Valley National Park in California, drenching the desert and the rest of Southern California. Now, amid the desert's echoing landscape, there sits a very misplaced lake.

The lake formed near Salt Creek, an area near the eastern edge of the park, according to SFGate. It's unclear exactly how big the lake is, but representatives from the park estimated it to be around 10 miles long. [Hell on Earth: Tour Death Valley]

Death Valley is not only the hottest place in the world, with temperatures that can reach 134 degrees Fahrenheit (57 degrees Celsius), but also the driest place in North America.

On average, Death Valley receives less than 2 inches (5 centimeters) of rain a year, according to the National Park Service. Typically, about 0.3 inches (0.76 cm) of that rainfall comes in March, but within a single day last week, 0.84 inches (2.13 cm) of rain fell in the park, according to SFGate.

This isn't much when compared with the rainfall in the rest of the country, or even the rain that this storm brought to other parts of Southern California. But unlike other areas, the desert has dry, compact soil that doesn't absorb water well, a National Weather Service meteorologist Todd Lericos told SFGate.

In the aftermath of the storm, California-based photographer Elliot McGucken captured just how bad California's famous desert is at absorbing water in his gorgeous images of the pop-up lake.

Editor's Note: This story was updated to correct the amount of rainfall that fell in Death Valley. It was 2.13 cm, not 213 cm.

• In Images: Mysterious Desert Varnish
• In Photos: Springtime in the Sonoran Desert
• Gallery: The Haunting Splendor of Chile's Atacama Desert

Originally published on Live Science.

The Great Lakes — Superior, Huron, Michigan, Ontario and Erie — make up the largest body of fresh water on Earth, accounting for one-fifth of the freshwater surface on the planet at 6 quadrillion gallons. The area of all the Great Lakes is 95,160 square miles (246,463 square kilometers) and span 750 miles (1,200 km) from west to east. The square mileage is larger than the state of Texas.

The lakes, called "the nation's fourth seacoast," are on the U.S. and Canadian border, touching Ontario in Canada and Michigan, Wisconsin, Minnesota, Illinois, Indiana, Ohio, Pennsylvania and New York in the United States. As of 2017, more than 30 million people live in the Great Lakes basin, according to the Environmental Protection Agency (EPA). This equates to 10 percent U.S. residents and 30 percent Canadian residents. More than 3,500 species of plants and animals inhabit the Great Lakes basin, as well, including 170-plus species of fish.

Today, the Great Lakes are popular recreation spots for boating, fishing and other recreational activities, and they still serve as an important mode of transportation of goods, but they have not always been in their current form. About 14,000 years ago, the Great Lakes area was covered with a glacier that was more than a half-mile (1 km) thick. As the glacier melted, it slowly moved toward Canada and left behind a series of large depressions that filled with water. These formed the basic shape of the Great Lakes, and about 10,000 years ago the Great Lakes took the form that is familiar today.

While the area had been inhabited for a very long time before European explorers arrived, Étienne Brûlé (circa 1592-1632), an advance man for the French explorer Samuel de Champlain (circa 1567-1635), is generally credited as the first European to discover the Great Lakes. Brûlé is believed to have reached Lake Huron around 1615, and went on to explore Lake Ontario, according to the Canadian Museum of History.

There are a number of rivers and tributaries connecting the Great Lakes. The Straits of Mackinac connect Lake Michigan and Lake Huron, and there is such a steady flow of water between these two bodies that they could be considered one lake. Lake Erie and Lake Ontario are connected by the Niagara River, including Niagara Falls. The St. Lawrence River connects Lake Ontario to the Gulf of St. Lawrence, which leads out to the Atlantic Ocean.

The Great Lakes are dotted with more than 35,000 islands. While many of the islands are small and uninhabitable, the largest is Lake Huron's Manitoulin Island (1,068 square miles or 2,766 square km), which is also the largest island in any inland body of water on the planet.

There have been a number of shipwrecks on the Great Lakes, as storms and reefs can make navigation treacherous. The last and one of the most famous shipwrecks was that of the SS Edmund Fitzgerald, a freighter that sank in Lake Superior during a storm on Nov. 10, 1975, killing the crew of 29.

The lakes have been changes considerably from pollution and invasive species. Currently, there are more than 140 federal programs designated for environmental restoration and management of The Great Lakes, according to the EPA. Eight U.S. states, Canada and 40 Tribal Nations are part of the initiative to clean up and protect the lakes. 

Quick facts about the five Great Lakes:

Lake Erie: The name was derived from erielhonan, the Iroquoian word for "long tail," which describes its shape. It is the fourth largest of the Great Lakes when measured in surface area (9,910 square miles / 25,700 square km.) and the smallest by water volume (116 cubic miles / 484 cubic km).

Lake Huron: Named for the Wyandot Indians, or Hurons, who lived there. Lake Huron is the second largest Great Lake by surface area (23,000 square miles / 59,600 square km) and has the longest shoreline (3,827 miles / 6,157 km), taking into account its many islands.

Lake Michigan: This is truly a great body of water, as the name is derived from the Ojibwa Indian word mishigami, meaning "large lake." However, it is only the third largest of the Great Lakes when measured by water surface (22,300 square miles / 57,800 square km). It has an unusual water flow that goes in almost a cul-de-sac formation, moving slowly in a circular pattern. It is also the only Great Lake located entirely in the United States. Michigan and Huron are actually two halves of one body of water, though, according to the University of Wisconsin. 

Lake Ontario: Ontario is the Huron word for "lake of shining water." This lake is the smallest of the Great Lakes when measured in surface area (7,340 square miles / 18,960 square km). While it is similar in width and length to Lake Erie, it is much deeper and holds about four times the water volume (393 cubic miles/1,640 cubic km). Situated downstream from Lake Erie, Lake Ontario is at the base of Niagara Falls.

Lake Superior: At 31,699 square miles (82,100 square km), it is the largest in surface area and in water volume (2,903 cubic miles / 12,100 cubic km), thus earning it the name Lake Superior. The name comes from the French word lac supérieur, meaning upper lake, as it is north of Lake Huron.

Additional reporting by Alina Bradford, Live Science Contributor.

Additional resources

• Twin Cities Pioneer Press: ‘Spectacularly Intact’ 1897 Shipwreck Discovered in Lake Superior
• Biography: Samuel de Champlain 
• The Travel Channel: The Great Lakes Video
• EPA: Physical Features of the Great Lakes

Lake Ontario is the smallest of all the Great Lakes, with a surface area of 7,340 square miles (18,960 square kilometers), but its waters run deep. It holds about four times the water volume, at 393 cubic miles (1,640 cubic km), as Lake Erie, although it is similar in width and length. In 2017, the water levels of Lake Ontario reached its highest in 100 years. This lead to massive flooding and ground erosion. 

The easternmost of the Great Lakes, Lake Ontario is positioned at the base of the Niagara Falls. It is bordered by Ontario, Canada, to the southwest and north and New York to the south. The St. Lawrence River provides the lake's outlet to the Atlantic Ocean. The lake has a number of lagoons and baymouth bars, which are formations made of sand, mud or other debris that close off bay areas.

There are a number of islands on the lake, including the Thousand Islands region, which is an archipelago of nearly 2,000 islands that line the U.S. and Canadian border. While many of the islands are small or even uninhabitable, the largest is Wolfe Island. It is 48 square miles (124 square km).

Lake Ontario may be the most polluted out of the five Great Lakes. All of the other lakes flow into it, giving it their pollution. It also receives runoff from farms and businesses around it, according to the University of Wisconsin Sea Grant Institute.

Formation and history

Like all of the Great Lakes, Lake Ontario as it is known today was the result of glacial shifting and melting at the end of the most recent Ice Age.

The lake's name comes from an Iroquois word for "a beautiful lake." The first European to see reach Lake Ontario was Étienne Brulé, the French explorer and protégé of Samuel de Champlain. Brûlé is believed to have reached Lake Huron and Lake Ontario around 1615, according to the Canadian Museum of History. 

In the 17th and early 18th centuries, the French built forts along the edges of the lake. The lake has a rich history of commerce and trade, especially following the War of 1812, when canals were built and traveled by heavy steamships. The lake was a hub of commerce until the railroads were built and eclipsed the steamers as a way to move shipment.

Lake Ontario water temperature

Because of the lake's depth and the warm weather that comes in from the southwest, Lake Ontario rarely freezes over. Water temperatures reach a high of about 75 degrees Fahrenheit (24 degrees Celsius) in August to a low of about 37 F (3 C) in February. The lake typically freezes just around the edges, closing its harbors from mid-December to mid-April, according to Encyclopedia Britannica.

While the entire region is affected by lake-effect snow, there is a prominent snow belt along the southeastern shore that can be deluged with 20 feet (600 centimeters) of snow annually. The impact of the lake-effect snow can be felt as far as Syracuse, N.Y., which is one of the snowiest cities in the United States.

Lake Ontario animals and plants

Walleye, Coho salmon and Chinook salmon and a number of trout varieties, including rainbow and steelhead, are some of the fish that swim the waters of Lake Ontario. Invasive mussels cover much of the bottom of the lake in the coastal areas.

Lake Ontario's climate is conducive to fruit trees, and the area has become a major growing area for apples, cherries, peaches, pears and plums.

Due to its location, Lake Ontario is host to a number of migratory birds. Swans, loons, ducks, geese, grebes and other water fowl are among the wildlife that inhabit Lake Ontario. Birds of prey such as hawks and eagles are also common in the area.

Additional reporting by Alina Bradford, Live Science Contributor

Additional resources

• Biography: Samuel de Champlain 
• The Travel Channel: The Great Lakes Video
• EPA: Physical Features of the Great Lakes

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Lake Huron is easy to find. It is the Great Lake that forms Michigan's mitten shape right next to Canada. It also has the longest shoreline of the Great Lakes. It is the second largest by surface area and the third largest by volume of water. This lake is also the fifth largest fresh water lake on the planet, according to the Michigan Economic Development Corporation.

The lake's surface area is 23,000 square miles (59,600 square kilometers) and its volume is 850 cubic miles (3,540 cubic km). The shoreline is 3,827 miles (6,157 km), taking into account its many islands, according to the Environmental Protection Agency (EPA). 

Lake Huron is situated between the eastern shore of Michigan and Ontario, Canada, to the north. Port Huron/Sarnia, where Huron meets the St. Claire River, is at the southernmost point of the lake. Lake Huron is connected to Lake Michigan by the Straits of Mackinac and, technically, these two lakes are one lake. The water from Lake Superior also flows into Lake Huron through the St. Mary's River. 

Of the lake's 30,000 islands, Manitoulin Island, which sits in the Georgian Bay, is the most prominent island, with more than 12,000 residents. It is also the world's largest freshwater island and Canada's 31st largest island. Amazingly, the island has over 100 freshwater lakes of its own. 

Formation and history

Ice glaciers melting at the end of the latest Ice Age were responsible for the formation of Lake Huron and all of the other Great Lakes.

It was the first of the Great Lakes to be explored by the Europeans in the 1600s. The French explorers Samuel de Champlain and Étienne Brûlé reached Georgian Bay in 1615, according to the Canadian Museum of History. Others soon followed, including Louis Joliet, who traveled Lake Huron in 1669 by canoe before coming upon Lake Erie.

Lake Huron is named for the Wyandot Indians, or Hurons, who lived there. But because it was the first of the Great Lakes to be explored by the French, they called it La Mer Douce, meaning fresh-water sea.

Traders and missionaries, as well as many Native Americans, have boated across Lake Huron. The shores have 120 lighthouses that once was used to guide these boats. The lake is known for its storms and sometimes dangerous sailing, though. On Nov. 9, 1913, Lake Huron was hit by the worst storm ever to hit the Great Lakes. The storm produced unprecedented wind gusts of 90 mph (145 kph) and ocean-like waves of more than 35 feet (11 meters) The powerful 16-hour storm, which was called The Big Blow, sank 10 ships and killed 235 seamen, making it the deadliest storm to hit any of the Great Lakes.

Overall, there have been more than 1,000 shipwrecks on the lake and there are many still at the bottom, some are preserved as artifacts. In 2012, more than 100 years after it sank, a dive team discovered the 238-foot steamer New York. [Image Album: Shipwreck Alley's Sunken Treasures]

Water temperatures

Lake Huron is a popular recreational spot, particularly in the summer months, when surface water temperatures can reach 73 F (23 C) in August. The lake does not freeze over often — about once a decade — and the last time it happened was in 2003. Low temperatures are about 34 F (1 C).

Because water flows in from both Lake Superior and Lake Michigan, water flows through Lake Huron much more quickly than other Great Lakes. It also has a large drainage area, which covers parts of Michigan and Ontario.

Lake Huron fishing

Round whitefish. ruffe, sea lamprey, smallmouth bass, walleye, white bass, white perch, white sucker and yellow perch are some of the predominant fish found in Lake Huron.

Lake Huron features some heavily forested areas, including Huron-Manistee National Forests, which boast 10,000 acres of pine, aspen and hardwood forest. The area is also home to what scientists believe are some 7,000-year-old petrified trees that are underwater.

Additional reporting by Alina Bradford, Live Science Contributor.

Additional resources

• Biography: Samuel de Champlain 
• The Travel Channel: The Great Lakes Video
• Encyclopedia Britannica: Lake Huron

Lake Superior is not only the largest of the Great Lakes; it is the largest body of fresh water on Earth. Situated on the northern edge of Wisconsin, Lake Superior extends from the upper peninsula of Michigan north to Ontario, Canada, and reaches west to the eastern edge of Minnesota. The name Superior refers to its size and also designates the lake's position as the northernmost of all the Great Lakes.

The lake is about 160 miles (257 kilometers) wide and about 350 miles (563 km) long. It has a surface area of 31,700 square miles (82,100 square km) and water volume of 2,900 cubic miles (12,100 cubic km). The shoreline measures 2,726 miles (4,385 km), according to the Environmental Protection Agency (EPA).

How deep is Lake Superior?

The deepest point in Lake Superior is 1,300 feet (400 meters) below the surface, making a complete freeze a rarity. Lake Superior boasts extremely clear water, with an average underwater visibility of 27 feet (8.2 m). It takes almost 200 years for the lake to refill with new water, according to the University of Wisconsin.

Lake Superior water temperature

Like all of the Great Lakes, Lake Superior is prone to lake effect snow, but the weather is generally moderate, with warmer temperatures than inland throughout the year. Winter temperatures around the lake rarely fall below minus 30 F (minus 34 C), well above inland temperatures. June and July are calm months, while October and November are prone to storms.

During most winters, the lake is 40 to 95 percent covered with ice, although it rarely completely freezes. The last time Lake Superior froze over was in 2014. Overall, the Great Lakes reached a 91 percent ice cover that year, which is the most the lakes have frozen since 1979. Freezing of the lakes is monitored because it affects hydropower generation, commercial shipping, the fishing industry and more, according to the Office of Oceanic and Atmospheric Research.

The average water temperature is 40 F (4.4 C) — lower than the other Great Lakes, which are farther south. The water temperatures during the summer months average about 55 F, but surface temperatures reached a record 68.7 F (20.4 C) in August 2010 and are affected by the amount of surface ice during the previous winter.

Formation and history

Lake Superior first took shape about 1.2 billion years ago as a result of the North American Mid-Continent Rift, which carved an arc-shaped scar stretching from Kansas through Minnesota. The first people to settle in the region arrived around 8000 B.C., after glaciers retreated, according to History of Lake Superior: A Timeline. By 500 B.C., Laurel people were trading for metal and other goods with different regions. By the early 1600s, the Ojibway people had established a village of several thousand on Madeline Island. 

French explorers, including Samuel de Champlain (circa 1567-1635) and his scout, Étienne Brûlé (circa 1592-1632), arrived in the mid-1600s, according to the Canadian Museum of History. 

The lake's name comes from the French word lac supérieur, which means "upper lake." It called this because it is north of Lake Huron, which was discovered first by Brûlé. The Objibways said that the lake was protected by Nanabijou, Spirit of the Deep Sea Water, according to the University of Wisconsin. 

Superior was a major mode of transportation for the fur industry and other trading activities during the Colonial period and remains a shipping hub today.

Because of varying depths and unpredictable weather, Lake Superior and the other Great Lakes have been prone to maritime accidents. One of the most well-known incidents occurred on November 10, 1975, when the Edmund Fitzgerald, a large cargo ship carrying iron ore, encountered a severe storm that killed the ship's 29 crew members.

Life on Lake Superior

Lake Superior is home to about 80 species of fish, including carp and varieties of trout, salmon and perch.

The Lake Superior region is also home to many common native plant species, including Michigan's state tree, the white pine, and Flowering Rush, an aquatic plant that grows along the shoreline. Lake Superior's basin is home to nearly 60 orchid species.

As with many lakes, Lake Superior is home to many species of birds, including varieties of hawks, loons, owls and woodpeckers. Duluth's Hawk Ridge, which is on the lake's north shore, hosts as many as 10,000 migrating birds of prey each day during the fall migration season.

There is a small population of endangered whooping cranes on the lake's north shore, one of only two crane species in North America. As of 2017, there were only 483 individuals in the wild across North America, according to the International Union for Conservation of Nature. 

Additional reporting by Alina Bradford, Live Science Contributor

Additional resources

• Twin Cities Pioneer Press: ‘Spectacularly Intact’ 1897 Shipwreck Discovered in Lake Superior
• Biography: Samuel de Champlain
• The Travel Channel: The Great Lakes Video
• EPA: Physical Features of the Great Lakes

Lake Erie is the warmest of all of the Great Lakes, but it also freezes over more than the other lakes. It is the fourth largest when measured in surface area, with round 9,910 square miles (25,700 square kilometers) and the smallest by water volume, with 116 cubic miles (484 cubic km), according the Environmental Protection Agency (EPA). 

Lake Erie touches four U.S. states — New York, Pennsylvania, Ohio and Michigan — and the Canadian province of Ontario. Buffalo, N.Y., is on the eastern end, and Toledo, Ohio, is on the western end. Cleveland, Ohio, and Erie, Pa., sit on the southern shore. 

As the southernmost of the Great Lakes, the majority of Lake Erie's water flows in through the Detroit River from the upper lakes — Lake Superior, Lake Michigan and Lake Huron — as well as tributaries such as the St. Clair River and Lake St. Clair. 

Its main outlet is Niagara Falls. The Niagara River, the source of the falls, runs 36 miles (58 kilometers) and connects Lake Erie and Lake Ontario.

Lake Erie has a tail-like shape, which is reflected in its name, which is derived from erielhonan, the Iroquoian word for "long tail." The lake is about 241 miles (388 km) long, 57 miles (92 km) wide and boasts 871 miles (1,402 km) of shoreline, including islands. Its size makes it the 11^th largest lake in the world, according to the Michigan Economic Development Corporation.

Lake Erie weather

Due to its southernmost position, Lake Erie is the warmest of all of the Great Lakes. While temperatures have reached as high as 85 F (29 C), water temperatures are generally in the low 70s F (21 C to 24 C) during the summer months, making Lake Erie a popular recreational area. 

During the winter, water temperatures reach freezing, and the lake freezes over more than the other Great Lakes because of its shallowness. Its average depth is 62 feet (19 m) and its maximum depth is 210 feet (64 m).

Water levels are 25 to 30 feet (7.6 to 9.1 m) in the lake's shallowest area, making it possible for strong winds to kick up fairly powerful waves.

Lake-effect snow has a huge impact on the surrounding communities, including Buffalo, N.Y.

Formation and history

Like all of the Great Lakes, Lake Erie is basically a divot formed from a moving glacier and is relatively young — less than 4,000 years old — in its current configuration.

Several native peoples lived on lake's shores, including the Erie tribe and the Iroquois. Lake Erie was the last of the Great Lakes to be explored by Europeans. French explorer Louis Joliet "discovered" the lake in 1669.

Battle of Lake Erie

The lake played a pivotal role in the War of 1812. The Battle of Lake Erie took place off the north shore on Sept. 10, 1813. U.S. Navy ships defeated the British Navy, gained control of the lake and regained Detroit. The site of the battle is now officially known as the River Raisin National Battlefield Park.

As the battle began, Captain Oliver Hazard Perry hoisted his battle flag, emblazoned with the words, "Don't Give Up the Ship." After the British surrendered, Perry sent a message to General William Henry Harrison: "We have met the enemy and they are ours." About 934 Americans fought in this battle and only 33 survived. 

Erie Canal

The Erie Canal was one of the first gateways to the West. Completed in 1825, it connected Lake Erie in the west to the Hudson River in the east, a distance of about 360 miles (580 km). It opened up the West to settlers and offered an inexpensive way to transport cargo. It was enlarged in the mid-1800s and again in 1903 to keep pace with growing demands. Today, it is mostly used for recreation.

Lake Erie pollution

By the 1960s, Lake Erie had become sort of a "poster child" for water pollution. Pollutants from factories, waste from city sewers, and fertilizer and pesticides from farms made their way to the lake, according to Cleveland Historical. As a result, levels of phosphorus and nitrogen increased, which led to algae blooms. The toxic algae caused "dead zones" by depleting the oxygen, and dead fish littered the shoreline. And in 1969, the Cuyahoga River, which flows through Cleveland, Ohio, caught fire.

The federal government responded to this situation by passing the Clean Water Act in 1972. The law tightened regulations on industrial dumping. 

While the water quality of Lake Erie has much improved, the lake continues to be prone to algae blooms and still has dead zones. "The dead zone in 2012 was the largest we've ever seen," researcher Anna Michalak, an earth scientist at the Carnegie Institution of Science at Stanford University in California, told Live Science. [Lake Erie Dead Zone: Don't Blame the Slime!] Low oxygen and algae blooms can affect the water supply for residents nearby.

Additional facts

Lake Erie is popular with sports fishermen and it boasts an extensive walleye fishery. Charter fishing boats also take tourists out to catch small mouth bass. Ice fishing is also popular on Lake Erie.

Lake Erie also has its own legendary lake monster — Bessie — which is mostly likely a huge sturgeon.

In 1999, Lake Erie was invaded by mayflies, which was seen as a sign of the lake's return to health and a balance of nature.

Due to its rich soil, the Lake Erie region has a large concentration of concord grapes. 

Additional reporting by Alina Bradford, Live Science Contributor.

Additional resources

• EPA: Water Quality of Lake Erie
• Biography: Samuel de Champlain
• The Travel Channel: The Great Lakes Video

Lake Michigan is the third largest of the Great Lakes (when measured by water surface) and the only Great Lake located entirely in the United States. Its name is derived from the Ojibwa Indian word mishigami, meaning large lake.

Lake Michigan's water surface is 22,300 square miles (57,800 square kilometers). It is the second largest of the Great Lakes by volume (1,180 cubic miles / 4,920 cubic km). Only Lake Superior is bigger.

Lake Michigan touches Indiana, Illinois, Michigan and Wisconsin. Approximately 12 million people live along the shores of Lake Michigan, according to the New World Encyclopedia. Major port cities include Chicago, Illinois (population: 2.7 million); Milwaukee, Wisconsin (600,000); Green Bay, Wisconsin (104,000); and Gary, Indiana (80,000).

There are a number of beaches along the coast, and the Great Lakes are sometimes referred to as the “Third Coast” behind the Pacific and Atlantic (the Gulf Coast notwithstanding). Some of the most popular “beach” towns on the Michigan side of the lake include St. Joseph, South Haven, Grand Haven and Holland.

On the northern end, Lake Michigan and Lake Huron are connected by the Straits of Mackinac, a 4- to 5-mile-wide (4.6 to 8 kilometers) channel, and technically, these two bodies of water are one lake.

Water temperature

Water temperatures on Lake Michigan make it to the 60s in July and August and can sometimes make it into the 70s when air temperatures have been in the 90s for a number of continuous days.

The water of Lake Michigan has an unusual circulatory pattern — it resembles the traffic flow in a suburban cul-de-sac — and moves very slowly. Winds and resulting waves keep Lake Michigan from freezing over, but it has been 90 percent frozen on a number of occasions. Ocean-like swells, especially during the winter, can result in a drastic temperature changes along the coast, shoreline erosion and difficult navigation.

The lake’s average water depth is 279 feet (85 meters) and its maximum depth is 925 feet (282 meters).

Life on Lake Michigan

Marshes, tallgrass prairies, savannas, forests and sand dunes that can reach several hundred feet, all provide excellent habitats for all types of wildlife on Lake Michigan.

Trout, salmon, walleye, and smallmouth bass fisheries are prevalent on the lake. The lake is also home to crawfish, freshwater sponges and sea lamprey, a metallic violet species of eel.

The lake is also home to a wide range of bird populations, including water birds such as ducks, geese and swans, as well as crows, robins and bald eagles. Predatory birds such as hawks and vultures are also prevalent on the lake, due to the wealth of wildlife to feast upon.

The pebble-shaped Petoskey stone, which is a fossilized coral, is unique to the northern Michigan shores of Lake Michigan and is the state stone.

Formation, discovery and history

The formation that is recognized as Lake Michigan today began about 1.2 billion years ago when two tectonic plates were ripped apart, creating the Mid-Continent Rift. 

French explorer Samuel de Champlain sent his underling Jean Nicolett to find the “Northwest Passage” but he ended up discovering Lake Michigan around 1634. In 1679, Nicolette explored the southernmost part of the lake where modern-day Chicago is.

Shipping and shipwrecks

Like all of the Great Lakes, Lake Michigan has had its share of shipwrecks. One of the most famous maritime disasters was the sinking of the Westmoreland, a steamer that sank on Dec. 7, 1854. The wreck was discovered by a diver on July 7, 2010, 155 years after the accident, in excellent condition.

Before the invention of radar in the 1940s, the Straits of Mackinac could be an extremely dangerous area to navigate. Ships were at the mercy of unpredictable storms, dangerous currents, fog, ice, shallow areas and rocky shoals. A number of ships met their demise trying to pass through this skinny channel — so many, in fact, that an underwater preserve was eventually created where divers can explore these sunken ships.

This preserve, known as the Straits of Mackinac Underwater Preserve, contains 12 marked shipwrecks. Some of the wrecks on the Lake Michigan side include the Sandusky, the Maitland and the Eber Ward.

The Sandusky, the oldest known ship in the preserve, was heading from Chicago to Buffalo with a cargo of grain in September 1856 when it was struck by a violent gale, according to the preserve’s website. There were no survivors. In June 1871, the Maitland was carrying a load of corn from Chicago to Buffalo when she collided with two ships. The crew was able to jump into their yawl boat, and no lives were lost. In 1909, the Eber Ward, a 213-foot-long (65 meters) wooden freighter, left Chicago, picked up a cargo of corn in Milwaukee and was on its way to Port Huron when it was gashed by ice, sinking within 10 minutes and killing five crewmen.

Today, passing through the Straits of Mackinac is much safer thanks to the use of advanced radar and icebreakers — ships designed to break through ice so that other boats can safely pass. Nearly four dozen lighthouses still stand along the beaches of Lake Michigan, a reminder of the area’s great shipping history.

Additional reporting by Traci Pedersen, Live Science Contributor.

Crystals to ice

Scientists have discovered that frozen, wintry lakes can fuel the growth of certain types of algae and zooplankton that thrive during the cold season, blooming under the lake's icy cover.

Here, ice forms on the surface of Lake Pääjärvi, a lake in southern Finland.

Read the full story about how researchers are investigating life under the ice in frozen lakes.

Hidden life

Lake Erie, the fourth largest of North America's five Great Lakes, hides concentrated communities of algae under a layer of lake ice, mostly the filamentous diatom Aulacoseira islandica.

Frozen falls

Frozen waterfall on the River Jägala in Estonia, in March 2011.

More frozen falls

Another view of the frozen waterfall on the River Jägala in Estonia, in March 2011.

Shoreline ice

Breaking ice on Estonia's Lake Võrtsjärv, a shallow lake in southern Estonia, in April 2011.

Piles and piles

Along the shore of Estonia's shallow Lake Võrtsjärv in southern Estonia, ice breaks in April 2011.

Cracks and fractures

Another pile of breaking ice on the shores of Estonia's Lake Võrtsjärv, a shallow lake in southern Estonia, in April 2011.

A lake?

Frozen Lake Võrtsjärv in Estonia, in January 2014.

Frozen beauty

Võrtsjärv is large but shallow — though it measures 104 square miles (270 square kilometers) the lake is only 20 feet (6 meters) deep.

Icy tundra

In January 2014, the large but shallow Lake Võrtsjärv in Estonia is frozen.

Glowing ice

Ice on Russia's Lake Baikal, an ancient and enormous lake in Siberia. It measures approximately 400 miles (644 kilometers) in length and over 5,000 feet (1,637 meters) in depth, and is the oldest and deepest lake on Earth.

Collateral damage

A boat is frozen into the ice covering the western shore of Lake Baikal near Bolshiye Koty, a rural location in Irkutsk Oblast, Russia.

Collecting specimens

In Burntside Lake, Minnesota, Kirill Shchapov, a doctoral candidate in biology at the University of Minnesota in Duluth, conducts a zooplankton tow, collecting the microscopic creatures by dragging a fine mesh net through the water.

Playtime

In northern Lake Michigan in January 2013, the Coast Guard icebreaker U.S.C.G.S Mackinaw is "hove-to" — in a stationary position facing the wind — during "ice liberty," a period when the crew is permitted to disembark and climb the ice.

Breathtaking allure

Lake Erie in February 2011.

Ice jewels

Ice on Lake Baikal, Russia. The lake's water is so clear that it appears blue when it freezes.

Suspended particles

This image of frozen Lake Winnipeg in Manitoba, Canada was taken during a February 2014 snowmobile survey. The ice ridges contain particulate matter, much of which were colonies of diatoms, a type of algae.

Ice work

Field work on Minnesota's La Salle Lake. At 213 feet (65 meters) in depth it is the second-deepest lake in the state.

More samples

In March 2015, researchers gathered samples from Lake Lämmijärv, part of Lake Peipus on the boundary between Estonia and Russia.

Ice melt

Ice melt at Lake Mälaren, Sweden. Mälaren is the third largest lake in Sweden, with a surface area of approximately 440 square miles (1,140 square kilometers).

Tech and samples

At West Long Lake, Nebraska in the Valentine National Wildlife Refuge, in January 2008, a researcher uses an integrated water column sampler to collect samples for processing.

Teamwork

A researcher transfers a sample to a rinse bucket at West Long Lake, Nebraska in the Valentine National Wildlife Refuge, in January 2008. The sample was collected using a pole-mounted Ekman dredge, for sampling benthic invertebrates.

Fractures in the ice

Ted Ozersky, an ecologist and professor at the University of Minnesota in Duluth, stands on the clear ice at Lake Baikal, Siberia.

Journey to the center

A group of researchers walk out to sample the deepest part of a prairie pothole shallow lake in west-central Minnesota, in an area known as the "Prairie Pothole region" of North America.

Data download

Photo of Leah Domine, a researcher at the University of St. Thomas in Minnesota, downloading data from a sonde — a tool containing measurement sensors — that was deployed under the ice in a prairie pothole shallow lake, in the so-called "Prairie Pothole region" of North America, in west-central Minnesota.

Reflections

This photo is a reflection of geologist George Swann, an associate professor in Palaeoclimatology at the University of Nottingham, sampling from a hole drilled through frozen Lake Baikal in Siberia.

Geometric ice

Autumn ice forming on Toolik Lake, Alaska, September 21, 2013.

Ridges and waves

Ice forming on Lake Ediza in Sierra Nevada, California, on July 8, 2006.

Sample taker

Jade Lawrence, a doctoral candidate in geology at Louisiana State University, drills holes in the ice in Lake E6 near Toolik Lake in Alaska, on May 11, 2013.

From A to B

Steve Sadro, an assistant professor of environmental science at the University of California, Davis, pulls a sled across Lake Toolik, Alaska on May 28, 2013.

Learning the trade

Winter sampling by undergraduates on Emerald Lake in Sierra Nevada, California, on March 28, 2013.

Indoor work

Sampling huts on Station No. 1 at Lake Baikal, Siberia.

Natural reactions

Gas bubbles from submerged wood at the shore frozen into the ice at Lake Stechlin in Brandenburg, Germany, in 2011.

Odd ice formations

Ice at the southern shore within a reed stand, at Lake Stechlin in Brandenburg, Germany, in 2011.

Deep, dark samples

Researchers Mike Sturm and Lena Vologina extract sediment cores from frozen Lake Baikal in Siberia.

Years of drought and over-irrigation have caused Utah's Great Salt Lake to shrink at an alarming rate, recent satellite photos show.

After the Great Lakes, Utah's Great Salt Lake is the largest body of water (by area) in the United States. Back in the middle of the 19th century, when pioneers first arrived in the area, the lake spread across roughly 1,600 square miles (4,100 square kilometers). Now, the lake covers an area of only about 1,050 square miles (2,700 square km), new satellite photos from NASA reveal. In October, the Great Salt Lake reached its lowest level in recorded history, with the water’s surface elevation at only 4,191 feet (1,277 meters).

These dramatic declines in water levels come from years of human activity — namely,  diverting river water, which would normally fill the lake, for agriculture and industry, according to NASA. The agency estimates that about 40 percent of the river's water is diverted from the lake. These activities, along with the ongoing drought in the West, have drained the historic lake. [Gallery: Rainbow of Life in Great Salt Lake]

The NASA images show changes in the Farmington Bay basin of Great Salt Lake, an area that is home to many diverse wildlife, including migratory birds. Decreasing water levels in the Bay not only affect the ecology of the area, but could divert the bird populations who migrate to the basin for food.

"Farmington Bay has been nearly desiccated as the result of the combined effects of drought and water withdrawals from the rivers feeding the lake," Wayne Wurtsbaugh, a watershed sciences researcher at Utah State University, said in a statement. "Farmington Bay is an immensely important feeding area for migratory shorebirds and waterfowl. Even at the low level we have now, it is still important, but the greatly reduced size has diminished its value."

The NASA satellite images show changes in the Farmington Bay basin from 2011 to 2016. Scientists estimate that more than three-quarters of the lake bed is now exposed in the bay, significantly diminishing the food available for wildlife.

In February, Wurtsbaugh and his colleagues released a white paper on how water development has impacted the Great Salt Lake. Their study found that river flow into the basin has been reduced by 39 percent since the middle of the 19th century. Reversing this trend would involve more conservation efforts, especially for agricultural irrigation, which accounts for approximately 63 percent of water usage in Utah, Wurtsbaugh said.

Even with conservation efforts and more ecologically conscious development, the lake could continue to diminish due to climate change, the researchers said.

"A wild card for the fate of the lake is what global climate change may do to the basin,” Wurtsbaugh said. "Warmer air temperatures are projected to lower runoff, but our data shown in the white paper suggests there haven't been climate change effects on the runoff yet."

Editor's Note: An earlier version of this story stated the lake’s lowest level was 4,191 feet deep. The story has been updated to reflect the correct measurement was 4,191 feet of elevation above sea level.

Original article on Live Science.

In winter, an icy freshwater lake can appear frozen in time. Though lakes are typically teeming with life — visible and microscopic — it's not hard to imagine that when temperatures drop and ice solidifies on a lake's surface, plant and animal activity in its depths would also "freeze."

But frozen freshwater lake ecosystems don't take a winter break after all. A new study finds that under the ice, certain forms of life are far more active than scientists thought.

In fact, cyclical winter activity of tiny aquatic organisms, like zooplankton and photosynthesizing algae, could play critical roles in the lake ecosystems' overall health, infusing the water with nutrients to fuel other organisms' spring and summer growth. [Yuck! Photos of 'Rock Snot' Algae Infestations]

About half of the world's lakes — approximately 50 million — freeze seasonally, but little is known about what goes on underneath their ice cover, the study authors wrote. Sea-ice studies, which are more numerous, show that ice cover drives algae production, a vital part of ocean food webs. Scientists suspected that ice-covered lakes could be similarly active.

Previous studies focused primarily on how lake ecosystems behaved in summer, "when most of the data on lakes have been collected," study lead author Stephanie Hampton, director of the Center for Environmental Research, Education and Outreach at Washington State University, told Live Science in an email.

So Hampton led an effort to collect and analyze data sets that represented winter conditions in lakes. Those data sets could then be compared to data sets of summer conditions.

Hampton and her colleagues first reviewed existing research, investigating 14 studies with data for 17 lakes. They then reached out directly to the scientific community for more data, gathering both under-ice and summer observations conducted between 1940 and 2015 from 101 lakes.

Scientists' findings varied widely from lake to lake, largely depending on the type of ice cover and how easily sunlight could penetrate it. When lakes are covered by clear ice, sunlight can reach the algae and zooplankton beneath and fuel their growth. At Lake Baikal in Siberia, winter algae blooms — under ice — are often larger than summer algae blooms. 

"Some hypothesize that clear ice in winter provides ready access to light for the relatively large filamentous algae that dominate those big winter blooms," Hampton told Live Science in an email, explaining that those filaments attach to the ice or become suspended near it. The ice provides a stable environment with access to plenty of light, enabling the algae to thrive.

"The lake is naturally nutrient poor, so these offshore algal blooms are not at levels that are a nuisance — they are important for feeding the food web," Hampton said. "And the algal blooms are largest when the ice is clear — a factor that is determined by the weather at the time of freezing."

The findings provide a first glimpse of how winter activity in lakes — even those that have frozen over — could be necessary for a healthy environment year-round. But as little as scientists know about life under freshwater lakes' ice, even less is known about how this balance will shift in a warming world, Hampton added.

Higher temperatures could lead to reduced ice cover or shorter periods of coverage, which could spell trouble for winter growth of algae and zooplankton, she said. Investigating lakes where winter ice cover is inconsistent could provide researchers with some insight into how lake ecosystems adapt to this variability. For instance, they may observe changes in the algal communities' composition, which could affect the lake's entire food web, Hampton said.

"There is a lot we do not know about how these dynamics will play out," Hampton told Live Science.

The findings were published online today (Nov. 28) in the journal Ecology Letters.

Original article on Live Science.

The Bolivian volcano Cerro Uturuncu is a massive barren peak rising from the high plateau of South America's Altiplano. If you've heard of the volcano, it may be because of recent news stories claiming that scientists have found a "lake" beneath its base, deep in the Earth's crust.

That's only partially true. There is no actual lake under Cerro Uturuncu — but there is an incredible amount of water locked up in the melted rock beneath the volcano, approximately enough to fill Lake Superior. This sort of dissolved water is a well-known driver of eruptions for volcanoes in subduction zones, where one piece of the Earth's crust is being pushed under another. Still, scientists were surprised at the sheer amount of water trapped beneath Cerro Uturuncu.

"It's probably about twice as much as would have been expected," said Jon Blundy, a petrologist at the University of Bristol in the U.K., who was involved in the new research that discovered the massive store of water. [See Stunning Photos of Volcano's Lava Lake]

A mystery anomaly

Blundy and his colleagues were studying the volcano because satellite measurements revealed the ground around the mountain was deforming. That's typically a sign that the magma under the volcano is on the move in some form or another. As they took seismic measurements of the crust under the volcano, they found an "anomaly" about 9 miles (15 kilometers) down. There, the seismic waves slowed and the electrical conductivity shot up.

Using andesite, an igneous rock collected from the volcano's old lava flows, the researchers created a mock-up of the subterranean conditions under Cerro Uturuncu in the laboratory. They subjected the rock to various pressures and temperatures to test its conductivity and other features. They could then extrapolate the data from these experiments to the real-world water reservoir under the volcano.

Fire and water

Contrary to elementary-school diagrams of how volcanoes work, researchers have discovered over the past decade or so that there are very rarely chambers of molten magma beneath the volcano's cone. Instead, volcanoes are fed by "mush" — a partially solid, partially liquid zone of very hot rock under great pressure. Rock melts under a range of temperatures, Blundy said, so the liquid (and gas) portions of the mush can get captured in the pores of portions of still-solid rock.

The Altiplano-Puna magma body of mush that underlies Cerro Uturuncu is about 10 percent liquid, Blundy and his colleagues found. Of that liquid, 10 percent by weight is dissolved water. Measured by the proportion of water molecules in the mix, water is about 25 percent of the melted rock, which explains the high electrical conductivity, Blundy told Live Science.

The entire magma body is about 120,000 cubic miles (500,000 cubic km) in size, Blundy said. Thus, the dissolved water comes to a weight of 1.4 X 10^16 kilograms — just about enough to fill Lake Superior, the largest of the Great Lakes. This water was dragged underground as the Nazca tectonic plate dove under the South American plate, and represents about 6 million years of water accumulation, Blundy said.

Similar systems are at work at other volcanoes in subduction zones, including Mount St. Helens in the Cascades. Cerro Uturuncu hasn't erupted for about 250,000 years, Blundy said. The uplift in the ground around the volcano is due to small amounts of melted rock getting squeezed out of the reservoir underneath, but it's not clear if there is a real reawakening imminent for the mountain, he said.

"What we are seeing is that these volcanoes are like little valves on top of the reservoirs, and they can be replenished with a little bit of melt moving up," Blundy said.

Original article on Live Science.

The 10 Best Freshwater Lakes to Swim In

Looking for a good way to cool off this summer? Try jumping in a freshwater lake.

Many freshwater lakes have clear, pristine waters, largely because they lack the nutrients that are gobbled up by algae. And these teensy plantlike organisms called protists can multiply fast, turning a body of water from glassy to murky.

Healthy freshwater lakes often support small fish and are usually surrounded by trees and vegetation that help prevent erosion. That makes freshwater lakes the perfect place to have a picnic, relax or dive into for a swim. Here are 10 recommendations of freshwater lakes in the United States, but feel free to add more in the comments section if you don't see your favorite freshwater lake in the countdown.

Sleeping Bear Dunes National Lakeshore

Located on the Michigan coast, Sleeping Bear Dunes National Lakeshore is a beautiful getaway within Lake Michigan. Visitors often rent houses and go hiking along the dunes or gaze out at the shipwrecks in the crystal-clear water from a viewpoint on South Manitou Island.

Swimming is also a must during the hot summer months.

Click "Next" to learn about Lake Tahoe . . .

Lake Tahoe

At 1,645 feet (501 meters) deep, Lake Tahoe is the second deepest lake within the United States and the 10th deepest in the world, according to the U.S. Geological Survey (USGS).

"I would find nothing more pleasurable than swimming in the sparkling clear water of Sand Harbor at Lake Tahoe while gazing up at snow-covered Mount Tallac at nearly 10,000 feet [3,048 m]," said Geoff Schladow, director of the Tahoe Environmental Research Center at the University of California, Davis. [A Buyer's Guide for the Adventure Junky]

Vacation seekers will find Lake Tahoe along the California and Nevada boarder. It's about 22 miles by 12 miles (35 by 19 kilometers) large, and its surface elevation is about 6,225 feet (1,897 m), making it the highest lake of its size in the United States, the USGS reported.

The water is about 65 to 75 degrees Fahrenheit (36 to 42 degrees Celsius), during August and September, the USGS said.

Tettegouche State Park

Explore Lake Superior from Tettegouche State Park in Minnesota. Visitors can hike its scenic trails, go rock climbing, try bird-watching and, of course, swim. If the North Shore's waters are too cold for a quick dunk, check out the 60-foot-tall (18 m) High Falls waterfall and warmer waters of the nearby Baptism River (shown here) on the North Shore of Lake Superior.

Emerald Lake

Hikers can find Emerald Lake in Colorado's Rocky Mountain National Park. The park has a 1.8-mile-long (about 3 km) trail that, with a total of 650 feet (198 m) elevation gain, leads visitors to the lake. But the climb isn't that strenuous, said Catherine O'Reilly, an associate professor of geology at Illinois State University.

Emerald Lake might be cold, but it, along with lakes around the world, are heating up due to climate change, O'Reilly told Live Science. In 2015, she co-authored a study on global lake surface temperatures, and found that they had increased an average of 0.61 degrees Fahrenheit (0.34 degrees Celsius) from 1985 to 2009.

The study was published in Geophysical Research Letters.

Crater Lake

Take a dip in the United States' deepest lake, located in the shell of a collapsed volcano in south-central Oregon. Crater Lake is covered with snow most of the year, but from late June to late October, visitors can hike down a steep 1-mile (1.6 km) trail to the lake for a refreshing dip. However, the water is pretty cold, so most people go swimming for just a few minutes, said Dave Grimes, a park ranger at Crater Lake National Park.

This year, the trail will close in mid-August for renovations, but it's expected to reopen in 2017, he said.

The lake is 1,943 feet (592 m) deep. Daredevils can jump off a 20-foot-tall (6 m) rock into the lake and still not get anywhere near the lake's bottom, Grimes said.

There aren't any native fish in Crater Lake, but people can fish non-native rainbow trout and Kokanee salmon, so long as they use artificial lures (no worms or eggs), Grimes said.

Bottomless Lakes

Bottomless Lakes State Park in New Mexico is just 14 miles (23 km) southeast of Roswell, so if you're a UFO enthusiast, there's that (In the summer of 1947, some people claim debris from a flying saucer crashed there). Aliens aside, visitors will enjoy peace and quiet — motorized boats aren't allowed, but people in canoes and kayaks can paddle through the water.

In addition to swimming, people can camp, fish, horseback ride, picnic, hike, bird watch and scuba dive, according to New Mexico State Parks.

However, the lakes aren't exactly bottomless. They are formed by sinkholes with depths from 17 to 90 feet (5 to 27 m) deep. But the lakes have the illusion of great depth because of greenish-blue aquatic plants within their waters.

Lake Crescent

Check out Lake Crescent, located deep in the temperate rainforest of Washington's Olympic National Park. Just go during the drier summer months — the rainforest gets drenched with about 12 feet (3.6 m) of rain a year, according to the National Park Service.

"The [Washington] peninsula is lush and green and cool in the summer time," said Stephanie Hampton, a professor in the School of the Environment at Washington State University.

There's limited development around Lake Crescent, but about 100 houses were grandfathered into the park and allowed to stay, she said. Moreover, the park transformed an old railroad into a fairly flat trail for hikers, who can swim in the water to cool off.

"Lake Crescent is very blue and beautiful," Hampton said. "You can see deep into the water." [The 10 Most Visited US National Parks]

Flathead Lake in Montana

Flathead Lake is the largest natural freshwater lake west of the Mississippi River in the continental United States, according to the National Park Service.

"It's a beautiful lake that is quite a destination for recreation," Stephanie Hampton, of Washington State University, told Live Science. "It has swimmable temperatures in the summertime."

Pyramid Lake

Practice your favorite swimming stroke in California's Pyramid Lake, located in the Angeles and Los Padres National Forests. People can also camp, picnic, boat and water-ski, and anglers can try their luck fishing for largemouth and smallmouth bass, trout, catfish, blue gill and crappie, according to the California Department of Water Resources.

At the lake's Emigrant Landing recreation area, people can swim and kayak in more protected areas.

Norris Lake

Immerse yourself in the blue waters of Norris Lake in Tennessee. The lake is also a hotspot for snorkeling, boating, fishing, water-skiing and golfing, according to the Norris Lake Marine Association. Norris Lake has more than 20 marinas and plenty of hotels, houseboats and restaurants, and 809 miles (about 1,300 km) of shoreline.

Norris Lake is also spotted with islands, some which make inviting picnic destinations.

Follow Laura Geggel on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+.

• Image Gallery: See Photos of Invasive Species
• The Great Lakes: North America's 'Third Coast' (Photos)
• Sleeping Bear Dunes National Lakeshore

During the rainy fall and winter, most Oregonians probably don't give much thought to Lost Lake, a shallow lake surrounded by pine trees that sits near a highway.

But drivers might do a double take during the summer. During the dry months, the 85-acre (0.34 square kilometers) lake vanishes and turns into meadow.

The reason? Two hollow lava tubes at the bottom of the lake are constantly draining the lake dry, much like a bathtub left unplugged. [Images: One-of-a-Kind Places on Earth]

"The lakebed begins to fill in the late fall, when the amount of rain coming in starts exceeding the ability of the lava tubes to drain off the water," said Jude McHugh, a spokeswoman for the Willamette National Forest in Oregon. "And it continues to fill all winter long in a series of rain or snowstorms."

As the rainy season peters out, the 9-foot-deep (2.7 meters) lake loses its water source, and water disappears down the lava tubes until it's gone, McHugh said. The lake's watery boom-and-bust cycle repeats itself every year, she added.

Lava tubes aren't uncommon in Oregon. The state is home to the towering Cascades, a range of mountains and active volcanoes that extends from southern British Columbia to Northern California.

When lava streams flow down a volcano the outside crust cools as it makes contact with air. Hot lava continues to flow under the hardened crust, "kind of like a subway tunnel," McHugh said.

After the hot lava drains away, a hollow tube remains. Some lava tubes become a unique ecosystem for animals and others attract tourists. Lava Beds National Monument in Northern California has "all kinds of lava tubes," McHugh said. "Little guys literally a foot [0.30 m] across, and ones you can walk in that are just massive."

But Lost Lake, located about 130 miles (209 km) southeast of Portland, sports just two small lava tubes. The lake likely formed about 3,000 years ago, when lava flowing from a volcanic vent blocked a river channel and created the lake, McHugh said.

"Several small streams feed into the lake intermittently, but the lava tube drain holes are the only known outlets," McHugh said.

It's not entirely clear where the drained lake water goes, but researchers have an idea. It likely falls down the lava tubes and seeps through layers of cracked volcanic rock as groundwater, McHugh said.

Lost Lake sits on volcanic rock that formed about 12,000 years ago, she said. When this "young" rock formed, it was filled with gas bubbles that left behind pores as they escaped into the atmosphere. The lava also cracked and fissured as it flowed over the terrain, she said.

It takes roughly seven to 10 years for water to filter down through all those cracks and pores, McHugh said.

"Here in western Oregon, it pops out at the valley floor and supplies drinking water and important habitat for humans, fish and all kinds of species," she said. "That water that fell today, there's some kid that's going to be born tomorrow that's going to be drinking it when he's 10."

However, people aren't always respectful of lava tubes. At Lost Lake, some people have tried to plug the drainage holes and have also thrown trash into the lake over the years, McHugh said.

"We do not want to interfere with natural processes, and we very much discourage that," McHugh said. What's more, even if a plug did work, the lake would likely overflow and flood the nearby highway, she said.

Follow Laura Geggel on Twitter @LauraGeggel. Follow Live Science @livescience, Facebook & Google+. Original article on Live Science.

Until now, no one knew for sure how many lakes exist on Earth.

Blame geography — most of the world's lakes are in places where humans don't live, said David Seekell, an environmental scientist at Umea University in Sweden. "This is something one would have assumed had been done long ago, and was in a textbook somewhere," Seekell said.

Lake size was a liability, too. Millions of lakes are too small for mapmakers to bother charting.

Instead of counting lake by lake, earlier estimates were statistical guesses, based on the number of lakes in a parcel of land or on average lake size. One widely cited study from 2006 estimated the lake total at 304 million. [5 Surprising Facts About Lakes ]

A new study published Sept. 16 in the journal Geophysical Research Letters sidesteps these problems. With high-resolution satellite data and supercomputers to check every cloudless pixel, researchers now have the best count yet of lakes on Earth. The result? There are 117 million lakes in the world.

Yet the bodies of water cover more land (3.7 percent of Earth's surface) than previous studies had predicted. This is because quite a few medium- to large-size lakes were missing from older databases, said Cory McDonald, a research scientist with the Wisconsin Department of Natural Resources, who was not involved in the study. 

"I was surprised that the total surface area they measured was much greater than previous estimates," said Cory McDonald, a research scientist with the Wisconsin Department of Natural Resources, who was not involved in the study. "We knew there problems with the extrapolation methods used to fill the data gap for the small lakes, but previous estimates assumed we had a pretty good handle on the medium- to larged-sized ones," he told Live Science in an email interview. "This study largely puts to rest the long-debated questions of 'How many lakes there are in the world and how much surface area do they cover?'"  

About 90 million of the lakes fall in the smallest size category, measuring 0.5 to 2.5 acres (0.2 to 1 hectare), the study reports. That's equal to a country house lot, a large farm pond or 1.9 American football fields.

"Most lakes are in the far North, and there's actually quite a few of them," said Seekell, a co-author of the new study. "Even if they're small and no one sees them, they are potentially important for global-scale environmental issues like the carbon budget," he told Live Science.

Climate scientists believe lakes influence greenhouse gas levels in the atmosphere. Lakes pump out carbon dioxide and methane — both greenhouse gases — but they can also lock away carbon for centuries by trapping it in their cool bottom muds. Without an accurate count, the role of lakes is difficult to assess, Seekell said.

According to the new results, the world's lakes cover about 2 million square miles (5 million square kilometers), which is 3.7 percent of the land uncapped by glaciers.

Most lakes are in the Northern Hemisphere between 45 degrees north latitude and 75 degrees north latitude. (Think about Canada, Russia, Alaska, Northern Europe and the Great Lakes.) This results from the tectonic scattering of continental landmasses and the past positions of glaciers, the researchers said. There is less land in the southern high latitudes, and the North's sizable plains were scraped by ice age glaciers, leaving behind millions of pothole lakes.

The majority (85 percent) of Earth's millions of lakes are at low altitudes, found at elevations less than 1,600 feet (500 meters) above sea level.

The study excluded the Caspian Sea, the world's largest lake, which covers an area of about 143,000 square miles (371,000 square km). Antarctica and Greenland were also left out of the study. (Antarctica has about 400 lakes buried by ice.)

The researchers plan to freely release the lake database, Seekell said. They also intend to update the count with higher-resolution data from the Landsat 8 satellite.

"Lakes are not static on the landscape, and in some parts of the world, they are disappearing quite quickly," Seekell said.

In certain regions of Russia and Alaska, higher temperatures are causing what was once permanently"frozen ground, called permafrost, to thaw, causing small lakes to dry up. Melting permafrost under a lake is like a cracked tub liner — the lakes drain out from their bottoms. Drought and overuse are also shrinking lakes. In northern China, for instance, more than 100 lakes disappeared during the 2000s from these causes.

Email Becky Oskin or follow her @beckyoskin. Follow us @livescience, Facebook & Google+. Original article on Live Science.

If you like lakes ...

Salty or fresh, lakes are some of the only freely available water sources on land. Aside from rivers and streams, the rest of the world's freshwater is locked up in ice or trapped underground. Yet much remains mysterious about these important natural resources. Here are some new and surprising facts from a recent count of Earth's lakes, published Sept. 16 in the journal Geophysical Research Letters.

Small but significant

There are 117 million lakes on Earth, covering 3.7 percent of the continental land surface. (This doesn't include Antarctica, Greenland or the Caspian Sea). About 90 million of these lakes are less than two football fields in size, or 0.5 to 2.5 acres (0.2 to 1 hectares).

Shoreline living

Added altogether, the shorelines of all the world's lakes roughly measure 250 times the length of the equator. The equator is 7,926 miles (12,756 kilometers) long.

Welcome to the North

Most of the world's lakes are in Canada, Russia, Alaska, Sweden and Finland. Though tropical countries are also flush with lakes, the northern countries lead the lake count, because there is simply less land farther south. Thank the tectonic placement of continents, which scattered most of the world's landmass in the Northern Hemisphere.

Ice Age effects

Most lakes lie low — 85 percent are at elevations less than 1,600 feet (500 meters) above sea level. The reasons are two-fold. First, mountainous terrain restricts lake size. Second, the countries with the most lakes were scraped flat by glaciers during the last ice age.

Splash in time

Lakes come and go. A new lake suddenly appeared near Gafsa, Tunisia, in August 2014, either from a sudden groundwater release or pooling rainwater. In permafrost regions throughout Russia and Alaska, small lakes are drying up as higher temperatures thaw permanently frozen ground (permafrost). In Mongolia, more than 100 lakes disappeared during the 2000s from drought and heavy demand for irrigation.

A volcano that once poked out of a salty lake in Iran now sits on the shores of the drying body of water. 

This extinct volcano sits by Lake Urmia, one of the largest lakes in the Middle East, according to NASA's Earth Observatory, But Lake Urmia is shrinking rapidly. Today, it holds only about 5 percent of its maximum volume. In 2013, only 20 percent of the normal surface area of the lake remained after the dry season, according to an Iranian Department of Environment report from March 2014. 

"The Lake has almost entirely lost its ecological functions, while the ecological conditions of many satellite wetlands is also in great danger," the report concluded. 

Now, the Department of Environment is working to save this salt lake, which is both a national park and a UNESCO biosphere reserve. The lake historically has been home to a dazzling array of birds, including flamingos and pelicans, according to UNESCO. The loss of water has driven many of these birds away. Meanwhile, salty sand storms from the now-dry lakebed are causing health problems for people who live close to Lake Urmia, according to Iran's Department of Environment. Blowing salt can also land in agricultural fields, literally salting the earth and hampering the growth of crops. [8 of the World's Most Endangered Places]

Drought and human use of water have brought the lake to its current state. Dams upstream remove water before it has the chance to reach the lake, and growing populations in the region are ever thirstier. To reverse the trend, Iran's government committed $500 million in March to halt the drying of the lake and instigate recovery. 

Saving the lake will require halting agricultural expansion and instituting water-saving techniques, according to Iran's Department of Environment. Meanwhile, plans are in place to construct dikes and dams to corral what little water is left in the lake in smaller areas, preventing water from flowing into shallow pools where it easily evaporates. 

This image, taken on June 23 by an astronaut aboard the International Space Station, clearly shows some of the green agricultural fields that are contributing to the lake's decline. A white-gray splotch below the fields on the lake's lower shore is the city of Urmia. Across the causeway that cinches the narrow point of the lake is the extinct volcano cone. Salt flats ring what little water is left in the lake and dominate its south side. 

Editor's Note: If you have an amazing nature or general science photo you'd like to share for a possible story or image gallery, please contact managing editor Jeanna Bryner at LSphotos@livescience.com.

Follow Stephanie Pappas on Twitter and Google+. Follow us @livescience, Facebook & Google+. Original article on Live Science.

Suzy Friedman, sustainable agriculture director for the Environmental Defense Fund, contributed this article to LiveScience's Expert Voices: Op-Ed & Insights.

“Lake Erie is sick. A thick and growing coat of toxic algae appears each summer, so vast that in 2011 it covered a sixth of its waters, contributing to an expanding dead zone on its bottom, reducing fish populations, fouling beaches and crippling a tourism industry that generates more than $10 billion in revenue annually.” March 15, the New York Times.

The environmental devastation of Lake Erie is a tragedy. But it’s one that can be reversed. For a decade, the Environmental Defense Fund has been working with farmers and other partners in the Western Lake Erie Basin to reduce fertilizer and sediment runoff. We count on farmers to produce safe and abundant supplies of food, but it’s runoff from farmland that finds its way into the lake and is largely responsible for the devastating algae blooms described by the New York Times. [Why Lake Erie is Under Attack from Algae Blooms]

The key question is: How do we get enough farmers to practice sustainable agriculture so that algal blooms and dead zones — whether in Lake Erie or the Gulf of Mexico — become a thing of the past? How do we actually win?

The answer lies in convincing farmers that sustainable agriculture is not at odds with high yields and profitability.  In fact, practices like more efficient use of fertilizer and the creation (or maintenance) of wetlands and buffer strips, which filter runoff before it can reach streams and rivers, can save farmers money and help improve the quality of their soil.

We call this combination of higher efficiency and filtering practices Growing Returns. It is part of EDF’s larger effort to advance a new era in conservation, one that rewards private landowners for protecting our natural resources. We want farmers and ranchers to be paid for providing benefits — healthy food, clean air and water and wildlife habitat — to all of society.

Meeting this challenge is not optional. We must have highly productive agriculture and healthy natural resources, because, quite simply, we all need to eat and we all need clean and abundant water.

The power of the market

The power of the marketplace can help us reach that goal. Farmers need to know that the market will buy — or even prefer — sustainably grown crops. And who dominates the market? It’s the processors and brand-name companies like Kellogg’s, Coca-Cola, General Mills, Walmart and McDonald's. [Should You Buy Organic?]

With that in mind, the EDF has begun a three-part campaign for the adoption of sustainable agricultural practices, which includes:

• Creating supply: Building on our existing base of farmer networks and trusted farm advisers in a dozen states, and our relationship with a small cadre of influential farmers, we intend to rapidly expand the amount of cropland managed along Growing Returns guidelines.
• Creating demand: The goal is to work with retailers like Walmart, the nation’s largest grocery buyer, to develop buying programs that give preference to agricultural products grown in ways that reduce environmental impacts.
• Easing the way: Collaborating with scientific experts, technology companies and agribusinesses to make it easier, less time-consuming, and less expensive for farmers to produce high yields using more efficient and sustainable practices.

None of this will be easy. For example, it will take time and plenty of trial and error before big companies, farmers and all the middlemen between them learn how to work together. But the payoff — the size of the environmental win in terms of reducing greenhouse gas emissions and reducing algal blooms linked to agriculture — is huge.

The views expressed are those of the author and do not necessarily reflect the views of the publisher.

Lake Tanganyika is not only the longest lake in the world, but also a freshwater Mecca.

Part of the Great Rift Valley, the lake cuts across 420 miles of East Africa and divides four nations. In total, the lake covers about 12,700 square miles and serves as Africa’s largest freshwater reservoir and the second largest in the world, according to the Food and Agriculture Organization of the United Nations.

Considered one of most biologically rich lakes on Earth, Tanganika is home to more than 2,000 species, more than half of which aren’t found anywhere else. And, according to the World Conservation Union, "no place on earth holds such a variety of life."

Follow Life's Little Mysteries on Twitter @llmysteries. We're also on Facebook & Google+.

In an effort to heighten public awareness of rip currents at surf beaches, each year, the National Oceanic and Atmospheric Administration designates the first full week of June as Rip Current Awareness Week, coinciding with the traditional start of the summer vacation season. Rip currents are powerful, narrow channels of fast-moving water, often forming at low spots or breaks in sandbars. They are prevalent along the east, Gulf and west coasts of the U.S., as well as along the shores of the Great Lakes. Moving at speeds of up to 8 feet per second, rip currents can move faster than an Olympic swimmer. According to the United States Lifesaving Association, lifeguards rescue tens of thousands of people from rip currents in the U.S. every year and 80 percent of surf beach rescues are attributed to rip currents. It is estimated that 100 people are killed by rip currents annually. Panicked swimmers often try to counter a rip current by swimming straight back to shore—against the strong current. This puts them at risk of drowning due to fatigue. The safest way to escape from a rip current is to swim parallel to the shore and swim back to land at an angle.

• In Photos: Best US Beaches
• Stunning Sands Gallery: A Rainbow of Beaches
• The World's Biggest Oceans and Seas

A mysterious object was spotted swimming in Iceland's Lagarfljot Lake by a local farmer.

In the video, you can see a snake-like creature slithering through the water. People have been spotting the creature, known has the "Iceland Worm Monster," in the lake since the early 1300s. The creature is said to be larger than a football field and many say they have seenit not only in the water but laying curled up nearby. However, Icelandic researchers have also noted that gases rising from the lakebed often carry debris to the surface creating tangles the could look like a monster floating across the lake.

A catastrophic prehistoric landslide left behind a giant lake along what is now a river in California, researchers have discovered. The landslide also apparently left its mark on the river's trout, in the form of a genetic similarity, the researchers added.

Scientists investigated Northern California's Eel River to study large, slow-moving landslides. The river stretches about 200 miles (320 kilometers) in length and carries extraordinarily large amounts of sediment down its course, the most of any river not fed by a glacier in the contiguous United States.

The researchers analyzed the landscape using a laser range-finding system mounted on an aircraft and hand-held GPS units. They discovered that along a stretch of the river, terraces on adjacent slopes stayed oddly similar in elevation, rather than decreasing downstream as expected.

"This was the first sign of something unusual, and it clued us into the possibility of an ancient lake," said researcher Benjamin Mackey, a geomorphologist at the California Institute of Technology. The stretch they detected most likely represented where a lake with relatively stable shores once was, explaining why the leftover terraces were all of similar elevation.

Evidence of a disaster

Altogether, the researchers found evidence of a giant landslide that dammed the upper reaches of the Eel River with a wall of loose rock and debris 400 feet (120 meters) high about 60 miles (100 km) southeast of Eureka, Calif. The result was a lake about 30 miles (50 km) long. [10 Longest Rivers]

"The presence of a dam of this size was highly unexpected in the Eel River environment given the abundance of easily eroded sandstone and mudstone, which are generally not considered strong enough to form long-lived dams," Mackey said.

Mackey and his colleagues studied isotopes of carbon to date the sediments within this former lake. The isotope carbon-14 is unstable and decays over time, so analyzing the ratio of carbon-14 to other carbon isotopes can shed light on how much time has passed. Results suggest the landslide occurred 22,500 years ago.

These findings match details from other studies that showed a dramatic drop in the amount of sediment deposited from the river just offshore in the ocean at approximately the same time. The landslide probably came from Nefus Peak, which bears a massive landslide scar on its southwestern flank.

"The damming of the river was a dramatic, punctuated affair that greatly altered the landscape," said researcher Joshua Roering at the University of Oregon.

Eventually, the dam was breached, which would have generated a huge flood. Landslide activity and erosion have since erased much of the evidence for the now-gone lake.

Landslide fish

This catastrophic event might explain the genetics of steelhead trout in the Eel River. Past research found a striking relationship between summer-run and winter-run steelhead trout in the river — a genetic similarity not seen among these types in other nearby rivers. The two kinds of fish are usually geographically isolated and don't normally interbreed. The scientists suggest both types of ocean-going trout mingled when the dam blocked their normal migration routes. "This period of gene flow between the two types of steelhead can explain the genetic similarity observed today," Mackey said.

Once the dam burst, the fish would have reoccupied their preferred spawning grounds and resumed different genetic trajectories, Mackey added.

"Although current physical evidence for the landslide dam and paleo-lake is subtle, its effects are recorded in the Pacific Ocean and persist in the genetic makeup of today's Eel River steelhead," Roering said. "It's rare for scientists to be able to connect the dots between such diverse and widely felt phenomena."

This region is not typically considered vulnerable to such large landslide dams, Mackey added. These findings "should encourage reassessment of landslide hazard in landscapes similar to the Eel River area," Mackey told LiveScience.

Mackey, Roering and their colleague Michael Lamb detailed their findings online today (Nov. 14) in the Proceedings of the National Academy of Sciences.

Follow LiveScience for the latest in science news and discoveries on Twitter @livescience and on Facebook.

The flooding in the south last month may be just what a ferocious fish ordered, as scientists say the overflowing Mississippi River may lead to a surge in the giant invasive fish called the Asian carp in new areas of the Mississippi and Missouri river basins.

The flooding stretched from the Midwest to the Gulf of Mexico covering 6.5 million acres of land. This water could serve as a throughway connecting the Mississippi and Missouri rivers to other lakes, bayous and marshes in the basin. The young fish, which float downstream before making their homes in a quiet "nursery," could ride these waters to other, not normally connected bodies of water.

"These fish do really well in a flood situation, it gives their young very good quality nursing habitat. Floods induce the fish to spawn," Duane Chapman at the U.S. Geological Survey, told LiveScience. "It should be a good year for reproduction and a lot of young will get trapped up on the floodplain."

Some of these new stretches may not be suitable for the invasive fish, while others may be just right, researchers say. But once the invasive fish bustle into an environment, they're usually there to stay, eating other fish out of house and home with their voracious appetite. A single Asian carp — weighing up to a whopping 100 pounds (45 kilograms) — can scarf down 5 to 10 percent of its body weight a day in plankton. [Read: 10 Scariest Sea Creatures]

In fact, they have already done damage in the Illinois River and threaten the Great Lakes. The fish's high rates of reproduction and insatiable appetite end up outcompeting native species in these areas. Their populations get so high they can be seen jumping out of the water behind boats, sometimes landing in the boat and hitting a person.

Footloose on the floodplain

Native to Southeast Asia and China, the various Asian carp, including the silver and bighead species, were introduced to the Mississippi and Missouri River basins starting in the 1960s during floods, which caused the overflow of catfish aquaculture ponds where the carp were being kept for their ability to keep algae at bay.

They've made their home in the Mississippi and Missouri rivers and have so far maintained a low population levels. The flooding to lead to an explosion of the population and the fish could spread to new areas, including currently uninhabited tributaries and lakes.

Now, the question on the minds of conservationists and others is: Will the carp survive in these new habitats? The fish are hearty, but low dissolved oxygen or warmer waters could make some of these new habitats unlivable.

"It's reasonable to assume that they are being moved around because there's all that water going through, but it's difficult to know if after they are moved they will thrive," Mike Kaller, at Louisiana State University, told LiveScience.

Similar flooding in 2008 didn't show this grand expansion of the carps' range, Kaller said, though this time around the waters are flowing through the open spillway, which could expand the population into Lake Pontchartrain and Lake Maurepas. A major flood in 1993 did end up increasing carp populations, though, said Chapman.

Reproductive impairment

Even if the fish do survive in these habitats, many of them won't be suitable for reproduction, which requires a swiftly moving water source to carry the eggs and larvae downstream. The fish can live for up to 25 years, though, especially in an area with few predators. Even if they can't reproduce, they will still wreak havoc on the ecosystems for a long time. 

"In those bodies of water they won't spawn, but they will grow up in there. They can live 25 years, so there will be carp in those lakes for a long time," Chapman said. "They will compete with the native fishes, if there is a shortage of food."

Mark Pegg, at the University of Nebraska, notes that the floods will take several months to fully recede, giving the fish enough time to find their way back to the river when the water starts getting low. Because they will have access to all of these new habitats, however, the population will most likely increase starkly. If these fish make it back to the rivers as the floodwater recedes, the overpopulation will be tremendous, he said.

"On the Missouri they are talking about sustained high water through the summer, the backwaters will be open to them for a pretty long period of time, my guess is that a pretty substantial number would make it back," Pegg told LiveScience. "That may not be the case on the Mississippi, once the water goes down the fish will probably be trapped."

The carp aren't the only ones hitching a ride on the floodwaters. Native species are spread the same way, and the flood will give them access to new habitats as well. "They might also have a good reproductive year," Pegg said. "Maybe they can eat some of the small Asian carp before they get too big. Might help control some of the non-native population."

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You can follow LiveScience staff writer Jennifer Welsh on Twitter @microbelover. Follow LiveScience for the latest in science news and discoveries on Twitter @livescience and on Facebook.

Plants living inside an animal? Yep, that's what scientists found when peering inside a spotted salamander: live green algae.

While the two species may seem like strange bedfellows, their intimate, one-of-a-kind relationship is helpful for both.

"We realized that they weren't just embedded in the tissues but actually inside the cell as well, and this came as a really big surprise," said study researcher Ryan Kerney at Dalhousie University in Halifax, in the Canadian province of Nova Scotia. [Image of salamander embryos with algae]

Such a mutualistic relationship (meaning it's helpful for both species involved) has been observed between algae and several invertebrates. However, this was the first time researchers saw algae invading an animal with a backbone. Researchers previously thought it wasn't possible for the algae to make their way into the salamander's tissues, because the plants would need to evade the vertebrate's advanced immune system, which typically launch an attack on any foreign invader.

Escaping immunity

The vertebrate immune system stops invaders, but it seems the green algae are able to avoid it by sneaking in before the animal develops fully. "Salamanders would be a good candidate as an exception because they have a poor immune system; they accept grafts from other species and it's thought to correlate with their ability to regenerate," Kerney told LiveScience.

The algae not only enter the embryo's egg sack, they get inside the individual cells of the embryo, cells that eventually become the adult salamander. In the embryo the algae were detected in many different parts, including the optic cup (which becomes the eye), the epidermis (which ends up as the skin) and the neural tube (a k a the early brain structures).

Once the algae get past the salamander's immune system, Glenn Tattersall, a researcher at Brock University, said, he isn't surprised the algae make it into the cells. "When you look at the salamander larvae — I call them pea soup — they are growing in a broth of algae," Tattersall, who wasn't involved in the study, told LiveScience. "It's not surprising that they will be in the tissues."

Breathing easier

Here's how the relationship works, the scientists figure: The salamander egg clutches are big gelatinous masses of about 100 eggs, which oxygen (an essential element for cell survival) has difficulty penetrating. When the algae are present, they keep the oxygen levels high, even in the middle of the mass, by using the salamander's carbon dioxide waste for photosynthesis (the process that, with the help of the sun's energy, turns carbon dioxide into sugars for growth, and gives off oxygen as a byproduct.) The algae also process the excess nitrogen that the embryo gives off.

Embryos infected with the algae develop faster, are more likely to survive and end up larger than their algae-less counterparts.

Most of the algae are shed by the time the salamander reaches adulthood, but the researchers noticed that the algae are still present in the reproductive tracts of some adults, and this may be one way they enter the embryos. "This may be passed on from one generation to the next or it may be acquired from the environment," Kerney said. "We suspect it may be a combination of both."

The algae haven't been found anywhere else in the environment — though not many people are looking, Kerney said.

"This suggests that the algae live in the salamander for its entire life," Tattersall said. "It only becomes symbiotic when it's exposed to light in the eggs."

The study was published yesterday (April 4) in the journal Proceedings of the National Academy of Sciences.

You can follow LiveScience staff writer Jennifer Welsh on Twitter @microbelover.

Lake Neusiedl, straddling the AustrianHungarian border, is the largest steppe lake in Central Europe.

Neusiedl covers an area around 120 square miles (315 square kilometers), with 90 square miles (240 sq km) situated in Austria and 30 square miles (75 sq km) in Hungary.

Lake Neusiedl, called the 'Sea of the Viennese' due to its close proximity to Vienna, has totally dried up at least 100 times since it formed around 16,000 B.C. Since the lake provides humidity and temperature buffering, the drying-up of the seabed causes major environmental disruptions. The Austro-Hungarian Water Commission has been controlling the water level via a dam since 1956.

Reeds, ponds and wetland areas that provide important habitat for fauna and flora as well as for migratory birds surround Lake Neusiedl, which is a protected wildlife sanctuary. The unique landscape of the Lake Neusiedl region, which encompasses an area of around 290 square miles (750 sq km) around the lake, was designated a UNESCO World Heritage Site in 2001.

The Leitha Mountain range, called 'Leithaberg' by locals, is visible in green northwest of the lake. The soils of the mountains, which are covered by dense deciduous woodland, are dominated by slate and marine limestone.

The Seewinkel area, the largest inland salt region in Austria and one of the most important in Europe, is located east of the lake. As visible, this area is characterised by numerous saline alkaline lakes scattered among grazed meadows.

The sunny climate of the area, the soil and the lake's ability to moderate extreme climate provide optimal conditions for the wine industry; today, wineries are located all around the region.

The famous Danube River , one of Europe's main traffic arteries, is visible running across the top of this image, taken by a European Space Agency satellite.

• The Great Lakes: North America's Third Coast
• The World's Biggest Oceans & Seas

Measured by surface area, the Caspian Sea is the world's largest inland water body.

The sea covers roughly 143,200 square miles (371,000 square kilometers) and borders five countries: Iran, Russia, Kazakhstan, Turkmenistan and Azerbaijan. To the ancient Greeks and Persians, the lake's immense size suggested it was an ocean , hence its name.

NASA's Terra satellite took this image of the Caspian Sea on June 4, 2010. The color of the Caspian Sea darkens from north to south, thanks to changes in the lake's depth and perhaps sediment and other runoff. The northern part of the lake is just 16 to 20 feet (5 to 6 meters) deep. The southern end, however, plunges more than 3,300 feet (1,000 m).

Just as the lake reaches a greater depth in the south, the nearby land reaches a greater height. The mountains of northern Iran line the southern end of the giant lake, and emerald green vegetation clings to those mountain slopes. In marked contrast to the mountains, sand seas line the southeastern and northern perimeters of the lake, and marshes occur along the lake shores in Azerbaijan to the west.

Multiple rivers empty into the Caspian Sea, the Volga, which runs through central Russia, being the largest.

Lacking an outlet, the Caspian Sea loses water only by evaporation, leading to the accumulation of salt. Although a lake, the Caspian is not a freshwater lake; the water delivered by the Volga River minimizes the lake's salt content at the northern end, but the Caspian grows more saline to the south. Kara-Bogaz-Gol is a saline inlet along the lake's eastern perimeter.

Geological research indicates that the Caspian Sea was once part of a prehistoric sea known as the Paratethys, according to a NASA statement. Tectonic forces uplifting the land and a drop in sea level left the Caspian landlocked more than 5 million years ago. Climate shifts have alternately raised and lowered the lake's water levels, sometimes nearly drying it out completely.

• The World's Biggest Oceans and Seas
• Iran's Salty Lakes Wax and Wan

Earlier this month, the Panama Canal closed for the third time in its 96-year history, when two artificial lakes linked to the canal, Gatún and Alajuela, reached their highest-recorded water levels.

Authorities closed the canal for 17 hours.

This image was taken on Dec. 17 by NASA's Earth Observing-1 satellite, several days after the canal's temporary closure. The image is of Lago Alajuela, the lake that serves as a reservoir for the Panama Canal , which lies to the southwest.

This image has been rotated so north is to the right. The canal lies off the top left corner of the image.

Ranging in color from dull green to tan, Lago Alajuela's waters appear choked with sediment, contrasting sharply with the surrounding green forest. This is most likely due to torrential rains, which can erode soils and deliver heavy sediment loads to streams, rivers and lakes. In Panama this is nothing unusual, as the rainy season lasts from May to January.

Usually the Panama Canal depends on huge quantities of water. Each trip through the canal requires roughly 52 million gallons (197 million liters) of water, but the heavy rains in early December proved to be too much for the region. The same rains that raised Lago Alajuela's water level and filled it with sediment also forced thousands of residents to evacuate, washed out roads, and caused deadly landslides .

• Great Lakes Seen Clearly From Space
• Is a Major Earthquake Looming for Panama and its Canal?
• The Great Lakes: America's Third Coast

This image, taken by an astronaut shows Pyramid Lake in western Nevada, roughly 40 miles (64 kilometers) from Reno.

Pyramid Lake is a remnant of the ancient and much larger Lake Lahontan, which formed during the last ice age when the regional climate was significantly cooler and wetter.

Pyramid Lake and the now-dry Lake Winnemucca, to its left, are two of seven smaller lakes that together formed a large single Lake Lahontan when water levels were higher. At its peak volume during the late Pleistocene Epoch (approximately 15,000 years ago), Lake Lahontan covered much of western Nevada and extended into California.

The deepest part of Lake Lahontan survives today as Pyramid Lake with a depth of 890 feet (270 meters). The lake also acts as the geographic sink for the Truckee River.

Pyramid Lake takes its name from one such pyramid-shaped deposit of tufa, rock formed by the precipitation of calcium carbonate from spring water, lake water, or a combination of the two. Over time, these deposits develop a wide variety of forms such as mounds, towers, sheets and reefs.

The tufa is exposed when water levels drop due to changes in regional climate, the diversion of water for human use, or both (Mono Lake in California for example).

The photograph also captures sunglint light reflected off of a water surface back towards the observer on opposite ends of the lake. Two large spiral whorls are visible in sunglint at the northern end, likely the result of wind patterns that disturb the water surface and cause localized variations in the amount of light reflected back to space.

• Great Lakes Seen Clearly from Space
• Observing Earth: Amazing Views from Above
• What's the Deepest Lake in the World?

Mother Earth could have parted the Red Sea, hatching the great escape described in the biblical book of Exodus, a new study finds.

A strong east wind, blowing overnight, could have swept water off a bend where an ancient river is believed to have merged with a coastal lagoon along the Mediterranean Sea, said study team member Carl Drews of the National Center for Atmospheric Research. While archaeologists and Egyptologists have found little evidence that any events described in Exodus actually happened, the study outlines a perfect storm that could have led to the 3,000-year-old escape.

"People have always been fascinated by this Exodus story, wondering if it comes from historical facts," Drews said. "What this study shows is that the description of the waters parting indeed has a basis in physical laws."

Drew and his colleagues used models that showed that a wind of 63 mph (101 kph), lasting for 12 hours, would have pushed back waters estimated to be 6 feet (1.8 meters) deep. This would have exposed mud flats for four hours, creating a dry passage about 2 to 2.5 miles (3.2 to 4 kilometers) long and 3 miles (4.8 km) wide.

To match the account in the Bible, the water would have to be pushed back into both the lake and the channel of the river, creating barriers of water on both sides of newly exposed mud flats, which is exactly what the models show could have happened.

As soon as the winds stopped, the waters would come rushing back. Anyone still on the mud flats would be at risk of drowning.

As the Bible story goes, Moses and the fleeing Israelites were trapped between the Pharaoh's advancing chariots and a body of water that has been variously translated as the Red Sea or the Sea of Reeds. In a divine miracle, a mighty east wind blew all night, splitting the waters and leaving a passage of dry land with walls of water on both sides. The Israelites were able to flee to the other shore. But when the Pharaoh's army attempted to pursue them in the morning, the waters rushed back and drowned the soldiers.

"The simulations match fairly closely with the account in Exodus," Drews said. "The parting of the waters can be understood through fluid dynamics. The wind moves the water in a way that's in accordance with physical laws, creating a safe passage with water on two sides and then abruptly allowing the water to rush back in."

A similar phenomenon is found on Lake Erie near Toledo, Ohio, where water will recede several feet when a strong wind blows through, Drews told OurAmazingPlanet.

The research shows how strong and persistent winds can affect water depths, and will also help with understanding storm surges, Drews said.

By pinpointing a possible site south of the Mediterranean Sea for the crossing, about 75 miles (121 km) north of the Suez reef, where other groups have focused, it also could be of benefit to experts seeking to research whether such an event ever took place.

The study is detailed in the online journal PLoS ONE.

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This article was provided by OurAmazingPlanet, a sister site to LiveScience.

Lake Tanganyika, the second oldest and the second-deepest lake in the world, is warmer than it has been in more than 1,500 years, a new analysis released today finds. 

The east African rift lake has experienced unprecedented warming during the last century, and its surface waters are the warmest on record. The warmer waters are linked to a decrease in the lake's productivity, likely affecting fish stocks upon which millions of people in the region depend, the study found. 

Rift lakes are created when two pieces of continental crust expand apart and eventually become ocean basins over millions of years. Lake Tanganyika is 13-million years old and nearly a mile deep (1.5 kilometers). The world's deepest lake is Lake Baikal in Siberia at 1,642 meters (5,387 feet).

Researchers took core samples from the lakebed that laid out a 1,500-year history of the lake's surface temperature, the first record of temperature variability for the lake over this time span. The rift is part of a giant crack in Africa that will eventually create a new ocean.

A high average temperature of 78.8 degrees Fahrenheit (26 degrees Celsius), measured in 2003, is the warmest the lake has been in that millennium and a half. Lake Tanganyika also experienced its biggest temperature change in the 20th century, which has affected its unique ecosystem that relies upon the natural conveyance of nutrients from the depths to jumpstart the food chain upon which the fish survive.

"Our data show a consistent relationship between lake surface temperature and productivity (such as fish stocks)," said geologist Jessica Tierney of Brown University."As the lake gets warmer we expect productivity to decline, and we expect that it will affect the fishing industry."

Warming causes productivity in the lake to decline because it creates stark differences in water density — the water at the surface become much warmer than the water at depth, and cold water is denser than warm water. The warmer, less dense surface waters are less likely to overturn and mix with the cooler waters below, so it becomes more difficult for winds to churn the water and cycle nutrients and oxygen between the lake's surface and depths. 

An estimated 10 million people live near the lake, and fishing is a crucial component for the region's diet and livelihood: Up to 200,000 tons of sardines and four other fish species are harvested annually from Lake Tanganyika, a haul that makes up a significant portion of local residents' diets, according to a 2001 report by the Lake Tanganyika Biodiversity Project. 

Lake Tanganyika is bordered by Burundi, the Democratic Republic of Congo, Tanzania, and Zambia — four of the poorest countries in the world, according to the United Nations Human Development Index. 

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