Glowing ring of plankton surrounding New Zealand islands linked to deadly underwater plateau — Earth from space

This dazzling satellite photo shows a glowing ring of plankton surrounding a remote group of New Zealand islands. The illuminated landmasses are hotspots for deadly whale stranding events, which are tied to the same underwater structure that birthed this spectacular bloom.

The gleaming ring encircles the Chatham Islands — a group of 10 islands in the Pacific Ocean around 520 miles (840 kilometers) west of Christchurch, on the east coast of New Zealand's South Island. The largest of those islands, Chatham Island and Pitt Island, are approximately 36 miles (58 km) and 9 miles (15 km) across, respectively. (The other landmasses are much smaller and are not clearly visible in the image.)

The Chatham Islands are surrounded by the Chatham Rise — a shallow underwater plateau that extends up to 900 miles (1,450 km) from the South Island's east coast. This hidden structure acts like a giant ramp that funnels cold, nutrient-rich waters to the ocean's surface. In the summer, warmer seasonal currents mix with this nutrient-rich water, providing the perfect conditions for algae to bloom.

The circular bloom in the photo was one of the largest in recent decades. It consists mostly of coccolithophores, a group of photosynthetic plankton, or "phytoplankton," that convert sunlight into energy and surround themselves with intricate calcium carbonate armor.

The satellite image was captured with a special near-infrared filter, which likely enhanced the algae's vivid hues. However, the blooming microorganisms would have been clearly visible to the naked eye from space, according to NASA's Earth Observatory.

Phytoplankton are the base of the pelagic (open-water) food web, similar to plants' role in terrestrial environments. As a result, the Chatham Islands are marine biodiversity hotspots that are home to various animals, including penguins, albatrosses, seals and sea lions, as well as commercially important populations of cod and lobsters.

At least 25 species of whales and dolphins, or cetaceans, are also drawn to the islands to feed, including orcas (Orcinus orca), sperm whales (Physeter macrocephalus) and pilot whales (Globicephala), according to New Zealand's Department of Conservation (DOC). However, this is not always a good thing for the visitors.

Large groups of cetaceans often get disoriented in the shallow waters and can end up accidentally swimming too close to shore and getting trapped as the tide goes out, which is often fatal without human intervention.

Chatham Island has experienced multiple strandings over the past few years, including an event in October 2022 when nearly 500 pilot whales were euthanized on Chatham Island after washing up over the space of around four days, according to a DOC report. In 1918, more than 1,000 pilot whales are also believed to have died there after washing ashore, which remains the most deadly whale stranding event in recorded history. (Pilot whales are particularly prone to stranding because they are highly social, so an entire pod can be dragged into danger by a single injured or disoriented individual.)

Cetaceans are not the only creatures that have met an untimely end on the Chatham Islands. The archipelago was previously home to at least eight endemic bird species that have since gone extinct, including the Chatham penguin (Eudyptes warhami). Most of these species disappeared between 150 and 200 years ago due to the island's first human settlers, who arrived there from Polynesia in the 15th century.

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