Yuck! Photos of 'Rock Snot' Algae Infestations
Get the world’s most fascinating discoveries delivered straight to your inbox.
You are now subscribed
Your newsletter sign-up was successful
Want to add more newsletters?
Delivered Daily
Daily Newsletter
Sign up for the latest discoveries, groundbreaking research and fascinating breakthroughs that impact you and the wider world direct to your inbox.
Once a week
Life's Little Mysteries
Feed your curiosity with an exclusive mystery every week, solved with science and delivered direct to your inbox before it's seen anywhere else.
Once a week
How It Works
Sign up to our free science & technology newsletter for your weekly fix of fascinating articles, quick quizzes, amazing images, and more
Delivered daily
Space.com Newsletter
Breaking space news, the latest updates on rocket launches, skywatching events and more!
Once a month
Watch This Space
Sign up to our monthly entertainment newsletter to keep up with all our coverage of the latest sci-fi and space movies, tv shows, games and books.
Once a week
Night Sky This Week
Discover this week's must-see night sky events, moon phases, and stunning astrophotos. Sign up for our skywatching newsletter and explore the universe with us!
Join the club
Get full access to premium articles, exclusive features and a growing list of member rewards.
Yuck!
Didymo, also known as "rock snot," is a type of freshwater algae that clumps on rocks and invades river bottoms.
Tendrils of Rock Snot
Didymo, also known as "rock snot," is a type of freshwater algae.
Lots of Clumps
Clumps of didymo, or rock snot, can be seen attached to this rock.
Rock Snot Blooms
Rock snot is so-called because of the way its tendrils attach to rocks in rivers.
Covering the River Floor
A didymo mat several centimeters thick covers the rocky substrate of the crystal clear Duval River. Thick and extensive blooms are known to affect the structure and function of river ecosystems. Didymo’s recent proliferation is likely unprecedented in eastern Canada and elsewhere around the world.
Hands Full
In 2013, the Duval River (tributary of the renowned Bonaventure River) experienced the most severe didymo bloom ever recorded in eastern Canada and comparable to extreme blooms observed over the past decade in New Zealand. In eastern Canada, recent climate warming may play a role in the establishment of conditions that favor didymo proliferation. Other Canadian provinces where didymo blooms have been identified as a concern include British Columbia and Alberta.
Spreading Rock Snot
Scientists think rock snot moves into new areas via contaminated fishing equipment and boats.
Get the world’s most fascinating discoveries delivered straight to your inbox.
Small Scale
A didymo cell and extracellular stalk produced through asexual reproduction.
Dried Rock Snot
Dried masses of didymo above the water line in Arkansas.
Didymo Cell
A scanning electron micrograph of a cell of didymo, a type of freshwater algae.

Denise Chow was the assistant managing editor at Live Science before moving to NBC News as a science reporter, where she focuses on general science and climate change. Before joining the Live Science team in 2013, she spent two years as a staff writer for Space.com, writing about rocket launches and covering NASA's final three space shuttle missions. A Canadian transplant, Denise has a bachelor's degree from the University of Toronto, and a master's degree in journalism from New York University.
