Climate Change May Spur Algae Infection Along the East Coast

"Rock snot" is taking over East Coast waterways as climate change speeds its growth.


In 2007 an invasive algae, Didymosphenia geminata, known as didymo, or “rock snot,” was identified in the cold waters near Hancock, New York. It grew in a thick mat, sometimes eight inches thick, covering rocks and the river bottom. The brownish-tan plant is characterized by its broad stalk that composes as 95% of the plant structure. It splits into more plants as it grows, quickly matting the bottom of the river.

Didymo is commonly referred to as β€˜rock snot’ because of how it looks, and it grows so thick that it interferes with the lifecycle of the aquatic species in the river. But what began as a didymo infection in New York has now become an infection spreading southwest into the Delaware River to the Delaware Gap Recreation area.

“It is alarming,” said Tracy Carluccio, deputy director of the Delaware Riverkeeper Network. “It can have a bad effect on fish and wildlife and critters that live at the bottom of the streams. It can have water-quality implications.”

So how did the didymo infestation make it so far downstream? Ecologists for the recreation area have some clues.

The aggressive algae thrive best in calm, stable waters and as the water quality changes in our rivers due to pollution and climate change, the algae can spread. It’s also easy to carry the algae spores from one body of water to another. If they catch to a fisherman’s boots or the bottom of a boat if it scrapes against a rock, the algae can be carried to another lake or stream. Ecologists also believe that early spring flooding may have boosted the algae further downstream.

This isn’t the only algae change to hit the news. Off the coast of New Jersey, an algae bloom hit record proportions. Easily visible from the town of Woodmere, the algae stretches along most of the 127-mile coast, sometimes 50 miles across at parts. Although it is part of the established ecosystem, this year brought a larger bloom than ever before and could be seen with satellite images from the National Oceanic and Atmospheric Administration (NOAA).

While both these algae types may not affect humans adversely, their impact on aquatic life is significant. The surplus algae interfere with how insects and microorganisms lay and hatch eggs which impact the larger species that feed off them. Algae change the composition and quality of the water which further harms the aquatic ecosystem.

Environmentalists are urging fisherman and boaters to wash all clothing and equipment with a mild soap and water solution and then advise them to leave clothing to soak before using it again. This will kill any algae spore present and will ensure that no other water is contaminated.

Photo credit: Wikipedia

Written by Chris Keenan

Chris Keenan is a green and general blog writer. He also maintains a personal cooking blog:


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  1. Chris,
    I have to take exception to your hypothesis. All of the known science on didymo points to its proliferation in cold water streams. Evidence shows that when a stream warms up, the didymo bloom is erased. Now, if you want to contend that climate change is turning our watersheds colder, your hypothesis might stand up. As a matter of fact, didymo thrives in nutrient poor water….The largest outbreaks have been in the coldest, most pristene streams and rivers.

  2. Hi John,
    It isn’t yet known just what has changed to allow didymo to take on the characteristics of an invasive species. However regarding you question on climate changes effect: “It has also been suggested that Didymospheniamay proliferate because of increased exposure to ultraviolet (UV) radiation. This could occur because the UV reduces the grazer populations that normally limit accumulation of Didymosphenia, or because Didymosphenia outcompetes other algal species under increased UV conditions. Under this theory, warmer winters and reduced flows may favour growth of Didymosphenia – in other words, climate change may be linked to the current
    range expansion being observed for Didymosphenia (Kilroy, 2004)”
    and this study published in 2004 by National Institute of Water & Atmospheric Research in NZ.
    I really hope research identifies some other cause, something we can more easily correct than global warming. But for now, we can’t rule it out.

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