(SOURCE) A greenish alga called Didymo — short for its scientific name Didymosphenia geminata — is spreading like a virus in freshwater rivers, lakes and streams throughout the world, leaving river bottoms and rocks coated in thick, tangled mats of gooey slime.
Largely unknown until the 1990s, the alga species also known as “rock snot” was discovered on western Canada’s Vancouver Island in 1988. By the mid-2000s, it began appearing further south — popping up in Tennessee in 2005 — and now it has spread to Europe, Asia and New Zealand.
It has caused huge headaches for boaters and fishermen, forcing local governments and environmental groups to conduct costly and difficult cleanups, the BBC notes. And when Dydimo populations explode in huge algal blooms, they can deplete a river’s oxygen, suffocating the rest of the fish and crustaceans living there.
Many have worked with natural resources departments across the U.S. and internationally to promote rules for treating boats, fishing equipment and water clothing like wading boots for biosecurity risks (like the warnings and guidelines posted here at the New York Dept. of Environmental Conservation).
But a study published this spring in the scientific journal Bioscience turns all of that on its head. Far from invading places where it previously had not been present, the study says, Didymo may have always been present in lakes, rivers and streams around the world, and only now are environmental changes triggering its sudden emergence.
“Claims that the recent blooms are caused by either a novel stalk-producing genotype or a single genotype rapidly introduced worldwide have been widely publicized and readily accepted,” write the study’s co-authors, Brad Taylor of Dartmouth College and Max Bothell of Environment Canada.
“However, few data support these claims,” they add.
Instead, they found that fossilized forms of the Didymo diatoms have been discovered in at least 11 countries in Europe, Asia and North and South America. The only continents where rock snot hasn’t been found, they add, are Africa, Antarctica and Australia.
This is counter-productive, the scientists say, because millions of dollars and hundreds (perhaps thousands) of man-hours are spent combating what is actually a native species in many areas, money and time that could be spent more wisely.
So why are Didymo blooms occurring in so many places today? The answer lies not in the water systems where the diatom is producing so explosively, but in what goes into those systems.