Invasive Mussel Not Harmed by Toxins, Invades Freshwaters of Europe, North America

Oct. 3, 2013 — While most freshwater mussels react stressfully and weaken when exposed to the toxins in blue-green algae in their water environment, the little zebra mussel is rather indifferent. It is not affected by the toxins, and this helps it outmatch stressed and weakened mussels, report researchers from the University of Southern Denmark. This is bad for the biodiversity, and in some countries the superior zebra mussels imposes great costs to the industry.

At first glance it looks like good news: Researchers have discovered that the freshwater zebra mussel (Dreissena polymorpha) is not damaged from exposure to toxins from blue-green algae (cyanobacteria) and other toxic substances that could constitute a problem for freshwater mussels. On the contrary, they seem completely unaffected and thus they manage significantly better in a water environment than other freshwater mussels -- and this is what worries the scientists: Many places in Europe the zebra mussels have already outmatched other mussel species and in the U.S. they are so widespread that they pose a threat.

"Zebra mussels live in large colonies in the Great Lakes in the United States, and they are a huge problem. They need something hard to attach themselves to and often they find a suitable surface on the inside of the pipes carrying water from the Great Lakes into factories and other industries along the lake. Often they sit so close that they block the water intake," explains associate professor Claudia Wiegand, who studies environmental stress physiology and aquatic toxicology at the Department of Biology, University of Southern Denmark.

Efforts to prevent the zebra mussels from attaching themselves to the pipes and remove those attached have already cost several million dollars.

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