This parasite, which scientists have found can almost totally destroy the spawning success of the small sunbleak minnow, Leucaspius delineatus, may pose threats to the diversity and stability of freshwater ecosystems, and is genetically very similar to a parasite that can be deadly to salmon, researchers say.

The findings were published today in the journal Nature by researchers from Oregon State University, the Winfrith Technology Centre in England, Idaho State University and the Weymouth Laboratory in England.

"This solves a mystery that fisheries researchers have been studying for decades, about why sunbleak minnows have been disappearing from Europe, where they were once quite common," said Michael Kent, a professor of microbiology and director of the Center for Salmon Disease Research at OSU.

"And to find a parasite that can have such a devastating effect on spawning success is a little alarming," Kent said. "There are still a lot of unanswered questions here, including knowledge of the host range of the parasite. It's unknown if it would be pathogenic to other groups of fishes, such as salmonids."

The minnows involved, both the invasive species and those dying out, are rather small, grey, innocuous fish no more than a few inches long that do not by themselves have any major commercial value, Kent said. But they are an integral part of the biodiversity of freshwater streams and lakes across Europe, and form an important part of the food chain for other fish, he said. The European sunbleak is now listed as a threatened species among European freshwater fish.

"This is another aspect of the concerns about invasive species that you always have to watch for," Kent said. "The new minnows that moved in did n
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Contact: Michael Kent
michael.kent@oregonstate.edu
541-737-8652
Oregon State University
22-Jun-2005