Science sheds light on rivers' algae infestation
Researcher suspects fishermen spread the goo
Judith Lavoie
CanWest News Service
Tuesday, April 10, 2007
VANCOUVER ISLAND - Years of research has failed to discover why a tiny freshwater algae nicknamed rocksnot started covering Vancouver Island river bottoms in thick, slimy goo.
"Vancouver Island has become the epicentre of this infestation," said Environment Canada freshwater ecologist Dr. Max Bothwell, who was initially called in to study the problem by the provincial government in 1993.
Brown and slimy with a distinct resemblance to sewage sludge, the algae Didymosphenia geminata has held a mysterious fascination for Bothwell for almost two decades.
"I really don't like calling it rocksnot," he said.
Instead, last year, a group of international scientists decided to start referring to it by the more flattering name of Didymo.
Bothwell, who works as a research scientist at Nanaimo's Pacific Biological Station and is an adjunct professor at Malaspina University-College, is a world expert on rocksnot and believes he may have uncovered the secret of why the freshwater algae are suddenly spreading out of its traditional northern hemisphere territory and appearing in pristine rivers in New Zealand.
Almost every river system in central Vancouver Island is now affected by Didymo, although it usually dies off in winter and may not reappear the next year.
Part of the mystery clarified for Bothwell after the surprise appearance of Didymo in New Zealand.
"It was clearly introduced. It may have come from Vancouver Island," he said.
Bothwell started looking at fishing information and figured out that there could be a connection between the spread of the blooming algae and fly fishermen wearing waders with felt bottomed soles, which are the perfect method of transportation for micro-organisms.
In New Zealand fishermen are now being told to wash their gear in hot water or freeze their waders after use to kill off the algae. Bothwell wants to see public education and similar rules in B.C.
There is an increased sense of urgency in Canada as Didymo has now been found in Quebec and New Brunswick, he said.
Didymo is not dangerous to humans, but it can affect fish. In other countries, it has devastated trout runs.
© The Vancouver Sun 2007
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Topic: Fly fishers spread slime (Read 1165 times)