A local environmental group is looking for a culprit after discovering thousands of dead clams washed up on the shore of a lake in Whiteshell Provincial Park. "You can't walk on the shore, along the edge of the water, without stepping on them," said Wilderness Committee local director Eric Reder, who described a "clumpy and fibrous" algae bloom on Meditation Lake.

A canoeist told him about the die-off of freshwater clams and a foul smell on the lake a couple of weeks ago, and Reder said he went earlier this week to see for himself.

The shallow lake is accessible only to hikers. Visitors willing to portage their canoe can use the body of water to access the deeper Horseshoe Lake, which is popular for fishing.

Meditation Lake is also close to the site of a logging operation involving trees that were knocked down in a wind storm in the park last year.

The Wilderness Committee is unhappy with logging in the Whiteshell and believes loggers are taking far more trees than necessary. While the group wonders whether there's a link between logging and lake contamination that could have led to the unusual die-off, Reder said it's impossible to prove.

He said he took water samples and sent them off to a private lab for analysis, but believes the die-off likely happened in late June or early July.

University of Manitoba parasitologist Lane Graham, whose areas of interest include clams, said he's only aware of one other major clam die-off, tied to cold temperatures on the Red River.

He said it's impossible to speculate without seeing the lake, but pointed out that freshwater clams "are frequently used as indicators of various environmental toxins" because they bioaccumulate, meaning they build up concentrations of toxins in their systems.

"Normally if something is strong enough to kill off the clams, you've normally got something else dead there as well," like fish or snails, he said.

A government spokesman said Manitoba Water Stewardship just learned of the dead clams and will investigate.