An unsolved phenomena that is currently being investigated: thousands of dead fish and seagulls washed to shores of Canada's Lake Erie. Scientists are testing samples from the dead animals, trying to decipher what caused the deaths.
Despite the uncertainty, one explanation is a phenomenon called 'lake inversion':
When a lake is 'inverted' cold water, which carries less oxygen than warmer water because it is heavier, is found close to the surface where most of the fish are. The lack of oxygen causes the animals to suffocate.
We'll see what later reports say.