Blue-Green Algae Toxicity in Black Lake, Kootenai County, Idaho

摘要

Black Lake in northern Idaho has experienced massive late summer and fall growths of toxic algae, Nostoc commune. Fatal toxicity to cattle and small mammals has resulted in three of the last four years. Environmental and phytoplankton parameters were monitored during summer and fall 1984 in order to delineate conditions required to cause toxicity. No toxic bloom occurred in 1984 despite favorable conditions in the form of high algal growth potentials and N:P ratios favoring blue-greens. Possible reasons for the absence of a toxic bloom include climatological trends and stratification pattern. Lack of a well developed hypolimnion along with the absence of a protracted calm, bright, and warm fall may override favorable conditions present, precluding a toxic bloom.