Nutrient bioassays on diatoms from the large lakes of the Greater Yellowstone Ecosystem

摘要

Diatom clones of seven species used in the studies were isolated from large lakes of the Greater Yellowstone Ecosystem prior to the experiments. Bioassays were performed using a semicontinuous dilution technique for 21 to 24 days, reaching a steady state in total biovolume. The growth rate was 0.05—0.08 day~(-1) and cultures were maintained at 10℃ on a 14:10 L:D cycle at 80-100 nmol photons m~(-2)s~(-1). In Yellowstone Lake, diatoms responded to N and N+P additions, while in Jackson and Lewis Lakes N+P additions resulted in the largest biovolume responses. Silicon additions had no effect. Fragilaria crotonen-sis became dominant with only N additions, while Stephanodiscus minutulus became dominant when N+P were added.