Lake eutrophication and the limiting CO₂ concept: a simulation Study

Summary

A computer model of phytoplankton population dynamics is used to simulate artificial eutrophication of Canadian Shield experimental lake 227. The model predicts seston C, N, and P concentrations of 600–750, 40–50, and 1–3 μg/l before fertilization, and 3000–3500, 550–700, and 30–50 μg/l after weekly nutrient addition, in accord with actual findings (Schindler 1971 b). Simulations suggest that at nutrient loading rates and CO₂ invasion rates measured in 227, N and P limited standing crop, but DIC concentrations affected plankton composition and species succession. Rates of nutrient addition three times higher than that used by Schindle produced carbon-limitation of phytoplankton standing crop. The high nutrient loading rates and low CO₂ invasion rates necessary for this latter limitation, however, suggests that its natural occurrence should be unusual, but predictable.