Phosphorus release from lake sediments as affected by chironomids

Summary

To determine if Chironomus riparius affected P release from lake sediment, we conducted two experiments with filtered lake water and Lake Mendota mud in darkness and under aerobic conditions. Six days after chironomids were added, median levels of total P in tubes with 0, 10 and 25 chironomids were 28, 92 and 114 μg/l, respectively. Mortality of chironomids was high (∼ 40% during the first week of the second experiment) and may explain the gradual decrease in P observed in the first experiment.

The maximum observed release rate of TP was 6mg/m²/day; if this rate was maintained in Lake Mendota during summer, it would provide a steady and significant amount of P to the community.