Effects of nutrient loading and insecticide application on the ecology of Elodea-dominated freshwater microcosms I. Responses of plankton and zooplanktivorous insects

Nutrient additions alone did not result in a pronounced increase in phytoplankton of macrophyte-dominated freshwater model ecosystems. Grazing by zooplankton and uptake of nutrients by macrophytes prevented phytoplankton from blooming. Nutrient additions resulted in an increase in zooplankton (Cladocera, Copepoda) and a zooplanktivorous insect. The application of nutrients in combination with the insecticide chlorpyrifos, however, caused a more pronounced increase in the abundance of phytoplankton and rotifers, most probably due to the decrease in arthropod grazers and predators.