Effects of nutrient loading and insecticide application on the ecology of Elodea-dominated freshwater microcosms. III. Oxygen metabolism, decomposition and responses of macroinvertebrate detritivores.

The effects of nutrient loading, and of a combination of nutrient loading and insecticide application, were studied in indoor microcosms intended to model drainage ditches. Nutrient additions hardly affected breakdown of particulate organic matter in litter bags. Only minor increases in the abundance of detritivores were observed. Dissolved oxygen concentrations, however, increased for a prolonged period. Application of the chlorpyrifos in nutrient-enriched cosms caused an elimination of important detritivore populations, resulting in a decreased decomposition of organic matter