Influence of Combinations of Pesticides and Fertilizers on Aquatic Productivity

Abstract

We have examined the effects of environmentally realistic concentrations of widely used pesticides and fertilizers for rice paddy in Western Ghats regions of India on chlorophyll and zooplankton production using a laboratory mesocosm. Malathion (100 µg·L−1), Cypermethrin (25 µg·L−1), Nitrate-nitrogen (8 mg·L−1) and Phosphate-phosphorus (8 mg·L−1) in different combinations such as pesticide-pesticide and pesticide-fertilizer were tested in fully factorial manner for a period of 42 days. Study revealed that, chlorophyll production was supported by addition of fertilizers, while combinations of fertilizers with either one or two pesticides reduce the zooplankton density and diversity rendering chlorophyll concentration more than control groups. This could indicate the reason for eutrophication of ponds located in agro-ecosystems. Single application of combinations of pesticides (in spite of presence of fertilizers) even at low concentrations can produce severe negative effects on several taxonomic groups zooplankton living in small shallow water.