Consistent effects of pesticides on community structure and ecosystem function in freshwater systems

Predicting ecological effects of contaminants remains challenging due to the vast number of chemicals and their unclear roles in biodiversity-ecosystem function relationships. This study examines the effects of 12 standardized pesticides, categorized into four classes and two types, on experimental pond ecosystems. Consistent effects of herbicides and insecticides on ecosystem function, and somewhat less consistent effects on community composition were observed. Pesticide effects on ecosystem function are mediated by changes in the abundance and community composition of functional groups. Herbicides reduce respiration and primary productivity via bottom-up effects by decreasing phytoplankton abundance. Insecticides impact respiration and primary productivity through top-down effects on zooplankton. The study suggests ecological risk assessment could be simplified by focusing on chemical classes/types and functional groups of organisms.

Samantha L. Rumschlag, Michael B. Mahon, Jason T. Hoverman, Thomas R. Raffel, Hunter J. Carrick, Peter J. Hudson, Jason R. Rohr