A Consideration of Trophic Dynamics in Some Tallgrass Prairie Farm Ponds

Abstract

It has been suggested by Fretwell (1977) and others that ecosystem structure is in part determined by the adaptations of species to the relative degrees of population regulation by food or.pr?dation. Data from five tall-grass prairie farm ponds show that the biomasses of trophic level consumer groups seem to vary systematically: ( 1 ) with the primary productivity of the ponds and ( 2 ) with each other in a manner indicative of predator-prey pairings. Mean body size of damselfly naiads decreases with increased primary production and fish biomass, while mean chironomid larvae body size increases. These data corroborate FretwelPs construct that some ecosystem patterns may be explained by the interactions between primary productivity and pr?dation. While these two factors do not (nor are shown to) completely regulate these farm pond ecosystems, they do account for some of the observed variation.