Rotifers are small planktonic animals commonly occurring and often dominant in the zooplankton of offshore marine environments, estuaries, slow-moving rivers, and freshwater lakes. They are important in the food chains of most aquatic ecosystems. The experimentally determined relationships proposed in this study will increase our understanding of the mechanisms determining the composition and structure of freshwater zooplankton communities in nature. This study should help explain patterns of species distribution, size, and morphology (e.g. body spines, mucus sheaths, flattened vs. oblate bodies) which can not be explained with current theory. Each species has a body size and form that may influence its hydrodynamic characteristics and, hence, affect the energetic balance between swimming and food collection. This may affect reproduction at low food levels. The kinds of species which can maintain positive population growth rates in low food environments will affect energy flow and food web relationships. The species structure of the zooplankton, in turn, affects the production of organisms higher in the food chain. Therefore, the basic research proposed in this study has direct application for understanding fundamental zooplankton community organization which, ultimately, affects energy flow and, hence, fish production for human or animal consumption.
