Productivity, consumers, and the structure of a river food chain.
We tested models of food chain dynamics in experimentally manipulated channels within a natural river. As light levels increased, primary productivity and the biomass of algae and primary predators increased, but the biomass of grazers remained relatively constant. In the presence of a fourth trophic level, algae and primary predators decreased, but grazers increased. These results match predictions of food chain models based on classical predator-prey theory and suggest that simple models of multitrophic level interactions are sometimes sufficient to predict the responses of natural communities to changes in environmental productivity and predators.
Wootton
J T
JT
Department of Integrative Biology, University of California, Berkeley, CA 94720, USA.
Power
M E
ME