THE COMMUNITY CONDITIONING HYPOTHESIS AND ITS APPLICATION TO ENVIRONMENTAL TOXICOLOGY

In this paper we present the community conditioning hypothesis, ''ecol ogical communities retain information about events in their history.'' This hypothesis, which was derived from the concept of nonequilibrium community ecology, was developed as a framework for understanding the persistence of dose-related responses in multispecies toxicity tests. We present data from three standardized aquatic microcosm (SAM) toxic ity tests using the water-soluble fractions from turbine fuels (Jet-A, JP-4, and JP-8). In all three tests, the toxicants depressed the Daph nia populations for several weeks, which resulted in algal blooms in t he dosed microcosms due to lower predation rates. These effects were s hort-lived, and by the second and third months of the experiments, the Daphnia populations appeared to have recovered. However, multivariate analysis of the data revealed dose/response differences that reappear ed during the later part of the tests, often due to differences in oth er consumers (rotifers, ostracods, ciliates), or algae that are not no rmally consumed (filamentous green algae and bluegreen ''algae''). Our findings are consistent with ecological theories that describe commun ities as the unique product of their etiologies. The implications of t his to environmental toxicology are that almost all environmental even ts leave lasting effects, whether or not we have observed them.