A test of the community conditioning hypothesis: Persistence of effects inmodel ecological structures dosed with the jet fuel JP-8

The foundation of the community conditioning hypothesis, the persistence of effects, was tested in a series of microcosm experiments. Experiments were conducted with the water-soluble fraction of the turbine fuel JP-8 using t he standard protocols for the standardized aquatic microcosm (SAM). A repea t trial was conducted using the SAM protocol but with a 126-d test period, twice the standard duration. The results were examined using a variety of c onventional univariate, multivariate, and graphical techniques. The princip al conclusions were as follows. Effects are persistent in these model ecolo gical systems long after the degradation of the toxicant. Patterns of impac ts are detectable at concentrations 15 times lower than an experimentally d erived single-species EC50. The replicate experiments are not replicable in the specific, but the broad pattern of the disruption of algal-herbivore d ynamics followed by more subtle effects are consistently repeated. The dura bility of the indirect effects and therefore the information about historic al events appears to be a consistent feature of these microcosm systems. Th e identity of the treatment groups persists. The critical features of the c ommunity conditioning hypothesis-persistence of information within ecologic al systems and the reappearance of patterns and therefore the nonequilibriu m dynamics-are again confirmed. The implications of these findings for envi ronmental toxicology, monitoring, and ecological risk assessment are discus sed.