A test of the community conditioning hypothesis: Persistence of effects in model ecological structures dosed with the jet fuel jp‐8

Abstract

AbstractThe 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 the standard protocols for the standardized aquatic microcosm (SAM). A repeat 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 conventional univariate, multivariate, and graphical techniques. The principal conclusions were as follows. Effects are persistent in these model ecological systems long after the degradation of the toxicant. Patterns of impacts are detectable at concentrations 15 times lower than an experimentally derived single‐species EC50. The replicate experiments are not replicable in the specific, but the broad pattern of the disruption of algal‐ herbivore dynamics followed by more subtle effects are consistently repeated. The durability of the indirect effects and therefore the information about historical events appears to be a consistent feature of these microcosm systems. The identity of the treatment groups persists. The critical features of the community conditioning hypothesis—persistence of information within ecologicalsystems and the reappearance of patterns and therefore the nonequilibrium dynamics—are again confirmed. The implications of these findings for environmental toxicology, monitoring, and ecological risk assessment are discussed.