Book Description

In this research program, new methods of data analysis were applied to the analysis of multispecies toxicity tests using three complex toxicants. The water soluble traction of the turbine fuels Jet-A, JP-4 and JP-8 have been examined as stressors for two microcosm protocols, the standardized aquatic microcosm (SAM) and the mixed flask culture (MFC). The SAM is a 3 L system inoculated with standard cultures of algae, zooplankton, bacteria, and protozoa. In contrast, the MFC is 1 L and is inoculated with a complex mixture of organisms derived from a natural source. Analysis of the organism counts and physical data were conducted using conventional and newly derived multivariate nonmetric clustering methods and computer visualization techniques. Several fundamental discoveries regarding the impacts of toxicants on ecological systems were made. The first is that recovery of an ecosystem in the sense that it returns to the original or reference state is not a property of these systems. In fact, it is unlikely that recovery is a property of other larger ecological systems. In our experiments the various treatment groups incorporated the information as to toxicant concentration that was expressed after periods of so- called recovery. The differentiation of the treatment groups occurred even after the elimination of the toxicant from the test system. Another fundamental discovery is that multispecies toxicity tests are not repeatable, although within one experiment the replicates of a treatment group are replicable. In other words, initial conditions are important. The outcome of this research may lead to a new viewpoint in describing the impacts of toxicants on complex ecological systems. This viewpoint is described as the Community Conditioning Hypothesis.