This study compares the dynamics of the effects of the water soluble fraction (WSF) of both Jet-A and JP-4 using the Standard Aquatic Microcosm (SAM) using several types of multivariate analysis. In these studies we investigate the common assumption in environmental toxicology, that after the initial stress, ecosystems recover to resemble the control or reference state. This assumption may be based more on our inability to observe an ecosystem with sufficient resolution to detect differences, than reality. Among the more interesting effects observed in both studies were the shifts in time of population peaks and some other variables compared to non-dosed microcosms. In both experiments, multivariate analysis was able to differentiate oscillations that separate the treatments from the reference group, followed by what would normally appear as recovery, followed by another separation into treatment groups as distinct from the reference treatment. These patterns generally were not detected by conventional analysis.
Two sets of related explanations exist for the observed phenomenon. First, the addition of the toxicant initiates an alteration in the community so that the quality of the food resources for the later successional stages is significantly different from the control. This difference in resource quality and quantity leads to the repeated and replicated oscillations. The second explanation is that the oscillations are the result of the intrinsic complex and perhaps even chaotic behavior of population interactions. The initial impact of the toxicant re-set the dosed communities into different regions of the n-dimensional space where recovery may be an illusion due to the incidental overlap of the trajectories of the systems occurring along a few axes. Some of the implications of complex or chaotic dynamics upon the prediction of ecological risk and in biomonitoring are discussed.