Development of Pattern Recognition Techniques for the Evaluation of Toxicant Impacts to Multispecies Systems
2007
Landis, Wayne G. | Matthews, Robin A.
A common assumption in environmental toxicology is that after the initial impact, ecosystems recover to resemble the control state. This assumption may be based more on our inability to observe an ecosystem with sufficient resolution to detect differences, than reality. Recent findings of complex and perhaps chaotic dynamics in two relatively simple types of microcosms demonstrate that complex dynamics and nonequilibrium systems are the rule rather than the exception. In the Standardized Aquatic Microcosm and the Mixed Flask Culture (MFC) microcosms, multivariate analysis and clustering methods derived from artificial intelligence research 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. The explanation may be that the oscillations are the result of the intrinsic chaotic behavior of population interactions, of which the alteration of detrital quality is but one of many. In fact, preliminary data indicate that material derived from the jet fuel may be released back into the water column due to the decay or organic material. 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 oscillation trajectories occurring along a few axes.
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