Unique Information Contributed by Multispecies Systems: Examples From the Standardized Aquatic Microcosm

Abstract

Single‐species toxicity tests are inadequate to predict the effects of chemicals in ecological communities although they provide data on the relative toxicity of different chemicals, and on the relative sensitivity of different organisms. Only multispecies studies can provide demonstrations of: (1) indirect trophic‐level effects, including increased abundances of species via increased food supply through reduced competition or reduced predation; (2) compensatory shifts within a trophic level; (3) responses to chemicals within the context of seasonal patterns that modify water chemistry and birth and death rates of populations; (4) chemical transformations by some organisms having effects on other organisms; and (5) persistence of parent and transformation products. Multispecies laboratory studies, such as the Standardized Aquatic Microcosm, have much to offer, with advantages of statistical power, speed of analyses, demonstrated reproducibility among laboratories, and modest expense (compared to field studies). The use of a chemically defined sediment facilitates the potential extraction of parent and transformation products by minimizing the problem of unextractable residues. The absence of fish prevents the potential elimination of zooplankton if fish predation exceeds production. Standardized Aquatic Microcosms also offer a wealth of analytical tools, including rapid statistical analyses, a mathematical model (MICMOD), and artificial intelligence methodologies.

A Life-History Approach to Predicting the Recovery of Aquatic Invertebrate Populations After Exposure to Xenobiotic Chemicals

“…Like all modeling approaches, our simplistic analysis also has inherent limitations. Perhaps most significantly, our model ignores secondary and communitylevel effects that may occur in freshwater systems [2]. For instance, it is possible that if predators or competitors of a given species are strongly affected by a toxic perturbation, then this species may rapidly undergo a resurgence in population size, freed from predatory or competitive pressure.…”

“…The environmental risks posed by xenobiotic chemicals in aquatic ecosystems are generally assessed through a combination of laboratory toxicity tests and small-scale field trials using artificial ponds (mesocosms) [1,2]. Typically, the concentrations that affect individual organisms are measured under controlled conditions and compared with those to which the organisms may be exposed in the environment.…”

Temporal changes in the sensitivity of coastal Antarctic zooplankton communities to diesel fuel: A comparison between single‐ and multi‐species toxicity tests

“…In the event of a fuel spill in the coastal environment, the response of the zooplankton community is related not only to the sensitivity of individual species within the community but also to the species composition of the zooplankton community, which changes temporally. Multi-species toxicity tests using functional groups of species or whole communities provide information about the community sensitivity and how this may vary with changing community structures through time [28]. Coupling multi-species tests with traditional single-species toxicity tests on key species within the community gives the present study greater depth.…”

“…Compared with multi-species tests, single-species toxicity tests are generally easier, quicker, and yield more consistent, repeatable results, making them potentially more cost effective. However, multi-species tests are more informative and environmentally relevant, because they can predict the response of the whole zooplankton community as a dynamic entity, and take into account the often complex interactions and interdependencies between species within a community [28].…”

How realistic are outdoor microcosms? A comparison of the biota of microcosms and natural ponds

“…falling between laboratory microcosms and the large, complex, real world macrocosms'' [8]. More recently, reiterating Odum's original view, Taub [26] noted that ''. .…”