Naturally-Derived Microcosms for Estimating Stress Effects in Aquatic Ecosystems

摘要

Traditional methods of estimating hazards of toxic stressors in aquaticecosystems have fail to account for ecologically important interactions within complex systems. A microcosm testing method was developed to assess the effects of chemical stresses (including complex mixtures) on naturally derived freshwater microbial communities. Microbial communities were collected on polyurethane foam artificial substrates and used to establish replicate laboratory ecosystems to be stressed with toxicants. Responses measured included taxonomic richness, standing crop biomass, enzyme activities, and gross system production and respiration. Both pure compounds and complex mixtures were used as stressors. Results were compared to single species tests and to measured ecosystem impacts. Measures of ecological structure (species richness, biomass) were consistently sensitive indicators of stress. Measures of ecological processes were often less sensitive than measures of structure. Microcosm responses were sensitive at environmental levels of toxicants and were more sensitive to conservative toxicants than to degradable toxicants.