TERRESTRIAL MULTISPECIES TOXICITY TESTING .1. DESCRIPTION OF THE MULTISPECIES ASSEMBLAGE

Criticism of extrapolation from single-species laboratory toxicity tests to the real environment initiated the search of new test protocols. One way to bridge the gap between the ecological and industrial point of view in the regulatory process is the development of multispecies tests based on the microcosm idea. During the last few years, practical knowledge has demonstrated that such tests are an attempt to make some kind of connection between a precisely controlled laboratory experiment and an observational field study whereby the greatest value of the microcosmology is attributed to the study of ecosystem-level functions. The first paper of the series presents the description of a terrestrial multispecies assemblage developed for screening purposes within the regulatory framework, discusses the problems of methodology, species selection, test protocol, and selection of test parameters, and demonstrates the construction of the multispecies assemblage. The test system itself is based on a section of agro-ecosystems and combines a hierarchical approach at the community, population, species and cellular level. Indicator organisms tested include members of the invertebrate groups nematodes, enchytracids, and arthropods. The plant species is incorporated in the testing protocol, too but to a lesser extend. Methods applied include histoenzymology, histopathology, morphology, and ecological parameters characterizing population dynamics and community structure. The test protocol combines the elucidation of the mode of action of the test chemical to the biochemical apparatus of the cell with the ecological effects and enables the demonstration of cause-effect relationships.