Age specific sensitivity of the nematode Aphelenchus avenae to mercury toxicity.

Although one of the ultimate goals of ecotoxicology is to predict the effects of chemical substances and compounds on whole communities and ecosystems, it is generally accepted by ecotoxicologists that single-species toxicity tests may provide an adequate first step toward the ecological risk assessment of pollutants in soil and water. Consequently, several toxicity tests (ASTM 1993) have been developed and standardized using single species such as Selenastrum capricornutum (freshwater alga), Daphnia magna (freshwater cladoceran), Mytilus edulis (blue mussel) and Oncorhynchus mykiss (rainbow trout). Nevertheless, some groups of organisms have seldom been used in single-species toxicity tests, despite the fact that such organisms can play a significant role in the functional organization of ecosystems. This is the case of the phylum Nematoda (see Kammenga et al. 1996), which contains many species showing a great variety of life cycles and feeding habits. Furthermore, terrestrial nematodes usually are very abundant and important for nutrient cycling (Freckman 1988), living in the soil pore water and therefore being in close contact with the bioavailable concentration of potential pollutants (Houx and Aben 1993).