DEVELOPMENT AND TESTING OF AN ASSAY FOR SOIL ECOSYSTEM HEALTH USING THE BACTERIAL-FEEDING NEMATODE CRUZNEMA-TRIPARTITUM

Survival and respiration rates of the bacterial-feeding nematode Cruzn ema tripartitum after incubation in soil for 48 hr provided a useful b ioassay of the presence and concentration level of biologically active toxicants. The assay provided an indication of toxicant activity at s ublethal levels, and a means of determining when the toxicant had decl ined to levels not deleterious to physiological function. Assays of so il contaminants based on the community structure of resident soil nema todes were more useful in undisturbed soils than in agricultural soils where the range of taxa was relatively narrow. Assays involving measu rement of survival and respiration rates of nematodes after immersion in an aqueous extract of contaminated soils were not useful due to deg radation and loss of contaminant during the extraction process. (C) 19 97 Academic Press.