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 Cruznema tripartitum after incubation in soil for 48 hr provided a useful bioassay of the presence and concentration level of biologically active toxicants. The assay provided an indication of toxicant activity at sublethal levels, and a means of determining when the toxicant had declined to levels not deleterious to physiological function. Assays of soil contaminants based on the community structure of resident soil nematodes were more useful in undisturbed soils than in agricultural soils where the range of taxa was relatively narrow. Assays involving measurement of survival and respiration rates of nematodes after immersion in an aqueous extract of contaminated soils were not useful due to degradation and loss of contaminant during the extraction process.