Determining the effects of pollutants on soil faunal communities and trophic structure using a refined microcosm system

Abstract

AbstractWe used a refined microcosm technique to investigate the toxicity of copper, cadmium, malathion, and the polychlorinated biphenyl, Aroclor 1254, to trophic groups of soil nematodes and to the microarthropod community. Comparisons of changes in nematode abundance in control soils through time indicated that day 7 was the most appropriate time to sample the microcosms after chemical application. Nematode abundance was reduced after exposure to copper at 100 μg/g, with fungivore, bacterivore, and omnivore–predator nematodes being the most sensitive groups. Cadmium did not affect the nematode or microarthropod communities. Microarthropods were far more sensitive to malathion than were nematodes, and total microarthropod abundance was lower than controls at 400 μg/g. Prostigmatid mites and “other” arthropods were the most affected groups. Aroclor 1254 also had a greater negative impact on microarthropods than on nematodes. Total microarthropod abundance declined at 2,500 μg/g, with prostigmatid and oribatid mites exhibiting the highest susceptibility. Strong differential sensitivity between nematode and microarthropod communities indicates that both groups should be examined to fully evaluate the biological impact of chemicals on soils. We conclude that microcosms with field‐collected soil microfaunal communities offer high resolution of the ecotoxicologic effects of chemicals in complex soil systems.