Responses of a free-living marine nematode community to mercury contamination: results from microcosm experiments.

A microcosm experiment was used to examine the effects of mercury contamination on a free-living nematode community in a Tunisian lagoon. Sediments were contaminated with three mercury concentrations (low, 0.084 ppm; medium, 0.167 ppm; and high, 0.334 ppm), and effects were examined after 60 days. Results from multiple-comparison tests showed significant differences between nematode assemblages from undisturbed control and those from mercury treatments. Most univariate measures decreased significantly with increasing level of Hg contamination. Results from multivariate analyses of the species abundance data demonstrated that responses of nematode species to mercury contamination were varied: Araeolaimus bioculatus was eliminated at all the mercury doses tested and seemed to be an intolerant species to mercury contamination; Marylynnia stekhoveni increased at low and medium concentrations and appeared to be an "opportunistic" species at these doses, whereas Prochromadorella neapolitana, which increased at all doses tested (0.084, 0.167, and 0.334 ppm), seemed to be a "mercury-resistant" species.