Relative tolerances of selected aquatic oligochaetes to combinations of pollutants and environmental factors

Abstract

The field distributions of many species of aquatic oligochaetes have been interpreted as indicating their tolerance to pollution in general and organic pollution in particular, but these tolerances have not been tested in the laboratory. The purpose of this study was to investigate the tolerances of selected oligochaete species to combinations of pollutants and environmental factors. Species were chosen for experimentation based on the results of a previous study on the tolerance of oligochaetes to individual pollutants and environmental factors (Chapman et al., 1982). 96-h LC 50 values were determined for 3 freshwater ( Limnodrilus hoffmeisieri, Tubifex tubifex and Stylodrilus heringianus) and 2 salt-water species ( Monopylephorus cuticulatus and Linnodriloides verrucosus) in relation to 4 pollutants (cadmium, mercury, pentachlorophenol and black liquor, a toxic component of pulp mill effluent). th different combinations of pH. temperature and salinity. Additional data were obtained for a 4th freshwater species: Quistadrilus (= Peloscolex) multisetosus. LC 50 values were shown to depend on the environmental factors, but the relative tolerance rankings of most species to cadmium, pentachlorophenol and black liquor remained reasonably consistent throughout. Tolerance rankings for mercury were not consistent under varying environmental conditions.