Reduction of population growth in Tisbe holothuriae Humes (Copepoda : Harpacticoida) exposed to low cadmium concentrations

Abstract

Replicate laboratory populations of T. holothuriae initiated by founder females standardized in terms of reproductive status, age and environmental background were exposed to three levels of cadmium for 24 days and compared with untreated controls. At a cadmium concentration of 159 µg l^-1 populations failed to increase and became virtually extinct, probably because of larval impairment. At concentrations of 2.3 and 40 µg l^-1 population growth occurred but total population size (males plus females plus copepodids) and both male and female numbers were significantly reduced relative to controls. Knowledge of the response of harpacticoids to low levels of toxic metals therefore appears to be significant in developing an understanding of the effects of metals on marine ecosystems.