Reproductive toxicity of dietary copper to a saltwater cladoceran, Moina monogolica Daday

In the present study, the chronic toxicity of dietary copper to Moina monogolica Daday was investigated. Microalgal growth inhibition tests were conducted for 96 h with the green algae Chlorella pyrenoidosa exposed to copper. The 96-h median effective concentration (95% confidence interval) was 509.12 (388.68-629.56) mu g/L. Then, C. pyrenoidosa was exposed for 96 h to a control and to seven dissolved copper concentrations. Cellular copper concentration accumulated in a dose-dependent manner and was plotted against cell density. These algae were used as food in a 21-d bioassay with M. monogolica in seawater to which no dissolved copper was added. Brood size was not reduced in the first brood, but significant reductions at all algal-exposure copper concentrations (44.78-817.17 mu g/L) were observed in all subsequent broods, with increasing magnitude in each brood. Neither longevity nor number of broods per female was significantly affected, even at the highest copper exposure, though both endpoints did show a consistent downward trend with increasing copper exposure. Total reproduction, brood size, and net reproductive rate were decreased significantly in all dietary copper exposures (algae exposed to 44.78-817.17 mu g/L). In contrast, the intrinsic rate of natural increase was reduced significantly only with algae exposed to greater than 619.27 mu g/L, most likely because of the heavy influence of early reproduction on this metric. Because cell density in algal cultures decreased with increasing copper concentrations, it is possible that changes in the nutritional content of the algal diet could have played a role in causing the observed changes in reproduction of M. monogolica.