Chronic ecotoxicity of copper and cadmium to the zebra mussel Dreissena polymorpha

Abstract

In order to evaluate ecological consequences of the long-term presence of metals in aquatic ecosystems, we investigated the filtration rate and survival of zebra mussels (Dreissena polymorpha) during chronic exposure to Cu and Cd. The filtration rate was measured once a week in laboratory experiments lasting 9-11 weeks. The lowest Cu concentration tested (13 micrograms/L) did not affect the filtration rate and survival of D. polymorpha, but the lowest Cd concentration (9 micrograms/L) did affect the filtration rate, but had no effect on survival. The EC50 for Cd decreased markedly from 388 micrograms/L to 27 micrograms/L when the exposure time was lengthened from 48 hours to 10 weeks. The largest decrease in EC50 for Cd was observed during the first week of exposure. In contrast, the EC50 for Cu did not decrease with increasing exposure time (chronic EC50: 43 micrograms/L). Since the chronic LC50 for Cd was 130 micrograms/L, the filtration rate appeared to be a far more sensitive endpoint for ecotoxicological laboratory experiments than mortality. D. polymorpha was capable of regulating the body concentration of the essential metal Cu at low concentrations in the water (13 micrograms/L). Cd was accumulated at every Cd concentration in the water, suggesting that Cd could not be regulated by D. polymorpha. It is concluded that the relation between short-term and long-term ecotoxicity was different for each metal and could not be predicted from the results of the short-term experiments.

Chronic ecotoxicity of Zn and Pb to the zebra mussel Dreissena polymorpha

“…Relatively low ACR's were observed for Cu and Zn, indicating that the effects of these metals increase with time, but not dramatically. The ACR for Cd was high, caused by a strong decrease of the ECs0 with time, as reported by Kraak et al (1992). Our results for Pb deviate from those of Kenaga (1982), since the ACR for this metal is as low as the one for the essential metal Zn.…”

“…Kenaga (1982) calculated acute-chronic ratios (ACR; the acute ECs0 divided by the chronic ECs0) for a number of substances and organisms and demonstrated that for Daphnia magna the ACRs for Pb and Cd were much higher than for Zn and Cu, possibly because Cu and Zn are essential metals, whereas Pb and Cd are not known to have any biological function. Kraak et al (1992) observed that the ECs0 for Cd for filtration rate of the zebra mussel Dreissena polymorpha decreased when exposure time was increased from 48 h to 10 weeks, whereas the effects of Cu did not increase during prolonged exposure. This seems to support the idea that during chronic exposure the effects of non-essential metals increase more than the effects of essential metals.…”

Single and Joint Toxic Effects of Copper and Zinc on Reproduction ofEnchytraeus crypticusin Relation to Sorption of Metals in Soils

“…This choice would be unjustified when joint effects are strongly-or more frequently-synergistic or antagonistic in comparison to SSA or when the alternate null model is better justified for a particular mixture. For organisms exposed to metal mixtures in water, joint effects of mostly binary and tertiary mixtures are in the range of 0.5 to 2 TU and approximately equally distributed between SSA and responses that are synergistic or antagonistic in comparison to this (e.g., Enserink et al, 1991;Kraak et al, 1992Kraak et al, , 1993Kraak et al, , 1994. This pattern may reflect true toxicological interactions inside the bodies of the organisms, since the metal fraction sorbed to particles is low in aquatic media (Enserink et al, 1991).…”

Comparaison de plusieurs supports analytiques inertes et biologiques pour apprécier la contamination métallique de la retenue du site électronucléaire de Cattenom, France

“…La capacité de régulation du zinc a été signalée pour des espèces de moules marines (Chan 1988, Martincic et al 1992. La moule zébrée est capable de réguler efficacement ses niveaux intracellulaires de cuivre jusqu'à une concentration dans l'eau de 13 ^g.Lau delà de ce seuil, le cuivre est accumulé (Kraak et al 1992). En revanche, le cadmium est accumulé dès qu'il est présent à de faibles teneurs dans l'eau et le relargage est très lent (Bias & Karbe 1985, Kraak et al 1992.…”

“…La moule zébrée est capable de réguler efficacement ses niveaux intracellulaires de cuivre jusqu'à une concentration dans l'eau de 13 ^g.Lau delà de ce seuil, le cuivre est accumulé (Kraak et al 1992). En revanche, le cadmium est accumulé dès qu'il est présent à de faibles teneurs dans l'eau et le relargage est très lent (Bias & Karbe 1985, Kraak et al 1992. La régulation ou, au contraire, un processus cumulatif impliquent la prise en compte de l'impact biologique de chaque élément, puisque la concentration dans le mollusque ne reflète plus nécessaire-ment celle dans l'eau.…”