Copper in Indigenous and Transplanted Zebra Mussels in Relation to Changing Water Concentrations and Body Weight

Abstract

Abstract-Zebra mussels, Dreissena polymorpha, were collected monthly from a copper-contaminated reservoir over a period of nearly 3 years. Copper concentrations in the organisms showed marked fluctuations reflecting changes in the water contamination. Bioconcentration patterns were influenced by the specific capacity of this sentinel organism to biologically integrate the continuously evolving water pollution; the sampling pattern, which inevitably introduced a certain subjectivity into monitoring results; and weight changes in the animals within the yearly cycle. Consequently, the successive monthly indications obtained with the zebra mussels provided a current biological assessment of a complex dynamic contamination situation. In a second experiment, caged mussels from three different populations were transferred for 3 months into the reservoir and sampled on six occasions. Mortality rates, attachment capacity, and a condition index revealed no substantial fitness disturbances in the transplanted organisms. Differences in dry weight throughout the experiment were attributable to the initial characteristics of each population. The influence of body mass on monitoring results was eliminated by replacing copper concentrations (g/g dry weight) with copper burdens (g/specimen). In terms of copper burdens, the three transplanted populations exhibited very similar metal patterns. Moderate quantitative differences between introduced and indigenous populations were interpreted as the result of physiological adaptation of the indigenous mussels to their contaminated environment. This study showed that the transfer technique with D. polymorpha is a useful tool for active biomonitoring programs.

Factors influencing the attachment strength ofDreissena polymorpha(Bivalvia)

“…The latter phenomenon, observed also in zebra mussels, emphasises that the attachment status of bivalves used in bioindication or research should be taken into account, as it may affect their responses (Rajagopal et al 2002). Reattachment strength, in itself, also may be an easy (although not very rapid) bioindication tool (Mersch et al 1996). Mussels would produce fewer byssal threads and their adhesion would be weaker in worse conditions.…”

Does zebra mussel (Dreissena polymorpha) represent the freshwater counterpart of Mytilus in ecotoxicological studies? A critical review

“…Camusso et al (1994) transplanted D. polymorpha specimens in cages for one month in two different sites along the lower course of the Po river (Northern Italy) demonstrating that Cd, Pb, Cr and Ni concentrations in mussel tissues were notably increased with respect to the beginning of the experiment and that levels of metals accumulated in transplanted mussels were comparable to those from the native ones. Similarly, Mersch et al (1996a) transplanted zebra mussels from three different populations of the Moselle River into the Mirgenbach Reservoir in order to evaluate Cu accumulation. Results showed that indigenous and introduced zebra mussels exposed in the same environmental conditions provided similar qualitative Cu patterns, emphasizing the technical feasibility of the transfer method and its suitability for active monitoring programs.…”

Caged Gammarus fossarum (Crustacea) as a robust tool for the characterization of bioavailable contamination levels in continental waters: Towards the determination of threshold values

“…Hence, as shown for bivalves, caged organisms exposed in sites of different trophic potential may exhibit different growth rates, which prevent a direct comparison of tissue concentrations. In such cases, there is a need to correct raw data to account for various growth rates (Bourgeault et al, 2010;Andral et al, 2004;Mersch et al, 1996).…”

“…Active approaches, based on transplanted organisms, have been developed more recently with the aim of resolving these limitations. Indeed, active approaches can be applied even if study sites are devoid of native organisms, they allow limiting biological variability as organisms are collected from the same population, and the exposure time can be controlled (Bourgeault et al, 2010;Bervoets et al, 2005;Andral et al, 2004;Mersch et al, 1996). If some active biomonitoring programmes have been implemented in the marine environment (Benedicto et al, 2011;Andral et al, 2004), no such approaches have been undertaken at a large scale to monitor contamination in continental waters.…”