PH08 Metals in the Environment: Aquatic Biological Perspectives
Exhibit Hall
8:00 AM - Thursday
(PH078) Bioavailability, lethal, and sublethal toxicity of copper to benthic freshwater invertebrates with different feeding behaviour.
Roman, Y1, De Schamphelaere, KAC1, Nguyen, L1, Janssen, CR1, 1 Ghent University - Laboratory of Environmental Toxicology and Aquatic Ecology, Gent, Belgium
ABSTRACT- We investigated the lethal and sublethal toxicity of copper to three benthic invertebrates with different feeding behaviour using chronic toxicity tests. Tubifex tubifex (Annelida: Oligochaeta), a sub-surface feeder, was monitored during 28 days for survival and reproduction. Surface-feeding Chironomus riparius larvae (Arthropoda: Diptera) were followed during 28 days for survival and emergence. Finally, Hyalella azteca (Arthropoda: Amphipoda), a surface collector, was monitored for 28-day survival and 42-day reproduction. The effects of organic carbon (OC at 3% and 10% of dry wt) and acid volatile sulphide (AVS at 0, 10, and 20 mmol / kg dry wt) amendments were investigated in artificial sediment using a 2x3 factorial design. Additionally, experiments were conducted with spiked natural sediments from the Ijzer River (Belgium, OC 6.5%, AVS 18 mmol / kg dry wt) and from a pond in Leuven (Belgium, OC 19%, AVS 55 mmol / kg dry wt). Sublethal toxicity occurred at concentrations that were on average 2, 3 and 4 times lower than lethal concentrations for C. riparius, T. tubifex and H. azteca, respectively. Sublethal toxicity was highest in artificial sediment with 3% OC and no added AVS, with EC50s being 98, 54 and 59 mg Cu / kg dry wt for T. tubifex, H. azteca and C. riparius, respectively. Sublethal toxicity was lowest in the Leuven sediment, with EC50s being 2700 mg Cu / kg dry wt for T. tubifex and 1500 mg Cu / kg dry wt for H. azteca, thus indicating up to a factor of 30 difference in sublethal toxicity in the different sediments tested. Although OC and AVS clearly ameliorated copper toxicity to all species, survival-EC50s were best correlated with AVS, whereas sublethal EC50s were best correlated with OC. Moreover, the relative importance of OC and AVS was dependent on the species investigated, pointing to the importance of feeding behaviour in sublethal Cu bioavailability. Possible mechanistic explanations for our findings will be proposed and the importance of our results for regulatory assessments of Cu in sediments will be discussed.
Key words: sediment, copper, bioavailability, benthic invertebrates