Sources and mechanisms of cadmium bioaccumulation by the freshwater decapod crustacean Macrobrachium australiense
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Date
2012-05-20
Journal Title
Journal ISSN
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Publisher
Society of Environmental Toxicology and Chemistry
Abstract
Metal bioaccumulation by aquatic invertebrates in the environment can often be explained by chemical parameters such as metal concentrations within the solution and particulate phases by exposure-dose-response relationships. Simple relationships of this type are not known for invertebrates in the highly turbid Strickland River, Papua New
Guinea. Here, indigenous prawns demonstrate significant differences in bioaccumulated metal concentrations (predominantly cadmium) between populations exposed to mining effluents compared to those in reference tributaries. However, metal concentrations of waters and sediments are not significantly different between sites.
This study investigated the potential sources and mechanisms of cadmium (Cd) bioaccumulation by the freshwater decapod Macrobrachium australiense using 109Cd-labelled 70 SETAC 6th World Congress/SETAC Europe 22nd Annual Meeting
water and food sources. Synthetic river water (SRW) was spiked with environmentally relevant concentrations of Cd and prawns were exposed for seven days with daily renewal of test solutions. Prawns were subsequently allowed to depurate in Cd-free SRW for fourteen days. Dietary assimilation of Cd was assessed through pulse-chase experiments where prawns were fed 109Cd-labelled fine sediment, filamentous algae and carrion (represented by cephalothorax tissue of water-exposed prawns). Radioanalyses
during the exposures were used to determine influx and efflux rate constants for Cd in water, and the assimilation efficiency (AE) and efflux rate (Ke) of Cd from each dietary source.
Results indicated that M. australiense readily uptake Cd from solution and that uptake rate increased linearly with increasing exposure concentration. During depuration, water efflux rates were low (0.9 ± 5 % d-1) and were not dependent on exposure concentration. AEs of dietary sources were comparable for sediment and algae (approx 50 %), but lower for carrion (33 %) and efflux rates were low (0.2-2.6 % d-1).
The results demonstrated that prawns are likely to bioaccumulate Cd readily from both water and food sources. The rapid uptake but slow efflux of bioaccumulated Cd may explain why monthly or weekly measurements of Cd in water and sediments provide inadequate information regarding exposure or dose to explain metal accumulation patterns. A biokinetic model of Cd accumulation by M. australiense is presented based on the findings.
Description
Keywords
Papua New Guinea, Biological accumulation, Metals, Cadmium, Prawns, Aquatic organisms, Sediments
Citation
Cresswell, T., Simpson, S. L., Twining, J., Mazumder, D., Smith, R. E. W., & Nugegoda, D. (2013). Sources and mechanisms of cadmium bioaccumulation by the freshwater decapod crustacean Macrobrachium australiense. Paper presented at the 6th World Congress/22nd Annual Meeting of the Society of Environmental Toxicology and Chemistry (SETAC), Berlin, Germany, 20-24 May 2012.