|
(70-84) Metal accumulation and effects on the condition of the bivalve Macoma balthica in estuarine environments. Duquesne, Sabine1, Barnbrook, Simon*,1, Giusti, Lorenzo1, Liess, Matthias2, Bird, David1, 1 University of the West of England, Frenchay Campus, Bristol, Avon, UK2 Department of Chemical Ecotoxicology, UFZ Center for Environmental Research, Leipzig, Germany, Germany ABSTRACT- A field study conducted in the Severn Estuary indicated that factors such as the suspended particulate load might influence metal bioavailability and consequently, accumulation in biota, especially for species living in sediment. To investigate this possiblity under realistic conditions, a new type of indoor microcosm was developed that consisted of undisturbed sediment cores taken from the field with their associated overlying water. The microcosms were used to measure metal uptake by the bivalve Macoma balthica exposed to metals under various environmental conditions (low or high loads of suspended particulates, different metals - cadmium and copper- at various concentrations, durations of exposure). Metal concentrations were subsequently analysed in the biota and also in abiotic compartments that included the different sediment fractions, the interstitial and overlying water and the suspended and deposited particulate material. Partitioning and recovery of metals in these various microcosm compartments showed, for example, that when exposed to Cd and a low suspended particulate load, Macoma ingested most metals from the overlying water and surface sediment. Metal exposure also induced sublethal biological effects as indicated by changes in the condition index (length/weight). In most cases, the index declined significantly during the experiment (ANOVA, p< 0.05), but in highly exposed individuals it remained unchanged. The causes of this phenomenon may originate from a reduced interaction between these individuals and their environment compared to the controls and/or a shift in the energy budget required to deal with the metal exposure. Key words: suspensions, accumulation, metal, condition index |
