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PW09 Exposure and Effect Endpoints
(PW159) A new water-sediment system to assess freshwater contamination using shredder and collector responses.
Pestana, J.1, Agra, A. R.1, Ré, A. 1, Nogueira, A. J. A.1, Soares, A. M. V. M.1, 1 Universidade de Aveiro, Campus de Santiago, 3810-193, Aveiro, Portugal
ABSTRACT- The great bulk of contaminants that enter in aquatic systems partitionate differently between water and sediment phases, depending on their physical-chemical properties, and on environmental conditions, such as pH and organic matter content. Moreover, effects of contaminants at the population level are determined by species sensitivity, by their position in the food chain and the functional relationships with other species. Heavy metal contamination of freshwater systems poses serious environmental risks to the macroinvertebrate communities. In most cases, these substances are taken up by organisms directly from water, but may also be ingested with substantially contaminated food. Usually, laboratory toxicity tests are focused in single species responses, evaluating damages in isolated compartments (e.g. sediment or water-column). There is an urge to develop toxicity tests that incorporate different species and that evaluate the functional linkage between them. In this study a water-sediment test system to simultaneously assess sublethal effects of cadmium with the shredder Echinogammarus meridionalis (Amphipoda, Crustacea) and the collector Chironomus riparius (Chironomidae, Diptera) is presented. During a 6-day exposure time, CPOM in the form of leaf discs are processed by the shredder, and the resulting FPOM constitute the food source available for the collector. E. meridionalis feeding rate and C. riparius growth were the endpoints considered. The use of this test design could improve the ecological relevance in laboratory toxicity testing.
Key words: macroinvertebrates, cadmium, freshwater, water-sediment systems
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