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(42-17) Biomagnification as important part in risk assessment. Eggens, Martin*,1, Kater, Belinda2, Janssen, Gerard1, Bakker, Joop1, 1 National Institute for Coastal and Marine Management/RIKZ, Haren, The Netherlands, The Netherlands2 National Institute for Fisheries Research, Yerseke, The Netherlands, The Netherlands ABSTRACT- Abstract In the period 1969 - 1986 large amounts of hexachlorobenzene (HCB) were drained into the tide dominated part of the Sea Harbour Channel of Delfzijl (the Netherlands). This resulted in very high HCB content in the channels sediment. In 1994 a large clean-up operation was carried out resulting in a reduction but not complete removal of HCB. On the north dike of the channel lives an Oystercatcher colony (Haematopus ostralegus) feeding at the intertidal area of the channel. The eggs of these birds contain elevated HCB-contents compared to those feeding at a reference area. Other organic contaminant levels (i.e. pentachlorophenol, organotin, DDT and lindane) were increased as well, probable due to the presence of harbour activities. The Sea Harbour Channel area thus represents a suitable location for biomagnification field studies and risk assessment of several organic compounds. By observation of tagged female Oystercatchers, individual feeding areas (< 100 m2) were identified. In this way the organic contaminants content of individual oystercatcher eggs could be related to the organic contaminants content of preys and the sediment the prey lives in. The present paper describes the bioaccumulation of several organic compounds at different trophic levels of the sediment-prey-egg food chain. In addition, bioassay responses on harbour sediment and potential effects on the oystercatcher population will be discussed. It is concluded that even below detection limit amounts of contaminants in the sediment can result in significant content in oystercatcher eggs. These contaminants levels may cause effects in the unborn chick. In addition, also biotransformation can play a very important role in risk assessment. Key words: food web, biomagnification, organic contaminants, risk assessment |
