PARENT SESSION

(06-04) Biomagnification of contaminants in wetland bird species: cormorants, spoonbills and great reed warblers in relation to reproductive output.

Van Hattum, Bert^*,1, Boudewijn, Theo², De Jonge, Jolande³, Den Besten, Piet³, ¹ Institute for Environmental Studies (IVM), Amsterdam, Netherlands, Netherlands² Bureau Waardenburg bv, Culemborg, The Netherlands³ Institute for Inland Water Management and Wastewater Treatment, Lelystad, Netherlands

ABSTRACT- Various wetland avian species are recovering from serious declines during the past decades, or may still be at risk in specific habitats in the Netherlands. Apart from habitat-specific stress factors (destruction, predation, disturbance, quality and availability of food), contaminant-related factors have been involved especially in habitats in the Rhine-Meuse basin. Results will be presented from studies on the biomagnification of contaminants in cormorants (Phalacrocorax carbo sinensis), spoonbills (Platalea leucorodia) and great reed warblers (Acrocephalus arundinaceus) in the Netherlands. Food chain transfer and biomagnification was confirmed especially in the piscivoreous food web of cormorants for: PCBs Hg, p,p'-DDE and some organochlorine pesticides (OCBs). For the spoonbill, feeding on small fish and invertebrates, and the insectivorous great reed warblers, similar results were obtained with lower contaminant levels in livers of chicks or eggs compared to cormorants. In all species, the contribution of non-ortho substituted PCB 126 to total dioxin equivalent TEQs was dominant. Comparisons were made with literature-derived generic critical effect levels for PCBs, dioxins, p,p'-DDE and Hg in order to evaluate potential contaminant-related risks in relation to other stress factors, which may have contributed to observed local effects on reproductive outcome. Exposure to non- and mono-ortho PCBs was assigned as a potential risk, especially for the cormorant. It is argued that the lack of species sensitivity information for most indigenous species, currently hampers a proper assessment of the relative role of contaminant-related effects. Potential suitable approaches to fill this gap and research needs will be discussed.

Key words: birds, biomagnification, planar PCBs, risk assessment