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(098) Modelling silver uptake and toxicity to marine organisms.
Playle, Richard*,1, Wood, Chris2, Walsh, Pat3, Hogstrand, Christer4, Bianchini, Adalto5, Grosell, Martin6, Nichols, Joel1, McDonald, Danielle2, Bury, Nic4, Walker, Paul4, 1 Wilfrid Laurier University, Waterloo, Ontario Canada, Canada2 McMaster University, Hamilton, Ontario Canada, Canada3 Rosenstiel School of Marine & Atmospheric Science, Miami, Florida U.S.A., U.S.A.4 Kings College, London, U.K., U.K.5 Fundacao Universidade Federal do Rio Grande, Rio Grande, Brazil, Brazil6 University of Copenhagen, Copenhagen, Denmark, Denmark
ABSTRACT- Biotic ligand models (BLMs) were developed for freshwater organisms. The "three Cs" (Concentration, Competition, Complexation) still apply in brackish water and seawater, but the concentration of metals must be higher to cause toxicity because both competition at biological membranes by cations (e.g., Na+, Ca2+, Mg2+) and complexation of metals in water by anions (e.g., Cl-, OH-, HCO3-, CO32-) are greater (but complexation of metals by natural organic matter (NOM) is probably reduced). In a multinational research effort at the University of Miami, we investigated the physiological and toxicological effects of silver ("cold" Ag and "hot" 110mAg, 0.1 to 2 uM = 11 to 216 ug/L Ag) on the gulf toadfish (Opsanus beta) and invertebrates (shrimp, sea slugs (Aplysia), sea urchins) in brackish water to 100% seawater. Euryhaline toadfish showed most Ag uptake by gills at lower salinities (less competition, less complexation), while Ag uptake in the gut was greatest in seawater (toadfish drink seawater to avoid dehydration); these results agree with BLM predictions. Toadfish livers and the hepatopancreas of shrimp and Aplysia were the main internal sites of Ag accumulation at all salinities, indicating their importance as metal storage organs. For all organisms studied, allochthonous NOM (collected by reverse osmosis from the Suwannee River, Georgia) had little effect on Ag uptake and toxicity at higher salinities but did reduce Ag accumulation at lower salinities, again in accord with BLM predictions. Funded by Kodak Canada and NSERC.
Key words: silver, seawater, biotic ligand models, fish
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