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(W/EH098) Ecotoxicological effects of mining activity on a hipersaline coastal lagoon: Mar Menor (Murcia-Spain). Marín, Lázaro1, Cesar, Augusto1,2, Vita, Rubén1, Marín, Arnaldo1, 1 2 ABSTRACT- Mar Menor is a hipersaline coastal lagoon located in the arid Iberian southeast. Streams of Mar Menor area experience both severe flash flood and periods of extensive drying. Historically, this lagoon received wastes from mining areas. Although mining activity is stopped since the 50th decade, drainage from old mine tailing continues to carry a heavy load of metals when desert-streams flowing into the lagoon. The goals of this study were to describe how contaminants in sediments influence and are linked with the water column after a flooding. We also quantify consequences of sediment-water column linkage for macrobiota responses. Sediment toxicity was evaluated with whole sediment 10-d toxicity tests using the amphipod Microdeutopus gryllotalpa. Water column toxicity was measured conducting embryo-larval chronic toxicity tests with three Mediterranean sea urchin species: Arbacia lixula, Paracentrotus lividus and Sphaerechinos granularis and performing Microtox® bioluminescence tests with 5, 10, 15 and 30 min of exposure times. Interface sediment-water toxicity tests were also developed with the same three species of sea urchins, indicating the diffusion of contaminants between these two compartments. Water column showed a high toxicity after a flooding event. Post-flood sediment resuspension contributed to transfer pollution from sediment to water column. Sediments maintained great toxicity before and after the inputs of desert-streams. Despite the great sediment contamination, the fauna and flora of Mar Menor is unexpectedly normal during drought years. Macrophytes may contribute to ecosystem stability by providing a refuge for fauna and fixing sediments. Key words: Coastal-lagoon, Amphipod, Sea urchin, Microtox® |
