| Summary: | Resumen del trabajo presentado al Society of Environmental Toxicology and Chemistry Europe 24th Annual Meeting, celebrado en Basel (Suiza) del 11 al 15 de mayo de 2014. The Ebro delta is a 320 km2 wetland area (NE Spain) of special interest for nesting and migratory birds, but with significant environmental threats due chemical products used both in agricultural areas and in the industrial activity developed in its river basin. Therefore, wild bird populations are at risk due to the presence of toxic elements in the environment, particularly non degradable elements such as mercury. Mercury is a global pollutant of special concern because it is highly toxic and it accumulates in the tissues of wildlife species and can adversely affect reproduction. On the other hand, selenium is known to be very active at counteracting Hg toxicity. Small amounts of selenium are essential for health, but it becomes toxic at high concentrations and causes low survival rates of chicks and adults. In this context, the total mercury (Hg) and selenium (Se) concentration have been determined in liver samples from 10 species of waterfowl (n=537) hunted in the Ebro delta. This liver samples came from two different sampling periods, 1993-95 (n=102) and 2007-11 (n=435). It has been observed a significant reduction of the mercury levels in the waterfowl species in the last twenty years (GLM, F1,307=12.897, p< 0.001). The mercury accumulation was marked by the diet of these species, thus a major ingestion of animal prey was associated with higher levels of mercury, as observed in species such as common shoveler (Anas clypeata) (1,923±343 d.w., n=35, 2007-11 period). Pintail (Anas acuta) (4,996±1234, n=14, 2007-11 period) and common shoveler (Anas clypeata) (4,311±385 d.w., n=35, 2007-11 period) were the species with higher levels of selenium. Both mercury and selenium generally show major accumulation in adults and in female individuals. Highest Hg levels in females contrast with the opposite trend found in other families of birds; and ...
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