Análise da dinâmica da bioacumulação de mercúrio em peixes: estudo de caso em ecossistemas costeiros fluminenses

Abstract

This dissertation investigated the dynamics of mercury (Hg) accumulation in two fish species, Mugil lisa (Mullet - TA) and Caranx crysos (Blue runner - XE), from the Guanabara Bay (BG) and Arraial do Cabo (AC) in Rio de Janeiro, highlighting the relationship between Hg, nitrogen and carbon isotopes, and lipids, while exploring aspects related to fish growth. The Hg levels found in Mullet were quite low, with 15 ± 5 μg·g −1 in BG and 25 ± 7 μg·g −1 in AC, while for Blue runner, the levels reached values of 134 ± 72 μg·g −1 in BG and 23 ± 11 μg·g −1 , all below the World Health Organization's maximum allowable limits. The δ15N and δ13C analysis yielded values of 12 ± 1 ‰ and -16 ± 2 for TA-BG and 13 ± 1 ‰ and -17 ± 1 ‰ for TA-AC, while for XE-BG it was 10 ± 1 ‰ and -16 ± 1 ‰, and for XE-AC the values were 13 ± 2 ‰ and -20 ± 2 ‰, indicating variations in carbon sources and trophic positions of the studied organisms. The lipid bands were more intense in the TA-AC species, and no statistically significant differences were observed between the Blue runners from both regions. Relative lipid areas proved to be essential indicators in investigating Hg contamination. Regarding fish growth, a hipoallometric pattern was observed in all species, with the phenomenon of Hg dilution observed for XE-BG, attributed to somatic growth. Although Hg levels were below the maximum allowable limits, the risk quotient assessment goes beyond simple dose consideration, incorporating consumption rate and consumer weight. Human exposure to Hg occurs mainly through seafood consumption, representing a significant health risk, especially in populations heavily dependent on these foods as a primary source of protein.