Influence of tropical reservoirs eutrophication on the polyunsaturated fatty acid profile in Astyanax altiparanae (Pisces: Characidae).

The eutrophication increases the quantity of algae that are deficient in highly unsaturated fatty acids (HUFA) n3, as EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), altering the bottom-up transfer of the entire food chain. Due to the importance of the fatty acids (FA) in physiological processes related to the main role of the membrane phospholipids (PL) and precursors of eicosanoids, and also the little knowledge about the influence of eutrophication in tropical ecosystems, it is important to understand how anthropogenic changes in the aquatic ecosystem affect the lipid quality, specifically n3 HUFAs. This study aimed to investigate the influence of eutrophication on the FA profile of the hepatic PL, as well as prostaglandin (PG) levels in Astyanax altiparanae females. Fish were collected in reservoirs with different eutrophication degrees: Jundiaí (Ju) reservoir and Embu-Guaçu (EG) branch, considered as mesotrophic points, and Barragem (Ba) and Aracati (Ar), branches from Guarapiranga reservoir, considered as supereutrophic and hypereutrophic points, respectively. The FA profile of the liver PL was analyzed by gas chromatography, and the concentration of liver PGE2 was analyzed using ELISA immunoassay kits. The degree of eutrophication did not alter the PG concentration and produced few modifications in the FA profile of hepatic PL. Fish collected at Ba and EG presented similar FA profiles, both with high percentages of n3 HUFA, especially DHA, in comparison to fish from Ju. However, no change was observed in the n3 HUFA profile of the fish from Ar. These data demonstrated that the FA profile in A. altiparanae seems to be more related to different physiological requirements of n3 HUFA of the species than eutrophication. So, this study contributed to findings on the trophic transfer dynamics in tropical freshwater reservoirs, where a direct effect of eutrophication on the availability of HUFA n3 to animals is not suggested.