Abstract

RUEDA-BERNAL, Ramiro; ACERO R, Arturo; CAMPOS-CAMPOS, Néstor Hernando  and  MARRUGO-NEGRETE, José Luis. Determination of the role of the Antillean shark Rhizoprionodon porosus (Carcharhinidae) in the flow of methylmercury within the trophic webs of the Colombian Caribbean. Rev. acad. colomb. cienc. exact. fis. nat. [online]. 2020, vol.44, n.170, pp.169-181.  Epub June 15, 2021. ISSN 0370-3908.  https://doi.org/10.18257/raccefyn.855.

Methylmercury (MeHg) is the most toxic organic form in which mercury can be found. It is a neurotoxin whose intake causes serious consequences in humans. In Colombia, different activities generate mercurial waste and marine ecosystems are the most affected due to the bioaccumulation and biomagnification capacity of species in different trophic levels. In this context, we evaluated samples of Rhizoprionodon porosus as biomonitor species (n=45) to verify MeHg contamination in the Colombian Caribbean and assess its spatial and temporal variation. Samples of tissue and stomach contents were collected during different times in three different departments, La Guajira, Bolívar and Atlántico. The samples were lyophilized, then liquid-liquid extractions with toluene and cysteine were performed, and concentrations were determined in sharks and their prey using a direct mercury analyzer (DMA80). With these results, we calculated the biomagnification factor of the metal in the compartments of the trophic Colombian Caribbean networks under study. In all three sites, the concentrations of MeHg were higher than those established as safe by the World Health Organization and the sectors adjacent to the Magdalena and Sinú rivers were the most affected. The Kruskal-Wallis test showed significant differences between sampling times of the different sites. The Spearman correlation showed that there was a relationship between the size of the individual and the concentration of MeHg, which allowed to conclude that R. porosus is bioaccumulating MeHg in the trophic networks of the Colombian Caribbean.

Keywords : Methylmercury; Bioaccumulation; Biomagnification; Rhizoprionodon porosus; Southern Caribbean.

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