Mercury (Hg) is a global pollutant which is widely distributed in the environmental compartments. Its occurrence in oceans and coastal ecosystems is well documented and can be related to natural or anthropogenic sources. The contribution of anthropogenic sources has changed the figures of natural cycles fluxes of Hg on the Earth, increasing its presence from the beginning of industrialization. The main route of Hg exposure to the human being is related to food consumption. Species of larger fish (e.g. tuna, swordfish, etc.) accumulate significant amounts of Hg and mono methylmercury (MMHg) which are a risk for human health. In this work, we have analysed Hg concentrations in muscle and liver in two tuna species (i.e. Thunnus alalunga and Thunnus thynnus) collected in the Gulf of Cadiz. These specimens did not have a commercial size and the weight ranged between 1.12-1.43 kg and 0.22-0.37 kg for T.alalunga and T .thynnus, respectively. Similar Hg concentrations in both target tissues were reported in each species. T. alalunga bioaccumulated higher amounts of Hg in the muscle (0.51-1.22 mg/kg) than T. thynnus, (0.18-0.33 mg/kg). Although, only T. alalunga had concentrations higher than legal limits (1.0 mg/kg). A preliminary exam of the weekly intake of Hg considering both species did not show risk for the general population. However, a more detail exam of Hg intake for fish consumption should be carried out according to the last recommendations of the Spanish Food Security and Nutrition Agency (AESAN, 2019) which reduced the amount recommended for fish consumption with high Hg concentrations, especially for risk groups.

Trabajo presentado en el XX Seminario Ibérico de Química Marina, celebrado en modalidad virtual del 1 al 3 de julio de 2020.