Estudi de la relació entre l’alimentació i els metalls pesants de tres espècies de peix del mar Mediterrani

Sala Alcoba, Sara
The concentrations of heavy metals (Cd, Sn, Ni, Cu, Zn, As, Se, Hg, Cr, Pb and Mn) were analyzed in the muscles of three species of fish (Oedalechilus labeo, Serranus cabrilla and Coris julis) from the Mediterranean Sea. A study of the feeding habits of each species was carried out, in more detail in the case of Oedalechilus labeo due to lack of bibliographic information, and it was investigated whether concentrations of metals were incorporated into the fish from its diet. Results are obtained showing that O. labeo is an omnivorous and opportunistic species that incorporates more metals than other species. Individuals of this species are divided into medium size (M) and large size (L) and higher metal levels are obtained in the large size, expressed in MPI values (O. labeo M: MPI = 104.76 Pg kg-1, O. labeo L: MPI = 121.03 Pg kg-1 fresh weight). It changes diet as it grows, because of it first feeds on planktonic organisms and as it grows, it adds benthic organisms to the diet, allowing more heavy metal uptake. A significant Hg bioaccumulation is found, which is closely related to the age of individuals, i.e. older individuals have more Hg bioaccumulated. In this species, a negative correlation of Zn and total length (TL), and positive of Pb and TL are shown. In the case of Coris julis and Serranus cabrilla it is observed that they are two carnivorous species that feed exclusively on benthic organisms. In the first, high concentrations of As are found, and in both, high levels of Hg. S. cabrilla shows a negative correlation between Cu and TL, and higher concentrations of Se are found. The elements Cd, Cr and Sn have very similar values in the three species, therefore, they are incorporated in the body of the fish by other ways. Thanks to ANCOVA statistical analysis it is known that the loads of As and Cu vary significantly among the species regarding to the TL of the fish (As: p = 0.026, Cu: p = 0.019), suggesting different bioconcentration rates for each species according to their size. All concentrations of metals are within the established legal limits or within the usual values of the North Mediterranean coast ​
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