Metais em raias da costa do estado do Rio de Janeiro no final do século XX

Abstract

Metals may be necessary for metabolic actions in organisms, however, in high concentrations they have toxic effects. In the aquatic environment, the high bioavailability of these elements leads to bioaccumulation, causing damage to the biota and, in case of consumption, these damages are also extended to human health. Many species of batoids are demersal predators and, as a result, are susceptible to the ingestion of these metals, with the potential for later availability to human populations. Within this context, the goal of this study was to determine the concentration of metals in batoids, based on previously unpublished data. The data were obtained through the Marine Environment Monitoring Program (MoMAM), coordinated by the Brazilian Navy’s Instituto de Estudos do Mar Almirante Paulo Moreira (IEAPM), in partnership with several research institutions in the country. One of these institutions was the Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), where the muscle samples from batoids were processed and the metal data were generated. Sampling was carried out on the coast of the state of Rio de Janeiro using otter trawl and IEAPM research vessel. The sampling localities (with respective dates) were: Macaé (Jul., 1997), Rio de Janeiro (Guanabara Bay and Barra de Guaratiba) (Sep., 1997), Arraial do Cabo and Cabo Frio (Apr., 1998), São João da Barra (Atafona) (Nov., 1998), and Paraty (Dec., 1998). The following species of batoids were collected (with indication of the respective sample size): Zapteryx brevirostris (n = 29), Rioraja agassizi (n = 11), Rioraja castelnaui (n = 2), Sympterygia bonapartii (n = 1), Sympterygia acuta (n = 1), Psammobatis sp. (n = 3), Myliobatis freminvillii (n = 1) and Hypanus guttatus (n = 1). About 20 g of muscle tissue were removed from each batoid, which were kept under refrigeration and taken to UENF. For each sample, the concentrations of the following metals were determined: Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn, using ICP-AES. The results were expressed in μg.g-1 dry weight and later converted to wet weight for comparison with values of maximum allowed concentration (CMP) by Brazilian legislation. The concentrations of cadmium and lead in batoids of Rio de Janeiro, at the end of the 20th century, were above the CMP and above those found in batoids from other regions of Brazil. These metals are not responsible for biological activities and probably bioaccumulated. The concentrations of copper, zinc and nickel, which are essential metals for organisms, were at acceptable levels for maintaining biological functions. As for the concentrations of aluminum, iron, and manganese, which do not have an established CMP values, Fe and Mn had lower concentrations than the batoids from the Mediterranean Sea, whereas those of Al had higher concentrations than batoids from the coast of Paraná State.