Avaliação da presença de hidrocarbonetos policíclicos aromáticos e caracterização das populações bacterianas de Anomalocardia brasiliana e Crassostrea rhizophorae em estuários de Pernambuco após derramamento de óleo

Abstract

The present study was divided into two parts, the first aimed to analyze the concentration of PAHs and histologically evaluate the gills of the collected animals. And the second is to evaluate the presence and characterize the bacterial populations of shellfish and oysters, both in the estuaries of the State of Pernambuco after the oil spill. For this, samples of oysters (C. rhizophorae) and shellfish (A. brasiliana) were collected from locations on the northern and southern coasts of the state. The wet tissues of the animals were analyzed for total concentrations of polycyclic aromatic hydrocarbons (PAHs), and the gills were analyzed histologically. For the second analysis, total counts of mesophilic aerobic and psychotrophic bacteria, coagulase-positive Staphylococcus aureus, and determination of the Most Probable Number (MPN) of total and thermotolerant coliforms were quantified following the analytical guidelines of the “Ministério da Agricultura, Pecuária e Abastecimento” (MAPA). In addition, bacterial isolates obtained from the different points analyzed were characterized by sequencing (using universal primers from coding regions of the 16S rRNA gene) to identify the bacterial species present in the environment. In the first study, different PAHs concentrations were observed along the coast, being evidenced mainly by the total concentration in the shellfish from the north coast, which averaged four times higher compared to the south coast. The low molecular weight compounds naphthalene and anthracene were the representatives of the total concentration. As a result of exposure to these compounds, histological changes were observed in the gills of the bivalves, being more severe in the specimens sampled at the northern coast points. For the bacteriological analyses, it was observed that the mesophilic and psychrotrophic bacteria counts of both species concerning the analyzed locations remained below the threshold adopted for food safety. For the genus Staphylococcus, the results obtained are under the current Brazilian legislation, with no presence of coagulase-positive Staphylococcus. For total and thermotolerant coliform, the highest average was observed among the shellfish and oysters from the northern coast, with no thermotolerant coliforms identified in the samples. With this, it was possible to conclude that, for human consumption, both species are safe for eating, according to Brazilian legislation. But the persistence of polycyclic aromatic hydrocarbon residues in the environment caused alterations in the gill tissues of the bivalves, with emphasis on the specimens sampled from the northern coast, demonstrating an alteration in the health of the animals.