Fisheries safety monitoring in the Guanabara bay, Brazil following a marine fuel oil spill

Abstract

In January 2000, approximately 1,300 m3 (340,000 gallons) of marine fuel oil were released during a pipeline transference accident in the Cuanabara Bay, Rio de Janeiro, Brazil, reaching island and land shorelines situated at the north and northeast part of the bay. An Emergency Action Plan for oil recovery and cleanup was performed, and the effort of this strategy resulted in the recovery of approximately 40% of the spilled oil. Although there was no official fishery closure, several areas were, in practice, closed to marine traffic, and fishermen were not fishing in the oil-affected area; thus, there was a de facto fishery closure. Chemical and toxicological analyses were performed on water and sediment samples to evaluate the degree of the contamination of the affected area 10 days after the spill. The results of these analyses showed background levels for polycyclic aromatic hydrocarbons (PAHs) in finfish habitat in Cuanabara Bay. A study was then conducted as a cooperative effort among the governmental environmental agency (IBAMA), universities, and PETROBRAS to assess the degree of contamination of finfish from the area for hydrocarbons and microorganisms. Microbial essays and chemical analyses for PAHs were conducted on six composite samples of edible tissue of two species (Mugil lisa and Micropogonias furnieri) collected in nets and fish traps in the most affected area. The species were chosen based on their abundance, marketability, and feeding habits. Two samples collected in the bay 1 year before the oil spill were used as reference to PAHs. The microbial analyses were conducted according to the rules from the Health Ministry and also were done for other species collected by net fishing. All samples were found free of microbial contamination and were approved to be consumed in accordance with the MERCOSUL criteria. The concentration of PAHs in the samples collected after the oil spill were at the same level of the reference samples, confirming the expectation from the literature. These results were compared to three international concentration-based and risk-based criteria since there were no legal limits for PAHs in fishes. No sample analy:ed contained PAH contamination exceeding the criteria used as reference in this study. No carcinogenic compounds were detected in the samples. The net results of this work were the rapid resumption of the finfisheries and the acquisition of a preliminary database of PAH concentration and microbial conditions on finfish tissue for the Guanabara Bay.