Ecotoxicological quality of Caraguatatuba Bay sediment, São Paulo, Brazil

Abstract

Caraguatatuba Bay (-23.66363, -45.43035), at the northern seashore of São Paulo State, Brazil, is exposed to significant sources of marine pollution: domestic effluents and spills of oil and its derivatives. This is due to its proximity to the São Sebastião Channel, where the submarine emissary outfall takes place and where the largest oil transport terminal in Brazil is located. Due to their hydrodynamic characteristics, pollutants tend to deposit in the sediment, impacting the organisms associated with it. These organisms are of great ecological importance, linked to the basis of the food chain and many species are of nutritional and commercial interest. The region remains an important stronghold of artisanal fishermen and mollusk pickers, which raises concerns about the consumption of these organisms by the local population and tourists. The aim of this study was to evaluate the quality of the bay sediment by means of ecotoxicological tests on sediments collected at six points distributed in the bay, in the 2018 winter and in the 2019 summer. Total sediment acute toxicity tests were performed using the amphipod Leptocheirus plumulosus. Samples that presented different results compared to the control sample were only observed in the winter campaign, in three points: Indaiá and Centro Beaches, according to Dunnett's test (p ≤ 0.05) and Indaiá, Centro and Camaroeiro Beaches, according to the t-test (p ≤ 0.05). Sediment samples of these beaches showed adverse effect to the organisms of the assay, being considered toxic. Sediment samples from Porto Novo, Flexeiras and Palmeiras Beaches in winter and all points in the summer campaign did not cause adverse effects to the organisms and were not considered toxic. The three points which samples were considered toxic are on the beaches located from the center to the northern end of the bay where an inlet is formed. The distribution of points with toxicity follows the pattern of particle deposition and approaches the results of sanitary quality of the region according to CETESB, the São Paulo State Environmental Protection Agency.