Assessment of sediment toxicity from the Areia Branca off-shore harbor and the Potengi river estuary (RN), northeastern Brazil

Abstract

The present study aimed to evaluate the toxic potential of superficial sediments collected in Areia Branca harbor (AB) and Potengi River Estuary (PR). Both areas are situated in Rio Grande do Norte state and are under pressure of anthropogenic activities. Particle size, calcium carbonate content, organic matter, and Fe, Cd, Cu and Zn levels of all samples were analyzed. Acute toxicity assays using the amphipod Tiburonella viscana were performed with whole sediment samples, as well as chronic assays using copepods Tisbe biminiensis and Nitocra sp were conducted with samples from AB and PR, respectively. Principal component analysis (PCA) was performed to observe relationships between sediment variables and toxicity. The sediment analyses showed influence of anthropogenic sources for metals, especially Cu and Zn, while bioassays revealed toxicity in most samples from both areas (acute and chronic effects). PCA results showed the contribution of contamination sources on toxicity and an unexpected relationship between toxicity and CaCO3 rich sediments. These results emphasize the need for further studies to elucidate the relationship of calcium carbonates with contaminants in sediments, as well as the necessity of an integrated assessment using different lines of evidence (LOE) in order to subsidize the environmental management of tropical marine environments.