Toxicity of sediments and dredged material from a semi-arid coastal system to marine invertebrates

Abstract

Dredging involves the sediment excavation in order to increase the bathymetry of harbors by different methods. In urbanized and Industrial areas, dredging pose risks of negative effects on the biota due to sediment contamination. The Brazilian criteria for characterizing dredged material include chemical analyzes and comparison with sediment quality guidelines and toxicity testing, which require the development of novel and different biological models to be used in bioassays. In this study, we aimed to assess the quality of sediments collected during dredging activities of Mucuripe Bay (Fortaleza city, NE Brazil). Sediments were characterized for the concentration of metals and hydrocarbons, in order to establish the contamination status. Whole sediment toxicity was assessed by means of mortality of the amphipod Tiburonella viscana and the polychaete worm Armandia agilis, while chronic effects were evaluated on the fecundity of the copepod Tisbe biminiensis. Liquid phase exposures were determined in the acute toxicity of sediment-water interface (ISA) on the mysid Mysidopsis juniae, while chronic toxicity of ISA and elutriates (ELU) assessed by the embryo-larval development of the sea urchin Lytechinus variegatus. Results revealed that contaminated samples exhibited both acute and chronic toxicity. An integrative method for integrating different endpoints was employed and classified samples related to dredging activities as the most degraded. Extracts obtained from the material collected within the dredge were also tested for acute and chronic effects and exhibited toxicity as well. Based on our findings we recommend the analysis of material from dredger cistern and application of a set of bioassays in order to properly determine the quality of dredged sediments