Ecotoxicological assessment of sediments from the Mediterranean coast of Morocco using an integrated approach

The Moroccan Mediterranean coast, rich in aquatic resources, faces increasing anthropogenic pressures, highlighting the need for monitoring the structural and functional integrity of aquatic ecosystems. This study aims to assess the environmental quality of marine sediments collected from five sites along the Moroccan Mediterranean coast, in order to identify sediments that could pose a risk to aquatic organisms and implement measures to improve their condition. Sediment characteristics, metal levels, and toxic effects on the microalgae Tetraselmis suecica, the microcrustacean Artemia salina, and the sea urchin Paracentrotus lividus were studied to evaluate the quality of different sediment phases as a reservoir of contaminants. We also combined all bioassays (algal growth inhibition, mortality, and embryotoxicity) using the Toxicity Test Battery Integrated Index (TBI) to estimate the risk level of sediments. Results revealed differences in sensitivity among the test organisms, linked to their biological and granulometric characteristics, and also to their interactions with contaminants. The assessment was supported by the analysis of trace metal elements which demonstrated a consistency with the observed biological responses. The data integration using TBI approach indicated an ecotoxicological risk at almost all sites, except for station 1 (Strait of Gibraltar), showing the utility of this index and its important role in emphasizing the necessity for the sustainable management of marine ecosystems. Our study highlights the strong potential of a multi-species approach in biological assays for accurately assessing environmental risks in coastal marine ecosystems.