Assessment of sea waterquality using populations of the sea urchin Paracentrotus lividus(Lmk)

Abstract

The present study is a contribution to the evaluation of coastal water quality off Algiers, using the sea urchin Paracentrotus lividus as a bio-indicator. It also highlights the different demographic strategies of this species according to contrasting environmental factors. Ecotoxicological analyses were carried out to evaluate the metal contamination in the natural environment and the toxicity of the bioavailable fraction using the sea urchin. Concentrations of heavy metals (Cu, Zn, Cd, Fe, Pb, Cu) are compared to the ambient sediments of the studied areas and in sea urchin gonads. Direct effects on the features of life-history traits of sea urchins in the studied areas are also estimated. The results show metal pollution in both the biotic and abiotic fractions, with an increa-sing disturbance of the larval development of sea urchins outside Algiers bay towards the principal river of the town. However, despite a very strong concentration of lead pollution, the metal contamination in the whole Algiers bay remains paradoxically weak in comparison with the resultsanticipatedfor such a megapolis. The direct effect of metallic contamination on the life history of sea urchins is less obvious, since the variability observed between samples probably depends on other environmental factors. This study highlights morphological differences between samples of sea urchins and shows that abiotic factors such as hydrodynamics and substrate nature affect test shape and spine length. This is particularly suggested by the more flattened tests and longer spines of the sea urchins living outside Algiers bay.