Evaluation of metallic pollution of north eastern Algerian coasts using the demosponge Chondrilla nucula Schmidt, 1862

In the last couple of years, a “Sponge Watch” Programme was launched in the Gulf of Annaba (North-eastern Algeria) with a goal of involving for the first time the sponges as bioindicators of heavy metals contamination in the biomonitoring programmes of the Algerian coasts. This study aimed to investigate the potential of a sponge’s species (Chondrilla nucula Schmidt, 1862) in the assessment of trace metal elements in the Gulf. In this context, the seasonal variation in the concentration of four trace metals (Cupper, Zinc, Lead and Cadmium) was monitored in C. nucula from two different areas during a one-year period in 2017-2018. Furthermore, a complementary approach based on the analysis of three oxidative stress biomarkers (glutathione, glutathione S-transferase, and malondialdehyde) was performed on the same samples to better characterize the biological response of the sponge to this kind of environmental stress. Similar environmental conditions in both sites of the Gulf were detected. The highest concentrations of the studied elements were recorded in the humid season (winter and spring), while the lowest were in the dry season (late summer to autumn). Otherwise, significant (P ≤ 0.05) variations were recorded in the accumulation of all metals, with the exception of lead, which seemed regulated at a certain level. On the other hand, the sponge’s biochemical parameters showed significant temporal fluctuation and seemed to follow those of metals. Therefore, the sponge C. nucula seems to be a suitable sentinel species to be considered in the biomonitoring programmes although it shows less tolerance to lead.