Holothuria tubulosa as a bioindicator to analyse metal pollution on the coast of Alicante (Spain)

Metal pollution is a major concern worldwide. The concentration of several metals in marine sediments from Alicante, Spain (Western Mediterranean): Cabo de la Huerta, Albufereta, San Gabriel and Cabo de Santa Pola has been studied, being areas with contrasted metal stress due to anthropogenic pressures, and their bioaccumulation in different tissues of Holothuria tubulosa (body wall, guts and intestine). The metals with more different levels among samples were Fe, Al, V, Mn, Pb, Ga, As, Cr, Zn and B. The body wall was the tissue that showed a significantly different signature of metal levels compared to the other body parts and the sediment. The guts, followed by the intestines, were the tissues with greatest bioaccumulation.The standard guidelines for safety limits (US EPA) for As, Cr, Pb and Zn are in the range non-polluted. In all the areas, the quality guidelines for Effect Level, Probable Effect Level, Effect Range Low and Effect Range Medium for As, Cr, Pb and Zn are much lower than those established, indicating no biologically adverse effects resulting from exposure to these metals. Regarding the potential ecological risk, for all metals it is <40 with low risk in all zones.The metals studied present a negative Igeo (area not contaminated). Arsenic in Albufereta and strontium in all the areas studied are the only ones that present a level 2 (uncontaminated to moderately contaminated). The Enrichment Factor (EF), with Fe as the normalising element, had a level 1-3 (minor enrichment), with the exception of Pb, B, As and Sr.Despite the concentrations in sediments being lower compared with other parts of the world, the Biota -Sediment Assimilation Factor from the body wall was higher at As (9.2) and B (7.3). It is necessary to high-light the high levels of As in the body wall (17 to 23 mg/kg of dry material), this is surprising, and it seems to be a general trend throughout the world.

Automated summary

Metal pollution in marine sediments from Alicante, Spain has been studied, and it was found that the body wall of Holothuria tubulosa showed significantly different metal levels compared to other body parts. The guts and intestines were the tissues with the highest bioaccumulation. The study concluded that these metals did not have adverse effects on the organisms.