The European lancelet Branchiostoma lanceolatum (Pallas) as an indicator of environmental quality of Tuscan Archipelago (Western Mediterranean Sea)

Abstract

In June 2004 we found adults of Branchiostoma lanceolatum (Pallas, 1774; Cephalochordata) in sediment sampled within the integral reserve zone on the western side of Capraia island. The collecting site was located at 33 m depth in front of Punta del Fondo, by an extended Posidonia bed. The rippled substrate was dominated by coarse to very coarse sand (78.61%) while the silt-clay fraction accounted for less than 3%. The organic contamination analysis of the sediment gave results typical for unpolluted areas in the Mediterranean: total organic carbon 1.2%; 16 US-EPA PAHs 1.57 ng/g d.w., with a predominance of high molecular weight compounds; total PCBs 0.36 ng/g d.w., with a prevalence of higher chlorinated congeners; PBDE 16.26 pg/g d.w.; HCB and pp’-DDE below the limits of detection. Once abundant along the Italian coasts, B. lanceolatum is now rare and apparently confined to marine protected areas. In Tuscany, the species was known so far only from the Meloria Shoals. Most data in the literature suggest that its demise is related to the change in texture and eutrophication of the coastal sediments. Future studies should investigate the species’ tolerance to chemical pollutants.