Assessment of biological effects of environmental pollution along the NW Mediterranean Sea using mussels as sentinel organisms Izaskun Zorita, Itxaso Apraiz, Maren Ortiz-Zarragoitia, Amaia Orbea, Ibon Cancio, Manu Soto, Ionan Marigo ´mez, Miren P. Cajaraville * Biologia Zelularra eta Histologia Laborategia, Zoologia eta Biologia Zelularra Saila, Zientzia eta Teknologia Fakultatea, Euskal Herriko Unibertsitatea/ Universidad del Paı ´s Vasco, 644 P.K., E-48080 Bilbao, Basque Country, Spain Received 27 April 2006; received in revised form 17 October 2006; accepted 19 October 2006 The biomarker approach is suitable for assessment of environmental pollution in the NW Mediterranean Sea. Abstract With the aim of assessing the biological effects of pollution along three gradients of pollution in the NW Mediterranean Sea, a biomonitoring survey was implemented using a battery of biomarkers (lysosomal membrane stability, lysosomal structural changes, metallothionein (MT) in- duction and peroxisome proliferation) in mussels over a period of two years as part of the EU-funded BEEP project. Mussels from the most impacted zones (Fos, Genova and Barcelona harbours) showed enlarged lysosomes accompanied by reduced labilisation period of lysosomal membranes, indicating disturbed health. MT levels did not reveal significant differences between stations and were significantly correlated with gonad index, suggesting that they were influenced by gamete development. Peroxisomal acyl-CoA oxidase (AOX) activity was significantly inhibited in polluted stations possibly due to interactions among mixtures of pollutants. In conclusion, the application of a battery of effect and exposure biomarkers provided relevant data for the assessment of biological effects of environmental pollution along the NW Mediterranean Sea. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Biomonitoring NW Mediterranean Sea; Mytilus galloprovincialis; Lysosomal responses; Metallothioneins; Peroxisome proliferation 1. Introduction The Mediterranean Sea is a semi-enclosed basin covering an area of 2.5 million km 2 and containing 3.7 million km 3 of water. The water exchange time is of about 80 years and this slow turnover rate results in a high anthropogenic impact. Ur- banisation has been particularly growing along the coastline, to accommodate both permanent and temporal population (the Mediterranean is the greatest tourism destination in the world), with the result of a substantial modification of the coast and adverse effects on the quality of the environment. There is a large range of industrial activities widespread all along the Mediterranean basin, and a number of highly industrialised spots that are concentrated mainly in the NW part of the region. All these activities constitute sources of pol- lution through direct disposal, continental runoff and atmo- spheric transport (UNEP Chemicals, 2002). The presence of these pollution hot spots, located generally in semi-enclosed gulfs and bays near important harbours, big cities and indus- trial areas, is probably the major problem in the Mediterranean Sea (EEA, 1999). Regarding only petroleum hydrocarbon pol- lution, between 1987 and the end of 1996 an estimated 22 223 tonnes of oil entered the Mediterranean Sea as the result of shipping incidents causing localised damage to the Mediter- ranean marine and coastal environment (EEA, 1999), and 250 000 tonnes of petroleum hydrocarbons are discharged per year due to shipping operations (UNEP Chemicals, 2002). Other chemicals such as polychlorinated biphenyls (PCBs) and derivates, pesticides and metals are also continu- ous sources of pollution. * Corresponding author. Tel.: þ34 94 601 2697; fax: þ34 94 601 3500. E-mail address: mirenp.cajaraville@ehu.es (M.P. Cajaraville). 0269-7491/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2006.10.022 Environmental Pollution 148 (2007) 236e250 www.elsevier.com/locate/envpol