Effects of the fuel oil spilled by the Prestige tanker on reproduction parameters of wild mussel populations Maren Ortiz-Zarragoitia, Larraitz Garmendia, Mar  ıa Carmen Barbero, Teresa Serrano, Ionan Marig omez and Miren P. Cajaraville * Received 23rd April 2010, Accepted 2nd August 2010 DOI: 10.1039/c0em00102c The aim of this work was to assess possible effects of the Prestige oil spill on reproduction parameters of mussels along the Galician and Bay of Biscay coast. Studied endpoints included sex ratio, gonad histology and vitellogenin-like proteins using the alkali-labile phosphate (ALP) method. A high prevalence of haemocytic infiltration of follicles and severe oocyte atresia was found in most localities in April 2003. Spawning gonads were observed in most impacted populations in the same sampling. In April 2004 mature small sized follicles were observed. No histopathological changes were observed in April 2005 and 2006, except a high prevalence of necrotic gametes in 6 out of 22 localities in April 2006. Female ALP levels showed high interindividual variability in April 2004, which was reduced in April 2005 and 2006. No xenoestrogenic effects were observed in male mussels. Overall, gamete alterations were detected during 2003–2004 and a recovery trend was observed afterwards. Introduction On November 19th, 2002, the oil tanker Prestige broke in half and sunk in international waters 133 miles from the north western coast of the Iberian Peninsula. The Prestige transported 77 000 tones of heavy fuel oil no. 2 according to the French classification (UK classification type no. 6; Russian classification M-100). More than 60000 tones of fuel oil were spilled affecting mainly the coast of Galicia on the north west of the Iberian Peninsula. During the following months spilled oil also affected the whole northern coast of the Iberian Peninsula reaching up to Brittany. 1,2 The Prestige oil spill (POS) has been considered the most important ecological disaster ever to occur in the affected area. 1,3 Severe loss of intertidal invertebrate communities has been measured on POS affected beaches. 4,5 The area impacted by the POS is rich in bivalve production, Galicia being the most important European producer of mussels. Mussel production surpasses 200 000 Tn per year and employs more than 8000 full-time workers in Galicia. 6 Mussels have been used worldwide as sentinel species of environmental pollution in coastal areas. 7,8 Mussels are excellent indicators of contamination levels in the marine environment as they are sessile and filter feed from surrounding water. Furthermore, they show a low ability to metab- olize xenobiotic compounds like polycyclic aromatic hydrocarbons (PAHs) and accumulate them at high levels. 9,10 Mussels are sensitive species to accidental oil spills as effects on different biomarkers have been observed after Exxon Valdez in Alaska, 11 Aegean Sea in Gali- cia, 12 Sea Empress in Wales, 13 Coral Bulker in North Portugal, 14 Erika in Brittany 15 and the case of Prestige. 16,17 Studied biological endpoints in mussels affected by an oil spill usually show a rapid recovery in 1 to 2 years after the oil spill. 12,13,18 However, long lasting effects could not be discounted as shown in the case of wildlife Biologia Zelularra eta Histologia Lab., Zoologia eta Biologia Zelularra Saila, Zientzia eta Teknologia Fakultatea, University of the Basque Country UPV/EHU, Sarriena z/g, 48940 Leioa, Basque Country (Spain). E-mail: mirenp.cajaraville@ehu.es; Fax: +34 946013500; Tel: +34 946012697 Environmental impact Several works have used mussels as sentinel organism for chemical biomonitoring studies after oil spill events, but no studies have addressed the impact of oil spills on reproduction-parameters in wild mussel populations. Here we present for the first time a long- term (2003–2006) biomonitoring survey studying reproduction-related parameters, such as sex ratio, gonad histology and vitello- genin-like proteins, in 22 mussel populations from Galicia and the Bay of Biscay after the Prestige oil spill. Our results showed alterations in gamete development in mussels from the whole studied area in 2003 and 2004, but recovered later on (2005–2006). The applied reproduction-related biomarkers have been demonstrated to be a useful tool for pollution assessment and could be included in ongoing worldwide biomonitoring programmes studying mussels. 84 | J. Environ. Monit., 2011, 13, 84–94 This journal is ª The Royal Society of Chemistry 2011 Dynamic Article Links C < Journal of Environmental Monitoring Cite this: J. Environ. Monit., 2011, 13, 84 www.rsc.org/jem PAPER Published on 29 October 2010. Downloaded on 13/01/2014 15:25:06. View Article Online / Journal Homepage / Table of Contents for this issue