Follow-up trends of parasite community alteration in a marine fish after the Prestige oil-spill: Shifting baselines? A. Pe ´ rez-del-Olmo a, * , F.E. Montero b , J.A. Raga a , M. Ferna ´ ndez a , A. Kostadinova a, c a Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, PO Box 22085, 46071 Valencia, Spain b Department of Animal Biology, Plant Biology and Ecology, Autonomous University of Barcelona, 08193 Bellaterra, Barcelona, Spain c Central Laboratory of General Ecology, Bulgarian Academy of Sciences, 2 Gagarin Street,1113 Sofia, Bulgaria Prestige oil-spill impact on parasite communities in the sparid fish B. boops. article info Article history: Received 28 March 2008 Received in revised form 27 May 2008 Accepted 16 July 2008 Keywords: Oil-spill Boops boops North East Atlantic Parasite communities Multivariate analysis abstract This study evaluates the follow-up trends in the composition and structure of the parasite communities in the marine sparid Boops boops after the Prestige oil-spill. A total of 400 fish comprising 11 seasonal samples was analyzed from three impacted localities on the Atlantic coast of Spain. A large number of parasite species was recovered only after the spill thus suggesting a substantial alteration of the marine food webs. Post-spill communities exhibited higher richness and abundance due to the significant changes in the abundance of the common species, the latter indicating accelerated parasite transmission rates. Multivariate analyses at two nested scales detected a directional trend in parasite community succession towards the pre-spill situation, however, with no full support for community recovery. The state of parasite communities in 2005–2006 may provide the new baseline data which can serve as a framework for quantifying the impact of potential future spills in the region. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction A large body of literature has provided evidence that parasites are good indicators of environmental contamination (reviewed in MacKenzie et al., 1995; Williams and MacKenzie, 2003; Sures, 2004; Marcogliese, 2005). Generally, parasite transmission is altered in polluted habitats (MacKenzie et al., 1995; Williams and MacKenzie, 2003). Because ectoparasites are in direct contact with the polluted water, they may well reflect any direct negative effect of a pollutant on their reproduction and survival (Khan and Thulin, 1991) or their populations may increase, the latter effect usually attributed to a compromised immune response of the host (MacKenzie et al., 1995; MacKenzie, 1999; Moles and Wade, 2001; Khan, 2003). On the other hand, because endoparasites have complex life cycles, their transmission can be regulated through pollution effects on both their free-living stages and intermediate hosts (Poulin, 1992; Marcogliese and Cone, 1997; MacKenzie, 1999; Marcogliese, 2005). Furthermore, their numerical responses to pollution may reflect alterations in the local food webs since most parasites are trophically transmitted. Parasite communities, therefore, integrate the direct effects of toxicants on the individual species and the indirect effects mediated via impacts of pollution on different components of the food web and the structure of the local animal community. However, community level analyses related to pollution impacts have only rarely been attempted and then predominantly carried out in freshwater ecosystems (Valtonen et al., 1997, 2003; Lands- berg et al., 1998; Halmetoja et al., 2000; Galli et al., 2001; Her- nandez et al., 2007; but see Vidal-Martı ´nez et al., 2003 for a marine example). A common approach in these studies is to infer associ- ation between pollution and levels of parasitism by comparing the parasite prevalence (percentage of infected hosts) and/or intensity (number of parasites of a species per infected individual fish), and parasite community diversity indices in some cases, among host samples from differently impacted sites. Another characteristic feature of the use of parasites and/or parasite assemblages in fish as response indicators is that it is typically based on planned comparisons between sites chronically exposed to pollutants and unpolluted sites whereas catastrophic events, to the best of our knowledge, have never been addressed perhaps due to the lack of reference data. One such catastrophic event occurred in November 2002 when the oil tanker Prestige broke into two and sank over the Galician Bank (c. 240 km off the Galician coast of Spain) releasing c. 60 000 * Corresponding author. Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, PO Box 22085, 46071 Valencia, Spain. Tel.: þ34 963543657; fax: þ34 963543733. E-mail address: ana.perez-olmo@uv.es (A. Pe ´ rez-del-Olmo). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol 0269-7491/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2008.07.010 Environmental Pollution 157 (2009) 221–228