ARE FISH PARASITES USEFUL BIOINDICATORS OF THE "RESERVE EFFECT" IN THE MARINE PROTECTED AREA OF MEDES ISLANDS?

Abstract

Parasites are useful bioindicators of anthropogenic impacts such as pollution or overfishing, but also to assess the role of marine protected areas (MPAs) and effects of fisheries management on ecosystems. This study evaluates potential differences in metazoan parasite communities of Diplodus sargus (Sparidae) inside and outside the marine reserve of Medes Islands (NW Mediterranean), in order to explore the use of parasites as indicators of the “reserve effect”. In the framework of the project MAPUCHE, 54 specimens of D. sargus were captured outside (fished area), within the partially protected zone (buffer area) and inside the fully protected zone (no-take area) of the marine reserve. Fish specimens were captured with long line, gillnet and fishing rod by artisanal fishermen. Samples were gathered in winter, spring and summer in the fished and buffer areas and in spring in the no-take area (2008–2009). PERMANCOVA and GLM analyses of data among seasons revealed non-significant differences between fished and buffer area and an effect of season on parasite communities. Thus, pooled abundance data for spring of fished and buffer areas was compared with data from the no-take area. Multivariate analyses revealed a good differentiation of the parasite communities between the fished-buffer area and the no-take area. The higher abundance of the monoxenous parasites (Lamellodiscus spp.) agrees with previous studies indicating a higher density of D. sargus in the no-take area. Moreover, the homogeneous distribution of heteroxenous parasites in the no-take area reflects the already described site fidelity of this species.