Comparative study of the parasite fauna of Pagellus erythrinus and Diplodus sargus inside and outside the Marine Reserve of Medes Islands (NW Mediterranean)

Abstract

Parasites are used as biological tags in marine organisms, e.g. invertebrates, fishes and mammals. Some of these studies focus on migration events and/or stock separation of fishes, but they are also used as bio-markers for pollution events. In frame of the project “Una aproximación interdisciplinar al manejo y conservación marina: experiencias divergentes como base de estrategias globales” (Marine Protected Units in Chile and España, MAPUCHE), supported by the BBVA foundation, we studied the parasitic fauna of two fish species in the Marine Reserve of Medes Islands and its surroundings. The main goal of the study was to evaluate possible differences in the parasitic fauna of two fish species (taxonomic groups and abundance) inside and outside the reserve of Medes, in order to use parasites as a tag of the “reserve effect”. Both fish species were captured in the buffer zone (partially protected) and outside of the marine reserve of Medes Islands (NW Mediterranean). The selected species were the common pandora (Pagellus erythrinus) and the white seabream (Diplodus sargus). Fish specimens were all captured by long line or gillnet by artisanal fishermen from L’Estartit. The whole metazoan parasite fauna (ecto- and endoparasites) have been studied for 46 specimens of the common pandora and 42 of the white seabream throughout the four year seasons during 2008 and 2009. The buffer zone of Medes exhibit a minor anthropogenic impact (artisanal fisheries, recreational diving), whereas the unprotected areas in the surrounding waters are subjected to a higher degree of anthropogenic impacts (bottom trawling, recreational fisheries, spearfishing, among others). The results showed slight differences considering the presence and abundance of single parasite groups between fishes of the two studied zones. However, a general tendency of a distinct parasitic fauna in both zones (protected and unprotected) has not been observed. Statistical significant differences were detectable only for an Isopoda-species, which was more abundant in the buffer zone and very scarce in the unprotected area. Regarding the parasitic fauna and its connection to the existent whole fauna (invertebrates and vertebrates) in both areas, results will be discussed under consideration of the different degree of anthropogenic impact and the usefulness of parasites as indicators for the “reserve effect”