ecological effects of marine protected areas empafish project ...

EMPAFISH Booklet no. 1 Ecological effects of Atlanto-Mediterranean MPAs in the EU
unpublished data). In addition, unlike what happens in the areas outside the
MPA, these values of biomass remain stable in the protected areas.
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o Benthic community
The abundance and size structure of Patella ferruginea have been compared
between partial reserve and unprotected areas in the southern Corsica (Meier
2003). A positive trend in the populations of P. ferruginea has been noted in
the areas of the MPA, particularly inside the protected area where a no-take
zone was established. The role of hydrodynamics on the distribution of P.
ferruginea has been confirmed by the fact that the highest number of
individuals are found in the areas facing west. It is also interesting to note
that a positive effect of the MPA was found in the sea urchin Paracentrotus
lividus, for which a 25% difference was observed when comparing zones
inside and outside the protected areas. Series of observations started in 2002
show a stabilization of the population level in the areas exploited by sea
urchin fishermen (Culioli, unpublished data).
� Other biological (e.g. density-dependent) effects
Ethological studies on groupers (Epinephelus spp.) have allowed studying the
demography and the territoriality of large males in the sites from Pellu to
Lavezzi (Culioli & Quignard 1998). Inventories of dusky groupers (E.
marginatus) populations have been carried out in the whole of the Bonifacio
MPA (GEM 2001, 2003). The effects of certain environmental variables, such
as lunar cycle and meteorological changes, have been demonstrated thanks to
the fisheries studies on the MPA (Orsoni 2000).
� Effects on habitat (including impact of divers)
Impact of divers on Paramuricea clavata colonies was shown in the Pellu
diving spot (Pichot 1998), a site that is highly frequented by divers. The
Posidonia oceanica habitat has been studied in its inferior limits and in
carrying out the cartography (Meinesz & Verlaque 1989). Since 1998, various
studies have demonstrated a decrease in the size of the P. oceanica meadows
in the bays of Santa Manza and Figari, in the most interior side of the bays
(Ferrat et al. 2002).
These meadows are characterised by reduce vitality, little growth and general
detachment of rhizomes. The reduction in the Posidonia meadows can be
explained by an increase in the sediment load and its enrichment by
phosphates (Cancemi et al. 2003). The causes of this phenomenon have not
be ascertained, but the comparison with the Bay of Figari and the impact of
aquaculture plants have been studied, in order to test, among various
hypotheses, that of the organic input due to aquaculture.