ecological effects of marine protected areas empafish project ...

EMPAFISH Booklet no. 1 Ecological effects of Atlanto-Mediterranean MPAs in the EU
management measures have been adequate to protect a number of
ecologically as well as commercially important species (Pérez Ruzafa 1995,
1996, 2001, 2002a, 2003, 2004; García Charton 2005; García Charton et al.
2004). Fish families responding the best to protection measures –by having
higher abundance and/or biomass within the MPA, are serranids (groupers
and combers) and sparids (sea-breams) species.
Superimposed to the reserve effect, a “habitat effect” on ichtyofauna is
apparent, derived from the fact that this MPA harbour rocky habitats being
more complex (due to the importance of crevices, hangs, vertical walls, etc.)
than neighbouring unprotected areas, which are more heterogeneous (by
having a higher proportion of Posidonia and/or sand embedded in the rocky
matrix), all these differences having a great influence on the structure of fish
assemblage (García Charton & Pérez Ruzafa 1998, 1999, 2001; García
Charton et al. 2000, 2004). Hence, some fish species appeared to be more
abundant and/or big in size in unprotected areas used as control sites (some
labrids, other sparids, striped red mullet, etc.), because they show affinities
for these heterogeneous bottoms. This is an additional example on the
difficulties posed by habitat structure when trying to measure “reserve effect”
in singular sites selected to become a MPA (García Charton et al. 2004).
Comparing D. sargus genetic structure within CPIHMR with unprotected sites,
and with other MPAs –including other EMPAFISH case studies, such as
Cerbère-Banyuls and Tuscany archipelago, as well as control, unprotected
sites (González Wangüemert et al. 2002, 2004; Pérez Ruzafa et al. 2006), it is
observed that protected areas show significant higher allelic richness than
unprotected sites. In parallel, islands showed lower level of heterozygosis and
higher heterozygote deficit compared with coastal areas, making clear the
importance of considering the connectivity processes when designing an MPA.
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o Benthic communities
The abundance and size structure of sea urchins (Paracentrotus lividus and
Arbacia lixula) have been compared between partial reserve and unprotected
areas in 2001 and 2002, in relation with habitat structure (Pérez Ruzafa et al.
2002b). Density of edible sea urchins (P. lividus) was three times higher
within the marine reserve than in unprotected areas. This species showed
consistently a bimodal size structure in the marine reserve, while being
unimodal outside. In addition, spatial structure was different between both
zones, as P. lividus formed larger aggregations within the marine reserve,
while patches of sea urchins were significantly smaller outside. Variations in
habitat structure (rugosity, rocky cover, etc.) explain in part the observed
differences. Regarding A. lixula, no significant differences were found in
density or size.
� Fish movement (including spillover)
Within the CE project BIOMEX (http://biomex.univ-perp.fr), studies have been
undertaken to test the hypothesis that spillover from MPAs to neighbouring
areas should have as consequence the observation of gradients of fish