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The marine limpet Patella ferruginea 267

FIG. 1 Locations of the 55 study sites where we surveyed Patella ferruginea. For details of each site see Supplementary Table S1.

we tested the hypothesis that population structure and locations with healthy marine communities (because of
related reproductive success can be influenced by collection the sensitivity of the species to pollution and collection;
by people and by the type of substrate on which the Espinosa et al., 2007). Transects parallel to the coast were
populations are settled (artificial vs natural). The results will surveyed at each locality, by snorkelling on steep or sloping
assist in the conservation management of this species. shores and on foot on shallow sloping shores. All limpets
settled on the shore were recorded. At localities with sparse
Study area populations 100 m transects were surveyed, whereas 10 m
transects were used at sites with high densities (Supplemen-
We explored the shores of the mainland and of Zembra tary Table S1; Laborel-Deguen & Laborel, 1991b; Guerra-
and Zembretta islands, Tunisia, Pantelleria and the Egadi García et al., 2004). All specimens of P. ferruginea found
islands off western Sicily, the western Sicilian mainland, were measured with a calliper to the nearest mm along
Corsica, Sardinia and the Tuscany–Liguria coast of Italy the longitudinal axis (Guerra-García et al., 2004). Small
(Fig. 1, Supplementary Table S1). We visited sites where the individuals are difficult to detect (Guallart et al., 2006) and
species had been recorded previously on the Egadi islands therefore particular care was taken to record this component
and Pantelleria (Giaccone & Sortino, 1974), along the of the population. For graphical representations of size
Tuscany–Liguria coast (La Rochette: Curini-Galletti, 1979; frequencies we have only taken into consideration sites with
Quercianella: Terreni, 1981; Piombino: Biagi & Poli, 1986; at least 10 specimens. Data from the sites surveyed in the
Portofino: Porcheddu & Milella, 1991) and on Corsica Zembra archipelago were pooled because genetic analyses
(Laborel-Deguen & Laborel, 1990, 1991b). We also collected have shown that there is no limitation to gene flow in this
all available information on the status of the species area (Casu et al., 2012).
throughout the Mediterranean. The assumptions for parametric statistics were not met
by some of our data, with severe departures from normality
Methods and highly unequal variances. The ANOVA test is, however,
robust for deviation from normality (Underwood, 1997)
Sampling sites were selected on rocky habitats, where and if a Type I error is minimized (by using P,0.01)itis
the species settles, mainly in marine protected areas or at possible to conduct an analysis even if the condition of

© 2013 Fauna & Flora International, Oryx, 48(2), 266–275

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