Density and distribution of Patella ferruginea in a Marine Protected Area (western Sardinia, Italy): Constraint analysis for population conservation

Abstract

The endemic limpet Patella ferruginea is the most endangered invertebrate in the Mediterranean Sea. Our study examined a population of P. ferruginea in the Marine Protected Area of "Penisola del Sinis -Isola di Mal di Ventre" (western Sardinia, Italy). During the summer 2009, we carried out a systematic census of P. ferruginea along a 8114 m georeferenced perimeter of coast in the "no take-no entry area" to assess its density, spatial distribution, and morphometric characteristics. Our aim was to provide a detailed map of the distribution of P. ferruginea and to investigate the effects of accessibility, wave exposure and slope of the coast on its occurrence. Patella ferruginea showed the lowest mean density ever reported (0.02 ind/m) and a unimodal population structure characterised by fewer females and juveniles. Accessibility had a major negative effect on the occurrence of P. ferruginea. Exposure was also an important factor in influencing its density, size composition and specimen position within the mesolittoral, while the slope had little influence. Morphometric analysis showed the dominance of the Rouxi form, while the Lamarcki form was confined to exposed sites. Our results demonstrate a highly endangered population of P. ferruginea and suggest that human pressure represents the main risk factor.

The exploitation of limpets in a Mediterranean Marine Protected Area: assessing the effectiveness of protection in the intertidal zone

“…Intertidal assemblages are influenced strongly by hydrodynamics (Bustamante & Branch, 1996) and many studies have shown that limpet species tend to be more abundant on rocks exposed to mediumstrong wave action (Branch & Marsh, 1978;Branch, 1981;Denny, 2000;Denny & Blanchette, 2000;Tlig-Zouari et al, 2010). This pattern was confirmed also for the species considered in this study, as also observed around the Sinis Peninsula for P. ferruginea (Coppa et al, 2012).…”

“…The abundance of the natural predators of limpets was also recorded during every survey by means of 5-metre radius searches around each transect. The species considered where the crabs Pachygrapsus marmoratus and Eriphia verrucosa, and the whelk Stramonita haemastoma, which are the main predators of limpets acting in the intertidal shores of the study area (Coppa et al, 2012). Previous observations did not revealed any encounters between limpets and other kind of predators.…”

“…Despite this, illegal harvesting was often observed in protected sites. Two studies on the effectiveness of the local MPA in controlling limpet harvesting have been conducted for P. ferruginea in a remote area of the Sinis Peninsula (Coppa et al, 2012;. These works showed that the species is mainly present on hardly accessible shores and within the no-take/no-entry zone of the MPA, highlighting an ongoing temporal contraction of the local population.…”

Filling the limpet gap: molecular characterization of the genus Patella (Patellidae, Gastropoda) in the Algerian coasts of Oran

“…Moreover, in the Port of Oran dam, two of these species co-exist on the dam's artificial substrate at high densities: up to 20 individuals/square meter for P. ferruginea and 120 individuals/square meter for P. rustica (Kallouche 2014a). Interestingly, the density of P. ferruginea in this locality, regardless of the methods used to measure it, is several times higher than that found, for instance, in Sardinian protected areas (0.02 individuals/m, Coppa et al 2012) or on Alboran Island (0.06 individuals/m, Paracuellos et al 2003). In any case, this comparison should be taken as a simple indication as differences in census methodologies can greatly bias the figures (Guallart & Templado 2016).…”

Population dynamics and secondary production of Donax trunculus (Mollusca, Bivalvia) in the Gulf of Annaba (Northeast Algeria)

“…At this site, uncontrolled exploitation of D. trunculus has been exercised by dozens of fishermen over the past ten years, not subjected to any specific regulations or guardianship by the local authorities. This management and conservation problem is also found in other Mediterranean areas for endangered molluscs such as Patella ferruginea (Coppa et al, 2012) and Pinna nobilis (Coppa et al, 2013). As a result, at both Sidi Salem and Echatt, the total number in individuals and the production of D. trunculus were lower than those reported in several other sites along the Atlantic and Mediterranean shores.…”