Is the establishment of MPAs enough to preserve endangered intertidal species? The case of Patella ferruginea in Mal di Ventre Island (W Sardinia, Italy)

Abstract

The giant limpet Patella ferruginea is the most endangered endemic species in the Mediterranean Sea. It is at serious risk of extinction, especially along the coast of Corsica and Italy. The small population of P. ferruginea in the marine protected area (MPA) Penisola del Sinis ‐ Isola di Mal di Ventre (W Sardinia, Italy) is an isolated unit whose preservation is critical also from the perspective of conservation genetics. This study considered the impact of illegal harvesting on the conservation status of P. ferruginea in the MPA. Site accessibility (semi‐accessible and hardly accessible) and legal protection (Zone A, B, C) were considered in two field surveys conducted in the Mal di Ventre Island in 2011 and 2013. Furthermore, Zone A was monitored annually from 2009 to 2013 to assess population dynamics and extinction risk. In summer 2013 the total population size was estimated at 310 specimens (0.016±0.005 ind m‐1) with a significant decrease compared with 2011 (–52%), mainly due to poaching. Significantly higher density was found in the hardly accessible sites (0.039±0.007 ind m‐1 in 2013) and generally in Zone A (0.042±0.009 ind m‐1 in 2013). The size distribution showed a similar pattern, with larger sized individuals in those sites with maximum legal protection and a lower degree of accessibility. Juveniles (<25 mm) were almost absent and the mean individual growth rate (2.6±0.5 mm yr‐1) was lower in comparison with other Mediterranean populations. The population viability analysis predicted that, with current rates of harvesting, P. ferruginea may face local extinction within the next 10 years. Without a joint effort towards the protection of intertidal habitats by enforcement bodies, regulators, researchers and sea users, the MPA will not achieve its conservation objectives and P. ferruginea will disappear from Mal di Ventre Island. Copyright © 2015 John Wiley & Sons, Ltd.

New records of the distribution and conservation status of the endangered limpet Patella ferruginea in Sardinia (Italy, W Mediterranean)

“…In particular, the density recorded in the zone B of Mal di Ventre (0.009 ind m ‐1 ) was much lower than the value reported by Coppa et al . () for 2013 in the same area (zone B: 0.023±0.007 ind m ‐1 ). In addition, considering that P. ferruginea is a broadcast spawner with a protandric hermaphrodite reproductive strategy (Espinosa et al ., ; Rivera‐Ingraham et al ., ), the absence of juveniles (<25 mm) and of large specimens (>70 mm) in 2014 suggests a limited reproductive potential of the population and thus a high risk of local extinction.…”

“…These latest surveys confirm the alarming conservation status of P. ferruginea and the dramatic rate of decline of the population size inferred from previous studies (Coppa et al ., , ). In particular, the density recorded in the zone B of Mal di Ventre (0.009 ind m ‐1 ) was much lower than the value reported by Coppa et al .…”

“…In particular, Coppa et al (2012) undertook a systematic census of the entire 'no take -no entry' zone (zone A, according to Italian legislation) and of a small portion (<15%) of the general protection zone (zone B), to address the distribution and population size of the species on the island. In a more recent study, transects within different levels of legal protection (zones A, B, C) and accessibility (semi-and hardly-accessible) were analysed to detect population trajectories (Coppa et al, 2015). The authors showed that the density of P. ferruginea had greatly decreased in recent years, in particular on the rocky shores of the zone C. Accessibility of sites, influencing the scale of human harvest, had a major negative effect on the occurrence of P. ferruginea.…”

Beyond marine paper parks? Regulation theory to assess and address environmental non‐compliance

“…The ineffectiveness of Sinis MPA can be demonstrated also by considering the status of the protandric limpet Patella ferruginea (Coppa et al ., , ), the most endangered invertebrate of the Mediterranean Sea protected under Annex II of the Berne Convention, Annex II of the 1995 Protocol concerning Mediterranean Specially Protected Areas and Biological Diversity in the Mediterranean to the Barcelona Convention, and Annex IV of the Habitat Directive. In the first census, carried out in 2009, a detailed map of the distribution of P .…”

“…This review, and in particular the consideration of grey literature and the analysis of raw data, has been fundamental to define the conservation level of local biological resources and has provided the biological basis for the subsequent socio‐legal study. In fact, if only published literature had been considered (Guidetti et al ., ; Coppa et al ., , ; Marra et al ., ) no strong evaluation of this topic including temporal trends could have been carried out (only Coppa et al ., and Marra et al ., included temporal dynamics analysis). Regarding the raw data, it was decided to analyse those referring to the commercial sea urchin Paracentrotus lividus because: (1) it is one of the most intensively exploited invertebrates in Sardinia (Pais et al ., and literature therein); (2) there are more restrictive rules governing its exploitation inside the MPA (e.g fishing is allowed only in zone C and without breathing apparatus; fishermen have lower personal quota compared with outside; see Decree 28/10/2014, n. 1553 for more details); and (3) there is wide availability of spatial and temporal data.…”