Artificial marine micro-reserves as a new ecosystem-based management tool for marine conservation: The case of Patella ferruginea (Gastropoda, Patellidae), one of the most endangered marine invertebrates of the Mediterranean

Abstract

During the Anthropocene, species are becoming extinct at unprecedented rates, a trend that will be difficult to reverse, even if we ignore the possibility of a considerable extinction debt. Among the different factors that affect the natural environment, fragmentation of ecosystems by urbanization processes can cause a reduction in species population sizes, thus enhancing their risk of extinction. Nevertheless, some species can maintain stable populations in these urbanized ecosystems. This is the case of the intertidal mollusc Patella ferruginea (Gmelin, 1791), a broadcast spawner, and a sequential protandrous hermaphrodite limpet, whose populations have been historically decimated due to human harvesting. In this study, we analyse the benefits of a new marine conservation tool called ¨Artificial Marine Micro-Reserves¨ (AMMR) in P. ferruginea, one of the most endangered marine invertebrates of the Mediterranean Sea. The results showed that accessibility is the main factor concerning the conservation status of this species, with no-entry areas where populations achieve balanced sex-ratios and high reproductive outputs. The present study was conducted in Ceuta (North Africa, Gibraltar Area), and among its varying results, it shows that in the same body of water inside the port, the proportion of females of P. ferruginea in the area without accessibility (high protection) was 4.68 and 43.54 times higher than in the medium and low accessibility (non-protected areas), respectively. Therefore, the effective protection of these artificial areas has a positive effect on population size structures, as the female's percentage in the population is crucial for fostering the creation of genetic bridges for the recolonization of natural habitats. Furthermore, a potential ‘umbrella effect’ can be derived from the implementation of the proposed AMMR in other protected species, bioindicators, or commercially exploited species detected in artificial structures. In this sense, the creation of artificial marine microreserve networks (AMMRNs) in coastal defense structures is in line with the interdisciplinary approach of Ecosystem-Based Management (EMB), given that this methodology balances ecological, social and governmental principles for achieving humane sustainable development.