Manuel Maestre

Responses of the endangered limpet Patella ferruginea to reintroduction under different environmental conditions: survival, growth rates and life‐history

The mollusc Patella ferruginea, endemic to the Mediterranean, is the most endangered marine species of the list of the European Council Directive 92/43/EEC and it is presently under serious risk of extinction. Survival, growth rates and life‐history of this species were studied for the first time in this species. A total of 570 specimens (420 introduced in a new habitat and 150 as control) were marked and monitored over a three‐year period. Growth rates observed were mainly related to the availability of microalgal food. The mortality rate of transplanted specimens was high (50% mortality immediately after transplant). Seasonality in growth rates was observed in both control and transplanted specimens, with greater growth rates detected in spring‐summer (warm season) than in autumn‐winter (cold season). Smaller specimens of P. ferruginea had the greatest growth rates in comparison with the bigger specimens, therefore the potential ability to adapt in a new habitat was higher for small specimens immediately after removal. An elevated growth rate (appearing as a light‐ring in the border of the shell) was detected immediately after translocation, following which growth rate progressively stabilized over time. Using differential equations and the von Bertalanffy model, the longevity of P. ferruginea was estimated to range between 8.89 and 35.72 years depending on the environment. Transplantation should not be considered as a conservation measure given the elevated mortality rate.

Updated global distribution of the threatened marine limpet Patella ferruginea (Gastropoda: Patellidae): an example of biodiversity loss in the Mediterranean

Patella ferruginea is the most threatened macroinvertebrate in the western Mediterranean, where it is at serious risk of extinction. There is little information on the status of the various populations and most data were published more than 25 years ago. This study provides updated information on the global status of this species, and implications for management and conservation, and tests the hypothesis that population structure can be influenced by collection by people and by the type of substrate. Fifty-five localities were surveyed in Corsica, Sardinia, Tuscany and Sicily, on the islands of Egadi and Pantelleria, and on the Zembra archipelago and Tunisian coasts. The species is extinct on mainland Italy and Sicily but isolated individuals can be found on Egadi and Pantelleria. Populations on Corsica and Sardinia have declined dramatically during the last 25 years. The population in the Zembra archipelago is well preserved, although more widely on Tunisian coasts the species is highly threatened. The information provided here, combined with information from the literature, indicates a strong decline and/or extinction of many populations throughout the western Mediterranean and the presence of healthy populations only in some locations along the north African coast. The species exhibits an increase in density and mean size in areas free of human pressure but the type of substrate (natural or artificial) has no strong influence.

Antioxidant Defenses and Trace Metal Bioaccumulation Capacity of Cymbula nigra (Gastropoda: Patellidae)

The present study deals with the effect of trace metals on the endangered limpet Cymbula nigra. The Bay of Algeciras (Strait of Gibraltar) was used as the study site. Important industrial activity takes place in the area, including frequent oil spills. However, it is home to important populations of C. nigra. The objective of this work was to determine if these animals were being affected at a subcellular level by the pollutants present in their environment and to analyze the trace metal concentrations in the animal’s soft tissues. To determine the effects of water quality on the antioxidant activity and concentrations through field experimentation, a total of six sites were selected in Algeciras Bay, three located in the inner areas (environmentally degraded sites with higher levels of pollutants) and three in the outermost areas of the Bay. Stress associated to reactive oxygen species formation was assessed on digestive glands and gills as the enzymatic antioxidant activity of catalase (CAT), superoxide dismutase (SOD), and glutathione S-transferase (GST) and as the concentrations of lipid-soluble (α-tocopherol and β-carotene) and the water-soluble antioxidants (reduced and oxidized glutathione (GSH and GSSG)). Gills and digestive glands of those animals located in the inner areas of Algeciras Bay showed higher CAT activity values than those located in the outer areas. As a general pattern, we observed higher antioxidant activities and concentrations in digestive glands that in gills, suggesting the possibility that pollutants are mainly being incorporated by limpets through the food. As a general rule, larger animals showed greater concentrations of these compounds. Iron, zinc, and manganese, in this order, were present in the tissues at the highest concentrations. Chromium and manganese were found in significantly higher concentrations in those animals collected from the inner areas of the Bay. Through the present study, we provide the first data regarding the antioxidant defense levels and metal accumulation capacity of this species, and we reinforce the idea that this endangered species may be, in fact, relatively tolerant to degraded environments.

Assessment of conservation value of Cap des Trois Fourches (Morocco) as a potential MPA in southern Mediterranean

The marine habitats surrounding Cap des Trois Fourches (Mediterranean coast of Morocco) was explored in the framework of the MedMPAnet Project. Ten different communities were identified in the studied area, among which it is remarkable the presence of some key conservational habitats: seagrass meadows, dark and semidark cave communities, maërl beds and corraligenous assemblages. All the data was included in a GIS program (Geographic Information System) to elaborate a cartographic map of marine communities and species distribution. All the scientific data obtained support the proposal of Cap des Trois Fourches as a marine protected area. We also provided a map of management, suggesting the stricter protection of the areas with higher conservational interest.