Assessing habitat use of the endangered marine mollusc Patella ferruginea (Gastropoda, Patellidae) in northern Africa:: preliminary results and implications for conservation

The limpet Patella ferruginea Gmelin, 1791, endemic to the Mediterranean, is the most endangered marine species on the list of the European Council Directive 92/43/EEC on the Conservation of Natural Habitat of Wild Fauna and Flora (1992). Its Mediterranean range has progressively contracted to a few restricted areas and the species is now threatened with extinction. Seventeen stations were sampled along the littoral zone on the coast of Ceuta, North Africa, for quantifying environmental factors (water movement. siltation and suspended solids), and 70 transects were selected for P. ferruginea sampling. The study revealed the presence of a well-established population of P. ferruginea with values of density and size of 0.67 individuals m(-1) +/- 0.96 and 48.94 mm +/- 11.61 respectively (mean +/- standard error of mean). The biggest densities of P. ferruginea were found inside the harbour of Ceuta. The limpets were more abundant on artificial harbour stones than on natural rocky shores, and the areas. under the highest human pressure were characterised by the lowest densities and the smallest specimens probably due mainly to the predation for food and fishing. Human pressure is probably the main contributing factor to the currently endangered status of P. ferruginea. Programmes of environmental education to avoid its collection for fishing, food or for fun as decorative objects should be conducted, and further experimental studies dealing with the reproductive biology of this species are needed to property assess the future programmes of conservation. (C) 2003 Elsevier Ltd. All rights reserved.