Distribution and abundance patterns of three coexisting species of Patella (Mollusca Gastropoda) in the intertidal areas of the NW Iberian Peninsula: Implications for management

Abstract

Abstract Using a combination of geostatistical methods and generalized additive models (GAMs), we have analyzed the combined effect of spatial, environmental and biological factors on the density of Patella vulgata, Patella depressa and Patella ulyssiponensis, three limpet species coexisting in rocky intertidal areas of the Galician coast (NW Iberian Peninsula). The best multivariate GAM fit to the data explained, on average, 54% of the observed variation in density of these species, revealing the influence of spatial (latitude and longitude) and environmental factors (temperature). The influence of biological factors such as reproductive status and density of the species, as well as those of coexisting species, was also detected. The results suggest the existence of spatial and temporal segregation behaviours to decrease intra- and interspecific competition. They confirm P. vulgata as a migratory species and reveal P. depressa also as a migrant limpet, while P. ulyssiponensis belongs to the non-migratory group. Geostatistical analysis showed that P. depressa is the dominant species in areas more exposed to wave action, whilst P. vulgata dominates sheltered area. In addition, the three limpet species are spatially structured in patches, whose density and size vary according to the type of coast (Atlantic/Cantabrian) and to the degree of wave exposure. These results reveal the importance of carrying out assessments at the local level and in those areas particularly vulnerable to exploitation, such as sheltered areas, where densities and recruitment are lower. This information can be useful for decision-making aimed at the management of this resource, as well as for the efficient distribution of effort with respect to geographical fishing areas.