ALBERT

Description: The uptake of natural living resources for human consumption has triggered serious changes in the balance of ecosystems. In the archipelagos of Macaronesia (NE Atlantic), limpets have been extensively exploited probably since islands were first colonized. This has led to profound consequences in the dynamics of rocky shore communities. The Patella candei complex includes various subspecies of limpets that are ascribed to a particular archipelago and has been the focus of several taxonomic surveys without much agreement. Under a conservational perspective, we apply morphometric and genetic analyses to test subspecies boundaries in P. candei and to evaluate its current population connectivity throughout Macaronesia (Azores, Madeira, and Canaries). A highly significant genetic break between archipelagos following isolation by distance was detected ( F ST  = 0.369, p  〈 .001). Contrastingly, significant genetic differentiation among islands (i.e., Azores) was absent possibly indicating ongoing gene flow via larval exchange between populations. Significant shell-shape differences among archipelagos were also detected using both distance-based and geometric morphometric analyses. Adaptive processes associated with niche differentiation and strong barriers to gene flow among archipelagos may be the mechanisms underlying P. candei diversification in Macaronesia. Under the very probable assumption that populations of P. candei from each archipelago are geographically and/or ecologically isolated populations, the various subspecies within the P. candei complex may be best thought of as true species using the denomination: P. candei in Selvagens, Patella gomesii in Azores, Patella ordinaria in Madeira, and Patella crenata for Canaries. This would be in agreement with stock delimitation and units of conservation of P. candei sensu latu along Macaronesia. Testing the subspecies boundaries within the Patella candei complex in Macaronesia (NE Atlantic) using morphological and genetic data: implications for conservation.

Description: Exploitation of organisms can prompt the reduction in the number and size of target populations consequently affecting reproductive output and replenishment. Here, we investigated the effects of exploitation on the population structure of a protandrous patellid limpet, Patella aspera , an overexploited Macaronesian endemic. Timed dives were used to collect animals across eleven islands of Macaronesia. Individuals were inspected for sex, size, and gonad stage. Using catch effort (time per person) per island coastal perimeter as a surrogate for exploitation intensity, we found that limpet abundance (CPUE) and mean size tended to decrease with exploitation intensity. When considering the sex of animals separately, the size of the largest male, but not females, decreased with exploitation. In contrast, the size of the smallest male remained relatively consistent, whereas the size of the smallest female decreased significantly with exploitation. As exploitation is mostly targeting larger individuals, results suggest that males are compensating the removal of larger females, by undergoing sex change at smaller and presumably earlier sizes. These results have wider implications for the conservation of P. aspera , as a reduction in female size will likely affect the numbers of oocytes produced, hence fecundity. Regulations promoting the protection of the larger-sized animals should be enforced to safeguard the replenishment of the population. We investigated the effects of exploitation on the population structure of a protandrous patellid limpet. On top of effects on limpet abundance and mean size, results suggest that males are compensating the removal of larger females, by undergoing sex change at smaller sizes. Regulations promoting the protection of the larger-sized animals should be enforced to safeguard the replenishment of the population.