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Aim Given the paucity of data on the distribution of habitats and species for most marine species, particularly those that are rare and in need of protection, there is a need to model species distributions. Using the fan mussel, Atrina fragilis (Pennant 1777), as our case species, the aim of the study was to predict new areas of occurrence for A. fragilis, estimate the extent of potentially suitable areas, determine the proportion of these areas that are included in the recently designated nature conservation MPAs off the west of Scotland and identify possible environmental drivers in the distribution of A. fragilis. Location West coast of Scotland, UK. Methods Using a point process framework, we modelled presence-only data, including historic records. A quadrat survey employing digital still photography was conducted in areas of high and low suitability to verify the model, and subsequently, a targeted survey was undertaken in areas predicted as highly suitable by the models using towed video cameras. Results Five environmental variables were of prime importance in explaining the distribution of A. fragilis. The results from the verification survey support model performance. Atrina fragilis was found in 80% of the targeted transects undertaken. Approximately 14% of the total area predicted as suitable for A. fragilis occurred within recently designated marine protected areas ( MPAs) indicating considerable potential for recolonization given suitable protection. Main conclusions The verified model suggests that limited presence-only and historical records of rare species can perform well within a SDM framework allowing the identification of further suitable areas. The prominence of bathymetric ruggedness in the models is unexpected, given the understood ecological niche for A. fragilis and pinnids in general, but is consistent with the fact that seabed topography can offer protection from fishing pressure. These results will inform restoration objectives of the MPA network. [ABSTRACT FROM AUTHOR]

Sexual selection theory implies a tight coupling between the evolution of male sexual display and the sensory capabilities of the female. In sexually dimorphic species it is proposed that this might lead to sex differences in a species' perceptive abilities. However, supporting evidence for this is rare, and to date there is only one example; three-spined sticklebacks, Gasterosteus aculeatus. Here, the female's visual system is reported to become more red-sensitive during the summer breeding season; a time when sexually mature males display a red throat and belly to potential mates. In contrast, a shift in sensitivity is not apparent in males. These results, although commonly quoted, are surprising because previous observations suggest that both sexes may benefit from the detection of the male's red colour patch; in females the intensity of red coloration can influence the choice of mate, and in males the conspicuous red colouration can aid the detection of rival males. To investigate this paradox we repeated the original optomotor experiment using a fully controlled design. In contrast to the earlier result, we found that both males and females exhibit a shift in their sensitivity to red during the reproductive period. These new data therefore do not support the hypothesis that sex differences in perceptual abilities occur in sexually dimorphic species. [ABSTRACT FROM AUTHOR]

MPAs are expected to improve the conservation status of rare and important habitats and species. However, the reduction in anthropogenic pressure due to such management measures is rarely estimated. Although MPA networks may cover a large proportion of the seabed, designated areas that prohibit damaging fishing activity are often much smaller. This case study compares fishing pressure inside and outside areas covered by Scottish MPAs and MPA management measures, further relating its distribution to bottom ruggedness, which influences benthic communities and their exposure to mobile bottom fishing. While 7% of the study region was found to be within MPA boundaries, only 2.5% of the region was subject to management measures that restrict mobile bottom fishing. Taking historical levels of fishing as a benchmark, management measures have been applied to <0.6% of the swept area of existing mobile bottom fishing activity. This may be explained by the higher average seabed ruggedness within MPA management measures, which was also where some key species of conservation interest were found. These findings suggest that protection has been focussed in areas that already act as natural refugia for sensitive benthic species and lie away from the majority of fishing activity. While the measures do not reduce fishing pressure markedly, they do protect relatively pristine habitats from future fishing impacts. MPA management measures had higher average seabed ruggedness, suggesting a bias in protection for species and habitats within such areas. [ABSTRACT FROM AUTHOR]