Abstract Establishing large networks of fully protected marine protected areas (MPAs) is challenging because of displacement costs for fisheries. The use of partially protected areas is often proposed as an alternative. However, how conservation and fisheries outcomes of MPA networks are mediated through time by the level of protection remains uncertain. Here we use a metapopulation model of a commercially exploited demersal coastal fish to assess conservation and fisheries outcomes of alternative management policies. We compare the temporal performances of nonspatial management, large MPAs, or networks of MPAs in an overfished case study. In addition, we assess how the magnitude of both outcomes is mediated by larval connectivity and level of protection. We distinguish the relative contribution to fisheries outcomes of unprotected areas in between MPAs, and unprotected areas further away, receiving less displaced fishing effort and potential biomass export. We show that spatial management outperforms nonspatial management, that conservation and fisheries outcomes increase with increasing levels of protection, that fisheries outcomes in areas in between MPAs are higher when connected through larval dispersal, and that increases in catch are preceded by a short‐term decrease. Our results call for an increase in protection levels to meet both ecological and fisheries management goals.

1 Most fish stocks worldwide are fished at maximum sustainable yield (MSY) or overfished, as many fisheries management strategies have failed to achieve sustainable fishing. Identifying effective fisheries management strategies has now become urgent. 2 Here, we developed a spatially-explicit metapopulation model accounting for population connectivity in the north-western Mediterranean Sea, and parameterized it for three ecologically and economically important coastal fish species: the white seabream Diplodus sargus , the two-banded seabream Diplodus vulgaris and the dusky grouper Epinephelus marginatus . 3 We used the model to assess how stock biomass and catches respond to changes in fishing mortality rate ( F ) and in the size of fully protected areas within the existing system of multiple-use marine protected areas (MPAs). For each species, we estimated MSY and the corresponding values of stock biomass ( B MSY ) and fishing mortality rate ( F MSY ), providing crucial reference points for the assessment of fisheries management.

The filamentous chlorophyte Ostreobium sp. dominates shallow marine carbonate microboring communities, and is one of the major agents of reef bioerosion. While its large genetic diversity has emerged, its physiology remains little known, with unexplored relationship between genotypes and phenotypes (endolithic versus free-living growth forms). Here, we isolated 9 strains affiliated to 2 lineages of Ostreobium (>8% sequence divergence of the plastid gene rbc L), one of which was assigned to the family Odoaceae, from the fast-growing coral host Pocillopora acuta Lamarck 1816. Free-living isolates maintained their bioerosive potential, colonizing pre-bleached coral carbonate skeletons. We compared phenotypes, highlighting shifts in pigment and fatty acid compositions, carbon to nitrogen ratios and stable isotope compositions (δ 13 C and δ 15 N). Our data show a pattern of higher chlorophyll b and lower arachidonic acid (20:4ω6) content in endolithic versus free-living Ostreobium . Photosynthetic carbon fixation and nitrate uptake, quantified via 8h pulse-labeling with 13 C-bicarbonate and 15 N-nitrate, showed lower isotopic enrichment in endolithic compared to free-living filaments. Our results highlight the functional plasticity of Ostreobium phenotypes. The isotope tracer approach opens the way to further study the biogeochemical cycling and trophic ecology of these cryptic algae at coral holobiont and reef scales.

This study evaluates the fishing pressure exerted by the most common recreational and professional, small-scale fishing practices on vulnerable target and bycatch species in coastal and offshore waters of the western Mediterranean. By combining multiple data sources, we assembled a unique dataset on catches at multiple sites in these areas by recreational (RF) and small-scale fisheries (SSF), covering the period from 1997 to 2015. Furthermore, a framework with which to identify the vulnerable species among all the species caught is provided; it is based on the IUCN Red List, international conventions for the protection of flora and fauna, the Habitats Directive and the intrinsic vulnerability index of marine fish. Overall, about a quarter of exploited species targeted by SSF and RF in coastal waters were vulnerable, making up nearly 50% of the total SSF catch and nearly 20% of the total recreational catch. In offshore waters, 100% of the RF and SSF catch was made up of vulnerable species. Among the species caught as bycatch in both areas by SSF and RF, there was a total of 27 vulnerable vertebrate species, which included birds, cetaceans, elasmobranchs and sea turtles. Our results highlight the need to differentiate between different fishing methods or gears when studying the fishing impacts on vulnerable species. The results also indicate that, although RF and SSF are often considered to have a relatively low ecological impact, a range of different fishing methods are affecting vulnerable species in coastal or offshore waters in the western Mediterranean Sea, be they targeted or taken unintentionally as bycatch.