Unveiling functional linkages between habitats and organisms: Macroalgal habitats as influential factors of fish functional traits.

Understanding the relationship between the characteristics of habitats and their associated community is essential to comprehend the functioning of ecological systems and prevent their degradation. This is particularly relevant for in decline, habitat-forming species, such as macroalgae, which support diverse communities of fish in temperate rocky reefs. To understand the link between the functional habitats of macroalgae and the functional dimension of their associated fish communities, we used a standardized underwater visual census to quantify the macroalgal functional diversity, as well as the functional diversity, redundancy, and richness of fish communities in 400 sites scattered in three southern temperate marine realms. Our findings reveal that functional macroalgal habitats can be classified into three groups that shape the functional diversity, redundancy, and richness of fish when considering trait commonness. These results enhance our comprehension of the functional connections between the habitat and coexisting fish within marine ecosystems, providing valuable insights for the preservation of these habitats.

Assessing social-ecological vulnerability of coastal systems to fishing and tourism.

Detecting areas with high social-ecological vulnerability (SEV) is essential to better inform management interventions for building resilience in coastal systems. The SEV framework, developed by the Intergovernmental Panel on Climate Change, is a robust method to identify SEV of tropical coastal systems to climate change. Yet, the application of this framework to temperate regions and other drivers of change remains underexplored. This study operationalizes the SEV framework to assess the social-ecological implications of fishing and tourism in temperate coastal systems. We spatially represented the SEV of coastal systems and identified the social and ecological vulnerability dimensions underpinning this SEV. Our results demonstrate that different dimensions contribute differently to the SEV, suggesting the need for distinctive management intervention to reduce the vulnerability of coastal systems. Our findings also highlight that livelihood diversification and the protection of marine areas may be plausible strategies to build resilience in temperate coastal systems that face fishing and tourism pressures. With this study, we hope to encourage the application of the SEV framework to other drivers of change for building more resilient coastal systems.

Marine protected areas are more effective but less reliable in protecting fish biomass than fish diversity.

Marine protected areas (MPAs) provide multiple conservation benefits, thus raising the question of how good and consistent they are at their roles. Here, we quantified three components, namely, diversity, biomass, and other relevant variables, in numerous protected and unprotected areas across four marine ecoregions in south-western Europe. We created a "global conservation status index" (CSIglobal) as the sum of CSIdiversity, CSIbiomass, and CSIrelevant. We then tested whether CSI and its three components varied as a function of protection and marine ecoregion. MPA efficiency, defined as the effect size of protection on CSIglobal, was unreliable and varied with geography. CSIbiomass and CSIrelevant contributed to the unreliability of MPA efficiency, while CSIdiversity was reliable. CSIbiomass showed the major efficiency in protected areas (60%). Biomass of threatened species was the single largest variable that contributed to MPA efficiency. Our easy-to-use approach can identify high- and low-efficient MPAs and help to clarify their actual roles.

Building up marine biodiversity loss: Artificial substrates hold lower number and abundance of low occupancy benthic and sessile species.

Ocean sprawl is replacing natural substrates with artificial alternatives. We hypothesized that, after submersion, high occupancy, high mobility species colonize artificial substrates faster than low occupancy, low mobility species, a biodiversity divergence that will slowly fade out with time. Using quantitative visual census of species in 10 artificial and their adjacent natural substrates, we tested for the existence and temporal evolution of this divergence. Assigning species to one of three occupancy and one of three mobility categories, we found that artificial substrates increased the performance of high mobility, high occupancy species while decreased the performance of low occupancy species with medium and low mobility. This biodiversity divergence remained unchanged over the 50-year underwater timespan of the artificial substrates investigated. Our results suggest that proliferation of artificial substrates is building up a biodiversity loss driven by the least conspicuous and uncommon benthic and sessile species that is undermining coastal marine biodiversity.