Marine protected areas are a useful tool to protect coral reef fishes but not representative to conserve their functional role.

Anthropogenic actions have direct and indirect impacts on natural systems, leading to significant alterations in marine ecosystems worldwide. One of the most notable problems is species loss, as the disappearance of species from an area can compromise ecological functions. This is at the core of a severe biodiversity crisis. To address and reverse these processes, marine protected areas (MPAs) have been utilized as a crucial tool to mitigate species loss, increase biomass, and serve as a fisheries management tool. However, there is a lack of information assessing MPAs from the perspective of their contribution to maintaining ecological functions. In recent decades, functional diversity (FD) indices have been widely used to assess ecosystem functioning. In this paper, we conducted an assessment using a global database of reef fish abundance to analyze the effect of No-Take Zones (NTZ) on the FD and "true" diversity (TD) indices of tropical reef fish assemblages in seven tropical biogeographic regions. We found a significant protective effect for some indices, although these responses were dependent on the bioregion. At the bioregional level, NTZs included lower numbers of species and functional entities than open access areas. Consequently, the functional richness protected within these zones partially represented the functional diversity in each biogeographic province. However, smaller-scale functional diversity indices responded to NTZ protection depending on the bioregion. Therefore, these results reinforce that the assessed NTZs are responsive to the protection of functional diversity, although they are not sufficient for safeguarding ecosystem functions in tropical reefs. This highlights the importance of expanding the number of protection entities worldwide with management strategies focused on coral reef fish functionality, as well as effective local/regional assessments. Thus, a new paradigm is necessary in the planning and creation of MPAs to safeguard ecosystem functions, with a priority given to the protection of ecosystem functions and habitats.

Tropical rhodolith beds are a major and belittled reef fish habitat.

Understanding habitat-level variation in community structure provides an informed basis for natural resources' management. Reef fishes are a major component of tropical marine biodiversity, but their abundance and distribution are poorly assessed beyond conventional SCUBA diving depths. Based on a baited-video survey of fish assemblages in Southwestern Atlantic's most biodiverse region we show that species composition responded mainly to the two major hard-bottom megahabitats (reefs and rhodolith beds) and to the amount of light reaching the bottom. Both megahabitats encompassed typical reef fish assemblages but, unexpectedly, richness in rhodolith beds and reefs was equivalent. The dissimilar fish biomass and trophic structure in reefs and rhodolith beds indicates that these systems function based on contrasting energy pathways, such as the much lower herbivory recorded in the latter. Rhodolith beds, the dominant benthic megahabitat in the tropical Southwestern Atlantic shelf, play an underrated role as fish habitats, and it is critical that they are considered in conservation planning.

Effect of marine protected areas on distinct fish life-history stages.

The role of Marine Protected Areas on distinct life stages of Mediterranean reef fish species (classified on the basis of their economic value and mobility categories) was assessed in a network of marine reserves in SE Spain. Only abundance and biomass of adult of both commercial and demersal species were positively affected by protection. Gradients across reserve boundaries (as a clue to the occurrence of spillover) were observed for fish abundance but not for biomass, indicating a protected fish assemblage with a predominance of small-sized individuals. Also, post-larvae of commercial species were negatively related to protected zones. Active selection of settlement preferred habitats, larval accumulation favoured by the geomorphological configuration of the coast or mixed effects has been proposed as possible explanations. Juveniles showed high spatial variability resulting in a lack of response to fishing protection measures. We highlight the need of including early life stages and overall suitable habitats for them when designing MPA networks due to the crucial importance of these stages to successful fulfillment of MPA objectives.