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Patterns of population connectivity shape ecological and evolutionary phenomena from population persistence to local adaptation and can inform conservation strategy. Connectivity patterns emerge from the interaction of individual behavior with a complex and heterogeneous environment. Despite ample observation that dispersal patterns vary through time, the extent to which variation in the physical environment can explain emergent connectivity variation is not clear. Empirical studies of its contribution promise to illuminate a potential source of variability that shapes the dynamics of natural populations. We leveraged simultaneous direct dispersal observations and oceanographic transport simulations of the clownfish Amphiprion clarkii in the Camotes Sea, Philippines, to assess the contribution of oceanographic variability to emergent variation in connectivity. We found that time-varying oceanographic simulations on both annual and monsoonal timescales partly explained the observed dispersal patterns, suggesting that temporal variation in oceanographic transport shapes connectivity variation on these timescales. However, interannual variation in observed mean dispersal distance was nearly 10 times the expected variation from biophysical simulations, revealing that additional biotic and abiotic factors contribute to interannual connectivity variation. Simulated dispersal kernels also predicted a smaller scale of dispersal than the observations, supporting the hypothesis that undocumented abiotic factors and behaviors such as swimming and navigation enhance the probability of successful dispersal away from, as opposed to retention near, natal sites. Our findings highlight the potential for coincident observations and biophysical simulations to test dispersal hypotheses and the influence of temporal variability on metapopulation persistence, local adaptation, and other population processes.

Ecosystems are substantially changing in response to ongoing climate change. For example, coral reefs have declined in coral dominance, with some reefs undergoing regime shifts to non‐coral states. However, reef responses may vary through multiple heat stress events, with the rarity of long‐term ecological datasets rendering such understanding uncertain. Assessing coral reefs across the inner Seychelles islands using a 28‐year dataset, we document faster coral recovery from the 2016 than the 1998 marine heatwave event. Further, compositions of benthic and fish communities were more resistant to change following the more recent heat stress, having stabilized in a persistent altered state, with greater herbivory, following the 1998 climate disturbance. Counter to predictions, a macroalgal‐dominated reef that had regime‐shifted following the 1998 disturbance is transitioning to a coral‐dominated state following the 2016 heat stress. Collectively, these patterns indicate that reef systems may be more resilient to repeat heatwave events than anticipated. [ABSTRACT FROM AUTHOR]

Abstract The exceptional diversity of shallow‐water marine fishes contributes to the nutrition of millions of people worldwide through coastal wild‐capture fisheries, with different species having diverse nutritional profiles. Fishes in ecosystems are reservoirs of micronutrients with benefits to human health. Yet, the amount of micronutrients contained in fish species on coral reefs and in shallow tropical waters is challenging to estimate, and the micronutrients caught by fisheries remain uncertain. To assess whether micronutrient deficiencies could be addressed through specific fisheries management actions, we first require a quantification of the potentially available micronutrients contained in biodiverse reef fish assemblages. Here, we therefore undertake a broad heuristic assessment of available micronutrients on tropical reefs using ensemble species distribution modelling and identify potential mismatches with micronutrients derived from summarising coastal fisheries landings data. We find a mismatch between modelled estimates of micronutrients available in the ecosystem on the one hand and the micronutrients in small‐scale fisheries landings data. Fisheries had lower micronutrients than expected from fishes in the modelled assemblage. Further, fisheries were selective for vitamin A, thus resulting in a trade‐off with other micronutrients. Our results remained unchanged after accounting for the under‐sampling of fish communities and under‐reporting of small‐scale fisheries catches—two major sources of uncertainty. This reported mismatch indicates that current estimates of fished micronutrients are not adequate to fully assess micronutrient inventories. However, small‐scale fisheries in some countries were already selective towards micronutrient mass, indicating policies that target improved access, distribution and consumption of fish could leverage this existing high micronutrient mass. Enhanced taxonomic resolution of catches and biodiversity inventories using localised species consumption surveys could improve understanding of nature‐people linkages. Improving fisheries reporting and monitoring of reef fish assemblages will advance the understanding of micronutrient mismatches, which overall indicate a weak uptake of nutritional goals in fisheries practices. The decoupling between micronutrients in ecosystems and in fisheries catches indicates that social, economic, and biodiversity management goals are not shaped around nutritional targets—but this is key to achieve a sustainable and healthy planet for both people and nature. Read the free Plain Language Summary for this article on the Journal blog.

Ciguatoxins (CTXs), potent neurotoxins produced by dinoflagellates of the genera Gambierdiscus and Fukuyoa, accumulate in commonly consumed fish species, causing human ciguatera poisoning. Field collections of Pacific reef fish reveal that consumed CTXs undergo oxidative biotransformations, resulting in numerous, often toxified analogs. Following our study showing rapid CTX accumulation in flesh of an herbivorous fish, we used the same laboratory model to examine the tissue distribution and metabolization of Pacific CTXs following long-term dietary exposure. Naso brevirostris consumed cells of Gambierdiscus polynesiensis in a gel food matrix over 16 weeks at a constant dose rate of 0.36 ng CTX3C equiv g-1 fish d-1. CTX toxicity determination of fish tissues showed CTX activity in all tissues of exposed fish (eight tissues plus the carcass), with the highest concentrations in the spleen. Muscle tissue retained the largest proportion of CTXs, with 44% of the total tissue burden. Moreover, relative to our previous study, we found that larger fish with slower growth rates assimilated a higher proportion of ingested toxin in their flesh (13% vs. 2%). Analysis of muscle extracts revealed the presence of CTX3C and CTX3B as well as a biotransformed product showing the m/z transitions of 2,3-dihydroxyCTX3C. This is the first experimental evidence of oxidative transformation of an algal CTX in a model consumer and known vector of CTX into the fish food web. These findings that the flesh intended for human consumption carries the majority of the toxin load, and that growth rates can influence the relationship between exposure and accumulation, have significant implications in risk assessment and the development of regulatory measures aimed at ensuring seafood safety.

Abstract The low-latitude habitats of the South American reef system have a high endemism and represent important stepping-stones due to the connectivity with Amazon and Caribbean reefs. We provide the first seabed mapping, and analyze the benthic cover and fish assemblages of these extreme reefs. Fleshy macroalgae (2—66% of cover), algal turfs (0—47%), and sponges (3—25%) are the dominant benthic groups. The main reef builders are crustose coralline algae (2—23%) and only four coral species (0 to 18%), mainly the weedy Siderastrea stellata. Cluster analysis distinguished two groups. The first group includes the shallowest reefs (~ 17 m deep) where fleshy macroalgae are abundant together with higher siltation on the reefs (~ 31% covered by sediments). The second group, by contrast, includes the deeper reefs (22.5—27 m), which have much higher algal turf cover, and the lowest sediment cover (4%). The deeper reefs also have the highest cover of corals (18%) and sponges (25%). We recorded a total of 63 fish species, with the deep reefs being the richest. Analysis indicated that the composition of the benthos was considerably more homogeneous across the study area than the composition of fish assemblages, which had a higher turnover of species among reefs. Moreover, we identified the depth of the reef as a variable structuring the benthic assemblages. The fish assemblage is influenced, in turn, by the benthos. Overall, the seabed mapping revealed the existence of a single reef system with high spatial heterogeneity. Our results provide new insights into the structure of these extreme reefs that have evolved under the influence of sediment resuspension, moderate turbidity, and are warmer than other West Atlantic reefs located at middle- and high-latitudes.

Understanding patterns in community structure in large marine ecosystems is necessary for advancing community- and ecosystem-based approaches to marine fisheries management. We analyzed data from a large-scale, fishery-independent video survey to quantify the structure of reef fish communities on offshore hard-bottom reef habitats in the northern Gulf of Mexico (nGOM). A novel aspect of this work is that all species visualized on videos were identified and enumerated over a 13-year period, which allowed for a comprehensive analysis of fish community structure. We observed a total of 243 fish species from 54 families and 14 orders. Species richness and biodiversity varied considerably across the nGOM and were highest in regions that harbor extensive coral reef habitat (south Florida, Louisiana-Texas shelf). Multivariate analyses identified 12 species assemblages, with important fishery species and species of concern (i.e. IUCN-listed) occurring in the largest identified assemblages. One assemblage composed mostly of large-bodied fishery species accounted for 45% by number and 89% by weight of all fish observed. Species assemblages were most strongly associated with depth, temperature, and substrate composition, with weaker associations with the amount of attached algae and vertical relief, while species richness was positively correlated with bottom water temperature. In general, large-scale bathymetric and hydrographic factors (e.g. depth, temperature) were more important than local topographic structure and biogenic habitat in structuring reef fish communities at the spatial scales (i.e.1000 km) considered here. Our results advance ecosystem-based approaches to fisheries management by providing a basis for incorporating multispecies spatial dynamics into the monitoring and assessment of hard-bottom reef fish communities in the nGOM. [ABSTRACT FROM AUTHOR]

Understanding patterns of biodiversity change is essential as coral reefs experience recurrent cycles of disturbance and recovery. Shifts in the total cover and species composition of habitat‐forming corals can have far‐reaching consequences, including shifts in coral functional traits and impacts on local fish assemblages. We surveyed coral and fish assemblages along the southern coast of Hainan Island near Sanya, China, in 2006, 2010, and 2018, during a period with repeated mass bleaching events. We showed that coral biodiversity in this region is in a state of flux, with losses and gains in coral cover and an increase in species richness over time. Despite increasing species diversity, the region suffered a loss of coral trait diversity by 2010, with an incomplete recovery by 2018, owing to declines in species with key habitat‐forming traits (e.g., high surface areas and fractal structure) such as corymbose corals. Concurrently, there was an increase in functional redundancy due to the proliferation of the dominant encrusting and massive corals. Coral cover was positively associated with the abundance of reef fish, indicating that the changes observed in coral abundance can impact reef‐associated species. These results demonstrate that the slow recovery of coral biodiversity in southern Hainan Island has been hampered by the loss of specific coral traits and highlight the importance of protecting vulnerable coral traits in conservation and management strategies. [ABSTRACT FROM AUTHOR]

Sparisoma species (parrotfish) comprise an important functional group contributing to coral‐reef resilience. The morphological diagnostic characteristics for species identification are clearly described for adult forms but not for the early stages. Consequently, many taxonomical listings of Sparisoma larvae are restricted to the genus level. The aims of this study are to determine whether the morphological and molecular identification techniques are useful to assign the species taxonomic level to Sparisoma larvae occurring in the Gulf of Mexico and whether there is a set of diagnostic features that could be used to discriminate between species in larvae of different developmental stages. Morphological assignment of Sparisoma was performed based on morphological and meristic features for 30 larvae collected in the Gulf of Mexico from late August to mid‐September 2015. To corroborate and complement the morphological assignments, molecular identification was carried out using DNA sequences from regions of two mitochondrial genes, mitochondrial cytochrome oxidase I (mtDNA COI) and mitochondrial 16S rRNA (mtDNA 16S rRNA). COI and 16S gene trees for Sparisoma and related fish taxa were constructed using sequences available in the NCBI (National Center for Biotechnology Information) GenBank and BOLD (Barcode of Life Data) databases. Two morphotypes were identified based on morphology, but no diagnostic characteristics for species discrimination were found. Molecular identification, in contrast, successfully discriminated four early development stages of Sparisoma atomarium, three stages of Sparisoma radians, and two stages of Sparisoma chrysopterum and Sparisoma aurofrenatum, therefore demonstrating the successful and necessary application of molecular taxonomic approaches for species‐level identifications of Sparisoma larvae. [ABSTRACT FROM AUTHOR]

Understanding the diurnal and nocturnal activity of organisms is a key topic in behavioral ecology, with implications for population structure and management strategies. In reef systems, parrotfishes play crucial roles as nominal herbivores, but overfishing has led to population collapses with detrimental effects on reef functions. Parrotfish are good models to study diel rhythms, as they are often easily observed while sleeping at night. We assessed the distribution, sleeping substrate selectivity and sleeping areas of parrotfishes during the night in a subtropical rocky reef of the Southwestern Atlantic. We performed replicated visual censuses (50 × 2 m) at different depths to estimate parrotfish abundance, while quantifying the structural complexity of sleeping sites. Among the seven recorded parrotfish species, we focused on the four most abundant to determine their sleeping habitat selectivity. Active telemetry was used for the two most abundant species to define their sleeping site areas and sleeping hotspots. All four species exhibited a preference for sediment as a sleeping substrate, while avoiding zoanthids. Species distribution was influenced by depth, with Scarus zelindae predominantly sleeping in high-complexity substrate at intermediate depths and Sparisoma tuiupiranga sleeping in the rock–sand interface at deeper depths. Tagged Sparisoma axillare and Sparisoma frondosum exhibited similar sleeping areas in terms of size and geographical locations; showing high site fidelity, they returned to the same sleeping sites over consecutive nights. These results represent the first assessment of parrotfish distribution and habitat use at night in the Atlantic. This information is crucial for guiding management actions, particularly in the planning of no-take zones for fishing control and population recovery. [ABSTRACT FROM AUTHOR]

Groupers are one of the most important and commercial fishes; many of the species are classified as Life Reef Fish Trade (LRFT). The number of grouper species in these locations may be more diverse than at other sites. Identifying the species number of a grouper is essential for mapping reef fitness. However, morphological identification of groupers is relatively difficult. Molecular methods such as DNA barcoding could be an option and even serve as reliable validation. Therefore, this research was conducted to identify groupers belonging to the Serranidae family. The grouper samples were obtained from the fish market in Waisai, Raja Ampat, Indonesia. The DNA barcoding employed the COI genes to accurately identify groupers. The Qiagen DNeasy 96 tissue extraction kit was used to extract DNA, and Primer Fish F1/R1 was applied. The sequences were analysed using ClustalW in MEGA 7.0 and phylogenetic tree was generated using the NJ (Neighbour Joining) method. Eleven species of groupers belonging to five taxa were discovered in Waisai, Raja Ampat. Anyperodon, Cephalopholis, Epinephelus, Plectropomus, and Variola are the grouper genera. Epinephelus was the predominant genus within the serranidae family, with 51.4% of the total. The International Union for Conservation of Nature's (IUCN) Red List category puts the majority of grouper species in the 'Least Concerned' category. This study confirmed the effectiveness of DNA barcoding for species identification and the value of the COI gene for Grouper's phylogenetic research. The outcome offers information about fisheries resources, which should be helpful in managing fisheries in reef ecosystems. [ABSTRACT FROM AUTHOR]

Coral reefs are biodiverse marine ecosystems that are undergoing rapid changes, making monitoring vital as we seek to manage and mitigate stressors. Healthy reef soundscapes are rich with sounds, enabling passive acoustic recording and soundscape analyses to emerge as cost-effective, long-term methods for monitoring reef communities. Yet most biological reef sounds have not been identified or described, limiting the effectiveness of acoustic monitoring for diversity assessments. Machine learning offers a solution to scale such analyses but has yet to be successfully applied to characterize the diversity of reef fish sounds. Here we sought to characterize and categorize coral reef fish sounds using unsupervised machine learning methods. Pulsed fish and invertebrate sounds from 480 min of data sampled across 10 days over a 2-month period on a US Virgin Islands reef were manually identified and extracted, then grouped into acoustically similar clusters using unsupervised clustering based on acoustic features. The defining characteristics of these clusters were described and compared to determine the extent of acoustic diversity detected on these reefs. Approximately 55 distinct calls were identified, ranging in centroid frequency from 50 Hz to 1,300 Hz. Within this range, two main sub-bands containing multiple signal types were identified from 100 Hz to 400 Hz and 300 Hz-700 Hz, with a variety of signals outside these two main bands. These methods may be used to seek out acoustic diversity across additional marine habitats. The signals described here, though taken from a limited dataset, speak to the diversity of sounds produced on coral reefs and suggest that there might be more acoustic niche differentiation within soniferous fish communities than has been previously recognized. [ABSTRACT FROM AUTHOR]

The targeted capture of ultraconserved elements (UCEs) has substantially increased the amount of genetic data available for phylogenomic reconstructions. These capture datasets frequently contain mitochondrial DNA as a by‐product, often in the form of complete mitogenomes. These can be efficiently harvested to expand existing datasets without additional costs. Here, we present new mitochondrial genomes for six marine angelfish species (F: Pomacanthidae), assembled and annotated from off‐target UCE reads. We provide the first comparative analysis of all mitochondrial genomes available for the Pomacanthidae. Results showed that the average length of pomacanthid mitogenomes is 16.8 kbp. Total GC and AT content varied between 44.5% and 46.3%, and 53.7% and 55.5%, respectively. The architecture of angelfish mitogenomes was comparable to that seen in other fish species with 13 protein‐coding genes (PCGs), 22 transfer RNA genes, two ribosomal RNA genes and the control region. All 13 PCGs evolved under purifying selection, highlighting a high level of selection pressure and gene expression to preserve genetic integrity. The ND6 and ATP8 genes had the highest ratio of non‐synonymous (dN) to synonymous (dS) substitutions, indicating a relaxation of purifying selection constraints. Finally, these newly assembled mitogenomes will allow further investigations of the population genetics, systematics and evolutionary biology of one of the most prominent reef fish family in the aquarium trade. [ABSTRACT FROM AUTHOR]

The combination of the physical structural heterogeneity of the environment, oceanographic characteristics, and the benthic assemblage composition structures the habitat, consequently shaping the associated diversity of fish. Understanding the spatial variability of fish assemblages and how it relates to environmental factors is essential to identify potential variables that determine spatial patterns and predict impacts on fish assemblage metrics, thus providing valuable information for management. Here, we investigated reef fish micro-scale spatial distribution around Alcatrazes Island in the subtropical region of the Southwest Atlantic, Brazil. Multivariate Regression Trees were fitted to explore the effects of structural heterogeneity, wave power, depth, water temperature, and benthic cover on the structure of reef fish assemblages, addressing composition, richness, density, biomass, trophic groups, mobility, and conservation status. Our results suggest that depth, turf, and coral cover were the main predictors of fish assemblages in rocky reefs at Alcatrazes Island, revealing five distinct fish assemblages with different habitat preferences. These results provide additional insights into the relationship between reef fishes and their environment, providing empirical evidence for decision-makers to implement spatially based management policies, especially to prioritize zones for conservation along the island. [ABSTRACT FROM AUTHOR]

Understanding the spatiotemporal dynamics of fish species is a central concern in fish ecology and crucial for guiding management and conservation efforts. We constructed a joint species distribution model (JSDM) to simultaneously estimate the spatiotemporal distributions and densities for 21 reef fish species in the southeastern United States (SEUS). The model separately estimates encounter probability and positive density, and accounts for unobserved spatial and spatiotemporal variation using latent factors, where the correlations among species are induced. We applied the model to video data collected from a large‐scale, fishery independent survey. A clustering method was applied to the results of the JSDM to group species based on spatial and spatiotemporal synchrony in encounter probability and positive density. We found strong spatial associations among most of the reef fish species. However, species did exhibit differences in occupied habitat that varied with latitude and/or depth. Within their area of occupied habitat, almost all the species share similar spatial pattern of average density. However, for some species, annual distributions were less correlated with their expected average distributions perhaps due to differing responses to underlying spatiotemporal drivers. Some species show significant declines in abundance, for example, black sea bass, red porgy, and blueline tilefish, while a small number of species showed evidence of shifts in distribution, for example, black sea bass. The findings suggest that spatiotemporal management strategies may be of limited utility for reducing bycatch in these highly mixed reef fisheries due to high spatial correlations in occupied habitat and spatial patterns in density. Species‐specific responses to environmental change may also influence the spatiotemporal structure of reef assemblages. This work suggests management attention is needed for some of the lesser known species as they are showing declining trends in abundance. [ABSTRACT FROM AUTHOR]

Marine heatwaves (MHWs) are episodes of anomalous warming in the ocean that can last from a few days to years. MHWs have different characteristics in terms of intensity, duration and frequency and generate thermal stress in marine ecosystems. In reef ecosystems, they are one of the main causes of the decreased presence and abundance of corals, invertebrates and fish. The deleterious capacity of thermal stress often depends on biotic factors, such as the trophic control of predators on prey. Despite the evidence of thermal stress and biotic factors affecting individual species, the combined effects of both stressors on entire reef ecosystems are much less studied. Here, using a food web modelling approach, we estimated the rate of change in species' biomass due to different MHW characteristics. Specifically, we modelled the mechanistic link between species' consumption rate and seawater temperature (thermal stressor), simulating species' biomass dynamics for different MHW characteristics under different trophic control assumptions (top‐down, mixed trophic control and bottom‐up). We find that total reef ecosystem biomass declined by 10% ± 5% under MHWs with severe intensity and a top‐down control assumption. The bottom‐up control assumption moderates the total ecosystem biomass reduction by 5% ± 5%. Irrespective of the MHW characteristics and the trophic control assumption, the most substantial biomass changes occur among top, mesopredators and corals (5% to 20% ± 10%). We show that reef ecosystems where predators exert top‐down control on prey are prone to suffer species abundance declines under strong MHW events. We identify food web trophic control as a crucial driver that modulates the impacts of MHWs. Overall, our results provide a unified understanding of the interplay between abiotic stressors and biotic factors in reef ecosystems under extreme thermal events, offering insights into present baselines and future ecological states for reef ecosystems. [ABSTRACT FROM AUTHOR]

The age and daily growth of fish are registered through the deposition of increments in their otoliths, which are concretions formed by the precipitation of substances present in the endolymphatic fluid, mainly calcium carbonate (CaCO3). Faced with the need to fill some of the gaps in the knowledge on the occurrence and duration of the initial stages of snapper species' life cycles in the Abrolhos Bank, this study aimed to describe the growth rates, age, and period of pelagic larval duration (PLD) of three snapper species during the larval pre‐settlement phase, in the Abrolhos Bank region. The post‐larvae were captured using light traps. Otoliths were removed from 117 samples of snapper species; however, only 69 were viable for age estimation, of which 15 were Lutjanus analis, 25 were Lutjanus jocu, and 29 were Lutjanus synagris. Together, the samples presented individuals with total lengths ranging from 16.14 to 24.76 mm and ages from 21 to 39 days. Settlement marks were found for all three species, and the average PLD was ~25 days. The somatic growth of the snapper species was positively correlated with otolith growth. L. jocu presented the greatest daily growth compared to the other species. The three species use the Abrolhos Bank as a larval settlement site, demonstrating plasticity by using different habitats throughout their lives. [ABSTRACT FROM AUTHOR]

Species‐to‐species and species‐to‐environment interactions are key drivers of community dynamics. Disentangling these drivers in species‐rich assemblages is challenging due to the high number of potentially interacting species (the 'curse of dimensionality'). We develop a process‐based model that quantifies how intraspecific and interspecific interactions, and species' covarying responses to environmental fluctuations, jointly drive community dynamics. We fit the model to reef fish abundance time series from 41 reefs of Australia's Great Barrier Reef. We found that fluctuating relative abundances are driven by species' heterogenous responses to environmental fluctuations, whereas interspecific interactions are negligible. Species differences in long‐term average abundances are driven by interspecific variation in the magnitudes of both conspecific density‐dependence and density‐independent growth rates. This study introduces a novel approach to overcoming the curse of dimensionality, which reveals highly individualistic dynamics in coral reef fish communities that imply a high level of niche structure. [ABSTRACT FROM AUTHOR]

Biological invasions have modified habitat structure, forcing changes in ecosystem functions. Structural complexity modulates diversity and trophic pathways, but the roles of invasive species in mediating coral reef habitat attributes and trophic effects are poorly understood. We investigated the influence of invasive corals on reef structural complexity and their implications on reef fish trophic structure. To assess habitat complexity and trophic relationships, we used a digital probe to map reef rugosity and characterized benthic cover and fish abundances by video and visual estimates. We calculated a coral skeleton complexity index (for individual invasive and native colonies) by building high-resolution three-dimensional models with photogrammetry techniques. The study was conducted between February 2018 and March 2019 in Cascos Reef, located on the east coast of Brazil. We reveal that the complex morphology of the invasive coral Tubastraea spp. skeleton had a significant positive effect on reef rugosity, contributing to substrate complexity at a sub-metric scale. However, this likely did not promote reef fish diversity but altered the assemblage structure patterns, demonstrated by a negative relationship between coral colony complexity index and abundance of trophic groups such as roving herbivores and omnivores and a positive relationship with planktivores. Thus, our findings support that habitat attribute modification promoted by invasive corals can influence the benthos-fish dynamic, promoting some fish groups to the detriment of others, with pervasive implications for ecosystem functions. Global changes are increasing invasions worldwide, enhancing the need for effective policies for regulation and management to ensure human well-being and ecosystem services. [ABSTRACT FROM AUTHOR]

Abstract Coastal systems encompass a range of ecotones that are important for fish species, providing diverse micro-habitats and grounds for foraging, protection from predation, reproduction and areas for recruitment. However, most of these systems face major threats from human activities. Considering the increasing levels of human disturbance in coastal ecosystems, understanding fish-habitat associations may provide important insights into patterns of species occurrence and distribution in human-impacted systems, which can support the development of effective conservation and management measures. In this context, we investigated the relationship between seahorses (Hippocampus reidi) and both habitat complexity and different holdfast species, to determine possible variation between locations and among seasons. Data were obtained from the rocky reefs of Guanabara (Urca Beach) and Sepetiba (Duas Irmãs Island) bays, in southeastern Brazil. Seahorses were counted, and the holdfast being used by each individual was recorded and identified to species or assigned to a morphofunctional group. The beaches differed in holdfast composition and morphofunctional groups, yet sharing some morphofunctional groups. Seahorses were more frequently associated with branching holdfasts at both sites, and also with foliaceous and massive. Association with algae were particularly found in Urca, while the coral Carijoa riisei in Duas Irmãs Island.

Abstract Understanding the spatiotemporal dynamics of fish species is a central concern in fish ecology and crucial for guiding management and conservation efforts. We constructed a joint species distribution model (JSDM) to simultaneously estimate the spatiotemporal distributions and densities for 21 reef fish species in the southeastern United States (SEUS). The model separately estimates encounter probability and positive density, and accounts for unobserved spatial and spatiotemporal variation using latent factors, where the correlations among species are induced. We applied the model to video data collected from a large‐scale, fishery independent survey. A clustering method was applied to the results of the JSDM to group species based on spatial and spatiotemporal synchrony in encounter probability and positive density. We found strong spatial associations among most of the reef fish species. However, species did exhibit differences in occupied habitat that varied with latitude and/or depth. Within their area of occupied habitat, almost all the species share similar spatial pattern of average density. However, for some species, annual distributions were less correlated with their expected average distributions perhaps due to differing responses to underlying spatiotemporal drivers. Some species show significant declines in abundance, for example, black sea bass, red porgy, and blueline tilefish, while a small number of species showed evidence of shifts in distribution, for example, black sea bass. The findings suggest that spatiotemporal management strategies may be of limited utility for reducing bycatch in these highly mixed reef fisheries due to high spatial correlations in occupied habitat and spatial patterns in density. Species‐specific responses to environmental change may also influence the spatiotemporal structure of reef assemblages. This work suggests management attention is needed for some of the lesser known species as they are showing declining trends in abundance.

At present, the world is still experiencing a climate warming trend, which has severe implications for Earth's sustainable development. Increasing carbon sinks mitigates climate change and improves national and social development through carbon trade. As the largest carbon pool on the planet, the ocean serves as a major carbon sink. The fishery carbon sink is an important part of the ocean carbon sink, which can increase the capacity of aquatic fishery ecosystems to absorb atmospheric CO2. Marine ranching is a typical example of a carbon sink fishery and an effective model for ensuring the sustainability of the carbon sink effect of aquatic fishery ecosystems. Despite the fact that marine ranching plays an important role in enhancing the carbon capacity of fishery carbon sinks, there have been few studies on marine ranching carbon storage. Reef fish species are the target population for marine ranching conservation and enhancement and are the most typical biological community of an artificial reef ecosystem, with substantial ecological and economic benefits. Reef fish species have an important influence on the carbon cycling, deposition, and removal processes in the ocean. It is one of the key carbon storage components of the marine ranching carbon sink. However, there are currently only a few studies on the carbon storage capacity of reef fish. Therefore, estimating and predicting the carbon storage of reef fish are useful for assessing the carbon sink potential and formulating a stock enhancement strategy for reef fish based on the carbon sink target. Based on this, we conducted research on five species of reef fish. On the one hand, we determined the carbon content of reef fish and used the standing biomass of reef fish harvested by cage nets from Shique Beach marine ranching in April 2017, January 2018, May 2019, and December 2020 to estimate the carbon capacity of reef fish in the artificial reef area and contrast areas in spring 2017, winter 2018, spring 2019, and winter 2020. On the other hand, we used the Grey-Markov model, a prediction model that we initially employed in a fishery study, to predict the carbon potential of reef fish in the artificial reef area in spring 2021, winter 2022, spring 2023, and winter 2024. The results showed that the mean carbon contents of dry reef fish samples were 42.95%~50.19% and that the mean carbon contents of fresh reef fish samples were 11.05%~13.25%. The standing biomass carbon storage of reef fish decreased on a regular basis in reef areas, whereas it fluctuated in contrast areas. The standing biomass carbon storage values of reef fish in the reef area in spring 2017, winter 2018, spring 2019, and winter 2020 were 293.46 t, 104.49 t, 119.40 t, and 48.48 t, respectively. This equates to approximately 0.73 × 104~4.40 × 104 USD carbon sink economic value. The standing biomass carbon storage values of reef fish in contrast areas in spring 2017, winter 2018, spring 2019, and winter 2020 were 21.64 t, 59.07 t, 6.73 t, and 0 t, respectively. Reef fish in reef areas had much higher standing biomass carbon storage values than those in contrast areas. The average relative error of the validation data of the Grey-Markov model was 8%, which was 12% better than the prediction accuracy of the GM(1, 1) model; therefore, we were able to fully demonstrate the superiority of the Grey-Markov model for accurate short-term prediction of the carbon storage of reef fish. The standing biomass carbon storage values of reef fish in reef areas in spring 2021, winter 2022, spring 2023, and winter 2024 were 64.84 t, 49.84 t, 25.28 t, and 19.43 t, showing a decreasing trend. In summary, reef fish species have a strong carbon storage capacity and a high ecological value, which give them an important role in fishery carbon sinks. However, the carbon storage capacity of reef fish is expected to decline in the future, which may be related to their overexploitation. Reef fish species are the primary targets of traditional fisheries. Therefore, we can take the following measures: First, we should consider the carbon storage effect of reef fish; Second, marine ranching operators can strengthen their investment in the construction of artificial reef areas and conduct active stock enhancement of reef fish, which can increase reef fish resources and subsequently reef fish carbon storage. Third, we can strengthen the environmental protection and management of marine ranching. The findings of this study not only provide a basis for assessing the carbon storage potential of reef fish but also serve as a scientific reference for establishing a strategy to develop reef fish resources in marine ranching based on fishery carbon sinks.

This study aims to determine the abundance of fish in the recovery location of the coral reef ecosystem in Botutonuo waters, Gorontalo Province. The research was conducted in February - May 2023. The research location consisted of 2 sites, namely site A which had coral transplants with spider coral skeletons and site B which had no transplants (natural coral reefs). Observations were made 3 times with an interval of 2 weeks. Reef fish data was collected using the Underwater Visual Census (UVC) method, with a 50 m x 5 m line transect. Calculation of data using fish abundance rum. The results showed that the number of fish species found in the Botutonuo waters of Gorontalo Province at site A was 89 species with a total individual abundance of 2,429 ind/m2, while at site B there were 69 species with a total individual abundance of 2,054 ind/m2.

This study aimed to analyze the community structure of reef fish in the small island waters of Central Bangka. The research was conducted in March 2022 in the waters of Bebuar Island, Ketugar Island, Ketawai Island, and Gusung Asam Central Bangka Regency, Bangka Belitung Islands Province. The coral reef survey method uses purposive sampling and the coral reef fish visual census with data analysis of abundance, diversity index, uniformity, and dominance. In-site water quality measurements included six parameters: temperature, salinity, current, brightness, depth, and pH. The results showed that coral reef cover from 44.60 - 87.00% with the medium to very good category. The abundance of reef fish from 1 to 3 individuals/m2 was dominated by 18 species of the Pomacentridae family. The reef fish diversity index ranged from 2.47 to 2.90, including the medium category. The uniformity index value ranged from 0.79 - 0.94, including the high category, indicating that the species found were evenly distributed across all stations. The dominance index value ranges from 0.07 to 0.15, including low, where no species dominates significantly and the fish are evenly distributed. Temperature, brightness, pH, and salinity are factors that support the growth of coral and reef fish. A water current speed of 0.05 – 0.20 m/s is quite helpful in cleaning coral reefs from mud and can supply oxygen. Water conditions were categorized as good and fulfilled the seawater quality standards.

Accurate assessments of ecosystem condition are needed to inform management processes such as systematic conservation planning and protected area expansion, marine spatial planning and other effective area‐based conservation measures. Yet measuring the condition of dynamic and often largely inaccessible marine ecosystems is extremely difficult and presents a global challenge.Broad‐scale cumulative impact assessments have been used in South Africa as a proxy for marine ecosystem condition in national assessments and reporting because the data are more readily available, and knowledge exists on the impacts of various human activities (or pressures) on marine ecosystems. While useful for national reporting, assessments based on in situ ecological data are also needed at finer scales relevant to management.Applying the HELCOM BEAT approach, this study used in situ ecological data to identify potential methods and indicators that can be applied in South Africa to conduct integrated ecosystem assessments and to assess the suitability of current cumulative impact assessments as a proxy for condition.Aggregated fish indicators demonstrated greater sensitivity to varying human pressures compared with benthic community indicators, with responsiveness differing by location. Notably, site‐level differences in empirical condition emerged that broad‐scale cumulative assessments often missed. The study thus highlighted the varying suitability of cumulative impact scores as proxies for condition, indicating their reliability for fish communities. However, this is also dependent on the pressure types included, the biotic indicators used and the area of focus.Conservation decisions based solely on cumulative impact scores could misrepresent the actual condition of the environment, which makes it difficult to make management decisions, especially at finer scales. As such, conservation initiatives need to be regionally adapted to effectively address the unique pressures and conditions of each area and should be tailored to account for fine‐scale variability, instead of adopting a one‐size‐fits‐all approach. [ABSTRACT FROM AUTHOR]

The Gorgeous goby Lythrypnus pulchellus shows extreme sexual plasticity with the bidirectional sex‐change ability socially controlled in adults. Therefore, this study describes how the hierarchical status affects hormone synthesis through newborn hormone waste products in water and tests the influence of body size and social dominance establishment in sex reversal duration and direction. The associated changes in behavior and hormone levels are described under laboratory conditions in male–male and female–female pairs of similar and different body sizes, recording the changes until spawning. The status establishment occurred in a relatively shorter time period in male and female pairs of different sizes (1–3 days) compared to those of similar size (3–5 days), but the earlier one did not significantly affect the overall time of sex change (verified by pair spawning). The changes in gonads, hormones, and papilla occurred in sex‐changer individuals, but the first one was observed in behavior. Courtship started at 3–5 days in male pairs and from 2 h to 1 day in female pairs of both groups of different and similar sizes. Hormones did not gradually move in the new sexual phenotype direction during the sex‐change time course. Nonetheless, estradiol regulated sex change and 11‐ketotestosterone enabled bidirectional sex change and was modulated by agonistic interactions. Cortisol is associated with status and gonadal sex change. In general, similar mechanisms underlie sex change in both directions with a temporal change sequence in phases. These results shed new light on sex‐change mechanisms. Further studies should be performed to determine whether these localized changes exist in the steroid hormone synthesis along the brain–pituitary gonad axis during social and bidirectional sex changes in L. pulchellus. [ABSTRACT FROM AUTHOR]

Ciguatoxins (CTXs), potent neurotoxins produced by dinoflagellates of the genera Gambierdiscus and Fukuyoa, accumulate in commonly consumed fish species, causing human ciguatera poisoning. Field collections of Pacific reef fish reveal that consumed CTXs undergo oxidative biotransformations, resulting in numerous, often toxified analogs. Following our study showing rapid CTX accumulation in flesh of an herbivorous fish, we used the same laboratory model to examine the tissue distribution and metabolization of Pacific CTXs following long-term dietary exposure. Naso brevirostris consumed cells of Gambierdiscus polynesiensis in a gel food matrix over 16 weeks at a constant dose rate of 0.36 ng CTX3C equiv g−1 fish d−1. CTX toxicity determination of fish tissues showed CTX activity in all tissues of exposed fish (eight tissues plus the carcass), with the highest concentrations in the spleen. Muscle tissue retained the largest proportion of CTXs, with 44% of the total tissue burden. Moreover, relative to our previous study, we found that larger fish with slower growth rates assimilated a higher proportion of ingested toxin in their flesh (13% vs. 2%). Analysis of muscle extracts revealed the presence of CTX3C and CTX3B as well as a biotransformed product showing the m/z transitions of 2,3-dihydroxyCTX3C. This is the first experimental evidence of oxidative transformation of an algal CTX in a model consumer and known vector of CTX into the fish food web. These findings that the flesh intended for human consumption carries the majority of the toxin load, and that growth rates can influence the relationship between exposure and accumulation, have significant implications in risk assessment and the development of regulatory measures aimed at ensuring seafood safety. [ABSTRACT FROM AUTHOR]

Successful settlement and recruitment of reef fish are influenced by spatial and temporal processes and variables on distinct scales. Moreover, they require survival at various stages in different environments for species with a complex life cycle, as in the case of most reef fish. The variability in those processes can be explained by biotic and abiotic factors that affect pre and postsettlement stages. Despite the many benefits of marine protected areas (MPAs) for fish and fisheries, the positive effects of protected areas on the reproduction, settlement, and recruitment of reef fish are still unclear. The present study reviewed the biotic and abiotic factors that influence the settlement and recruitment of reef fish, especially regarding the role of MPAs in these processes. This bibliographic review shows that the larval settlement is shaped by the interaction of biological traits (e.g., life history) and environmental factors (e.g., temperature, currents), which are determinants of the life cycle and population structure of reef fish. The main contribution of MPAs to these processes is the export of eggs and larvae to adjacent regions. However, further research is needed on the issues of settlement and recruitment in the specific context of MPAs. The absence of studies on this topic, particularly how protection affects, directly and indirectly, recruitment variability and how this is reflected in the adult population, hinders MPAs objectives and seems to be a serious shortcoming in attempts to support future populations at ecologically adequate levels. [ABSTRACT FROM AUTHOR]

Fusiliers of the family Caesionidae comprise a group of Indo‐Pacific reef fishes important in the live bait and artisanal fisheries in many parts of its range, particularly in the Indian Ocean region. Using newly generated mitochondrial COI sequences of 10 species of caesionid fishes from the Laccadive archipelago, we carried out a molecular phylogenetic analysis, which has helped improve our understanding of the diversity, distribution, and systematics of this poorly known group of fishes. The two speciose genera within Caesionidae, Caesio and Pterocaesio, were revealed to be paraphyletic, and as a result, four names earlier considered as subgenera within Caesionidae (Flavicaesio, Odontonectes, Pisinnicaesio, and Squamosicaesio) were elevated to the status of distinct genera. We also discovered the presence of a new lineage in the Central Indian Ocean, sister to Caesio caerulaurea and Caesio xanthalytos, but distinct from both in several morphological characters and a genetic distance of between 2% and 3% in the mitochondrial COI gene. We describe this lineage as Caesio idreesi, a new species, with a distribution spanning the Laccadive Sea and the Bay of Bengal. Our genetic data also helped confirm the first confirmed records of two species, Pisinnicaesio digramma and Squamosicaesio randalli, from the Central Indian Ocean, and a new distribution record for C. xanthalytos in the Laccadive Sea. Combined, these results have helped bridge key biodiversity knowledge gaps of the family Caesionidae and form an excellent baseline for further investigations on their taxonomy, systematics, and life history. [ABSTRACT FROM AUTHOR]

Virtual reality (VR) enables standardized stimuli to provoke behavioural responses in animals; however, in fish studies VR has been limited to either basic virtual simulation projected below the bowl for freely swimming individuals or a simple virtual arena rendered over a large field of view for head-restrained individuals. We developed a novel immersive VR set-up with real-time rendering of animated 3D scenarios, validated in a proof-of-concept study on the behaviour of coral reef postlarval fish. Fish use a variety of cues to select a habitat during the recruitment stage, and to recognize conspecifics and predators, but which visual cues are used remains unknown. We measured behavioural responses of groups of five convict postlarval surgeonfish, Acanthurus triostegus , to simulations of habitats, static or moving shoals of conspecifics, predators and nonaggressive heterospecifics. Postlarval fish were consistently attracted to virtual corals and conspecifics presented statically, but repulsed by their predators (bluefin jacks, Caranx melampygus). When simulated shoals repeatedly passed nearby, they were again attracted by conspecifics, showing a tendency to follow the shoal, whereas they moved repeatedly to the back of the passing predator shoal. They also discriminated between species of similar sizes: they were attracted more to conspecifics than butterflyfish, Forcipiger longirostris , and repulsed more by predators than parrotfish, Scarus psittacus. The quality of visual simulations was high enough to identify visual cues (size, body shape, colour pattern) used by postlarval fish in species recognition. Despite a tracking technology limited to fish 2D positions in the aquarium, preventing the real-time updating of the rendered viewpoint, we could show that VR and modern tracking technologies offer new possibilities to investigate fish behaviour through the quantitative analysis of their physical reactions to highly controlled scenarios. • Immersive virtual reality set-up with automated tracking for fish behaviour. • Highly realistic and well-controlled animated 3D scenarios. • Real-time collection of numerous parameters about fish kinematics. • Proof of concept study on postlarval surgeonfish, Acanthurus triostegus. • Modelling of reactions to virtual habitat, adult conspecifics and predators. [ABSTRACT FROM AUTHOR]

Tetraodontidae is the most speciose family of Tetraodontiformes and is represented by fish popularly known as pufferfishes. They are characterized by modified jaws with four dental plates and the ability to inflate their bodies. Tetraodontids are distributed throughout the world and have a wide range of habitat use. One of its genera, Sphoeroides , shows a biogeographical pattern, with 19 of its 21 species restricted to coastal regions of the Americas. Although represented in large-scale phylogenies, the evolutionary history and biogeography of the genus have not been explored in detail. The present study aims to understand the historical and biogeographic processes that shaped the evolutionary history of Sphoeroides. Including samples from all biogeographic regions of its occurrence, we reconstruct a phylogenetic/biogeographic history hypothesis for the genus. Our results show that Sphoeroides is a paraphyletic group comprising Colomesus; indicate a central role of the biogeographic barriers of the Atlantic Ocean in the diversification of the genus; and identified a cryptic species in Brazilian waters, formally known as S. spengleri , described here through integrative taxonomy. We also propose nomenclatural changes given the position of Colomesus deeply nested within Sphoeroides. [ABSTRACT FROM AUTHOR]

A core challenge in ecology is identifying the factors that determine species distribution and functional diversity of species assemblages. Reef fish are the most diverse group of vertebrates, form taxonomically rich and functionally diverse communities and represent a key source of food for humans. We examine regional distribution patterns of reef fish species richness and functional diversity and investigate how these are determined by historical, biogeographic, energetic, and anthropogenic factors. We compiled data from 3,312 underwater visual censuses performed at 122 locations comprising rocky and coral reefs along the Eastern Tropical Pacific (ETP). We used generalized linear mixed‐effects models (GLMMs) implemented in a Bayesian framework to investigate whether distance from quaternary refugia, distance from mainland, shelf area, primary productivity, sea surface temperature (SST), human population gravity, and conservation status influence reef fish species richness and functional diversity in the ETP. Species richness and functional richness (FRic) peaked towards the center of the ETP and our null model suggests that FRic followed a spatial pattern that would be predicted by species richness. Additionally, functional evenness (FEve) was highest at higher latitudes whereas functional dispersion (FDis) was homogeneous throughout the ETP. Species richness was negatively influenced by shelf area and distance from mainland, but positively influenced by SST and conservation status. FEve was influenced by human population gravity and FDis by shelf area. Reef fish species richness and functional diversity in the ETP exhibited a strong division within the region mainly mediated by SST and human population gravity. Our results also suggest that dominant species within small shelf areas share more common traits than dominant species in large areas. This study uncovers previously unknown regional patterns of reef fish functional diversity and provides new insights into how historical, biogeographic, energetic, and anthropogenic factors influence complementary biodiversity facets. [ABSTRACT FROM AUTHOR]

Chaetodontidae, known as butterflyfishes, are typical fish in coral ecosystems, exhibiting remarkable interspecific differences including body colour patterns and feeding ecology. In this study, we report genomes of three butterflyfish species (Chelmon rostratus , Chaetodon trifasciatus and Chaetodon auriga) and a closely related species from the Pomacanthidae family, Centropyge bicolour , with an average genome size of 65,611 Mb. Chelmon rostratus , comprising 24 chromosomes assembled to the chromosome level, could be served as a reference genome for butterflyfish. By conducting a collinearity analysis between butterflyfishes and several fishes, we elucidated the specific and conserved genomic features of butterflyfish, with particular emphasis on novel genes arising from tandem duplications and their potential functions. In addition to the two melanocyte-specific tyr genes commonly found in fish, we found the gene tyrp3 , a new tyrosinase-related proteins gene in the reef fish, including butterflyfish and clownfish, implicating their involvement in the pigmentation diversity of fish. Additionally, we observed a tandem duplication expansion of three copies of nell1 gene in C. rostratus genome, which likely contribute to its unique jaw development and distinctive morphology of its sharp mouth. These results provided valuable genomic resources for further investigations into the genetic diversity and evolutionary adaptations of reef fish. [ABSTRACT FROM AUTHOR]

Interactions between bottlenose dolphin and recreational rod and reel fisheries are a complex issue for resource managers in the United States, which may impact anglers' catch and lead to dangerous situations for scavenging or depredating dolphins. To examine this issue, we analyzed data collected by observers on for-hire fishing vessels off the eastern U.S. Gulf Coast from 2009 to 2020. A generalized additive model indicated number of anglers, number of discarded fish, proximity to shore, prior scavenging events, type of released fish, and area fished were all significant predictors of scavenging by dolphins. The Florida panhandle had the highest odds of scavenging, while scavenging in the Big Bend and Tampa Bay has increased through time. The Florida panhandle is a wellknown area for illegal feeding of dolphins, suggesting human behavior may be influencing fisheries interactions. Model outputs indicate that dolphins are primarily cuing on fishing activity rather than number of discards, but are more likely to scavenge discards from the family Lutjanidae (snappers), which comprised 40% of observed discards but 80% of scavenging events. This study highlights factors influencing the frequency of dolphin scavenging events, guiding managers and scientists on additional studies and mitigation measures needed to address this issue. [ABSTRACT FROM AUTHOR]

In tropical marine ecosystems, the coral-based diet of benthic-feeding reef fishes provides a window into the composition and health of coral reefs. In this study, for the first time, we compare multi-assay metabarcoding sequences of environmental DNA (eDNA) isolated from seawater and partially digested gut items from an obligate corallivore butterflyfish (Chaetodon lunulatus) resident to coral reef sites in the South China Sea. We specifically tested the proportional and statistical overlap of the different approaches (seawater vs gut content metabarcoding) in characterizing eukaryotic community composition on coral reefs. Based on 18S and ITS2 sequence data, which differed in their taxonomic sensitivity, we found that gut content detections were only partially representative of the eukaryotic communities detected in the seawater based on low levels of taxonomic overlap (3 to 21%) and significant differences between the sampling approaches. Overall, our results indicate that dietary metabarcoding of specialized feeders can be complimentary to, but is no replacement for, more comprehensive environmental DNA assays of reef environments that might include the processing of different substrates (seawater, sediment, plankton) or traditional observational surveys. These molecular assays, in tandem, might be best suited to highly productive but cryptic oceanic environments (kelp forests, seagrass meadows) that contain an abundance of organisms that are often small, epiphytic, symbiotic, or cryptic. [ABSTRACT FROM AUTHOR]

Over the last few decades, the tourism industry in the Maldives has experienced exponential growth. This rise in tourism has created a new demand for reef fish and anecdotal reports indicate that exploitation of reef fish is increasing; however, currently, there is little monitoring of the reef fish fishery. This project integrated fish biomass data from underwater visual fish surveys with locations of resorts to examine correlations between fish populations and tourism development. Maps of human presence throughout the archipelago were used to classify surveyed reefs as community, resort or uninhabited. Spatial statistics and regression analysis suggest that distance to a resort has no significant impact on the amount of fish biomass found at nearby reefs. However, the breakdown of biomass by trophic level show an absence of apex predators across all sites, which likely indicates fishing pressure and resource exploitation of large-bodied species readily caught through hook and line fisheries. Additionally, a high level of herbivore biomass across all sites could be playing an important role in reef recovery. As the fishery develops and reef fish demand grows, the Maldives will need to create a management plan that allows for the recovery of apex predators, as well as protects the abundance of herbivores.

There are two major theories for setting up ecological communities, the Niche Theory and the Neutral Theory. Both seek to explain the main factors that form a community, which is a great challenge, since each community has its particularities and the environment has different ways to manifest. We devised a process-oriented study that sought to establish the role of environmental niche driven by coastal upwelling in the assembly of reef fish communities from exposed and sheltered environments a few kilometers apart, in the region of Arraial do Cabo (southwestern Atlantic). A multivariate hierarchical generalized linear mixed model fitted with Bayesian inference was applied to abundance and presence-absence data from visual census, together with environmental data from satellite and reanalysis. We found a stronger contribution of random effects to abundance variance with 24% for sites and 20.7% for sheltered vs. exposed locations, and weaker environmental effects with 7.1% for surface chlorophyll-a concentration (SCC) and 5.4% for sea surface temperature (SST). Environmental effects had a stronger contribution in the presence-absence model, with 20.1% for SCC and 14.6% for SST. The overall influence of the upwelling environment across all species was negative, e.g., Gymnothorax moringa and Canthigaster figueiredoi showing negative responses to SCC and Parablennius pilicornis and Malacoctenus delalandii to SST. The joint action of migration-niche mechanisms is inferred from the dominance of spatio-temporal structure, limited influence of life history traits and phylogeny, explaining around 95% of species niches in the abundance model. Our results bring new evidence for the importance of different filters for community assembly other than the environment, such as phylogenetic history and dispersal. We also discuss the balance between niche (environment) and neutral (stochasticity) processes for the assembly of reef fish communities in a tropical-subtropical transition zone.

Consumers mediate nutrient cycling through excretion and egestion across most ecosystems. In nutrient‐poor tropical waters such as coral reefs, nutrient cycling is critical for maintaining productivity. While the cycling of fish‐derived inorganic nutrients via excretion has been extensively investigated, the role of egestion for nutrient cycling has remained poorly explored. We sampled the fecal contents of 570 individual fishes across 40 species, representing six dominant trophic guilds of coral reef fishes in Moorea, French Polynesia. We measured fecal macro‐ (proteins, carbohydrates, lipids) and micro‐ (calcium, copper, iron, magnesium, manganese, zinc) nutrients and compared the fecal nutrient quantity and quality across trophic guilds, taxa, and body size. Macro‐ and micronutrient concentrations in fish feces varied markedly across species. Genera and trophic guild best predicted fecal nutrient concentrations. In addition, nutrient composition in feces was unique among species within both trophic guilds (herbivores and corallivores) and genera (Acanthurus and Chaetodon). Particularly, certain coral reef fishes (e.g., Thalassoma hardwicke, Chromis xanthura, Chaetodon pelewensis and Acanthurus pyroferus) harbored relatively high concentrations of micronutrients (e.g., Mn, Mg, Zn and Fe, respectively) that are known to contribute to ocean productivity and positively impact coral physiological performances. Given the nutrient‐rich profiles across reef fish feces, conserving holistic reef fish communities ensures the availability of nutritional pools on coral reefs. We therefore suggest that better integration of consumer egestion dynamics into food web models and ecosystem‐scale processes will facilitate an improved understanding of coral reef functioning. [ABSTRACT FROM AUTHOR]

Abiotic and biotic factors are known drivers that modulate community assembly from a regional species pool. Recent evidence has highlighted the intrinsic role of phylogenetic history on communities' response to the environment. Understanding its exact role poses a challenge because community assembly is embedded in a spatio‐temporal context where dispersal capabilities and biotic interactions may also determine species niches, especially in isolated oceanic islands. We unravelled how reef fish abundances from four oceanic islands in the southwestern Atlantic responded to environmental variability through seven years considering their phylogenetic history, functional traits and species co‐occurrence patterns. Species response to environmental variation was assessed through a multivariate hierarchical generalized linear mixed model that allows the inclusion of spatio‐temporal random effects, fitted with Bayesian inference. We found a strong phylogenetic signal (0.98) and a relatively low variance in abundance explained by functional traits, from around 30% in spring to 33% in summer, based on a posterior probability > 0.9. The most important environmental factor was surface chlorophyll‐a concentration, a proxy for primary productivity, explaining up to 23% of abundance variance. The global spatial and temporal effects on abundance were also low, with a maximum of 18% for sampling sites in spring. Our study offers a synthesis of the influence of complex phylogenetic history and geographical isolation on reef fish species niches in isolated oceanic islands, gaining new insights into how assembly processes have shaped these isolated communities. [ABSTRACT FROM AUTHOR]

Objective: Since 2010, three spatially disjunct reef fish video surveys have provided fishery‐independent data critical to the assessment and management of reef fishes in the Gulf of Mexico. Although analytical approaches have recently been developed to integrate data from these surveys into a single measure of relative abundance and size composition, a more parsimonious approach would be to integrate survey efforts under a single Gulf‐wide survey design. Accordingly, we conducted a retrospective analysis of historical video‐ and habitat‐mapping data to develop a novel stratified random sampling design for conducting surveys of natural and artificial reef habitats. Methods: We conducted a series of classification and regression tree analyses to delineate both spatial and habitat strata, and conducted simulations to assess the performance of an optimized survey design. Result: Spatially, classification and regression tree results identified three depth strata (10–25 m, >25–50 m, >50–180 m) and three regional strata (north‐central Gulf, Big Bend, southwest Florida) in the eastern Gulf. For both natural and artificial reefs, habitat strata were delineated based on a combination of relative relief (low, medium, high) and size of the individual reef feature, although reef scale differed markedly between natural (<100 m2, 100–1000 m2, >1000 m2) and artificial habitats (<25 m2, 25–100 m2, >100 m2). To optimize effort among sampling strata, effort was allocated proportionally based on a combination of habitat availability and managed‐species richness for each stratum. Simulation results indicated that relative median biases were <10% and relative median absolute deviations <30% on estimates of abundance for most species examined on natural reefs under the optimal design, except Greater Amberjack Seriola dumerili. These measures of bias and imprecision were similar or higher for most species simulated using simple random and stratified random survey designs. Estimated relative median bias and relative median absolute deviations were notably higher for artificial reef surveys. Conclusion: Based on these results, survey efforts were integrated as the Gulf Fishery Independent Survey of Habitat and Ecosystem Resources (G‐FISHER) in 2020. Impact statementData from reef fish video surveys were analyzed to develop a new survey design in the Gulf of Mexico. The new design provides better estimates of reef fish abundance from natural and artificial reef habitats and will improve the assessment and management of multiple reef fishes. [ABSTRACT FROM AUTHOR]

Feeding ecology studies are crucial for understanding energy flow in reef ecosystems. In this study, we used an integrative approach to investigate the diel-feeding ecology of the sergeant-major Abudefduf saxatilis. To examine the possibility of diel-periodicity and size-class differences in foraging behaviour, we tracked fish individuals until their first bite on two subtropical reefs. During each observation, we recorded the substratum that was bitten and estimated the individual’s total length. To assess the diet, we analysed the stomach contents of five individuals from each location. In total, we observed 2,703 individuals biting seven substrates. Our results showed no significant differences in substrate use for diel-periodicity. However, we found significant differences between two size classes. Despite this, both populations tended to forage near the surface in the water column in the morning and on the benthos in the afternoon, although this tendency was not statistically significant. Smaller individuals fed mostly in the water column, while larger individuals foraged on all substrates, likely due to their different energetic demands. Our findings indicate this species has an omnivorous, generalist diet, comprising 12 items from both benthos and plankton. The lack of differences in diel-periodicity is likely due to the sergeantmajor’s opportunistic behaviour [ABSTRACT FROM AUTHOR]

The lionfish is an exotic invasive fish native to the Indo-Pacific, which is established in the western Atlantic Ocean and the Caribbean Sea. Lionfish can affect native fishes and invertebrates through direct predation or competition for food. The present review aims to analyze the most relevant characteristics of the biology and ecology of lionfish as an invasive alien species, with an emphasis on Cuba. We provide a current view of the well-known lionfish as a successful invasive fish, and we put in this context the information regarding lionfish in Cuban waters, enriching the background knowledge, and giving novel and relevant information. The compilation of numerous publications on the subject has allowed for a more complete analysis of essential aspects of this invader in the Cuban archipelago. The consulted literature records that the first report of lionfish in Cuba occurred in 2007; subsequently, sightings of lionfish were reported in numerous localities. In 2010, the lionfish was considered an invasive alien species, which currently is established in various habitats, at depths up to 188 m, throughout the Cuban archipelago (e.g., coral reefs, mangroves, seagrass beds, submerged artificial structures). In addition, it has reached very high densities (12.42 ind./100 m2), which exceed those reported in the Indo-Pacific as well as in many locations in the Western Atlantic. It has been confirmed that the lionfish in Cuba also presents numerous characteristics that guarantee its success as an invader, among them: less quantity and diversity of parasites than other Atlantic fishes found in similar environments, a high number of gametes in the gonads, reproductive activity during all year and wide diet. The most important fish families for the lionfish diet in Cuba have been Pomacentridae, Gobiidae, Scaridae, Holocentridae, Mullidae, Labridae and Acanthuridae; and the most important crustacean orders are Decapoda, Mysida, Stomatopoda and Isopoda. In Cuba, as in the entire invaded region, numerous investigations have been directed to evaluate the impact of this invader on ecosystems, and although there is enough information, their results differ. Additional studies are required to assess the impact of lionfish as a predator after several years of invasion on a larger geographic scale in Cuba and other areas of the region. This knowledge will allow the development of more effective control strategies. Periodic lionfish culling have been carried out in Cuban MPAs as a control strategy, and some positive results have been observed, such as the average size reduction; however, further efforts are still required. Due to the importance of the study of lionfish as an invader, this review is a necessity as it provides, for the first time, a comprehensive analysis of lionfish information and results from Cuba, which is adequately contrasted with previous studies of other areas, particularly, from the Greater Caribbean. [ABSTRACT FROM AUTHOR]