Deep Reef Research Articles

Underlying drivers of coral reef vulnerability to bleaching in the Mesoamerican Reef

Coral bleaching, a consequence of stressed symbiotic relationships between corals and algae, has escalated due to intensified heat stress events driven by climate change. Despite global efforts, current early warning systems lack local precision. Our study, spanning 2015–2017 in the Mesoamerican Reef, revealed prevalent intermediate bleaching, peaking in 2017. By scrutinizing 23 stress exposure and sensitivity metrics, we accurately predicted 75% of bleaching severity variation. Notably, distinct thermal patterns—particularly the climatological seasonal warming rate and various heat stress metrics—emerged as better predictors compared to conventional indices (such as Degree Heating Weeks). Surprisingly, deeper reefs with diverse coral communities showed heightened vulnerability. This study presents a framework for coral reef bleaching vulnerability assessment, leveraging accessible data (including historical and real-time sea surface temperature, habitat variables, and species composition). Its operational potential lies in seamless integration with existing monitoring systems, offering crucial insights for conservation and management.

Genome-resolved metagenomics revealed novel microbial taxa with ancient metabolism from macroscopic microbial mat structures inhabiting anoxic deep reefs of a Maldivian Blue Hole.

Blue holes are vertical water-filled openings in carbonate rock that exhibit complex morphology, ecology, and water chemistry. In this study, macroscopic microbial mat structures found in complete anoxic conditions in the Faanu Mudugau Blue Hole (Maldives) were studied by metagenomic methods. Such communities have likely been evolutionary isolated from the surrounding marine environment for more than 10,000 years since the Blue Hole formation during the last Ice Age. A total of 48 high-quality metagenome-assembled genomes (MAGs) were recovered, predominantly composed of the phyla Chloroflexota, Proteobacteria and Desulfobacterota. None of these MAGs have been classified to species level (<95% ANI), suggesting the discovery of several new microbial taxa. In particular, MAGs belonging to novel bacterial genera within the order Dehalococcoidales accounted for 20% of the macroscopic mat community. Genome-resolved metabolic analysis of this dominant microbial fraction revealed a mixotrophic lifestyle based on energy conservation via fermentation, hydrogen metabolism and anaerobic CO2 fixation through the Wood-Ljungdahl pathway. Interestingly, these bacteria showed a high proportion of ancestral genes in their genomes providing intriguing perspectives on mechanisms driving microbial evolution in this peculiar environment. Overall, our results provide new knowledge for understanding microbial life under extreme conditions in blue hole environments.

Insights from tensile fracture properties and full-field strain evolution of deep coral reef limestone under dynamic loads

Coral reef limestone (CRL) commonly undergoes dynamic tension when underground structures of island reefs encounter impacts, explosions, or seismic activities. Given the complexity of biological pores, the dynamic tensile fracture characteristics of CRL are poorly understood. Therefore, the dynamic tensile fracture behaviors of deep CRL were systematically observed by Split Hopkinson Pressure Bar tests and digital image techniques. Comparing to traditional rocks, the macro-pores near failure band would significantly change cracking path. The failure patterns are dominated by loading rate. The strongly dependence of dynamic tensile strength and dynamic crack initiation toughness on loading rate suggests the two indices overcome the effect of CRL macro-pores under dynamic impacts. At low loading rates, tensile fractures predominantly follow intergranular cracks, whereas transgranular cracks dominate at higher rates. The fractal dimension of fracture surface decreases with increasing crack propagation velocity, loading rate, and dynamic crack initiation toughness. Due to the unique marine sedimentary environment, the mechanical heterogeneity in multiple scales distinguishes CRL from terrestrial rock materials. The insights into underlying mechanisms of dynamic tension provide support to optimization of blasting scheme and stability assessments for island underground engineering.

Reefal ostracod assemblages from the Zanzibar Archipelago (Tanzania)

Abstract. Tropical reefs encompass tremendous biodiversity yet are imperiled by increasing natural and anthropogenic disturbances worldwide. Meiobenthic biota on coral reefs, for example, ostracods, may experience substantial diversity loss and compositional changes even before being examined. In this study, we investigated the reefal ostracod assemblages from the highly diverse and productive ecosystem in the Zanzibar Archipelago (Pemba, Zanzibar, and Mafia islands), Tanzania, to understand how their diversity and faunal structure vary in response to water depth, benthic community type, and human impacts. We characterized four distinct ostracod faunas associated with different benthic habitats, which were deep fore reefs, shallow fringing reefs, degraded fringing reefs, and algae-covered intertidal flats. We identified typical ostracod associations, i.e., Bairdiidae versus Loxoconchidae–Xestoleberididae, that showed affinities towards hard corals or algae on the reef platforms, respectively. The highest diversity was found on shallow fringing reefs where coral-affined and algae-affined taxa exhibited maximum overlap of their distributional ranges, while the sand flats, mangrove, and marginal reefs within the intertidal zone had much lower diversity with a high dominance of euryhaline taxa. Along the western coast of Zanzibar Island, coastal development likely resulted in a unique faunal composition and comparatively low diversity of ostracod assemblages among those in reefal habitats, in conjunction with overall reef ecosystem degradation. This study represents the first large-scale assessment of shallow-marine ostracods in the Zanzibar Archipelago. It lays a solid foundation for future research into the ecological significance of ostracods on coral reefs.

Decadal-scale time series highlight the role of chronic disturbances in driving ecosystem collapse in the Anthropocene.

Biome degradation characterizes the Anthropocene Epoch, and modern ecology is deeply involved with describing the changes underway. Most research has focused on the role of acute disturbances in causing conspicuous changes in ecosystem structure, which leads to an underappreciation of the chronic effects causing large changes through the cumulative effects of small perturbations over decades. Coral reefs epitomize this trend, because the changes in community structure are profound, yet the data to quantify these effects are usually insufficient to evaluate the relative roles of different disturbance types. Here, four decades of surveys from two coral reefs (9 and 14 m depth) off St. John, US Virgin Islands, are used to quantify the associations of acute and chronic events with the changes in benthic community structure. These reefs profoundly changed over 36 years, with coral death altering species assemblages to depress abundances of the ecologically important coral Orbicella spp. and elevating the coverage of macroalgae and crustose coralline algae/turf/bare space (CTB). Linear mixed models revealed the prominent role of chronic variation in temperature in accounting for changes in coverage of corals, macroalgae, and CTB, with rising temperature associated with increases in coral cover on the deep reef, and declines on the shallow reef. Hurricanes were also associated with declines in coral cover on the shallow reef, and increases on the deep reef. Multivariate analyses revealed strong associations between community structure and temperature, but weaker associations with hurricanes, bleaching, and diseases. These results highlight the overwhelming importance of chronically increasing temperature in altering the benthic community structure of Caribbean reefs.

Invertebrate sounds from photic to mesophotic coral reefs reveal vertical stratification and diel diversity.

Although mesophotic coral ecosystems account for approximately 80% of coral reefs, they remain largely unexplored due to their challenging accessibility. The acoustic richness within reefs has led scientists to consider passive acoustic monitoring as a reliable method for studying both altiphotic and mesophotic coral reefs. We investigated the relationship between benthic invertebrate sounds (1.5-22.5kHz), depth, and benthic cover composition, key ecological factors that determine differences between altiphotic and mesophotic reefs. Diel patterns of snaps and peak frequencies were also explored at different depths to assess variations in biorhythms. Acoustic recorders were deployed at 20m, 60m, and 120m depths across six islands in French Polynesia. The results indicated that depth is the primary driver of differences in broadband transient sound (BTS) soundscapes, with sound intensity decreasing as depth increases. At 20-60m, sounds were louder at night. At 120m depth, benthic activity rhythms exhibited low or highly variable levels of diel variation, likely a consequence of reduced solar irradiation. On three islands, a peculiar peak in the number of BTS was observed every day between 7 and 9 PM at 120m, suggesting the presence of cyclic activities of a specific species. Our results support the existence of different invertebrate communities or distinct behaviors, particularly in deep mesophotic reefs. Overall, this study adds to the growing evidence supporting the use of passive acoustic monitoring to describe and understand ecological patterns in mesophotic reefs.

Sponge abundance and diversity patterns in the shallow and mesophotic reefs of the northern Red Sea

Accumulating data on the increasing degradation of coral reefs worldwide has led to a focus on the unique mesophotic coral ecosystem (MCE) as a potential refuge for threatened shallow-water species (i.e., the deep reef refugia hypothesis: DRRH). Sponges play a crucial role in coral-reef functioning but are often overlooked in benthic surveys. This knowledge gap is especially true for the Red Sea, where data on sponge abundance, coverage and species composition are scarce. Furthermore, to date, no study has examined mesophotic sponges in the Red Sea. Here we compared sponge abundance and diversity metrics between shallow and mesophotic reefs at two sites in the Gulf of Aqaba, northern Red Sea. We also examined the role of biotic and abiotic parameters in determining sponge variability between sites and depths. Sponge diversity metrics significantly varied with increasing depth and between sites. Sponge species composition also differed significantly between depth and sites. However, parameters measured in the water column, that is, Total Organic Carbon (TOC), Particulate Organic Carbon (POC), NOx, etc., did not differ between depths and sites, except for Synechococcus and Prochlorococcus concentration, which did. The findings indicated that site characteristics and biotic interactions may play an essential role in determining sponge diversity and community composition. Between-site differences in sponge fauna revealed in the study highlight the importance of considering the variability in the benthic communities and the factors controlling it when designing management tools for coral reefs, particularly for the northern Red Sea.

Depth and structure as environmental drivers of fish communities across a shallow to mesophotic gradient in the northern US Virgin Islands

The factors that drive fish communities on coral reefs are varied, complex, and often location specific. In the northern United States Virgin Islands, the large areas of mesophotic coral ecosystems across an insular shelf provide a multitude of gradients along which fish communities form. Using a stratified-random visual fish census, we collected comprehensive data on fish communities across a seascape scale. Fish density and diversity showed responses to depth and hard relief, with these factors occasionally interacting in ways that are species specific. Analysis of trophic groups showed that densities of all groups were positively associated with relief, but while herbivores and invertivores decreased with depth, planktivores and piscivores increased, and piscivores additionally showed an interaction. Some commercially important species occurred more frequently and in larger sizes on deeper reefs, suggesting that mesophotic reefs shelter more fisheries resources, although they are less commonly sampled in visual census programs. Understanding how fish communities change across the seascape informs patterns of ecosystem function, such as identifying areas of resilience and vulnerability. This dataset is a valuable contribution to more completely understanding the ecology and conservation of fishes in the western Atlantic.

Expansion of an established fishery-independent survey into the US Virgin Islands' upper mesophotic zone: feasibility and management implications

A three-year pilot study, the Deep Coral Reef Monitoring Program (DCRMP), expanded the National Coral Reef Monitoring Program's (NCRMP) established fishery-independent, diver-based reef fish visual survey to upper mesophotic reefs (&gt;30 to 50 m) in the United States Caribbean for the first time. The new DCRMP sample domain (&gt;30 to 50 m) encompassed 2.4 times more survey area than NCRMP (0 to ≤30 m) and collected high quality data (CV &lt;20%) on coral reef fishes [three survey years, 29 (5) species; mean (standard deviation)]. For the four representative, fishery-targeted, analysis species selected (i. e., grouper, snapper, triggerfish, and parrotfish), domain-wide density and length comparisons between surveys showed similar or statistically higher abundances and larger lengths for fishes at deeper depths (&gt;30 to 50 m). These results highlight the importance of surveying the entire insular shelf in St. Thomas and St. John, US Virgin Islands for fisheries management applications. Furthermore, the DCRMP survey leveraged NCRMP's methods and resources resulting in a seamless extension to deeper waters. However, if these programs were fully integrated and optimized within a single survey design, approximately half the sites would be needed to achieve the same level of precision, offering substantial time and cost savings. The principles of probabilistic sampling successfully used in the present fishery-independent survey design (0 to 50 m) can be applied more broadly to develop an "ideal" large-scale, multi-gear survey from 0 to about 500 m to encompass the entire depth ranges of managed species in the US Caribbean.

Genomic, morphological, and physiological insights into coral acclimation along the depth gradient following an in situ reciprocal transplantation of planulae

Mesophotic coral reefs have been proposed as refugia for corals, providing shelter and larval propagules for shallow water reefs that are disproportionately challenged by global climate change and local anthropogenic stressors. For mesophotic reefs to be a viable refuge, firstly, deep origin larvae must survive on shallow reefs and, secondly, the two environments must be physically connected. This study tested the first condition. Planulae of the reef-building coral Stylophora pistillata from 5–8 and 40–44 m depth in the Gulf of Aqaba were tested in a long-term reciprocal transplantation experiment for their ability to settle and acclimate to depth in situ. We assessed survival rates, photochemical, physiological, and morphological characteristics in juveniles grown at either their parental origin or transplantation depth. Differences in gene expression patterns were compared between mesophotic and shallow corals at the adult, juvenile, and planula life stages. We found high mortality rates among all mesophotic-origin planulae, irrespective of translocation depth. Gene expression patterns suggested that deep planulae lacked settlement competency and experienced increased developmental stress upon release. For surviving shallow origin juveniles, symbiont photochemical acclimation to depth occurred within 8 days, with symbiont communities showing changes in photochemical traits without algal symbiont shuffling. However, coral host physiological and morphological acclimation towards the typical deep phenotype was incomplete within 60 days. Gene expression was influenced by both life stage and depth. A set of differentially expressed genes (DEGs) associated with initial stress responses following transplantation, latent stress response, and environmental effects of depth was identified. This study therefore refutes the Deep Reef Refugia Hypothesis, as the potential for mesophotic-origin S. pistillata planulae to recruit to the shallow reef is low. The potential remains for shallow planulae to survive at mesophotic depths.

Two new species of the deepwater cardinalfish genus Epigonus (Epigonidae) from deep reefs off Curaçao, southern Caribbean

Two new species of the deepwater cardinalfish genus Epigonus (Epigonidae) from deep reefs off Curaçao, southern Caribbean

Dynamic compressive properties and self-similarity characteristics of deep coral reef limestone subjected to high loading rates

Coral reef limestone is a kind of porous anisotropic geo-material. Understanding its dynamic mechanical properties subjected to high loading rates is of great significance to the blasting excavation and military attack defense of the reef underground space. In this paper, the Split Hopkinson Pressure Bar tests were carried out on the specimens of deep coral reef limestone in the South China Sea, and the difference of dynamic response between deep reef limestone and shallow calcified coral skeleton was revealed. The results show that the pore structure affects the dynamic deformation response of coral reef limestone, which makes the strain rate of the specimen independent of other mechanical parameters. However, the high loading rate overcomes the influence of the primary pore structure on the strength, so that the dynamic compressive strength and the degree of breakage are linearly related to the stress rate. In addition, under high loading rate, the coral framework limestone is mainly damaged by tension, which is significantly different from the calcified coral skeleton along the coral growth line. At the same strain rate, the fractal dimension of the dry specimen is greater than that of the saturated one, and the self-similarity characteristics of the specimen fragments that reach the crushing level at higher strain rate are poor. The viscous effect of water hinders the propagation of cracks in the coral framework limestone, but free water reduces the surface energy of the crystal boundary. These two kinds of mechanisms compete with each other, and the key factors controlling the competition mechanism are water content and loading rate.

The marine fishes from southern Mindanao, Philippines, including a DNA barcode reference library of commercially important species

The Philippines has been long known for its multispecies fisheries, and while there is a growing effort to document fish diversity, collections-based species inventories remain insufficient in southern Mindanao. Market survey efforts conducted in Pujada Bay, Davao Gulf, and Sarangani Bay in the last ten years resulted in documenting 556 species of marine fishes from 82 families, while underwater fish visual census (FVC) surveys conducted in Davao Gulf from 2019 to 2022 revealed 365 species in 42 families. Combining the data from market surveys, FVC, and published literature, we present 771 species of marine fishes (770 teleosts, 1 elasmobranch) belonging to 94 families. Of the 771 species documented, 130 are deep reef and deepwater species, while 20 species await further taxonomic investigations for species-level identifications.Moreover, 498 cytochrome oxidase I (COI) genetic barcodes were produced representing 357 species from 59 families, which covers 46% of the total number of species reported and 63% of the market survey data. Genetic distances based on taxonomic ranks were concordant with other barcoding studies on marine fishes. Samples (20 species) with pairwise genetic distances that did not conform with the expected intra- and interspecific threshold suggest cases that also need to be investigated further (e.g., incomplete lineage sorting, introgressive hybridization, crypticspeciation). All market survey data used in genetic barcoding correspond to tissue samples, live-color photographs, and preserved specimens. This work complements the DNA barcode libraries reported recently in the country, and this serves as an additional reference for future biodiversity management and conservation efforts.

An Aggregation of the Pandalid Shrimp, Heterocarpus ensifer, on Deep Reef Habitats of the West Florida Slope, Eastern Gulf of Mexico

An Aggregation of the Pandalid Shrimp, Heterocarpus ensifer, on Deep Reef Habitats of the West Florida Slope, Eastern Gulf of Mexico

Molecular fossils in reefal carbonates and sponges of the deep fore reef of Mayotte and Mohéli, Comoro Islands, western Indian Ocean

Microbial carbonates are common components of Quaternary tropical coral reefs. Previous studies revealed that sulfate-reducing bacteria trigger microbial carbonate precipitation in supposedly cryptic reef environments. Here, using petrography, lipid biomarker analysis, and stable isotope data, we aim to understand the formation mechanism of microbial carbonate enclosed in deep fore reef limestones from Mayotte and Mohéli, Comoro Islands, which differ from other reefal microbial carbonates in that they contain less microbial carbonate and are dominated by numerous sponges. To discern sponge-derived lipids from lipids enclosed in microbial carbonate, lipid biomarker inventories of diverse sponges from the Mayotte and Mohéli reef systems were examined. Abundant peloidal, laminated, and clotted textures point to a microbial origin of the authigenic carbonates, which is supported by ample amounts of mono-O-alkyl glycerol monoethers (MAGEs) and terminally branched fatty acids; both groups of compounds are attributed to sulfate-reducing bacteria. Sponges revealed a greater variety of alkyl chains in MAGEs, including new, previously unknown, mid-chain monomethyl- and dimethyl-branched MAGEs, suggesting a diverse community of sulfate reducers different from the sulfate-reducers favoring microbialite formation. Aside from biomarkers specific for sulfate-reducing bacteria, lipids attributed to demosponges (i.e., demospongic acids) are also present in some of the sponges and the reefal carbonates. Fatty acids attributed to demosponges show a higher diversity and a higher proportion in microbial carbonate compared to sponge tissue. Such pattern reflects significant taphonomic bias associated with the preservation of demospongic acids, with preservation apparently favored by carbonate authigenesis.

Plastic pollution in a coral reef climate refuge: Occurrence of anthropogenic debris, microplastics, and plasticizers in the Gulf of Aqaba

The Gulf of Aqaba in the northern Red Sea, considered a coral reef refuge from the negative effects of climate change, is however being subjected to increasing amounts of plastic contamination. We quantified the levels of benthic plastic debris, microplastics, and plasticizers within the coral reef's surrounding seawater and sediment over time. Our results indicate that the coral reefs of the GoA have relatively lower levels of plastic pollution compared to reefs in other regions. The measured benthic debris in the Red Sea reefs was found to be 0.093 ± 0.091 item/m2 and fell within the reported levels found in other tropical coral reefs, with boating and fishing materials being the most abundant type. Deep mesophotic reefs were found to have significantly higher levels of benthic plastic debris compared to the shallower reefs. Microplastic levels in the surrounding seawater of the reef were 0.516 ± 0.317 microplastics/m3. These concentrations in the reef's surrounding waters are comparable to the levels observed in surface waters from the central Red Sea. The target plasticizers appeared infrequently in samples, and the concentrations for the majority of them were below the level of quantification (LOQ = 14.7 ng/l for water and 14.7 ng/g for sediment). The findings from this study provide a valuable scientific basis for shaping regional policies and implementing management strategies aimed at controlling and mitigating plastic pollution. Such policies can ensure the long-term protection of the reefs in the northern Red Sea, turning them into a secure coral refuge shielded from both global and local anthropogenic stressors.

Impacts of coral bleaching on reef fish abundance, biomass and assemblage structure at remote Aldabra Atoll, Seychelles: insights from two survey methods

IntroductionCoral bleaching immediately impacts the reef benthos, but effects on fish communities are less well understood because they are often delayed and confounded by anthropogenic interactions.MethodsWe assessed changes in fish abundance, biomass and community composition before and after the 2015/16 coral bleaching event at Aldabra Atoll, Seychelles, where local human impacts are minimal, but reefs suffered 50% bleaching-induced coral mortality. We monitored 12 shallow (2–5 m water depth) and nine deep (15 m water depth) permanent survey sites using two survey methods: indicator surveys recording 84 taxa over six years (pre-: 2014; post-bleaching: 2016–2019, 2021), sizing fish based on six size-class categories, and extended fish surveys recording 198 taxa over two years (pre-: 2015; post-bleaching: 2020) with size estimates to the nearest cm (excluding fish &amp;lt; 8 cm).ResultsDuring indicator surveys, mean fish abundance did not change on deep reefs. However, abundance increased by 77% on shallow reefs between 2014 and 2016, which was mainly driven by increases in herbivores and omnivores, likely as a response to elevated turf algae cover following coral mortality. Overall (and functional group-specific) indicator fish biomass did not differ between 2014 and 2016 and remained at or above pre-bleaching levels throughout 2016–2021. In contrast, extended fish surveys in 2015 and 2020 showed a 55–60% reduction in overall abundance on shallow and deep reefs, and a 69% reduction in biomass on shallow reefs, with decreases in biomass occurring in all functional groups. Biomass on deep reefs did not differ between 2015 and 2020. Multivariate analysis of both data sets revealed immediate and long-lasting differences between pre- and post-bleaching fish community compositions, driven largely by herbivorous, omnivorous and piscivorous taxa.DiscussionResults from the indicator surveys suggest that the bleaching event had limited impact on fish abundance and biomass, while the extended surveys recorded changes in abundance and biomass which would otherwise have gone undetected. Our findings improve understanding of the shift a broad community of fish undergoes following a mass coral bleaching event and highlights the value of survey methods that include the full suite of species to detect ecological responses to environmental drivers.

Submerged reef and inter-reef morphology in the Western South Atlantic, Abrolhos Shelf (Brazil)

Submarine geomorphology is a main environmental driver defining the seascape and associated benthic habitat. In this sense, eustatic sea-level fluctuations plays a major role in shaping the morphology of the seafloor. During the last deglaciation, changes in rates of sea-level rise led to moments of stillstand and rapid rise acceleration, forming and drowning distinct shelf geomorphological features. Here, we present and discuss the morphology and associated habitats related to submerged reefs and inter-reef areas along the southern Abrolhos inner shelf (western South Atlantic, Brazil). Our aim is to discuss the morphological evidence of reef drowning and related sea-level/climate events, and the formation of distinct habitats during the post-Last Glacial Maximum transgression. Multibeam echosounder data and sub-aquatic video footage are the basic datasets. Automatic seabed classification was carried out by combining morphometric analysis, acoustic backscatter and ground-truthing. Results show the presence of two clusters of submerged reefs (14-23 m and 24-35 m deep), associated with longitudinal and transverse bedforms, banks, and shelf-incised valleys. Rhodolith beds comprise the main inter-reef benthic habitat. Distinct reef clusters defined by reef top depths indicate that reef drowning occurred in two different moments. The shallower reefs are likely related to the rapid sea-level rise associated with MWP 1C, while deeper reefs are interpreted as remanent carbonate build-ups. Habitats are strongly influenced by the marine geodiversity forming a mosaic of reef, inter-reef and bedforms classes that seem to be associated with an antecedent paleo landscape marked by shelf-incised valleys and paleochannels. Submarine geomorphology is an environmental component that drives geodiversity and is driven by distinct seafloor processes acting in different time and spatial scales, as well as being able to quantify biogenic phenomena, for example, surrogacy and provide records of sea-level changes.

Two new species of Varicus from Caribbean deep reefs, with comments on the related genus Pinnichthys (Teleostei, Gobiidae, Gobiosomatini, Nes subgroup).

Tropical deep reefs (~40-300 m) are diverse ecosystems that serve as habitats for diverse communities of reef-associated fishes. Deep-reef fish communities are taxonomically and ecologically distinct from those on shallow reefs, but like those on shallow reefs, they are home to a species-rich assemblage of small, cryptobenthic reef fishes, including many species from the family Gobiidae (gobies). Here we describe two new species of deep-reef gobies, Varicusprometheussp. nov. and V.roatanensissp. nov., that were collected using the submersible Idabel from rariphotic reefs off the island of Roatan (Honduras) in the Caribbean. The new species are the 11th and 12th species of the genus Varicus, and their placement in the genus is supported by morphological data and molecular phylogenetic analyses. Additionally, we also collected new specimens of the closely-related genus and species Pinnichthysaimoriensis during submersible collections off the islands of Bonaire and St. Eustatius (Netherland Antilles) and included them in this study to expand the current description of that species and document its range extension from Brazil into the Caribbean. Collectively, the two new species of Varicus and new records of P.aimoriensis add to our growing knowledge of cryptobenthic fish diversity on deep reefs of the Caribbean.

A marine protected area network does not confer community structure resilience to a marine heatwave across coastal ecosystems.

Marine protected areas (MPAs) have gained attention as a conservation tool for enhancing ecosystem resilience to climate change. However, empirical evidence explicitly linking MPAs to enhanced ecological resilience is limited and mixed. To better understand whether MPAs can buffer climate impacts, we tested the resistance and recovery of marine communities to the 2014-2016 Northeast Pacific heatwave in the largest scientifically designed MPA network in the world off the coast of California, United States. The network consists of 124 MPAs (48 no-take state marine reserves, and 76 partial-take or special regulation conservation areas) implemented at different times, with full implementation completed in 2012. We compared fish, benthic invertebrate, and macroalgal community structure inside and outside of 13 no-take MPAs across rocky intertidal, kelp forest, shallow reef, and deep reef nearshore habitats in California's Central Coast region from 2007 to 2020. We also explored whether MPA features, including age, size, depth, proportion rock, historic fishing pressure, habitat diversity and richness, connectivity, and fish biomass response ratios (proxy for ecological performance), conferred climate resilience for kelp forest and rocky intertidal habitats spanning 28 MPAs across the full network. Ecological communities dramatically shifted due to the marine heatwave across all four nearshore habitats, and MPAs did not facilitate habitat-wide resistance or recovery. Only in protected rocky intertidal habitats did community structure significantly resist marine heatwave impacts. Community shifts were associated with a pronounced decline in the relative proportion of cold water species and an increase in warm water species. MPA features did not explain resistance or recovery to the marine heatwave. Collectively, our findings suggest that MPAs have limited ability to mitigate the impacts of marine heatwaves on community structure. Given that mechanisms of resilience to climate perturbations are complex, there is a clear need to expand assessments of ecosystem-wide consequences resulting from acute climate-driven perturbations, and the potential role of regulatory protection in mitigating community structure changes.