Siderastrea Stellata Research Articles

Turbidity buffers coral bleaching under extreme wind and rainfall conditions

Coral reefs in turbid waters have been hypothesized to be a refuge from climate change. These naturally occurring communities were brought into the spotlight because some of their species exhibited record levels of resistance to marine heatwaves (MHWs) by disturbance-tolerant corals. However, long-term monitoring data on the drivers of coral bleaching in these extreme reef habitats are scarce. Here, we describe the population structure and bleaching rates of a widespread and resilient coral (Siderastrea stellata). We examine the links between environmental factors, namely, rainfall, wind speed, turbidity, solar irradiance, sea surface temperature, MHWs, and coral bleaching status under the worst recorded drought cycle in the Tropical South Atlantic (2013–2015). We examined 2880 colonies, most of which (∼93%) fit in the size group of 2–10 cm, with a small number (∼1%) of larger and older colonies (>20 cm). The results indicated the absence of MHWs and normal sea surface temperature variations (between 26.6 °C and 29.3 °C), however, we detected an extreme rainfall deficit (30–40% less annual volume precipitation). In general, a high proportion (44–84%) of bleached colonies was found throughout the months when turbidity decreased. Siderastrea is the only reef-building coral that comprises this seascape with encrusting and low-relief colonies. During drought periods, cloudiness is reduced, turbidity and wind speed are reduced, and solar irradiance increase, driving coral bleaching in turbid reefs. However, episodic rainfall and higher wind speeds increase turbidity and decrease coral bleaching. Our hypothesis is that turbidity decreases during drought periods which increases bleaching risk to corals even without thermal stress. Our results suggest that turbidity may have related to wind and rainfall to provoke the coral bleaching phenomenon.

Unveiling the hidden threat of microplastics to coral reefs in remote South Atlantic islands

The widespread presence of marine microplastics (< 5 mm) is a significant concern, as it may harm marine biodiversity and ocean ecosystems. Corals' capacity to ingest microplastics has emerged as a significant threat to reef ecosystems, owing to the detrimental physiological and ecological effects it can trigger. The extent of the impact of microplastics on Brazilian corals remains unclear and this study aimed to investigate its distribution and characteristics in four coral species: Favia gravida, Mussismilia hispida, Montastrea cavernosa, and Siderastrea stellata, found in the Trindade and Martim Vaz Islands – the most isolated archipelago of Brazil, located about 1200 km (680 miles) east of the coast. This study aims to reveal the extent of microplastic distribution in the coral reef environment, assess the amount of microplastics in different coral species, and compare each species' capacity to adhere and accumulate microplastics. A high concentration of ingested and adhered microplastics was detected in all coral species evaluated in the present study. No significant differences were observed in the sampling points which indicates that although the sampling points are located at different distances from the coast, the microplastic pollution is equally distributed in the region. Polyethylene (PE), polyvinyl chloride (PVC), polypropylene (PP), poly(methyl methacrylate) (PMMA), Rayon, and Nylon particles were detected, with a predominance of PE (45.5 %). No significant differences in microplastic concentration were detected among the various species and locations studied. Our research presents findings that demonstrate the extensive occurrence of microplastic contamination in coral colonies located on remote islands.

Photobiology of Symbiodiniaceae hosted on Siderastrea stellata in the southwestern Atlantic

The health of the coral species Siderastrea stellata was investigated as an indicator of climate changes impacts at the Fernando de Noronha Marine National Park, southwestern Atlantic Ocean. Chlorophyll a maximum quantum yield and Rapid Light Curves (RLCs) were produced using a red-light pulse amplitude modulated fluorometer, Mini-PAM in S. stellata colonies. We collected genetic material from the same colonies in order to identify Symbiodineaceae hosted in each of them, considering that the colonies showed very different pigmentations between them. Our findings showed that colonies with pink pigmentation may be associated with higher temperatures, while indicating a high saturation point (Ek) and consequent greater efficiency in the dissipation of radiant energy. Our genetic analysis also demonstrated a high fidelity in association with Cladocopium spp. predominantly. Despite this, we hypothesized that this association may be the result of changes in populations of Breviolum spp. due to stressful events.

Heatwaves and a decrease in turbidity drive coral bleaching in Atlantic marginal equatorial reefs

Tropical reefs can occur naturally under suboptimal environmental conditions, where few reef-building corals thrive. These unique reefs are especially important for understanding resistance to global warming, but they are understudied. We studied a coral bleaching event that occurred in turbid reefs (~ 19 m deep) in the equatorial southwestern Atlantic. Mass bleaching was observed in 91% of the Siderastrea stellata colonies in 2020, whereas only 7.7% of the colonies were bleached in 2019 and 10.9% in 2022. The year 2020 had the highest heat stress recorded in this century in this region according to the degree of heating weeks such as 17.6°C-week. In the first semester of 2020, the region also underwent three marine heatwaves (MHWs) above the average temperatures (1.3, 1.5, and 2.0°C). The lowest turbidity and wind speed matched long-lasting, repeated, and severe MHWs. These reef-building corals are dominant under moderate turbid waters and high sea temperature (26–29°C), however they are near the maximum tolerance limit. In this regard, these low-latitude reefs are warming twice as fast (0.2°C/decade) as other regions (e.g., Abrolhos and Coral Coast) (0.1 to 0.13°C/decade) in the South America reef system demonstrating that they cannot be considered climate-change refugia. These results suggest that even turbid marginal reefs and tolerant corals are highly susceptible to mass bleaching, especially when heatwaves and a decrease in turbidity occur simultaneously.

Intake of trace contaminants by corals in Abrolhos reef bank (western South Atlantic) during two decades of coastal impacts

Abrolhos is the largest and most diverse coral reef system in the South Atlantic. It is home to several endemic coral species and a site of cetaceous reproduction. Like any other reef ecosystem worldwide, it experiences multiple disturbances associated with increasing sea surface temperatures, El Niño events, and, most recently, oil spill pollution. In addition to these global stressors, the Abrolhos region may have been impacted by coastal human interventions, a large-scale mining disaster, floods, and extra-tropical cyclones that affected the region during the last 20 years. Among these stressors, the Fundão dam collapse (the largest in the Southern Hemisphere) deserves special attention since it delivered significant amounts of iron tailings to the nearby coast. To investigate the region's recent history, we collected, dated, and performed detailed geochemical and isotopic analyses on two coral colonies (i.e., Siderastrea stellata and Mussismilia harttii), in order to determine if effects of recent human activity on reef systems (and most recent natural impacts) could be detected thorough bioaccumulation of metals in their skeletons. In this context, we detected an abrupt increase in Fe and Mn concentrations in the coral skeleton, which are among the main constituents of the Fundão dam tailings. We show that a concomitant increase in metal concentrations tracks contaminant dispersion of the Fundão dam tailings released to the western South Atlantic. Besides this event, our data also show that coastal dredging activities in the nearby coral reef site (i.e., at the Tomba channel) and two natural episodes (i.e., the flood of 2013 and the anomalous extra-tropical cyclonic activity in 2008) were also recorded in the coral skeleton based on changes in Rare Earth Elements distribution, Rb and U concentrations.

Marine animal forests in turbid environments are overlooked seascapes in urban areas

Marginal reefs can provide meaningful information about the structure and dynamics of ecosystems under suboptimal environmental conditions. In addition to their different characteristics, these environments can also occur in urbanized areas. In this note, we characterize marine animal forests (MAFs) on turbid-zone reefs on an urban coast in the equatorial southwestern Atlantic. Overall, the sandstone ferruginous reefs (6-10 m depth) exhibited a flat topography and gentle slope (1-2 m above the seabed). Benthic cover is composed mainly of sponge gardens and ascidians. In addition, we found a low-relief coral carpet with only one massive reef-building coral (Siderastrea stellata) and Zoantharia. The ascidians and sponges had a higher diversity (at least 15 species) than the cnidarians (two species) in these forests. The main animals forming this seascape are weedy and stress-tolerant species adapted to challenging environmental conditions, such as swell waves, mesotidal regimes, moderate turbidity waters, and periodic burial. In this regard, these conditions and human impacts have shaped a unique MAF. Remarkably, the studied formations seem similar to high-latitude marginal reefs or low-latitude reefs under the influence of upwelling, which sustains soft corals and non-framework building coral communities along with sponges and ascidians. In particular, the shallow MAFs along the semi-arid coast of Brazil seem to lack some of the characteristics of low-latitude reefs under high sedimentation, whose structure was described as coral rubble within sedimentary matrices. This suggests that factors other than periodic burials and low light availability affected these MAFs. These overlooked forests are widespread in this area and have been neglected in studies, despite their richness (> 31 taxa) and valuable ecosystem goods and services. In the context of urbanized areas subject to climate change and pollution impacts, jetties, and dredging activities, it is necessary to consider these lush forests in impact assessments and conservation policies.

Microbiota of healthy and bleached corals of the species Siderastrea stellata in response to river influx and seasonality in Brazilian northeast.

Although coral bleaching is increasing worldwide due to warming oceans exacerbated by climate change, there has been a growing recognition that local stressors may play an additional role. Important stressors include the physicochemical and microbiological influences that are related to river runoff. Here, we investigated the microbiota associated to mucus and tissue of endemic coral Siderastrea stellata, collected from Brazilian northeast coral reefs of Barra de Santo Antônio (subject to river runoff) and Maragogi (minimal river runoff) during both the rainy and dry seasons. We sequenced the V4 region of 16S rDNA and used multiple R packages to process raw data and performed statistical analysis to reveal the microbial community structure composition and functional predictions. Major dissimilarities between microbial communities were related to seasonality, while healthy and bleached specimens were mainly associated with the enrichment of several less abundant taxa involved in specific metabolic functions, mainly related to the nitrogen cycle. We were not able to observe the dominance of groups that has been previously associated with bleachings, such as Vibrionaceae or Burkholderiaceae. The influx of freshwater appears to increase the homogeneity between individuals in Barra de Santo Antonio, especially during the rainy season. By contrast, we observed an increased homogeneity between samples in Maragogi during the dry season. Understanding the dynamics of the coral microbiota and how bleaching appears in response to specific environmental variables, in addition to determining the conditions that lead to a more robust coral microbiota, is essential for choosing the most appropriate area and conservation methods, for example.

Prevalence and extent of coral diseases in shallow and mesophotic reefs of the Southwestern Atlantic

Coral reef ecology has advanced in many fields, but disease patterns across depth gradients remain unclear. By comparing the prevalence and extent of bleaching and diseases in 160 colonies of Siderastrea stellata between shallow and mesophotic reefs, we observed that prevalence was high (75%) regardless of depth, but the extent was about two times greater in mesophotic than shallow reefs (14.4% vs. 6.6% of colony area, respectively). Across the shallow reefs, where S. stellata co-occurred with Montastraea cavernosa, M. cavernosa showed lower prevalence (27% of 30 colonies) and extent (1.8% of colony area) compared to S. stellata. Besides bleaching, five coral diseases afflicted S. stellata and two affected M. cavernosa. Because diseases are spread over the entire gradient of depth, any attempt of managing the diseases should consider both shallow and deep reefs to be effective.

Mid to late 20th century freshening of the western tropical South Atlantic triggered by southward migration of the Intertropical Convergence Zone

In the tropical Atlantic Ocean, the Intertropical Convergence Zone (ITCZ) is an important climate feature controlled by the interhemispheric sea surface temperature (SST) gradient, and greatly influences rainfall patterns over the adjacent continents. To better understand ITCZ dynamics in the context of past and future climate change, long-term oceanic records are needed, but observational data are limited in temporal extent. Shallow-water corals provide seasonally-resolved archives of climate variability over the tropical ocean. Here we present seasonally-resolved records of stable oxygen (δ18O) and carbon (δ13C) isotope values of a Siderastrea stellata coral from northeastern Brazil (Maracajaú, ~5°S). We show that the long-term trends in the record of coral δ18O values are not primarily driven by SST but by hydrological changes at the sea surface. Combining the record of coral δ18O values with instrumental SST, we present the first reconstruction of seawater δ18O changes (δ18Oseawater) in the western tropical South Atlantic back to the early 20th century, a parameter that is related to changes in sea surface salinity. The reconstructed δ18Oseawater changes indicate a prominent freshening between the mid-1940's and mid-1970's, which coincides with a weakening of the Atlantic interhemispheric SST gradient during this time interval. Our results suggest that the weakened Atlantic SST gradient resulted in a southward shift of the thermal equator that was accompanied by a southward migration of the ITCZ, resulting in freshening of the western tropical South Atlantic during the mid to late 20th century.

CORAL DISEASES IN NORTHEASTERN BRAZILIAN REEFS

In the last decade, corals from northeastern Brazil have experienced bleaching events linked to thermal anomalies, the consequences of which have been the appearance of disease outbreaks affecting different species. As a way to explain and monitoring diseases progression and other characteristics regarding the identification in the field for coral diseases, this article aimed to demonstrate the particularities that follows each diseases symptom. This study presents the results of an assessment of the presence of coral diseases on six coastal reefs in northeastern Brazil, including marine protected areas. After 300 hours of visual censuses, a total of 875 colonies were observed; of these, 114 colonies had some disease, representing 13.02% of the colonies analyzed. Five diseases/syndromes were recorded in four host coral species: white syndrome, white plague, red band, dark spots, and white band. This is the first record of white band on the Brazilian coast. The massive coral Siderastrea stellata showed colonies with all registered diseases, which arouses great concern for conservation of the Brazilian coast.

Oil Spill Disaster in Southwest Atlantic Coast: an Evaluation of Short-Term Effects on Coral Reef Benthic Assemblages

Oil pollution has significantly contributed to coral reef decline in the last five decades and a major oil spill reached Brazilian tropical coast in August 2019. Here, we report the first evidence of direct crude oil contact from that spill on reef coral species, and evaluate the effects of this disaster on coral vitality and benthic assemblage structure on the largest coastal marine protected area (MPA Costa dos Corais) in Brazil. We compared benthic cover in reefs with and without oil and monitored Siderastrea stellata colonies 90 days after oil contact. Oil stains between 0.5 and 150 cm were found in two of the 17 reef sites investigated. Multivariate analyses did not detect significant differences between oiled and non-oiled reefs and there was no evidence of S. stellata health deterioration. These results indicate minimal acute effects on coral vitality and intertidal reef benthic assemblage structure. Future studies should investigate oil effects on specific aspects of coral biology as growth, reproduction, bleaching susceptibility and metagenomics which can deteriorate over longer time frames, and we recommend long-term coral reef monitoring to support a robust assessment and mitigation of chronic oil impacts.

An urban intertidal reef is dominated by fleshy macroalgae, sediment, and bleaching of a resilient coral (Siderastrea stellata)

We provide a baseline assessment of benthic cover, salinity, temperature, and bleaching in an urban intertidal reef. The cover is composed of a weedy coral (Siderastrea stellata), algae, and sand sediments. Fleshy macroalgae provided the most of the cover (23% to 43%), followed by coral (16% to 24%), and sediment (6% to 19%). Most of the tidal pools presented high algae cover with seasonal differences; whereas, the coral and sediment cover did not differ significantly over time. The bleached colonies ranged from 6% (November) to 76% (March) over the months according to the stress levels (warming and runoff). Temperature (30.3 to 33.5 °C), and salinity (35.2 to 43.2) characterized an extreme reef habitat. S. stellata resistance to chronic and acute stress makes it a bioindicator of environmental stress. The results highlight those marginal reefs may be simplified habitats, composed of monospecific coral populations and morphogically-simple macroalgae adapted to current pressures but its long-term survival is unlikely due to climate change.

SCREENING OF BACILLUS SP. ISOLATED FROM CORAL SIDERASTREA STELLATA FOR ANTIMICROBIAL ACTIVITY AGAINST ENTEROPATHOGENIC STRAINS OF SALMONELLA AND ESCHERICHIA COLI / SCREENING DE BACILLUS SP. ISOLADOS DO CORAL SIDERASTREA STELLATA PARA ATIVIDADE ANTIMICROBIANA CONTRA LINHAGENS ENTEROPATOGÊNICAS DE SALMONELLA E ESCHERICHIA COLI

Siderastrea stellata is a coral endemic to Brazilian waters and is widely distributed throughout the coast of Bahia state. Exposure of the coral to pathogens stimulates the production of important enzymes by associated symbiont microorganisms. Besides being natural sources of bioactive compounds, these microorganisms possess characteristics that help them survive under extreme conditions. Sixty-eight bacterial strains isolated from the S. stellata coral were analyzed for antimicrobial activity against ten pathogenic bacteria. The cultivation of marine isolates was carried out in liquid or solid seawater. Eight isolates produced antimicrobial compounds against at least two of the ten pathogenic bacteria tested. When isolates were grown in Mueller-Hinton broth, a distinct biocidal spectrum was observed, indicating that the culture medium directly influences the production of antimicrobial compounds. Through molecular characterization of activity-positive isolates, they were identified as belonging to the genus Bacillus . The bioactive compounds produced by the Bacillus stratosphericus SS85 and SS69 strains were stable after storage time for three months. This is the first paper reporting on the antimicrobial activity of microorganisms isolated from coral Siderastrea stellata .

Histopatological effects of bleaching and disease on the coral Siderastrea stellata from coastal reefs of Brazil

ABSTRACT Histological analysis of bleached samples of Siderastrea stellata Verrill, 1868, with white plague disease and with alteration in the color pattern, revealed drastic tissue and cellular disturbances, such as lysis of the external epithelium, hyperplasia of gastrodermis, apoptosis of epithelial cells and zooxanthellae, and degradation of mesenteric filaments and reproductive cells. Fungal hyphae, diatoms, and cyanobacteria were present in diseased samples and colonies with alteration in the color pattern. Furthermore, bleached and diseased samples showed significant reductions in the number of zooxanthellae per 100 µm2 of gastrodermis and significant reductions in the diameters and volumes of stage V oocytes. We found that bleaching events, diseases, and colonies with alteration in the color pattern promoted degradation of reproductive cells, resulting in the consequent interruption of the reproduction of the coral S. stellata, which is one of the most common Brazilian coral species. The implications of these indirect effects of bleaching, disease, and changes in coral color patterns in the population dynamics of Brazilian reefs are discussed.

Coral recovery after a burial event: insights on coral resilience in a marginal reef

Scleractinian reef-building corals can lose their endosymbiotic photosynthetic dinoflagelates (Symbiodiniaceae) and bleach in response to drastic changes in environmental conditions, such as extreme temperature fluctuations and burial events. As bleaching episodes are becoming more frequent and intense worldwide, post-bleaching recovery is critical for coral resilience. We report an in situ experiment in which a previously monitored colony of the coral Siderastrea stellata was found detached, overturned, buried, and bleached (95% of its surface). We reattached the coral to the reef and documented its recovery during 6 months by quantifying its surface area and health condition using 3D models derived from structure-from-motion photogametry of videos obtained in the field. The coral showed the first signs of recovery from a bright-white bleached state within 2 days and fully recovered to a healthy-like state in roughly 1 month, demonstrating that the endosymbiotic algal community recovered fast. Understanding the mechanisms of this fast recovery in marginal reefs in which post-bleaching mortality of dominant reef-building corals like S. stellata is relatively low (< 10%) may provide insights on how reef-building corals will cope with future climate change.

Benthic Cnidaria community in the oceanic archipelago of Trindade and Martin Vaz, Southwestern Atlantic Ocean

Based on literature review, recent surveys, and specimens’ identification, we examined benthic cnidarian species richness across the oceanic Trindade and Martin Vaz Archipelago (TMA), Southwestern Atlantic Ocean. A total of 37 species (three Hydrozoa and 34 Anthozoa) are reported, including seven new records. The zooxanthellate scleractinian corals Montastraea cavernosa, Mussismilia hispida, Mussismilia leptophylla and Siderastrea stellata were the most commonly found species, while some species, such as the azooxanthellate coral Polycyahtus sp., were only found at one site. Although Martin Vaz Island has a lower diversity (11 species) compared to Trindade Island (37 species), fewer studies have been conducted in the former. Likewise, research in the TMA has focused on shallow water communities (<40 m depth), and comprehensive surveys of benthic Cnidaria species of mesophotic and deeper water habitats are needed. All data presented herein are discussed in the light of species ecology and distributional patterns and we also report tissue necrosis in some Octocorallia colonies.

Thermal stress and tropical reefs: mass coral bleaching in a stable temperature environment?

This study reports on the deepest records (~ 24 m depth) of coral bleaching in a naturally temperature-stable environment (> 26 °C with an intra-annual variability of ~ 2 °C), which was recorded during a mass bleaching event in the locally dominant, massive scleractinian coral Siderastrea stellata in equatorial waters of Brazil (SW Atlantic). An inter-annual analysis (2002–2017) indicated that this bleaching event was related to anomalies in sea surface temperature (SST) that led to the warmest year (2010) in this century (1 to 1.7 °C above average). Such anomalies caused heat stress (28.5–29.5 °C) in this equatorial environment that resulted in a bleaching event. Our results suggest that the increase in SST, low turbidity, and weak winds may have acted together to affect these stress-tolerant corals in marginal reefs. The equatorial coastline of Brazil is characterized by low intra-annual and inter-annual variations in SST, which suggests that the S. stellata corals here may be acclimatized to these stable conditions and, consequently, have a lower bleaching threshold because of lower historical heat stress.

Stress factors in the photobiology of the reef coral Siderastrea stellata

The coral species Siderastrea stellata Verril 1868 is endemic and common in Brazil. This species is a colonial, massive, zooxanthellate coral and one of the most important reef builders in many reef areas. The photosynthetic symbionts are very sensitive to environmental variations, such as sedimentation and temperature variations, which can disturb the complex interaction between the animal host and endosymbiont. In this study, we simulated the conditions found in the field in a series of experiments that evaluated chlorophyll a fluorescence emissions. Chlorophyll a maximum quantum yield and Rapid Light Curves (RLCs) were generated using a red light pulse amplitude modulated fluorometer, Mini-PAM, in S. stellata colonies under different irradiance, temperature and burial levels. Moreover, the PSII fluorescence yield was tested using a chlorophyll a fluorescence spatial detection method, which was implemented for the first time using an imaging system for S. stellata coral species. S. stellata showed great adaptive capacity under different light regimes between 50 and 160 μmol photons m-2 s-1. When a moderate burial level factor was analyzed synergistically with temperatures below 18 °C, we observed resilient colonies. However, at critical burial levels and high temperatures (28 °C) after 10 days, lower maximum quantum yields of PSII chlorophyll a fluorescence were detected, exhibiting an abrupt decrease after 96 h of burial. Continuous evaluations of coral environments and a strong understanding coral ecophysiology are extremely important for the establishment of minimum health risk levels for coral reef environments and coastal management measures. We conclude that ecophysiological aspects are highly specific and should be evaluated according to the preconditions of organism acclimatization. The chlorophyll a fluorescence imaging technique was shown to be an efficient tool for evaluating the physiologic status of zooxanthellae over the surface of a coral such as S. stellata. In turn, the photobiology results indicated the life history of this species in the upwelling waters of the region, as this species had higher Fv/Fm values at lower temperatures and intermediary burial conditions than at higher temperatures.

Effects of turbidity and depth on the bioconstruction of the Abrolhos reefs

Turbidity increase is one of the main stressors to coral reefs. It affects light availability and will act together with global sea level rise to reduce potential photosynthesis that is important to light-enhanced calcification in corals. Corals are the main contributors to the morphological complexity of reefs through skeletal calcification. Bioconstruction by corals is a multifactorial process that is controlled by physical (e.g., irradiance and turbidity) and biological factors such as photoacclimation process. In this paper, we intend to show how turbidity and photobiology might interplay to produce a coral species distribution that controls reef growth and structural complexity. The Abrolhos complex is composed by a group of reefs closer to the coastline characterized by a high light attenuation value (Kd490 = 0.11), and another one about 60 km far from the coast characterized by a light attenuation coefficient of Kd490 = 0.08. In these reefs, different coral communities produce bioconstruction potential accordingly. We used data collected for 7 yrs, with the AGRRA (Atlantic and Gulf rapid reef assessment) Protocol. Coral species cover and distribution data were used to estimate reef bioconstruction [sensu Done (1995)] rates. A field experiment examined the metabolic function of five species (Mussismilia braziliensis, Mussismilia hispida, Mussismilia harttii, Montastraea cavernosa and Siderastrea stellata) through respirometry and rapid light curves (RLC). Bioconstruction potential and primary gross productivity demonstrated a substantial variability between reefs and species. In combination, these functional responses meant that coral species distribution is controlled by local factors and acclimation process. Therefore, our results suggest that these functional responses are useful tools to understand photoacclimation process and its consequences, species distribution and the space occupation on Abrolhos bank. We highlight the deleterious effect of turbidity in bioconstruction. This suggests that the local processes that increase sediment runoff is an immediate impact and must be controlled.

Limited potential of deep reefs to serve as refuges for tropical Southwestern Atlantic corals

AbstractThe deep reef refuge hypothesis (DRRH) predicts that deep coral reefs may act as refuges against major disturbances affecting shallow reefs, but to date, a few studies have explicitly examined its validity at the community level. We sampled 19 Brazilian reefs distributed between 3 and 61 m depth and tested five DRRH predictions regarding species diversity, distribution, and functional profile of communities. The first prediction was that deep reefs (&gt;30 m depth) should host greater gamma diversity to be able to export species to shallow reefs (&lt;30 m). Second, depth‐generalist species should dominate the shallow reefs; otherwise, local extirpation in shallow areas could not be reverted by the deep reefs. Third, alpha diversity should be greater in deep reefs due to reduced anthropogenic pressure in deeper areas. Fourth, beta diversity should be smaller among shallow than deep reefs due to the human‐induced spread of a few disturbance‐adapted species near sea surface. Finally, the functional composition of shallow reefs should be a subset from that of deep reefs to allow functional recovering of shallower areas. Contrary to expectations, coral communities presented twice more gamma diversity in shallow than deep reefs (13 vs. seven effective species) and only three out of 17 species occurred along the entire gradient. Additionally, the alpha diversity of rare, typical, and dominant species was similar between shallow and deep reefs, and the beta diversity of rare and typical species was about 50% greater in shallow than deep reefs. Supporting the DRRH, coral communities of both reefs were dominated by reef‐building, zooxanthellated, gonochoric corals with brooding or broadcast reproductive mode (Siderastrea stellata and Montastraea cavernosa). However, soft corals were observed only in shallow reefs and azooxanthellated corals were recorded only in deep reefs. These findings revealed a limited potential of deep reefs to serve as refuges for Southwestern Atlantic coral communities, though they may work for two depth‐generalist dominant species. We strongly recommend preventing human disturbances at any depth and including both shallow and deep reefs in regional conservation actions.