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Although reef corals worldwide have sustained epizootics in recent years, no coral diseases have been observed in the southwestern Atlantic Ocean until now. Here we present an overview of the main types of diseases and their incidence in the largest and richest coral reefs in the South Atlantic (Abrolhos Bank, eastern Brazil). Qualitative observations since the 1980s and regular monitoring since 2001 indicate that coral diseases intensified only recently (2005–2007). Based on estimates of disease prevalence and progression rate, as well as on the growth rate of a major reef-building coral species (the Brazilian-endemic Mussismilia braziliensis), we predict that eastern Brazilian reefs will suffer a massive coral cover decline in the next 50 years, and that M. braziliensis will be nearly extinct in less than a century if the current rate of mortality due to disease is not reversed. [Copyright &y& Elsevier]

Rhodolith beds are known worldwide to host high biodiversity to several taxa. Despite their importance, few ecological data explored the influence of rhodolith features and environmental variables on associated biodiversity, a gap that has been hampering the mapping of diversity hotspots and priority areas for conservation. In this study, we investigated large-scale spatial variations of rhodolith beds and their associated fauna, using annelid polychaetes as a biological model. We aimed to identify proxies, based on rhodolith features and environmental variables, to detect biodiversity hotspots across Southwestern Atlantic beds, laying the groundwork for mapping priority areas for conservation. With this goal, we sampled a total of 136 rhodolith nodules across seven sites with beds under distinct latitudes, depths, distances from the mainland coast of Brazil, and rhodolith densities. For each nodule sampled, we measured the volume, diameter, and mass of sediment trapped, as well as the attributes of the associated polychaetes (abundance, richness, diversity, and composition). Our results revealed a complex network of collinearities and synergisms between the rhodolith features and the majority of the polychaetes attributes (i.e., abundance, diversity, and composition). Polychaete richness, in contrast, can be explained by the combination of two proxies: (1) rhodolith nodule diameter and (2) distance of the rhodolith bed from the mainland coast. Nearshore rhodolith beds and larger nodules were associated with higher values of richness. Additionally, rhodoliths with a hollow morphology were also associated with higher values of polychaete richness. These results suggest that nearshore rhodolith beds with large and hollow nodules could be priority areas for conservation. However, further multi-taxa studies using our framework are still needed to explore other regions and scales, delineating more comprehensive proxies for predicting ecological patterns of the rhodoliths associated fauna and to identify priorities for conservation across Southwestern Atlantic beds. • Rhodolith beds in Southwestern Atlantic globally recognized for high biodiversity. • Polychaetes were used to identify proxies for detecting biodiversity hotspots. • Species richness is linked to rhodolith nodule diameter and distance from mainland coast. • Rhodolith beds with large, hollow nodules and close to the mainland coast, may be priority areas for conservation. [ABSTRACT FROM AUTHOR]

The existence of a reef system composed by crustose coralline algae and scleractinian corals, under the influence of the world's largest freshwater plume, led us to investigate how much light is available for reef-building organisms at the bottom of the Amazon shelf. We analyzed ocean color data from MODIS Aqua to assess the plume dynamics and estimate the benthic light availability over the Amazon shelf. These methods may be applied to other river-dominated shelves. Four zones were detected regarding the bottom light regime. The seasonal changes of the dynamic forcing over the shelf reflect little in the light parameters over the Amazon shelf. Three zones presented constant light regimes along the year: dark coastal zone under the permanent influence of the plume; dim-light zone in the deeper northern shelf; and high-light zone in the shallower southern shelf. Only one zone presented a seasonally changing benthic light regime, and it was located under the seasonally variable edge of the plume over the northern mid-to-outer shelf. The minimum light level estimated in the deeper dim-light zone was ∼2 μE m−2 s−1 which is sufficient for reef-building organisms to thrive. The cause of the incipient living coverage and low vitality of crustose coralline algae, previously reported in the northern shelf, cannot be attributed to a lack of light, but might be related to sedimentation processes associated to the plume. Thus, the potential, in terms of light, for reef builders to develop along this and other river-influenced margins is much greater than previously anticipated. • Seasonally-displacing plume edge in northern shelf receives varying benthic light. • Dark benthic light zone is under plume and confined to mid and inner northern shelf. • Dim light regime under clear oceanic water in deep outer and edge of northern shelf. • Southern shelf with high light regime due to shallow shelf and clear oceanic waters. • Benthic light in Amazon shelf enough for reef-builders to thrive along the year. [ABSTRACT FROM AUTHOR]

Southwestern Atlantic reefs (Brazilian Province) occur along a broad latitudinal range (∼5°N-27°S) and under varied environmental conditions. We combined large-scale benthic cover and environmental data into uni- and multivariate regression tree analyses to identify unique shallow (<30 m) benthic reef communities and their environmental drivers along the Brazilian Province. Turbidity was the leading environmental driver of benthic reef communities, with the occurrence of two main groups: clear-water (dominated by fleshy macroalgae) and turbid (dominated by turf algae). Seven out of 14 scleractinian coral species were more abundant in the turbid group, thus corroborating the photophobic nature of some Brazilian corals. The most abundant scleractinian in Brazil (Montastraea cavernosa), largely dominated (71–93% of total coral cover) both, the shallow turbid and deeper clear-water reefs. Because these habitat types are widely recognized as potential climate refuges, local threats (e.g. pollution, overfishing) should be averted. [Display omitted] • Two groups of benthic reef communities occur in SW Atlantic: clear-water and turbid. • Fleshy algae dominate clear-water communities and turf algae dominate turbid ones. • Depth further split clear-water communities and distance offshore split turbid ones. • Extensive Montastraea reefs prevail on shallow turbid and deeper clear-water reefs. [ABSTRACT FROM AUTHOR]

Abstract: We performed a biological survey in the novel system of sinkhole-like structures (“buracas”) of the Abrolhos Bank, Brazil. We found dissimilar benthic assemblages and higher nutrient concentration, microbial abundance (and activity) and fish abundance inside the buracas than in the surrounding rhodolith beds. Our results support the view that these cup-shaped structures trap and accumulate organic matter, functioning as productivity hotspots in the mid and outer shelf of the central portion of the Abrolhos Bank shelf, where they aggregate biomass of commercially important fishes. This distinctive system is being increasingly pressured by commercial fisheries and needs urgent management measures such as fishing effort control and representation in the network of Marine Protected Areas (MPAS). [Copyright &y& Elsevier]

Abstract: The diversity of bacterial communities associated with three Brazilian endemic reef corals from genus Mussismilia (M. hispida, M. braziliensis, and M. harttii) at a single site was assessed using 16S rRNA clone libraries. The study site, Pedra do Leste, is a coastal reef within the largest and richest South Atlantic coralline reef complex (Abrolhos Bank) and is subject to high fishing pressure, high sedimentation loads, and other land-based stressors. The three coral species are Neogene relicts with unique biological and morphological traits that enable them to survive relatively high sedimentation levels. Our results show that sequences affiliated with γ-Proteobacteria predominated, accounting for more than 60% of the examined sequences. Indeed, the most frequent species were related to Alteromonas, Marinomonas, Neptuniibacter, and Vibrio, which are copiotrophic microorganisms common in environments highly affected by anthropogenic stress. Principal component analysis revealed that bacterial communities of M. braziliensis and M. hispida were more similar to each other than to M. harttii-associated bacteria. Such pattern is likely related to distinct morphological properties of M. harttii, such as the existence of phaceloid colonies, in which polyps are not connected by soft tissue. This is the first investigation assessing the bacterial communities of the three Brazilian endemic Mussismilia species at the same location. [Copyright &y& Elsevier]

Novel and unusual sinkhole-like features are described for the Abrolhos Bank continental shelf, eastern Brazil, based on geophysical and geological assessments. These unusual structures are large cup-shaped depressions similar to sink/blueholes (10–75m in diameter, 8–39m in height), occurring in a consolidated carbonate substrate in the mid and outer shelf. A total of 36 such features, locally named buracas, were found between 41 and 161km off the coast and between 24 and 65m depth (the bottom of these features may be as deep as 93m). The buracas’ walls are mainly composed of encrusting coralline algae. Radiocarbon dating has provided ages of 5400±90yr Cal BP, 8630±90yr Cal BP and 39,200±400yr BP. Besides providing a comprehensive description of these novel structures within the mesophotic zone, the potential mechanisms by which these sinkhole-like structures originated are discussed here, as well as the possible active mechanisms impeding their filling with sediments and biogenic material. We hypothesize that their origin could be related to either typical sinkhole formation during subaerial exposure or to a partially Holocene growth pattern influenced by antecedent morphology and gas/fluid escaping due to organic matter decomposition. The buracas are relevant not only because they comprise outstanding novel features, but also because they are relevant targets for marine conservation, as they enhance productivity and aggregate biomass in a region under growing fishing pressure. [ABSTRACT FROM AUTHOR]