Spatial and temporal dynamics of the abundance of crustose calcareous algae on the southernmost coral reefs of the western Atlantic (Abrolhos Bank, Brazil)

Crustose calcareous algae (CCA) constitute one of the main reef builders on the Abrolhos Bank, Brazil. Once CCA taxonomy is locally understood, differences in growth-forms may be useful for the delimitation of taxa using characteristics such as the presence or absence of surface protuberances. Here, growth-forms were used to identify and quantify the most common CCA taxa on the shallow reefs (3-10 m) of the Abrolhos Bank to determine possible changes in the CCA community over a period of 10 years, and the ecological significance of CCA to local reefs was interpreted. The CCA assemblages were surveyed from 2006-2015 by using fixed photoquadrats at four sites in the inner (10-20 km from the mainland) and mid-shelf reefs (40-75 km from the mainland). The five most common CCA taxa were Pneophyllum conicum, the Lithophyllum kaiserii / Lithophyllum sp. complex, Melyvonnea erubescens, the Hydrolithon boergesenii / Porolithon onkodes complex and Peyssonelia sp. The overall mean CCA cover on the reefs was 20%. A comparison with a previous monitoring study in the same region indicated that the CCA cover nearly doubled from 2003-2008 to 2006-2015. This study reveals that the coral-killing species P. conicum dominated CCA flora on the shallow Abrolhos reefs in the last decade, and the local specific abundance of CCA slightly fluctuated over time and was species-and site-specific. The information obtained in this study contributes to the understanding of the ecology of the key calcifying components of the Abrolhos reefs and provides a useful baseline for exploring the responses of CCA to future environmental changes.PELDMudancas Climaticas scientific programmes of the Brazilian National Science Agency (CNPq)Brazilian IODP Program (CAPES/MEC)P&D Program ANP/BrasoilFAPERJDiretoria Pesquisa Cient, Inst Pesquisas, Jardim Bot Rio De Janeiro, Rua Pacheco Leao 915, BR-22460030 Rio De Janeiro, RJ, BrazilUniv Fed Rio de Janeiro, Inst Biol, BR-21941599 Rio De Janeiro, RJ, BrazilUniv Fed Espirito Santo, Dept Oceanog, Ave Fernando Ferrari 514, BR-29090600 Vitoria, ES, BrazilUniv Fed Sao Paulo, Inst Mar, Campus Baixada Santista, BR-11030400 Santos, SP, BrazilUniv Fed Paraiba, Ctr Ciencias Aplicadas & Educ, Campus 4 Litoral Norte, BR-58297000 Rio Tinto, PB, BrazilUniv Fed Sao Paulo, Inst Mar, Campus Baixada Santista, BR-11030400 Santos, SP, BrazilANP/Brasoil: 48610.011015/2014-55Web of Scienc

Reef fish and benthic assemblages of the Trindade and Martin Vaz Island group, southwestern Atlantic

O conjunto insular de Trindade e Martin Vaz (CITMV) está localizado a aproximadamente 1.120 km da costa brasileira. Apesar de sua importância, salientada pela presença de diversas espécies endêmicas de peixes, não existem informações detalhadas sobre as assembléias de peixes e bentos do CITMV. É apresentada aqui a primeira caracterização quantitativa das assembléias de peixes e bentos do CITMV em um gradiente de profundidade entre 5 e 45 m. Informações qualitativas adicionais sobre assembléias recifais entre 45 e 100 m foram obtidas utilizando-se técnicas avançadas de mergulho (TRIMIX) e um veículo de operação remota (VOR). Assim como outras ilhas oceânicas brasileiras, a CITMV possui assembléias depauperadas de peixes e bentos, possivelmente devido ao seu isolamento e pequeno tamanho em comparação ao continente. A profundidade foi o fator que mais afetou a estrutura das assembléias de peixes, com a densidade da maioria das espécies declinando com o aumento da profundidade. Os recifes profundos (>; 45 m) foram caracterizados pela presença de bancos extensivos de rodolitos e recifes rochosos esparsamente cobertos por algas coralináceas incrustantes, corais negros (Cirripathes sp.) e alguns corais massivos e em de forma de placa. Peixes parcialmente ou obrigatoriamente planctívoros (e.g. Cephalopholis furcifer and Clepticus brasiliensis) também dominaram em recifes profundos. Características similares foram registradas para recifes mesofóticos ao longo do Atlântico Ocidental. Evidências de sobrepesca (obtidas aqui e em outros estudos recentes), a presença de quatro espécies de peixes endêmicas e com distribuição restrita, e o aumento no número de espécies novas ainda não descritas, indicam que a adoção de medidas de conservação baseadas no princípio da precaução é urgentemente necessária para garantir a manutenção dos ecossistemas frágeis e únicos do CITMV.The Trindade and Martin Vaz island group (TMVIG) is located at about 1,120 km off the Brazilian coast. Despite its importance, highlighted by the presence of several endemic fish species, the TMVIG lacks detailed information on the structure of fish and benthic assemblages. Presented here is the first quantitative assessment of reef fish and benthic assemblages of the TMVIG in a depth gradient ranging from 5 to 45 m. Additional qualitative information on reef assemblages between 45 and 100 m was obtained using advanced gas diving techniques (TRIMIX) and a remotely operated vehicle (ROV). Similarly to other Brazilian oceanic islands, the TMVIG possesses depauperated fish and benthic assemblages, possibly due to its isolation and small size in comparison to the mainland. Depth was the most important factor affecting the structure of fish assemblages, with the density of most fish species declining with depth. Deep reefs (>; 45 m) were characterized by the presence of extensive rhodolith beds and rocky reefs sparsely covered with crustose coralline algae, black coral (Cirripathes sp.) and a few massive or plate-like reef corals. Part-time or obligatory planktivorous fishes (e.g. Cephalopholis furcifer and Clepticus brasiliensis) also dominated deep reefs. Similar characteristics were recorded in mesophotic reef ecosystems across the Western Atlantic. Evidence of overfishing (obtained here and in other recent studies), the presence of four endemic and restricted range fish species, as well as the increase in number of new (and still undescribed) endemic taxa, indicates that the adoption of precautionary conservation measures are urgently needed in order to maintain the fragile and unique ecosystems of the TMVIG

Photobacterium sanctipauli sp nov isolated from bleached Madracis decactis (Scleractinia) in the St Peter & St Paul Archipelago, Mid-Atlantic Ridge, Brazil

Five novel strains of Photobacterium (A-394T, A-373, A-379, A-397 and A-398) were isolated from bleached coralMadracis decactis (scleractinian) in the remote St Peter & St Archipelago (SPSPA), Mid-Atlantic Ridge, Brazil. Healthy M. decactis specimens were also surveyed, but no strains were related to them. The novel isolates formed a distinct lineage based on the 16S rRNA, recA, and rpoA gene sequences analysis. Their closest phylogenetic neighbours were Photobacterium rosenbergii, P. gaetbulicola, and P. lutimaris, sharing 96.6 to 95.8% 16S rRNA gene sequence similarity. The novel species can be differentiated from the closest neighbours by several phenotypic and chemotaxonomic markers. It grows at pH 11, produces tryptophane deaminase, presents the fatty acid C-18:0, but lacks C-16:0 iso. The whole cell protein profile, based in MALDI-TOF MS, distinguished the strains of the novel species among each other and from the closest neighbors. In addition, we are releasing the whole genome sequence of the type strain. The name Photobacterium sanctipauli sp. nov. is proposed for this taxon. The G + C content of the type strain A-394(T) (=LMG27910(T) = CAIM1892(T)) is 48.2 mol%

Extensive Rhodolith Beds Cover the Summits of Southwestern Atlantic Ocean Seamounts

Calcium carbonate production by marine organisms is an essential process in the global budget of CO32-, and coralline reefs are the most important benthic carbonate producers. Crustose coralline algae (CCA) are well recognized as the most important carbonate builders in the tropical Brazilian continental shelf, forming structural reefs and extensive rhodolith beds. However, the distribution of CCA beds, as well as their role in CO32- mineralization in mesophotic communities and isolated carbonate banks, is still poorly known. To characterize the bottom features of several seamount summits in the Southwestern Atlantic (SWA), side-scan sonar records, remotely operated vehicle imagery, and benthic samples with mixed-gas scuba diving were acquired during two recent research cruises (March 2009 and February 2011). The tops of several seamounts within this region are relatively shallow (similar to 60 m), flat, and dominated by rhodolith beds (Vitoria, Almirante Saldanha, Davis, and Jaseur seamounts, as well as the Trindade Island shelf). On the basis of abundance, dimensions, vitality, and growth rates of CCA nodules, a mean CaCO3 production was estimated, ranging from 0.4 to 1.8 kg m(-2) y(-1) with a total production reaching 1.5 x 10(-3) Gt y(-1). Our results indicate that these SWA seamount summits provide extensive areas of shallow reef area and represent 0.3% of the world's carbonate banks. The importance of this habitat has been highly neglected, and immediate management needs must be fulfilled in the short term to ensure long-term persistence of the ecosystem services provided by these offshore carbonate realms.Brazilian Research Council (CNPq)Brazilian Research Council (CNPq

Long-term effects of competition and environmental drivers on the growth of the endangered coral Mussismilia braziliensis (Verril, 1867)

Most coral reefs have recently experienced acute changes in benthic community structure, generally involving dominance shifts from slow-growing hard corals to fast-growing benthic invertebrates and fleshy photosynthesizers. Besides overfishing, increased nutrification and sedimentation are important drivers of this process, which is well documented at landscape scales in the Caribbean and in the Indo-Pacific. However, small-scale processes that occur at the level of individual organisms remain poorly explored. In addition, the generality of coral reef decline models still needs to be verified on the vast realm of turbid-zone reefs. Here, we documented the outcome of interactions between an endangered Brazilian-endemic coral (Mussismilia braziliensis) and its most abundant contacting organisms (turf, cyanobacteria, corals, crustose coralline algae and foliose macroalgae). Our study was based on a long (2006–2016) series of high resolution data (fixed photoquadrats) acquired along a cross-shelf gradient that includes coastal unprotected reefs and offshore protected sites. The study region (Abrolhos Bank) comprises the largest and richest coralline complex in the South Atlantic, and a foremost example of a turbid-zone reef system with low diversity and expressive coral cover. Coral growth was significantly different between reefs. Coral-algae contacts predominated inshore, while cyanobacteria and turf contacts dominated offshore. An overall trend in positive coral growth was detected from 2009 onward in the inshore reef, whereas retraction in live coral tissue was observed offshore during this period. Turbidity (+) and cyanobacteria (−) were the best predictors of coral growth. Complimentary incubation experiments, in which treatments of Symbiodinium spp. from M. braziliensis colonies were subjected to cyanobacterial exudates, showed a negative effect of the exudate on the symbionts, demonstrating that cyanobacteria play an important role in coral tissue necrosis. Negative effects of cyanobacteria on living coral tissue may remain undetected from percent cover estimates gathered at larger spatial scales, as these ephemeral organisms tend to be rapidly replaced by longer-living macroalgae, or complex turf-like consortia. The cross-shelf trend of decreasing turbidity and macroalgae abundance suggests either a direct positive effect of turbidity on coral growth, or an indirect effect related to the higher inshore cover of foliose macroalgae, constraining cyanobacterial abundance. It is unclear whether the higher inshore macroalgal abundance (10–20% of reef cover) is a stable phase related to a long-standing high turbidity background, or a contemporary response to anthropogenic stress. Our results challenge the idea that high macroalgal cover is always associated with compromised coral health, as the baselines for turbid zone reefs may derive sharply from those of coral-dominated reefs that dwell under oligotrophic conditions

An extensive reef system at the Amazon River mouth

Large rivers create major gaps in reef distribution along tropical shelves. The Amazon River represents 20% of the global riverine discharge to the ocean, generating up to a 1.3 x 10(6)-km(2) plume, and extensive muddy bottoms in the equatorial margin of South America. As a result, a wide area of the tropical North Atlantic is heavily affected in terms of salinity, pH, light penetration, and sedimentation. Such unfavorable conditions were thought to imprint a major gap in Western Atlantic reefs. We present an extensive carbonate system off the Amazon mouth, underneath the river plume. Significant carbonate sedimentation occurred during lowstand sea level, and still occurs in the outer shelf, resulting in complex hard-bottom topography. A permanent near-bottom wedge of ocean water, together with the seasonal nature of the plume's eastward retroflection, conditions the existence of this extensive (similar to 9500 km(2)) hard-bottom mosaic. The Amazon reefs transition from accretive to erosional structures and encompass extensive rhodolith beds. Carbonate structures function as a connectivity corridor for wide depth-ranging reef-associated species, being heavily colonized by large sponges and other structure-forming filter feeders that dwell under low light and high levels of particulates. The oxycline between the plume and subplume is associated with chemoautotrophic and anaerobic microbial metabolisms. The system described here provides several insights about the responses of tropical reefs to suboptimal and marginal reef-building conditions, which are accelerating worldwide due to global changes.Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Coordenadoria de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERS)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)BrasoilMCTIBrazilian NavyU.S. NSFGordon and Betty Moore Foundation (GBMF)Univ Fed Rio de Janeiro UFRJ, Inst Biol, BR-21941599 Rio De Janeiro, RJ, BrazilUniv Fed Rio de Janeiro, COPPE, Inst Alberto Luiz Coimbra Posgrad & Pesquisa Engn, Lab Sistemas Avancados Gestao Prod, BR-21941972 Rio de Janeiro, RJ, BrazilInst Pesquisas Jardim Bot Rio de Janeiro, BR-22460030 Rio De Janeiro, RJ, BrazilUniv Sao Paulo, Inst Oceanog, BR-05508120 Sao Paulo, SP, BrazilUniv Fed Espirito Santo, Dept Oceanog, BR-29199970 Vitoria, ES, BrazilUniv Estadual Norte Fluminense, Lab Ciencias Ambientais, Ctr Biociencias & Biotecnol, BR-28013602 Campos Dos Goytacazes, RJ, BrazilUniv Fed Fluminense, Inst Geociencias, BR-24210346 Niteroi, RJ, BrazilUniv Fed Fluminense, Inst Biol, BR-24210130 Niteroi, RJ, BrazilUniv Fed Rio de Janeiro, Museo Nacl, BR-20940040 Rio De Janeiro, RJ, BrazilFed Univ Para, Inst Estudos Costeiros, BR-68600000 Braganca, PA, BrazilUniv Fed Sao Paulo, Dept Ciencias Mar, BR-11070100 Santos, SP, BrazilUniv Fed Pernambuco, Dept Oceanog, BR-50670901 Recife, PE, BrazilUniv Georgia, Dept Marine Sci, Athens, GA 30602 USAUniv Fed Paraiba, BR-58297000 Rio Tinto, PB, BrazilUniv Estadual Santa Cruz, Dept Ciencias Biol, BR-45650000 Ilheus, BA, BrazilUniv Fed Sao Paulo, Dept Ciencias Mar, BR-11070100 Santos, SP, BrazilU.S. NSF: OCE-0934095GBMF: 2293GBMF: 2928Web of Scienc

Rhodolith Beds Are Major CaCO3 Bio-Factories in the Tropical South West Atlantic

Rhodoliths are nodules of non-geniculate coralline algae that occur in shallow waters (<150 m depth) subjected to episodic disturbance. Rhodolith beds stand with kelp beds, seagrass meadows, and coralline algal reefs as one of the world's four largest macrophyte-dominated benthic communities. Geographic distribution of rhodolith beds is discontinuous, with large concentrations off Japan, Australia and the Gulf of California, as well as in the Mediterranean, North Atlantic, eastern Caribbean and Brazil. Although there are major gaps in terms of seabed habitat mapping, the largest rhodolith beds are purported to occur off Brazil, where these communities are recorded across a wide latitudinal range (2°N - 27°S). To quantify their extent, we carried out an inter-reefal seabed habitat survey on the Abrolhos Shelf (16°50′ - 19°45′S) off eastern Brazil, and confirmed the most expansive and contiguous rhodolith bed in the world, covering about 20,900 km2. Distribution, extent, composition and structure of this bed were assessed with side scan sonar, remotely operated vehicles, and SCUBA. The mean rate of CaCO3 production was estimated from in situ growth assays at 1.07 kg m−2 yr−1, with a total production rate of 0.025 Gt yr−1, comparable to those of the world's largest biogenic CaCO3 deposits. These gigantic rhodolith beds, of areal extent equivalent to the Great Barrier Reef, Australia, are a critical, yet poorly understood component of the tropical South Atlantic Ocean. Based on the relatively high vulnerability of coralline algae to ocean acidification, these beds are likely to experience a profound restructuring in the coming decades