Mussismilia Hispida Research Articles

Geographic patterns of Symbiodinium diversity associated with the coral Mussismilia hispida (Cnidaria, Scleractinia) correlate with major reef regions in the Southwestern Atlantic Ocean

Shallow water reef-building corals associate with photosynthesizing dinoflagellates (Symbiodinium spp.) that may affect growth and resilience of their hosts. Understanding host–symbiont associations is critical for assessing the susceptibility of corals to climatic changes. Despite that, the diversity of Symbiodinium associated with corals from the Southwestern Atlantic Ocean is poorly known. Here, we describe diversity across major Symbiodinium clades associated with colonies of the endemic reef-building coral Mussismilia hispida (Verrill, 1902) along the Brazilian coast. By analyzing the 18S rDNA gene, we found that M. hispida associates with three clades of Symbiodinium (A, B and C). Moreover, the geographic distribution of host–symbiont associations is related to temperature and turbidity and closely follows previously recognized reef regions along the Brazilian coast. These results suggest that similar ecological processes are likely shaping both the reef communities and the host–symbiont associations over M. hispida distribution along the coast. Our study provides an advance in the understanding of symbiont diversity in a key reef-building coral. In addition, it contributes new insights for future investigations aiming at comprehending the factors determining Symbiodinium geographic distribution.

Effects of the alien coral Tubastraea tagusensis on native coral assemblages in a southwestern Atlantic coral reef

The alien coral Tubastraea spp. has invaded Atlantic coral reefs since 1940s, but their effects on native coral assemblages are poorly understood. In this study the effects on coral assemblage structure and tissue mortality in native competitors by alien coral were investigated. We compared native coral cover in zones with and without T. tagusensis and evaluated the mortality of native coral species in natural encounters with T. tagusensis. Additionally, we evaluated the effects of contact with this invader on two native corals, Siderastrea stellata and Montastraea cavernosa, using a manipulative experiment. Multivariate analyses detected significant differences between coral assemblages in invaded and non-invaded zones. In the invaded zone, we observed greater cover of T. tagusensis on reef walls (34.9 ± 4.2 %) than on reef tops (18.5 ± 4.1 %). Madracis decactis and Mussismilia hispida were significantly less abundant in invaded zone than in non-invaded zones at the reef walls. Manipulative experiments showed a significant increase in tissue mortality of S. stellata (3.2 ± 1.4 cm2) after 60 days of contact with T. tagusensis and no effects on M. cavernosa after 90 days of contact. In natural encounters, 52 and 0.1 % of the S. stellata and M. cavernosa colonies, respectively, showed tissue mortality. These results indicate that competitive interactions with native competitors are important to understand alien coral establishment on coral reef. Our study documents the negative effects of the alien coral on coral reef assemblages and reinforces the urgent need for monitoring and management actions to control the expansion of this invader on Brazilian reefs.

Draft genome sequence of Kocuria sp. SM24M-10 isolated from coral mucus.

Here, we describe the genomic features of the Actinobacteria Kocuria sp. SM24M-10 isolated from mucus of the Brazilian endemic coral Mussismilia hispida. The sequences are available under accession number LDNX01000000 (http://www.ncbi.nlm.nih.gov/nuccore/LDNX00000000). The genomic analysis revealed interesting information about the adaptation of bacteria to the marine environment (such as genes involved in osmotic and oxidative stress) and to the nutrient-rich environment provided by the coral mucus.

Effects of habitat structure on the epifaunal community in Mussismilia corals: does coral morphology influence the richness and abundance of associated crustacean fauna?

Coral habitat structures increase abundance and richness of organisms by providing niches, easy access to resources and refuge from predators. Corals harbor a great variety of animals; the variation in coral species morphology contributes to the heterogeneity and complexity of habitat types. In this report, we studied the richness and abundance of crustaceans (Decapoda, Copepoda, Peracarida and Ostracoda) associated with three species of Mussismilia exhibiting different growth morphologies, in two different coral reefs of the Bahia state (Caramuanas and Boipeba-Morere, Brazil). Mussismilia hispida is a massive coral; M. braziliensis also has a massive growth pattern, but forms a crevice in the basal area of the corallum; M. harttii has a meandroid pattern. PERMANOVA analysis suggests significant differences in associated fauna richness among Mussismilia species, with higher values for M. harttii, followed by M. braziliensis and later by M. hispida. The same trend was observed for density, except that the comparison of M. braziliensis and M. hispida did not show differences. Redundancy and canonical correspondence analysis indicated that almost all of the crustacean species were more associated with the M. harttii colonies that formed a group clearly separated from colonies of M. braziliensis and M. hispida. We also found that the internal volume of interpolyp space, only present in M. harttii, was the most important factor influencing richness and abundance of all analyzed orders of crustaceans.

Microbiota of the major South Atlantic reef building coral Mussismilia.

The Brazilian endemic scleractinian corals, genus Mussismilia, are among the main reef builders of the South Atlantic and are threatened by accelerating rates of disease. To better understand how holobiont microbial populations interact with corals during health and disease and to evaluate whether selective pressures in the holobiont or neutral assembly shape microbial composition, we have examined the microbiota structure of Mussismilia corals according to coral lineage, environment, and disease/health status. Microbiota of three Mussismilia species (Mussismilia harttii, Mussismilia hispida, and Mussismilia braziliensis) was compared using 16S rRNA pyrosequencing and clone library analysis of coral fragments. Analysis of biological triplicates per Mussismilia species and reef site allowed assessment of variability among Mussismilia species and between sites for M. braziliensis. From 173,487 V6 sequences, 6,733 coral- and 1,052 water-associated operational taxonomic units (OTUs) were observed. M. braziliensis microbiota was more similar across reefs than to other Mussismilia species microbiota from the same reef. Highly prevalent OTUs were more significantly structured by coral lineage and were enriched in Alpha- and Gammaproteobacteria. Bacterial OTUs from healthy corals were recovered from a M. braziliensis skeleton sample at twice the frequency of recovery from water or a diseased coral suggesting the skeleton is a significant habitat for microbial populations in the holobiont. Diseased corals were enriched with pathogens and opportunists (Vibrios, Bacteroidetes, Thalassomonas, and SRB). Our study examines for the first time intra- and inter-specific variability of microbiota across the genus Mussismilia. Changes in microbiota may be useful indicators of coral health and thus be a valuable tool for coral reef management and conservation.

Polymorphic Microsatellite Loci for Endemic Mussismilia Corals (Anthozoa: Scleractinia) of the Southwest Atlantic Ocean.

In the Southwest Atlantic, coral reefs are unique due to their growth form, low species richness, and a high level of endemic coral species, which include the most important reef builders. Although these reefs are the only true biogenic reefs in the South Atlantic Ocean, population genetic studies are still lacking. The purpose of this study was to develop a suite of microsatellite loci to help gain insights into the population diversity and connectivity of the endemic scleractinian coral with the largest distributional range along the Southwest Atlantic coast, Mussismilia hispida Fourteen microsatellite loci were characterized, and their degree of polymorphism was analyzed in 33 individuals. The number of alleles varied between 4 and 17 per loci, and H o varied between 0.156 and 0.928, with 2 loci showing significant heterozygote deficiency. Cross-amplification tests on the other 2 species of the genus (Mussismilia braziliensis and Mussismilia harttii) demonstrated that these markers are suitable for studies of population diversity and structure of all 3 species of Mussismilia Because they are the most important reef builders in the Southwest Atlantic, the developed microsatellite loci may be important tools for connectivity and conservation studies of these endemic corals.

Antagonism between invasive pest corals Tubastraea spp. and the native reef-builder Mussismilia hispida in the southwest Atlantic

The biological invasion of the scleractinian corals Tubastraea coccinea and Tubastraea tagusensis into the Atlantic has resulted in their juxtaposition with native reef corals. We used microcosm and field experiments to investigate and separate the effects of chemical vs. physical mechanisms potentially responsible for observed antagonistic interactions between the invasive corals and the endemic (southwest Atlantic) reef-building coral Mussismilia hispida. In the short term microcosm experiment M. hispida extruded a substantial amount of mesenterial filaments in an aggressive response to proximity to both invasive species within a few hours. However, in the field only the native coral suffered necrosis, which was visible after only four days. The use of physical barriers to separate chemical and physical effects demonstrated that antagonistic effects were far greater in the absence of a physical barrier than in the partial or complete barrier treatments, so although there is evidence that these invasive corals may produce allelochemicals against possible competitors we demonstrated that the main mechanism Tubastraea spp uses to exclude the native coral species is principally a rapid physical response.

Biological oxygen demand optode analysis of coral reef-associated microbial communities exposed to algal exudates

Algae-derived dissolved organic matter has been hypothesized to induce mortality of reef building corals. One proposed killing mechanism is a zone of hypoxia created by rapidly growing microbes. To investigate this hypothesis, biological oxygen demand (BOD) optodes were used to quantify the change in oxygen concentrations of microbial communities following exposure to exudates generated by turf algae and crustose coralline algae (CCA). BOD optodes were embedded with microbial communities cultured from Montastraea annularis and Mussismilia hispida, and respiration was measured during exposure to turf and CCA exudates. The oxygen concentrations along the optodes were visualized with a low-cost Submersible Oxygen Optode Recorder (SOOpR) system. With this system we observed that exposure to exudates derived from turf algae stimulated higher oxygen drawdown by the coral-associated bacteria than CCA exudates or seawater controls. Furthermore, in both turf and CCA exudate treatments, all microbial communities (coral-, algae-associated and pelagic) contributed significantly to the observed oxygen drawdown. This suggests that the driving factor for elevated oxygen consumption rates is the source of exudates rather than the initially introduced microbial community. Our results demonstrate that exudates from turf algae may contribute to hypoxia-induced coral stress in two different coral genera as a result of increased biological oxygen demand of the local microbial community. Additionally, the SOOpR system developed here can be applied to measure the BOD of any culturable microbe or microbial community.

Bacterial communities and species-specific associations with the mucus of Brazilian coral species

We investigated the existence of species-specific associations between Brazilian coral species and bacteria. Pyrosequencing of the V3 region of the 16S rDNA was used to analyze the taxonomic composition of bacterial communities associated with the mucus of four coral species (Madracis decactis, Mussismilia hispida, Palythoa caribaeorum, and Tubastraea coccinea) in two seasons (winter and summer), which were compared with the surrounding water and sediment. The microbial communities found in samples of mucus, water, and sediment differed according to the composition and relative frequency of OTUs. The coral mucus community seemed to be more stable and resistant to seasonal variations, compared to the water and sediment communities. There was no influence of geographic location on the composition of the communities. The sediment community was extremely diverse and might act as a "seed bank" for the entire environment. Species-specific OTUs were found in P. caribaeorum, T. coccinea, and M. hispida.

<p class="SP86052"><strong>Spongiopsyllus redactus, a new species of Entomolepididae (Copepoda, Siphonostomatoida) associated with a scleractinian coral in Brazil</strong></p>

The family Entomolepididae is represented in the South Atlantic Ocean solely by Spongiopsyllus, a monotypic genus found previously in association with sponges. A recent survey on the Boa Viagem Reefs, located off Salvador, Bahia State, on the northeastern region of Brazil, has revealed a new species of the genus, Spongiopsyllus redactus n. sp., found associated with the endemic scleractinian coral Mussismilia hispida (Verrill). The new species is distinguished from its congener, S. adventicius Johnsson, 2000, by differences in the number of segments of the antennule, the ornamentation of the distal endopodal segment of the antenna, and the setation of the maxilliped and P1. An updated key to the species of Entomolepididae is also provided.

Proximity to competitors changes secondary metabolites of non-indigenous cup corals, Tubastraea spp., in the southwest Atlantic

Competition for space changes species’ distributions and community organization on tropical rocky shores, and the presence of secondary metabolites in the tissues of non-indigenous species may aid them in establishing and expanding their range through negative competitive interactions. The aim of this study was to describe the range of chemical substances produced by the non-indigenous cup corals Tubastraea coccinea and T. tagusensis and to test whether they varied in the field when the corals were placed in proximity to two local competitors. Cholest-5-en-3β-ol and 9-octadecanoic acid were two common secondary metabolites found in the tissues of Tubastraea. In the competition interaction experiment, necrosis was detected on the tissues of the coral Mussismilia hispida, and this species induced variation in sterol, alkaloid, and fatty acid production in Tubastraea tissues. In contrast, a sponge overgrew Tubastraea colonies. These results indicate that chemical defense may contribute to the ability of these non-indigenous corals to invade native communities.

Marinomonas brasilensis sp. nov., isolated from the coral Mussismilia hispida, and reclassification of Marinomonas basaltis as a later heterotypic synonym of Marinomonas communis

A Gram-negative, aerobic bacterium, designated strain R-40503(T), was isolated from mucus of the reef-builder coral Mussismilia hispida, located in the São Sebastião Channel, São Paulo, Brazil. Phylogenetic analyses revealed that strain R-40503(T) belongs to the genus Marinomonas. The 16S rRNA gene sequence similarity of R-40503(T) was above 97 % with the type strains of Marinomonas vaga, M. basaltis, M. communis and M. pontica, and below 97 % with type strains of the other Marinomonas species. Strain R-40503(T) showed less than 35 % DNA-DNA hybridization (DDH) with the type strains of the phylogenetically closest Marinomonas species, demonstrating that it should be classified into a novel species. Amplified fragment length polymorphism (AFLP), chemotaxonomic and phenotypic analyses provided further evidence for the proposal of a novel species. Concurrently, a close genomic relationship between M. basaltis and M. communis was observed. The type strains of these two species showed 78 % DDH and 63 % AFLP pattern similarity. Their phenotypic features were very similar, and their DNA G+C contents were identical (46.3 mol%). Collectively, these data demonstrate unambiguously that Marinomonas basaltis is a later heterotypic synonym of Marinomonas communis. Several phenotypic features can be used to discriminate between Marinomonas species. The novel strain R-40503(T) is clearly distinguishable from its neighbours. For instance, it shows oxidase and urease activity, utilizes l-asparagine and has the fatty acid C(12 : 1) 3-OH but lacks C(10 : 0) and C(12 : 0). The name Marinomonas brasilensis sp. nov. is proposed, with the type strain R-40503(T) ( = R-278(T) = LMG 25434(T) = CAIM 1459(T)). The DNA G+C content of strain R-40503(T) is 46.5 mol%.

Bacterial Community Associated with Healthy and Diseased Reef Coral Mussismilia hispida from Eastern Brazil

In order to characterize the bacterial community diversity associated to mucus of the coral Mussismilia hispida, four 16S rDNA libraries were constructed and 400 clones from each library were analyzed from two healthy colonies, one diseased colony and the surrounding water. Nine bacterial phyla were identified in healthy M. hispida, with a dominance of Proteobacteria, Actinobacteria, Acidobacteria, Lentisphaerae, and Nitrospira. The most commonly found species were related to the genera Azospirillum, Hirschia, Fabibacter, Blastochloris, Stella, Vibrio, Flavobacterium, Ochrobactrum, Terasakiella, Alkalibacter, Staphylococcus, Azospirillum, Propionibacterium, Arcobacter, and Paenibacillus. In contrast, diseased M. hispida had a predominance of one single species of Bacteroidetes, corresponding to more than 70% of the sequences. Rarefaction curves using evolutionary distance of 1% showed a greater decrease in bacterial diversity in the diseased M. hispida, with a reduction of almost 85% in OTUs in comparison to healthy colonies. integral-Libshuff analyses show that significant p values obtained were <0.0001, demonstrating that the four libraries are significantly different. Furthermore, the sympatric corals M. hispida and Mussismilia braziliensis appear to have different bacterial community compositions according to Principal Component Analysis and Lineage-specific Analysis. Moreover, lineages that contribute to those differences were identified as alpha-Proteobacteria, Bacteroidetes, and Firmicutes. The results obtained in this study suggest host-microbe co-evolution in Mussismilia, and it was the first study on the diversity of the microbiota of the endemic and endangered of extinction Brazilian coral M. hispida from Abrolhos bank.

Marinobacterium coralli sp. nov., isolated from mucus of coral (Mussismilia hispida)

A Gram-negative, aerobic bacterium, designated R-40509(T), was isolated from mucus of the reef builder coral (Mussismilia hispida) located in the São Sebastião Channel, São Paulo, Brazil. The strain was oxidase-positive and catalase-negative, and required Na(+) for growth. Its phylogenetic position was in the genus Marinobacterium and the closest related species were Marinobacterium sediminicola, Marinobacterium maritimum and Marinobacterium stanieri; the isolate exhibited 16S rRNA gene sequence similarities of 97.5-98.0 % with the type strains of these species. 16S rRNA gene sequence similarities with other type strains of the genus Marinobacterium were below 96 %. DNA-DNA hybridizations between strain R-40509(T) and the type strains of the phylogenetically closest species of the genus Marinobacterium revealed less than 70 % DNA-DNA relatedness, supporting the novel species status of the strain. Phenotypic characterization revealed that the strain was able to grow at 15-42 °C and in medium containing up to 9 % NaCl. The isolate could be differentiated from phenotypically related species by several features, including its ability to utilize d-alanine, l-alanine, bromosuccinic acid, β-hydroxybutyric acid and α-ketovaleric acid, but not acetate or l-arabinose. It produced acetoin (Voges-Proskauer), but did not have esterase lipase (C8) or catalase activities. It possessed C(18 : 1)ω7c (35 %), summed feature 3 (iso-C(15 : 0) 2-OH and/or C(16 : 1)ω7c; 25 %) and C(16 : 0) (22 %) as major cellular fatty acids. The DNA G+C content was 58.5 mol%. The name Marinobacterium coralli sp. nov. is proposed to accommodate this novel isolate; the type strain is R-40509(T) (=LMG 25435(T) =CAIM 1449(T)).

Diversity and pathogenic potential of vibrios isolated from Abrolhos Bank corals

We performed the first taxonomic characterization of vibrios and other culturable microbiota from apparently healthy and diseased Brazilian-endemic corals at the Abrolhos reef bank. The diseases affecting corals were tissue necrosis in Phyllogorgia dillatata, white plague and bleaching in Mussismilia braziliensis and bleaching in Mussismilia hispida. Bacterial isolates were obtained from mucus of 22 coral specimens originated from the Abrolhos Bank (i.e. Itacolomis reef, Recife de Fora reef and Santa Barbara Island) in 2007. Vibrios counts in the water and coral mucus were approximately 104 cfu ml(-1) and 106 cfu ml(-1) respectively. One hundred and thirty-one representative vibrio isolates were identified. Most vibrio isolates (n = 79) fell into the core group using the pyrH identification marker. According to our analysis, diseased corals did not possess a unique vibrio microbiota. Vibrio species encompassed strains originated from both apparently healthy and diseased corals. The pathogenic potential of representative vibrio isolates (V. alginolyticus 40B, V. harveyi-like 1DA3 and V. coralliilyticus 2DA3) were evaluated in a standardized bioassay using the animal model Drosophila melanogaster and caused 25-88% mortality. This is the first taxonomic characterization of the culturable microbiota from the Brazilian-endemic corals. Endemic Brazilian corals are a reservoir of the vibrio core group. Vibrio alginolyticus, V. harveyi and V. coralliilyticus are dominant in the mucus of these corals and may be a normal component of the holobiont.

Archaea, Bacteria, and Algal Plastids Associated with the Reef-Building Corals Siderastrea stellata and Mussismilia hispida from Búzios, South Atlantic Ocean, Brazil

Reef-building corals may be seen as holobiont organisms, presenting diverse associated microbial communities. Best known is the symbiotic relationship with zooxanthellae, but Archaea, Bacteria, fungi, viruses, and algal plastids are also abundant. Until now, there is little information concerning microbial communities associated with Brazilian corals. The present study aims to describe the diversity of Archaea, Bacteria, and eukaryotic algal plastid communities associated with two sympatric species, Siderastrea stellata and Mussismilia hispida, from Southeastern Brazil, using 16S rRNA gene libraries. Since corals present a high number of other associated invertebrates, coral barcoding (COI) was performed to confirm the exclusive occurrence of coral DNA in our samples. Our analysis yielded 354 distinct microbial OTUs, represented mainly by novel phylotypes. Richness (Chao1 and ACE) and diversity (H') estimations of the microbial communities associated with both species were high and comparable to other studies. Rarefaction analyses showed that microbial diversity of S. stellata is higher than that of M. hispida. Libshuff comparative analyses showed that the highest microbial community similarity between the two coral species occurred in the bacterial libraries, while archaeal and plastidial communities were significantly different. Crenarchaeota dominated archaeal communities, while Proteobacteria was the most abundant bacterial phylum, dominated by alpha-Proteobacteria. Plastids were also represented by novel phylotypes and did not match with any 16S rRNA sequences of Cyanobacteria and zooxanthellae from GenBank. Our data improves the pool of available information on Brazilian coral microbes and shows corals as sources of diverse prokaryotic and picoeukaryotic communities.

Genomic diversity of vibrios associated with the Brazilian coralMussismilia hispidaand its sympatric zoanthids (Palythoa caribaeorum,Palythoa variabilisandZoanthus solanderi)

A taxonomic survey of the vibrios associated with the Brazilian endemic coral Mussismilia hispida and the sympatric zoanthids (i.e. Palythoa caribaeorum, Palythoa variabilis and Zoanthus solanderi). Mucus of 54 cnidarian specimens collected in three different places at São Sebastião in two consecutive years (i.e. 2005 and 2006) was used for taxonomic characterization of the cnidarian microbiota. Ninety-eight of the 151 vibrio isolates fell within the vibrio core group according to partial 16S rDNA sequences. We performed the sequencing of recA and pyrH genes of all vibrio isolates. The most abundant taxa belonged to the vibrio core group (Vibrio harveyi, Vibrio rotiferianus, Vibrio campbellii and Vibrio alginolyticus), Vibrio mediterranei (=Vibrio shillonii) and Vibrio chagasii. With the exception of V. chagasii which was found only in the mucus of M. hispida, the other species appeared in different hosts with no evidence for the presence of host-specific clones or species. Using rep-PCR analysis, we observed a high genomic heterogeneity within the vibrios. Each vibrio isolate generated a different rep-PCR fingerprint pattern. There was a complete agreement between the grouping based on rep-PCR and concatenated sequences of pyrH, recA and 16S rDNA, but the pyrH gene has the highest discriminatory power for vibrio species identification. The vibrio core group is dominant in the mucus of these cnidarians. There is a tremendous diversity of vibrio lineages within the coral mucus. pyrH gene sequences permit a clear-cut identification of vibrios. The taxonomic resolution provided by pyrH (but not recA) appears to be enough for identifying species of vibrios and for disclosing putative new taxa. The vibrio core group appears to be dominant in the mucus of the Brazilian cnidarians. The overrepresentation of these vibrios may reflect as yet unknown ecological functions in the coral holobiont.

Thermal stress assessment using carbon and oxygen isotopes from Scleractinia, Rocas Atoll, northeastern Brazil

More than 430 C and O isotope analyses were carried out on carbonates from six coral species collected during June 1995, July 1998 and February 1999 at Rocas atoll, offshore northeastern Brazil: Siderastrea stellata Verrill 1868, Porites branneri Rathbum 1887, Porites astreoides Lamarck 1816, Mussismilia hispida Verrill 1902, Madracis decactis Lyman 1859 and Montastrea cavernosa Linnaeus 1886. Samples were collected in pools within the ring of the atoll, at water depths from 1.0 to 7.0 m. Oxygen isotope chemistry demonstrated that the studied species experienced several periods of bleaching; calculated temperature for one species vary, suggesting important changes within the time scale of coral growth. The species P. branneri, P. astreoides, M. cavernosa and the Brazilian endemic species M. hispida registered temperature variations during coral growth more accurately than did S. stellata and M. decactis. Carbon isotope behaviour in coral skeletons of the species examined at this atoll seems to have maintained a close relationship between density and/or zooxanthelar productivity: the greater the algal density, the heavier the δ13C values in skeletons.

Branqueamento de corais nos recifes da Bahia e sua relação com eventos de anomalias térmicas nas águas superficiais do oceano

A partir de 1993 foram registrados vários eventos de branqueamento de coral na Bahia, com recuperação total dos corais afetados. O primeiro registro ocorreu em Abrolhos no verão de 1993/1994, quando o percentual de colônias branqueadas variou entre 50 e 90%. No verão de 1997/1998, ocorreu no Litoral Norte da Bahia uma anomalia térmica de 1 ºC, com temperaturas medidas no campo de 29 a 30,5 ºC, o que causou branqueamento em 60% dos corais. De 1998 a 2005, foi observado que nos recifes costeiros, localizados muito próximos (&lt;5km) ou adjacentes à costa, a permanência de anomalias térmicas de 0,25 ºC por mais de duas semanas causou branqueamento em mais de 10% dos corais. Porém para os recifes de Abrolhos, localizados a mais de 10 km da costa, apenas anomalias acima de 0,50 ºC com duração de mais de duas semanas causaram branqueamento em mais de 10% dos corais. Mussismilia hispida, Siderastrea spp., Montastraea cavernosa, Agaricia agaricites e Porites astreoides foram as espécies de coral mais afetadas pelo branqueamento e são as espécies mais freqüentes nos recifes costeiros. Todas as espécies apresentaram graus diferentes de branqueamento, "fraco" ou "forte". Nos recifes da Bahia há uma forte relação entre o branqueamento de corais e os eventos de anomalias da temperatura da superfície do mar (TSM), e os recifes mais afetados pelo branqueamento foram os recifes costeiros. Estes recifes localizados muito próximos da costa estão mais expostos aos efeitos dos impactos provenientes de processos que ocorrem na região costeira, sugerindo que, muito provavelmente, os corais mais expostos a níveis elevados de nutriente e sedimento, e variações sazonais mais altas da TSM, podem já estarem mais resistentes aos efeitos pós branqueamento como, por exemplo, doenças infecciosas e mortalidade em massa.

Vibrios dominate as culturable nitrogen-fixing bacteria of the Brazilian coral Mussismilia hispida

Taxonomic characterization was performed on the putative N 2-fixing microbiota associated with the coral species Mussismilia hispida, and with its sympatric species Palythoa caribaeorum, P. variabilis, and Zoanthus solanderi, off the coast of São Sebastião (São Paulo State, Brazil). The 95 isolates belonged to the Gammaproteobacteria according to the 16S rDNA gene sequences. In order to identify the isolates unambiguously, pyrH gene sequencing was carried out. The majority of the isolates ( n=76) fell within the Vibrio core group, with the highest gene sequence similarity being towards Vibrio harveyi and Vibrio alginolyticus. Nineteen representative isolates belonging to V. harveyi ( n=7), V. alginolyticus ( n=8), V. campbellii ( n=3), and V. parahaemolyticus ( n=1) were capable of growing six successive times in nitrogen-free medium and some of them showed strong nitrogenase activity by means of the acetylene reduction assay (ARA). It was concluded that nitrogen fixation is a common phenotypic trait among Vibrio species of the core group. The fact that different Vibrio species can fix N 2 might explain why they are so abundant in the mucus of different coral species.