Thesea pyrrha sp. nov., a new shallow-water octocoral (Cnidaria, Anthozoa) from southwestern Atlantic, and implications on the systematics of the genus.

The family Plexauridae Gray, 1859 is characterized by grouping octocorals that have thick branches and coenenchyme. However, due to their relatively simple body plan, the establishment of homologous and, therefore, systematically informative morphological characters is a challenge for the systematics of Octocorallia. During the last decade, molecular studies suggested that Plexauridae is polyphyletic, with representatives grouping with Acanthogorgiidae Gray, 1859 and also Gorgoniidae Lamouroux, 1812. Represented by 22 extant species, mostly of which occur in the Atlantic Ocean, the plexaurid genus Thesea Duchassaing Michelotti, 1860 has also been purported to be polyphyletic, with a Pacific lineage related to the former Paramuriceidae and an Atlantic lineage more closely related to Gorgoniidae. Thus, aiming to further improve our understanding of the evolutionary position of the Southwestern Atlantic Thesea, sequencing of the extended Octocorallia barcode reinforces the need for a re-evaluation of the position of the genus within plexaurids. Molecular and macro and micromorphological analyzes indicate the occurrence of an undescribed species distributed from Rio de Janeiro to Santa Catarina, here named Thesea pyrrha sp. nov. Results presented herein also suggest that T. pyrrha is close related to Adelogorgia and Psammogorgia, both genera exclusive to the Pacific Ocean.

Western boundary currents drive sun-coral (Tubastraea spp.) coastal invasion from oil platforms.

Most marine species have a planktonic larval phase that benefit from the surface oceanic flow to enhance their dispersion potential. For invasive species, the interaction of environmentally resistant larvae with different flow regimes and artificial substrates can lead to complex larval dispersion patterns and boost geographic expansion. In the Southwest Atlantic, the invasive corals Tubastraea spp. (sun-coral) have been recorded biofouling on oil platforms since the late 1980s. These platforms are considered important vectors for the established populations throughout the Brazilian coast. However, we still do not know how the position of these structures relative to regional flow contribute to the natural dispersion potential of these invaders on a regional scale. Herein, we used an eddy-resolving ocean model (ROMS) and an Individual Based Model (IBM-Ichthyop) to simulate the natural dispersion patterns of sun-coral larvae from all oil platforms on Brazilian oil-producing basins, for the austral summer and winter along 6 years (2010-2015) in 90-day simulations. We found that mortality rates by advection were significantly higher during the winter (p = 0.001) and when sources of larvae were compared throughout this season (p = 1.9 × 10-17). The influence of two western boundary currents and persistent eddy activity contribute to the dispersal of larvae to distances up to 7000 km. The effectiveness of each oil-producing basin as vectors for the entire Brazilian coastline, measured as the percentage of larval supply, highlights the importance of the northern Ceará (59.89%) and Potiguar (87.47%) basins and the more central Camamu (44.11%) and Sergipe-Alagoas (39.20%) basins. The poleward shift of the Southern branch of the South Equatorial Current during the winter causes larvae released from the Sergipe-Alagoas and Camamu basins to enter the North Brazil Current, expanding their dispersion towards the north. The Brazil Current disperses larvae southwards, but strong mesoscale activity prevents their dispersion to the coast, especially for those released from the oil platforms on Campos and Santos basins. Within this complex hydrodynamic setting, a few source areas, like those in the Sergipe-Alagoas and Camamu basins, can potentially contribute to the spread of larvae along nearly all the Brazilian coast. Therefore, oil platforms act as possible chronic sources of sun-coral propagules to the coast, emphasizing the urgency for a more detailed set of actions to control and monitor these invasive exotic species.

The flourishing and vulnerabilities of zoantharians on Southwestern Atlantic reefs.

In the Southwestern Atlantic reefs (SWA), some species of massive scleractinians and zoantharians are adapted to turbid waters, periodic desiccation, and sediment resuspension events. Moreover, phase shifts in this region have mostly been characterized by the emergence of algae and, less typically, zoantharians. However, nutrient excess and organic pollution are key drivers of the hard coral habitat degradation and may, thus, favor the emergence of novel zoantharian-dominated habitats. Many zoantharian species, particularly those from the genera Palythoa and Zoanthus, have traits that could help them thrive under conditions detrimental to reef-building corals, including rapid growth, several asexual reproduction strategies, high morphological plasticity, and generalist nutrient acquisition strategies. Thus, in a near future, stress-tolerant zoantharians may thrive in nutrient-enriched subtidal SWA locations under low heat stress, such as, upwelling. Overall, coral-zoantharian phase shifts in the SWA may decrease the species richness of reef communities, ultimately influencing ecosystem functioning and services, such as the provision of nursery habitats, fish biomass production, and coastline protection. However, zoantharians will also be threatened at intertidal zones, which are expected to experience higher heat stress, solar radiation, and sea-level rise. Although zoantharians appear to cope well with some local stressors (e.g., decreasing water quality), they are vulnerable to climate change (e.g., heatwaves), invasive species (Tubastraea spp.), microplastics, diseases, and mostly restricted to a narrow depth range (0-15 m depth) in SWA reefs. This shallow zone is particularly affected by climate change, compressing the three-dimensional habitat and limiting depth refugia in deeper SWA reefs. As mesophotic ecosystems have been hypothesized as short-term refuges to disturbances for some species, the narrow depth limit of zoantharians seems to be a potential factor that might increase their vulnerability to growing climate change pressures in SWA shallow-water reefs. Together, these could lead to both range expansions in some locations and loss of suitable reef habitats in other sites. Additional research is needed to better understand the systemic responses of these novel SWA reefs to the concert of increasing and interactive local and global stressors, and their implications for ecosystem functioning and service provisions.

The microbial profile of a tissue necrosis affecting the Atlantic invasive coral Tubastraea tagusensis.

The Southwestern Atlantic rocky reef ecosystems are undergoing significant changes due to sun-corals (Tubastraea tagusensis and T. coccinea) invasion. At Búzios Island, on the northern coast of São Paulo State, where the abundance of T. tagusensis is particularly high, some colonies are displaying tissue necrosis, a phenomenon never reported for this invasive nor any other azooxanthellate coral species. Using next-generation sequencing, we sought to understand the relationship between T. tagusensis tissue necrosis and its microbiota. Thus, through amplicon sequencing, we studied both healthy and diseased coral colonies. Results indicate a wide variety of bacteria associated with healthy colonies and an even higher diversity associated with those corals presenting tissue necrosis, which displayed nearly 25% more microorganisms. Also, as the microbial community associated with the seven healthy colonies did not alter composition significantly, it was possible to verify the microbial succession during different stages of tissue necrosis (i.e., initial, intermediate, and advanced). Comparing the microbiome from healthy corals to those in early tissue necrosis suggests 21 potential pathogens, which might act as the promoters of such disease.

High regenerative capacity is a general feature within colonial dendrophylliid corals (Anthozoa, Scleractinia).

The regenerative capacity of cnidarians plays an essential role in the maintenance and restoration of coral reef ecosystems by allowing faster recovery from disturbances and more efficient small-scale dispersal. However, in the case of invasive species, this property may contribute to their dispersal and success in nonnative habitats. Given that four Indo-Pacific members of the coral genus Tubastraea have invaded the Atlantic, here we evaluated the ability of three of these species (Tubastraea coccinea, Tubastraea diaphana, and Tubastraea micranthus) to regenerate from fragments of undifferentiated coral tissue to fully functional polyps in response to differences in food supply and fragment size. For comparative purposes, another colonial dendrophylliid (Dendrophyllia sp.) was included in the analyses. All dendrophylliids displayed regenerative ability and high survival rates that were independent of whether or not food was supplied or fragment size. However, regeneration rates varied between species and were influenced by fragment size. Temporal expression of key genes of the regenerative process (Wnt and FGF) was profiled during whole-body regeneration of T. coccinea, suggesting a remarkable regenerative ability of T. coccinea that points to its potential use as a laboratory model for the investigation of regeneration in colonial calcified anthozoans.

Erythropodium caribaeorum (Duchassaing and Michelotti, 1860) (Cnidaria: Alcyonacea), an additional alien coral in the Southwestern Atlantic.

Invasive species may compromise biodiversity and ecosystem services, and represent a steadily growing concern for coastal marine ecosystems. The marine aquarium trade (MAT) is the source of some of the world's worst aquatic invasions, inflicting multimillion-dollar losses in infected regions. In the Southwestern Atlantic (SWA), two Indo-Pacific coral species were recently introduced as a result of the MAT and already dominate the substrate at the introduction site in Southeastern Brazil (Praia Vermelha, Angra dos Reis, Rio de Janeiro State). Herein, based on morphological and molecular evidence, we report a Caribbean native coral species likely introduced by the MAT in Praia Vermelha, Erythropodium caribaeorum (Duchassaing Michelotti 1860). While the eradication of coral species that already have a pest status in the SWA is unlikely, we propose that the eradication of the three species still contained to their introduction sites, including E. caribaeorum, is still feasible and depends on a rapid and integrated embracement of the task by core stakeholders. Priority actions for the regulation of MAT and hobbyism in Brazil are proposed.

Microbiome of the Southwestern Atlantic invasive scleractinian coral, Tubastraea tagusensis.

BACKGROUND: Commonly known as sun-coral, Tubastraea tagusensis is an azooxanthellate scleractinian coral that successfully invaded the Southwestern Atlantic causing significant seascape changes. Today it is reported to over 3500 km along the Brazilian coast, with several rocky shores displaying high substrate coverage. Apart from its singular invasiveness capacity, the documentation and, therefore, understanding of the role of symbiotic microorganisms in the sun-coral invasion is still scarce. However, in general, the broad and constant relationship between corals and microorganisms led to the development of co-evolution hypotheses. As such, it has been shown that the microbial community responds to environmental factors, adjustment of the holobiont, adapting its microbiome, and improving the hosts' fitness in a short space of time. Here we describe the microbial community (i.e. Bacteria) associated with sun-coral larvae and adult colonies from a locality displaying a high invasion development. RESULTS: The usage of high throughput sequencing indicates a great diversity of Bacteria associated with T. tagusensis, with Cyanobacteria, Proteobacteria, Bacteroidetes, Actinobacteria, Planctomycetes, and Firmicutes corresponding to the majority of the microbiome in all samples. However, T. tagusensis' microbial core consists of only eight genera for colonies, and, within them, three are also present in the sequenced larvae. Overall, the microbiome from colonies sampled at different depths did not show significant differences. The microbiome of the larvae suggests a partial vertical transfer of the microbial core in this species. CONCLUSION: Although diverse, the microbiome core of adult Tubastraea tagusensis is composed of only eight genera, of which three are transferred from the mother colony to their larvae. The remaining bacteria genera are acquired from the seawater, indicating that they might play a role in the host fitness and, therefore, facilitate the sun-coral invasion in the Southwestern Atlantic.

Description of the mitochondrial genome of the tree coral Dendrophyllia arbuscula (Anthozoa, Scleractinia).

Dendrophylliidae is one of the few monophyletic families within the Scleractinia that embraces zooxanthellate and azooxanthellate species represented by both solitary and colonial forms. Among the exclusively azooxanthellate genera, Dendrophyllia is reported worldwide from 1 to 1200 m deep. To date, although three complete mitochondrial (mt) genomes from representatives of the family are available, only that from Turbinaria peltata has been formally published. Here we describe the complete nucleotide sequence of the mt genome from Dendrophyllia arbuscula that is 19 069 bp in length and comprises two rDNAs, two tRNAs, and 13 protein-coding genes arranged in the canonical scleractinian mt gene order. No genes overlap, resulting in the presence of 18 intergenic spacers and one of the longest scleractinian mt genome sequenced to date.

Mitochondrial genome rearrangements in the scleractinia/corallimorpharia complex: implications for coral phylogeny.

Corallimorpharia is a small Order of skeleton-less animals that is closely related to the reef-building corals (Scleractinia) and of fundamental interest in the context of understanding the potential impacts of climate change in the future on coral reefs. The relationship between the nominal Orders Corallimorpharia and Scleractinia is controversial-the former is either the closest outgroup to the Scleractinia or alternatively is derived from corals via skeleton loss. This latter scenario, the "naked coral" hypothesis, is strongly supported by analyses based on mitochondrial (mt) protein sequences, whereas the former is equally strongly supported by analyses of mt nucleotide sequences. The "naked coral" hypothesis seeks to link skeleton loss in the putative ancestor of corallimorpharians with a period of elevated oceanic CO2 during the Cretaceous, leading to the idea that these skeleton-less animals may be harbingers for the fate of coral reefs under global climate change. In an attempt to better understand their evolutionary relationships, we examined mt genome organization in a representative range (12 species, representing 3 of the 4 extant families) of corallimorpharians and compared these patterns with other Hexacorallia. The most surprising finding was that mt genome organization in Corallimorphus profundus, a deep-water species that is the most scleractinian-like of all corallimorpharians on the basis of morphology, was much more similar to the common scleractinian pattern than to those of other corallimorpharians. This finding is consistent with the idea that C. profundus represents a key position in the coral <-> corallimorpharian transition.

Novel organization of the mitochondrial genome in the deep-sea coral, Madrepora oculata (Hexacorallia, Scleractinia, Oculinidae) and its taxonomic implications.

Madrepora is one of the most ecologically important genera of reef-building scleractinians in the deep sea, occurring from tropical to high-latitude regions. Despite this, the taxonomic affinities and relationships within the genus Madrepora remain unclear. To clarify these issues, we sequenced the mitochondrial (mt) genome of the most widespread Madrepora species, M. oculata, and compared this with data for other scleractinians. The architecture of the M. oculata mt genome was very similar to that of other scleractinians, except for a novel gene rearrangement affecting only cox2 and cox3. This pattern of gene organization was common to four geographically distinct M. oculata individuals as well as the congeneric species M. minutiseptum, but was not shared by other genera that are closely related on the basis of cox1 sequence analysis nor other oculinids, suggesting that it might be unique to Madrepora.

A pesca demersal de profundidade e os bancos de corais azooxantelados do sul do Brasil / The deep-sea demersal fisheries and the azooxanthellate corals from southern Brazil

A pesca demersal voltada as espécies de peixes (i.e. Lophius gastrophisus, Urophisys brasiliensis, Genipterus brasiliensis) e crustáceos (Chaceon ramosae e Chaceon sp.), com grande valor comercial no talude continental superior do sul do Brasil aumentou significativamente nas últimas décadas. A compilação de todos os dados até então publicados acerca dos pontos de ocorrência dos corais escleractíneos azooxantelados em águas sul-brasileiras entre 24º e 35º S, sobrepostos com as principais áreas de atuação das quatro modalidades de pesca demersais (arrasto de profundidade, emalhe e espinhel de fundo e covos), demonstrou que as frotas em questão vêm utilizando as áreas com ocorrência de corais, como principais áreas de esforço, indicando que os recifes de profundidade possuem elevada importância ecológica perante os ecossistemas da plataforma e talude continental, sendo importantes reservatórios da biodiversidade marinha profunda. Entretanto, desde as fases iniciais desta exploração evidenciou-se através de relatos de observadores de bordo, a captura, como "bycatch", de grandes quantidades de corais de profundidade. Desta maneira, visando não só apenas a proteção dos ecossistemas coralíneos de profundidade, mas também a sustentabilidade econômica da pesca, é recomendada a criação de áreas de exclusão da pesca demersal em locais com ocorrência de Scleractinia azooxantelados.

Demersal fishing of important commercial fishes (Lophius gastrophisus, Urophisys brasiliensis and Genipterus brasiliensis) and crustaceans (Chaceon ramosae and Chaceon sp.) along the upper slope off southern Brazil has increased dramatically in the last decade. Compilation of available data on the distribution of azooxanthellate corals between 24º and 35º S, compared with the distribution of bottom-longline, bottom-gillnets, trawl and trap fisheries shows that commercial fishing takes place over coral areas, providing evidence deep-sea reefs are important reservoirs of deep marine biodiversity. Since the initial phase of exploitation by demersal fisheries, onboard observers are describing large captures of corals as "bycatch" suggesting deep-sea communities are being destroyed even before being studied. In order to ensure protection of deep-sea coral ecosystems and economic sustainability of demersal fisheries in southern Brazilian waters, adoption of excluded fishing areas in those locations where azooxanthellate Scleractinia occur is strongly recommended.