Tropical Southwestern Atlantic Research Articles

Distribution and New Records of the Bluntnose Sixgill Shark, Hexanchus griseus (Hexanchiformes: Hexanchidae), from the Tropical Southwestern Atlantic

The bluntnose sixgill shark, Hexanchus griseus, is a widely distributed demersal species found in tropical and temperate waters of the Pacific, Atlantic, and Indian Oceans, inhabiting continental shelves and slopes, islands, and mid-ocean ridges at depths ranging from 200 to 1100 m. In the Southwestern Atlantic, this species has been recorded from northeastern to southern Brazil, Argentina, and Uruguay. Despite this, the known distribution of this species in the Southwestern Atlantic is very patchy and, in some cases, still mostly ignored in the literature, such as in northeastern Brazil. This study, therefore, aimed to report 23 new records of Hexanchus griseus in the Tropical Southwestern Atlantic and highlight the presence of this species off the northeastern Brazilian coast. So far, Hexanchus griseus was officially reported from the Fernando de Noronha Archipelago, Saint Peter and Saint Paul Archipelago, and the state of Ceará along the northeast coast of Brazil. Herein, the known distribution is extended to the continental shelf breaks and upper slopes of other Brazilian states, reinforcing the previously reported occurrence of the species near the Saint Peter and Saint Paul Archipelago.

Lionfish on the loose: Pterois invade shallow habitats in the tropical southwestern Atlantic

Lionfish (Pterois spp.) evolved in the Indo-Pacific with predators and prey and invaded regions (e.g., the Caribbean Sea and Mediterranean) where no such balance yet exists. In 2020, four lionfish were recorded on mesophotic reefs of the Amazon offshore Coast and Fernando de Noronha Archipelago. However, until now, there were no records of invasive lionfish in Brazilian nearshore waters or even such a high number of individuals. In this article, we report the continuing invasion process along the Brazilian Province by multiple sightings (72) of lionfish from March to May 2022 in estuaries, seagrass beds, and artificial and natural reefs across 240 km of the Brazilian coast. These are the first records of lionfish in coastal northeast Brazil and the shallowest records (1–16 m) from South Atlantic tropical waters. The largest simultaneous records of lionfish in breakwaters, fishing weirs, and marambaias (artificial reefs used as fishing grounds) on the Brazilian Northeastern coast indicate that these man-made structures are suitable habitats for this species. Most of the lionfish (58%) were recorded in artificial reefs and fishing weirs. Moreover, the detection of invasions in marginal reefs, estuaries, and two marine protected areas characterized by moderately turbid water and high sedimentation rates highlights the adaptability of the lionfish, making it extremely difficult for divers and fishers to capture them. We call for an urgent management plan considering that the invaded tropical region hosts a high level of endemism, and rare and/or cryptic taxa, which increases the risk of impacts since these are primary lionfish prey.

Ocean warming and increased salinity threaten Bostrychia (Rhodophyta) species from genetically divergent populations

Increased greenhouse gas concentrations in the Earth's atmosphere have resulted in global change, such as ocean warming and sea level rise. Increased salinity in estuaries is expected as a result of sea level rise and warming. Thus, we analysed the interactive effects of increased temperature and salinity on multiple physiological responses of Bostrychia montagnei and B. calliptera from two biogeographic provinces, Tropical Southwestern Atlantic (TSA) and Warm Temperate Southwestern Atlantic (WTSA). Macroalgae were cultured under three salinities (15, 25 and 35 PSU) and three temperatures: mean sea surface temperature (SST: 27 °C for TSA and 24 °C for WTSA), an RCP8.5 ocean warming scenario (SST + 5 °C), and a maximum temperature to test the algal upper thermal tolerance limits (RCP8.5 + 2 °C). Macroalgae from both localities decreased their growth under increased temperature and salinity. RCP8.5 + 2 °C was lethal for both macroalgae from TSA. RCP8.5 and RCP8.5 + 2 °C at 35 PSU were lethal for B. calliptera from WTSA, due to the interactive effects between increased temperature and salinity. Overall, increased salinity decreased the effective quantum yield and relative electron transport rate in algal photosynthesis. Our results demonstrated that the macroalgae synthesized proteins, carbohydrates (polysaccharides and low molecular weight carbohydrates), and antioxidants to tolerate detrimental temperatures and salinities. Our results also demonstrated that the macroalgae adjusted their pigment contents (phycobiliproteins, total carotenoids, and chlorophyll a) for efficient light-harvesting under thermal and saline stress. Our findings suggest that ocean warming and increased salinity in estuaries will be detrimental to B. montagnei and B. calliptera populations from both biogeographic provinces, especially to those from TSA that already live closer to their upper thermal tolerance limits.

Trophic structure of coastal meta-ecosystems in the tropical Southwestern Atlantic

Coastal and oceanic ecosystems have their own structural and functional dynamics, but they are typically connected by the transfer of nutrients and organisms. These organic matter and energy flows mean these environments function as a meta-ecosystem. In the tropics, the transfers between estuaries and the neritic ecosystems or nearshore can be driven by estuarization events, which are poorly understood. Here, we analyze the effects of seasonal estuarization on the trophic structure of estuarine and neritic ecosystems connected by biological and physical flows in space and time. Specifically, we evaluated trophic connectivity and the flow of fish species from the South Atlantic, based on the assumption of meta-ecosystem functionality. We used standard sampling gear and fishing effort to evaluate the estuarine and neritic ecosystems during the dry and the rainy seasons of the region. The diet and trophic niche of fish species were estimated for both environments. We also reconstructed the trophic connections between species and food items for each season to evaluate the changes in the food web of each environment. During the dry season, the estuarine and neritic ecosystems are both characterized by a simpler trophic structure in terms of biomass distribution among trophic levels, but in the rainy season, the migration of species associated with estuarine and oceanic ecosystems to the neritic ecosystem changed the trophic structure of this area. The movements of organisms between ecosystems increases the complexity of the trophic structure of neritic ecosystem, allowing the transfers of organic matter and energy, confirming this complex as a meta-ecosystem.

Five new species of Western Atlantic stardrums, Stellifer (Perciformes: Sciaenidae) with a key to Atlantic Stellifer species.

Five new species of Stellifer are described from the Caribbean Sea and tropical southwestern Atlantic. Among the previously recognized stelliferine genera, Stellifer is unique by having a pair of variably developed appendages on the posterior margin of the anterior gas chamber, which is lacking in Bairdiella, Corvula, Elattarchus, Odontoscion and Ophioscion. However, recent genetic studies indicated that Stellifer and Ophioscion are not monophyletic. The genus Ophioscion Gill, 1863 is recognized herein as a junior synonym of Stellifer Oken, 1817. Of the five new species described, Stellifer cervigoni n. sp., S. collettei n. sp., and S. musicki n. sp. have a pair of knob-like diverticula along the posterior margin of the anterior gas chamber, which is absent in S. macallisteri n. sp., and S. menezesi n. sp. Stellifer cervigoni n. sp. is found along the southern Caribbean coast of Colombia and Venezuela; it can be distinguished from other species by having a jet-black roof of mouth and inner opercular lining. Stellifer collettei n. sp. is found from Surinam to southeastern Brazil, while S. musicki n. sp. is endemic to northern Brazil. Stellifer macallisteri n. sp. has an oblique, terminal mouth and it is found in Colombia, Venezuela and Dominican Republic. Stellifer menezesi n. sp. has a subterminal mouth and is found from northeastern to southeastern Brazil. These results bring the number of valid species of Stellifer in the Atlantic to 18, and a key to the identification of these species is included.

Impacts of a changing environment on marginal coral reefs in the Tropical Southwestern Atlantic

The peculiar shallow-water reefs of the Tropical Southwestern Atlantic Ocean have thrived in conditions considered suboptimal (e.g., moderate turbidity, higher level of nutrients, and resuspension of sediments) under the optics of classical coral reefs. Recently, these marginal reefs have been hypothesized to provide climate-change refugia from natural and anthropogenic impacts; yet with little empirical evidence. Therefore, in this article we discuss the known effects of multiple pressures on the Brazilian reefs. A wide evaluation of the peer reviewed literature reported that bleaching events affected 26 species of scleractinians, hydrocorals, octocorals, and zoanthids in turbid-zone reefs over the last 26 years (1994–2020) in the Tropical SW Atlantic Brazil. Between 1994 and 2018 no species suffered post-bleaching mass mortality. However, the recent and intense heatwaves of 2019 and 2020 caused higher mortality rates in several key foundation corals (e.g., Millepora alcicornis, Millepora braziliensis, and Mussismilia harttii) showing that the SW Atlantic reefs are not long-term protected and universal refuges. Moreover, other direct and indirect human pressures threaten these tropical reefs. Local and regional (e.g., pollution and fisheries) and large-scale pressures (e.g., global warming and marine heatwaves) act simultaneously on the health of these reefs, which intensifies negative species-specific impacts. We outline the occurrence of pressures that have been important factors responsible for the reduction in species richness and reef fish biomass, changing geo-ecological functions, altered reef composition and dominant morpho-functional groups, as well as phase shifts. Along with large-scale climatic changes, such as heatwaves, fisheries, urbanization, mining disasters, oil spills, increased sedimentation, increased warming, marine debris, contamination by domestic, agricultural, and industrial effluents, and introduction of invasive species are likely the most severe pressures on Brazilian reefs. We discuss that the “Brazilian reef refuge hypothesis” could be partially applied for some stress-tolerant massive corals during acute disturbances (short-term refuge); yet should not be assumed as a reef ecosystem-wide feature under ongoing environmental change. Therefore, we argue that it is essential to alleviate the main local and regional human impacts and to adopt resilient-based management strategies at local and global scales to protect the low-functional redundancy and higher endemism of these unique marginal coral reefs.

Spatial and temporal patterns of spawning aggregations of fish from the Epinephelidae and Lutjanidae families: An analysis by the local ecological knowledge of fishermen in the Tropical Southwestern Atlantic

Local knowledge is a fundamental source of information for starting spawning aggregation studies in areas where this phenomenon is still unknown or little studied. Among the species that present this reproductive strategy, groupers and snapper represent two of the most relevant components of artisanal and commercial capture worldwide and are highly susceptible to overfishing. We conducted interview-based surveys to examine if local ecological knowledge can determine potential areas of spawning aggregations in southeast Brazil. Fifty-one local fishermen targeting groupers and snappers were asked about spawning aggregation areas and seasonality using charts and geographic information system (GIS) analysis. Information was obtained for 31 potential spawning aggregation sites, where black grouper (Mycteroperca bonaci) represented the most important resource for the fishermen interviewed, followed by yellowtail snapper (Ocyurus chrysurus). In addition, red grouper (Epinephelus morio), mutton snapper (Lutjanus analis) and dog snapper (Lutjanus jocu) were also mentioned as important resources that have spawning in aggregation as a reproductive strategy. The main possible spawning aggregation areas indicated occur within the Abrolhos Bank, the largest and richest reef complex in the South Atlantic. The lack of published records of spawning aggregations in Brazil, hinders the suitable implementation of measures that can protect this phenomenon and consequently the perpetuation of these and potentially other species. Therefore, additional studies and particularly in situ validation, are needed to determine the occurrence and status of the aforementioned aggregations.

Sustainability of the seaweed Hypnea pseudomusciformis farming in the tropical Southwestern Atlantic

Seaweed culture is generally referred to as a sustainable production system. Nevertheless, this concept is biased by an environmental approach only, neglecting the economic and social dimensions of sustainability. The objective of this study was to assess the sustainability of the seaweedHypnea pseudomusciformiscultivation and its use as human food consumption. We developed a pilot farming with the Association of Algae Producers of Flecheiras and Guajiru, in the municipality of Trairi, Northeastern Brazil. We applied a set of indicators to access environmental, social, and economic dimensions of sustainability. The environmental indicators showed highly efficient use of energy, nitrogen and phosphorus, which increased in the algae biomass during culture by 383%, 894%, and 1860%, respectively. Besides, H. pseudomusciformis culture absorbs carbon, does not pollute, and shows low risk to the local biodiversity because of it is a native species. Social indicators revealed that 51% of all investment stays in the local community, and the income distribution is equal among workers. The farm presented a high labor demand, which is socially inclusive. The H. pseudomusciformis farm was highly profitable, with an internal rate of return of 119%, recovery of invested capital in 1.2 years and positive externalities, generating 262.00 US$.t−1 as additional income. The farm showed high performance in the environmental, economic, and social dimensions of sustainability. Thus, this activity may be a sustainable manner to produce high-quality human food and raw materials for industry. The results obtained in the present study provide secure information for farmers, investors, and policymakers, which may encourage small and medium farmers to start seaweed farming in tropical Atlantic Southwestern coast.

Integrative taxonomy reveals extreme morphological conservatism in sympatricMugilspecies from the Tropical Southwestern Atlantic

Integrative taxonomy reveals extreme morphological conservatism in sympatric<i>Mugil</i>species from the Tropical Southwestern Atlantic

First description of seagrass meadows from Fernando de Noronha archipelago in the tropical Southwestern Atlantic

Abstract Global challenges for seagrass conservation include increasing societal recognition of the importance of seagrass and assessing its distribution and status. We present the first characterization of a Halodule wrightii meadow in the Fernando de Noronha Archipelago, Brazil. The seagrass was registered in Sueste Bay, which is the most sheltered coastal environment of the archipelago and is also where the only mangrove on a Brazilian oceanic island is located. The mean shoot density was 6690 ± 2670 shoots.m−2, the mean aboveground and belowground biomasses were 15.33 ± 8.46 gDW.m−2 and 69.51 ± 61.65 gDWm−2, respectively. Additionally, the mean leaf length and width were 7.7 ± 1.7 cm and 0.05 ± 0.02 mm, respectively. In Fernando de Noronha, H. wrightii is a food source for sea turtles and is probably the only seagrass population on the Northeastern coast that was not affected by the crude oil spill that reached the Brazilian coast in 2019. Our results represent an essential starting point for raising awareness about the importance of seagrass in one of the most important marine protected areas on the Brazilian coast.

Integrative taxonomy identifies a new stingray species of the genus Hypanus Rafinesque, 1818 (Dasyatidae, Myliobatiformes), from the Tropical Southwestern Atlantic.

An integrative approach by the congruence of genetics, morphology and ecological niche modelling (ENM) was used to delimit a new species of Hypanus (Rafinesque, 1818), a recently resurrected genus of marine stingrays comprising eight species, five of which occur in the western Atlantic. The species with the widest distribution, Hypanus americanus (Hildebrand and Schroeder, 1928), from the northeastern coast of the United States to southeastern Brazil, was demonstrated to be paraphyletic based on protein-coding mitochondrial genome analyses. This data set also indicates that the genetic distance between the new species Hypanus berthalutzae sp. nov. and its three closely related species (H. americanus, H. longus and H. rudis) varies from 0.82% to 3.14%. In addition, Bayesian Analysis of Population Similarity using the mitochondrial gene mt-nd2 supports the separation of H. berthalutzae sp. nov. (southwestern Atlantic) from its sister species H. rudis (eastern Atlantic). Similarly, morphological and morphometric analyses corroborated four morphotypes within the H. americanus species group and indicated the ventral caudal fold height and length and interspiracular and interorbital lengths as useful measurements to distinguish among them. Claspers of adult males also exhibit morphological differences among species. The ENM agreed with molecular and morphological analyses and delimits the distribution of H. berthalutzae sp. nov. to shallow areas close to shore along the Brazilian coast, from the mouth of the Amazon River to São Paulo State, including the northeastern oceanic islands, suggesting that the great outflow of fresh water and sediments and the Mid-Atlantic Ridge might act as barriers. The integration of these data to describe a new species provides information relevant to their conservation status, because all species of the H. americanus species group are under the "data-deficient" status.

Echinodermata from Barra de Mamanguape, Northeast of Brazil, Tropical Southwestern Atlantic

The Mamanguape River estuary represents an important environment for marine species, where there are the combination of soft-bottoms and reefs zones. The present study reports on the echinoderm species inhabiting Barra de Mamanguape, at Northeast coast of Brazil. A total of 83 specimens were analyzed, belonging to 13 species, 10 families and the classes Crinoidea, Ophiuroidea, Echinoidea and Holothuroidea. The Ophiuroidea was the most representative with seven species. The crinoid Tropiometra carinata (Lamarck, 1816) and the ophiuroid Ophiophragmus luetkeni (Ljungman, 1872) were new records for Paraiba coast. Concise taxonomic descriptions, figures and ecological notes for recorded species were provided. Comparisons between young and adult specimens of Ophioderma appressa (Say, 1825) were included. This brings information about the arrangement of species in the ecosystem, besides contributes to fill knowledge gaps about echinoderms from Northeast coast.

Geometric morphometrics as a tool to identify species in multispecific flatfish landings in the Tropical Southwestern Atlantic

Fisheries statistics of many countries are still limited by the use of common names in multispecific captures, where little is known about the correct taxonomic identification of captured species. Homonymy is a known obstacle for commercially exploited Pleuronectiformes, traditionally grouped as flatfishes in Brazilian fisheries statistics. The present study was based on visits to 14 artisanal fish landing points and four industrial landing sites along the coast of Rio de Janeiro, in the southwestern Atlantic, between 2013 and 2016. A total of 176 Pleuronectiformes specimens were collected under the flatfish category. Standardized and scaled images were used for a geometric morphometric analysis based on anatomical landmarks in order to identify how species were distributed in the morphospace and to point out diagnostic character not used by the known literature for the group. A total of four different groups were identified as the main target for the commercial flatfish category, being associated with four species of Paralichthyidae: Paralichthys isosceles Jordan, 1891, P. patagonicus Jordan, 1889, P. orbignyanus (Valenciennes, 1839) and Xystreurys rasile (Jordan, 1891). A canonical analysis independently isolated P. isosceles and X. rasile, while strongly associating P. patagonicus and P. orbignyanus. These results were corroborated by an UPGMA analysis of Procrustes distances based on the consensus form. The analysis identified that tail shape and relative eye and jaw positions are of significant importance for species separation. The combination of the results of the analysis and specific ocelli positioning allowed for the selection of diagnostic characters for all species without the need for laboratory examinations. Conflicts between the literature and the specific composition of flatfish landings are also discussed. Geometric morphometrics were demonstrated herein as useful not only in quantifying differences in scarcely studied body parts, but also as a tool able to identify the consistency of a multispecies commercial category used by the fishery statistics, as well as useful in pointing out characteristics capable of dismembering flatfishes into monospecific categories.

Vertical distribution and structure of copepod (Arthropoda: Copepoda) assemblages in two different seasons down to 1,200 m in the tropical Southwestern Atlantic

The vertical distribution of copepod assemblages, ascertained from the surface down to 1,200 m, was investigated during two sampling periods (rainy and dry seasons), at four depths, in the oligotrophic waters of the southwestern Atlantic Ocean. Total density, diversity, and richness differed among sampling depths. Copepod density decreased with depth in the two sampling periods, with a maximum at 1 m and a slight decrease at 800 m. Higher diversities were observed at 250 m and 1,200 m during the rainy season and at 1 m and 1,200 m during the dry season. The maximum number of species was found at 1,200 m during the rainy season and at 1 m during the dry season. Various copepod assemblages were delimited in the water column in the two sampling periods. The deeper copepod assemblages occupied a wider range of depths. Salinity and temperature influenced the structure of copepod assemblages and reflected the hydrographic characteristics of the water masses in the region. Candaciapachydactyla (Dana, 1849), Scolecithrixdanae (Lubbock, 1856), and Agetuslimbatus (Brady, 1883) were the indicator species found at 1 m. The effects of different environmental factors on the copepod assemblages suggest that these consortia occupy distinct niches in the ocean.

Trophic relationships in tidepool fish assemblages of the tropical Southwestern Atlantic

AbstractTrophic studies are fundamental to understanding the dynamics of assemblages and functional roles of species within ecosystems, contributing to the identification of factors responsible for the organization and structure of communities. This study aimed to analyse the trophic organization of tidepool fish assemblages in the tropical Southwestern Atlantic, based on the underlying idea that food resources are not limiting and that trophic guild formation is not driven by food competition. Diets were based on feeding index values of food categories for 12 representative species collected in six tidepools (20º49′ S, 40º36′ W) at quarterly intervals (2005 to 2007). The main food categories were small crustaceans, polychaetes and macroalgae. Multivariate techniques evidenced two multispecific trophic guilds: small‐prey carnivores, including Bathygobius soporator, Bathygobius geminatus, Malacoctenus delalandii and Halichoeres poeyi, and herbivores, including Sparisoma axillare and Acanthurus bahianus. Other species presented significantly different diets and were classified into the following guilds: omnivores feeding on filamentous algae and copepods (Abudefduf saxatilis); large‐prey carnivores (Labrisomus nuchipinnis); omnivores feeding on polychaetes and filamentous algae (Stegastes fuscus); and polychaete feeders (Ahlia egmontis). Gymnothorax funebris and Gymnothorax moringa were classified as carcinophagores and piscivores, respectively. Trophic organization appears related to species convergence toward the use of abundant food resources, driven by a combination of factors allowing some resource partitioning through inter‐specific differences in consumer size, microhabitat, behavior, and trophic specialization.

Growth models of Rhizophora mangle L. seedlings in tropical southwestern Atlantic

The present study selected and compared regression models that best describe the growth curves of Rhizophora mangle seedlings based on the height (cm) and time (days) variables. The Linear, Exponential, Power Law, Monomolecular, Logistic, and Gompertz models were adjusted with non-linear formulations and minimization of the sum of the squares of the residues. The Akaike Information Criterion was used to select the best model for each seedling. After this selection, the determination coefficient, which evaluates how well a model describes height variation as a time function, was inspected. Differing from the classic population ecology studies, the Monomolecular, Three-parameter Logistic, and Gompertz models presented the best performance in describing growth, suggesting they are the most adequate options for long-term studies. The different growth curves reflect the complexity of stem growth at the seedling stage for R. mangle. The analysis of the joint distribution of the parameters initial height, growth rate, and, asymptotic size allowed the study of the species ecological attributes and to observe its intraspecific variability in each model. Our results provide a basis for interpretation of the dynamics of seedlings growth during their establishment in a mature forest, as well as its regeneration processes.

Toxin production, growth kinetics and molecular characterization of Ostreopsis cf. ovata isolated from Todos os Santos Bay, tropical southwestern Atlantic

The toxin profile and hemolytic activity of a strain of Ostreopsis cf. ovata (UFBA013) isolated from Todos os Santos Bay (northeastern Brazil) were evaluated under different levels of N and P. Phylogenetic analyses based on ITS rDNA region (ITS1-5.8S-ITS2) placed UFBA013 within the Atlantic/Mediterranean/Pacific clade of O. cf. ovata. Growth experiments were conducted in f/2 medium modified by adding N and P (P: 0–36 μM; N: 0–882 μM). The growth kinetics was adequately described by logistic equations. The best growth (highest Gm) was recorded under levels of N/P = 0/18, 129/5 and 441/36, while one of the lowest Gm was obtained under P-depletion. The maximum and specific maximum growth rates (as vm; cells mL−1 d−1 and μm; d−1) were achieved with N limitation (N/P = 441/36) and P-limitation/depletion (753/5.3 and 441/0) and are the highest values reported in the literature, most similar to isolates from Pacific and Mediterranean areas. The control experiment (N/P = 441/18) also yielded similar values to those from some Mediterranean isolates, but higher than formerly reported for Brazilian isolates. In all conditions assayed, no palytoxin (PLTX) was detected. The ovatoxins (OVTXs) a, b, c, d and e did not show significant differences in cell quota between exponential and stationary phases. A significant relationship was detected between OVTXs concentration and hemolytic activity.

Composition and cross-shelf distribution of ichthyoplankton in the Tropical Southwestern Atlantic

The spatial distribution, abundance, and composition of ichthyoplankton are key ecological features for the conservation of biodiversity and sustainability of fisheries. Despite their importance, knowledge about these features in the equatorial waters of the planet is still scarce. The aim of this study was to assess these features in the Tropical Southwestern Atlantic (northeastern Brazil). Two oceanographic cruises were carried out (2010) on the continental shelf. The collections were performed at 54 stations distributed in three coast parallel profiles covering a wide geographical area (20,100km2). A total of 3723 fish larvae and 3829 fish eggs were sampled. Larval identification resulted in 15 taxa belonging to 13 families. Eggs of family Engraulidae were the most abundant and represented 40.8% of the total eggs. The largest concentration of fish larvae and eggs was found on the outer shelf, because of the mixture of coastal and oceanic species. On the continental shelf, the abundance of fish larvae was higher near the marine protected area, mesophotic reefs and large tropical mangrove ecosystems. The present results provide a baseline assessment of a poorly studied region of the planet along a coast with high turbidity, and sea surface temperatures. Moreover, the results highlight the need for rigorous monitoring to detect shifts in diversity and abundance of ichthyoplankton on a continental shelf with a large number of rich tropical ecosystems.

Contrasting patterns of connectivity among endemic and widespread fire coral species (Millepora spp.) in the tropical Southwestern Atlantic

Fire corals are the only branching corals in the South Atlantic and provide an important ecological role as habitat-builders in the region. With three endemic species (Millepora brazilensis, M. nitida and M. laboreli) and one amphi-Atlantic species (M. alcicornis), fire coral diversity in the Brazilian Province rivals that of the Caribbean Province. Phylogenetic relationships and patterns of population genetic structure and diversity were investigated in all four fire coral species occurring in the Brazilian Province to understand patterns of speciation and biogeography in the genus. A total of 273 colonies from the four species were collected from 17 locations spanning their geographic ranges. Sequences from the 16S ribosomal DNA (rDNA) were used to evaluate phylogenetic relationships. Patterns in genetic diversity and connectivity were inferred by measures of molecular diversity, analyses of molecular variance, pairwise differentiation, and by spatial analyses of molecular variance. Morphometrics of the endemic species M. braziliensis and M. nitida were evaluated by discriminant function analysis; macro-morphological characters were not sufficient to distinguish the two species. Genetic analyses showed that, although they are closely related, each species forms a well-supported clade. Furthermore, the endemic species characterized a distinct biogeographic barrier: M. braziliensis is restricted to the north of the Sao Francisco River, whereas M. nitida occurs only to the south. Millepora laboreli is restricted to a single location and has low genetic diversity. In contrast, the amphi-Atlantic species M. alcicornis shows high genetic connectivity within the Brazilian Province, and within the Caribbean Province (including Bermuda), despite low levels of gene flow between these populations and across the tropical Atlantic. These patterns reflect the importance of the Amazon–Orinoco Plume and the Mid-Atlantic Barrier as biogeographic barriers, and suggest that, while M. alcicornis is capable of long-distance dispersal, the three endemics have restricted ranges and more limited dispersal capabilities.

Occurrence of Octopus insularis Leite and Haimovici, 2008 in the Tropical Northwestern Atlantic and implications of species misidentification to octopus fisheries management

The genus Octopus has been treated as a “catch all” taxon because many species have morphological similarities. To investigate the taxonomic status of the Octopus species in the Tropical Northwestern Atlantic (TNA) and the Tropical Southwestern Atlantic (TSA), we sampled Octopus insularis Leite and Haimovici, 2008 in three areas of the northeastern Brazilian coast, four Brazilian oceanic islands and one island in Western Caribbean, Mexico. Samples of Octopus maya Voss and Solis, 1966 were obtained from the cultivation center of the Universidad Nacional Autonoma de Mexico (UNAM) in Sisal city. Specimens previously identified as Octopus vulgaris Cuvier, 1797 were collected in two regions of southeast Brazil, in an industrial port in Progreso city (southern Gulf of Mexico) and from a fish market in Isla Mujeres, Mexico (Western Caribbean). Molecular species attribution was completed based on morphology of fresh specimens identified by an octopus specialist and then checked against previous identification (cultivation center and GenBank sequences). Molecular analysis of both mitochondrial (cytochrome oxidase I) and nuclear genes (elongation factor-1α), including GenBank data, confirmed that one specimen collected at the Western Caribbean from Mexico and identified as O. insularis, shared the same haplotype of the species from the type locality, indicating the occurrence of this species in the Caribbean Sea. Phylogenetic analyses indicated that 21 GenBank sequences from TNA identified as O. vulgaris grouped within the O. insularis clade and are most likely to be to the latter species. The COI analysis also showed that 18 individuals collected in fishing landings and fish markets, previously identified as O. vulgaris, had the identical haplotype of O. maya collected in the UNAM cultivation center. These results corroborate the misidentification of species in Mexican fisheries. Based on molecular and morphological data we extended the distribution of O. insularis to the TNA and revealed cases of misidentification among the most commercially exploited octopus species in this region.