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Background: Like all cnidarians, the subclass Ceriantharia (Cnidaria, Anthozoa) is known for producing cnidocysts, which mainly serve for prey immobilization, predator defense, and locomotion. Aim: The present study aimed to understand the variability of the cnidom, i.e., the inventory of all cnidocyst types, in the ceriantharians (tube anemones) Ceriantheomorphe brasiliensis (10 individuals) and Cerianthus sp. (seven individuals). Methods: In each individual, 30 intact cnidocysts of each identified type were measured in the following parts of tube anemones: marginal tentacles (four from each individual), labial tentacles (four from each individual), column, actinopharynx and metamesenteries. Each of these structures was divided into three levels (high, middle, and low) and the cnidom was analyzed. Statistical descriptive parameters (mean, standard deviation, minimum and maximum) of the sizes of all types of cnidocysts were calculated. The normality of the data for cnidocyst length was assessed using a Shapiro-Wilk test (α = 0.05). Based on the acceptance or rejection of the normality, either linear models or generalized linear models were used to evaluate variations in cnidocyst lengths. The normality of the cnidocyst length was tested by Shapiro-Wilk, and due to its rejection, generalized linear mixed models were applied to test the cnidocyst lengths variations. Results: The analysis of Ceriantheomorphe brasiliensis revealed 23 categories of cnidocysts, thereby expanding the understanding of its cnidome. The cnidoms of Ceriantheomorphe brasiliensis and Cerianthus sp. presented intraspecific variations, both qualitatively and in the lengths of cnidocysts. The cnidoms of the two species studied also showed qualitative intra-individual variations between different levels (high, middle, low) within each structure of the tube anemone (tentacles, actinopharynx, column and metamesenteries). Some cnidocyst types, such as atrichs from the column of C. brasiliensis, presented a length gradient along the column, from larger lengths at the "low" level to smaller lengths at the "high" level. Conclusions: The cnidom of a tube anemone could be better described if samples are taken at different levels of the structures, as observed in C. brasiliensis. In addition, we can conclude that the cnidocyst lengths of both C. brasiliensis and Cerianthus sp. present intraspecific variation, which is coincident with that observed in actiniarian sea anemones. Moreover, as main conclusion, this work also proved that individuals of tube anemone species could present qualitative intra-structure variations in both the cnidom and cnidocyst lengths. This characteristic appears as an exception in cnidom variations, and has so far not been recorded even in the most studied actiniarian sea anemones. Finally, the intra-structure cnidocyst variations could reveal different functions of the different levels of a particular body part of the organisms.

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Trindade Island is an important wildlife refuge in the South Atlantic Ocean and hosts the largest nesting population of green turtles (Chelonia mydas) in Brazil, about which temporal ecological dynamics are still not well understood. The present study examines 23 years of nesting for green turtles at this remote island to evaluate annual mean nesting size (MNS) changes and post-maturity somatic growth rates. Our results show a significant decrease in annual MNS over the study; Whereas MNS during the first three consecutively monitored years (1993-1995) was 115.1 ± 5.4 cm, during the last three years (2014-2016) it was 111.2 ± 6.3 cm. There was no significant change in post-maturity somatic growth rate over the course of the study; the mean annual growth rate was 0.25 ± 0.62 cm/year. These findings suggest an increase in the relative proportion of smaller, presumptive neophyte nesters appearing in Trindade during the study period.

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Scytosiphon is a common intertidal genus widely distributed on temperate coasts worldwide. Recently, eight species have been delimited with molecular tools. Although S. lomentaria is the only species that predominates in the macroalgal literature of the Southwestern Atlantic Ocean (SwAO), unpublished molecular data obtained for a population study of S. lomentaria revealed hidden species diversity of Scytosiphon among the individuals collected from four localities at the SwAO. The aim of this study was to revise the identity and phylogenetic relationships of Scytosiphon from temperate coasts of the SwAO using DNA data. Thalli were collected from the Argentinean coast between 39° S and 43° S, from which cox1 and rbcL gene sequences were obtained. Phylogenies and haplotype networks were inferred and morphology of gametophytes was studied. Four species were recognized, S. lomentaria, S. promiscuus, S. shibazakiorum, and one species that belongs to a complex of species known as "Scytosiphon Atlantic complex." This complex was known to occur only in the North Atlantic, however, the results found in this study revealed that it has an extended distribution range that includes the southern hemisphere, where its populations have high genetic diversity and unique haplotypes. The morphological differences among the four species were subtle; denoting that previous Scytosiphon records from the SwAO attributed to the renowned S. lomentaria could represent different species. In addition, sex ratio and genome-wide single nucleotide polymorphisms (SNPs) analyses were done for populations of S. promiscuus presumably introduced to the SwAO, and the results indicated that they included female-dominant parthenogenetic populations, which were probably introduced from Japan.

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Brazil is a tropical country with remarkably diverse marine habitats that harbour a rich diversity of fish. Only a small portion of this fish diversity has been investigated for parasites, and thus the diversity of their trematode parasites remains unexplored. Moreover, only 5 out of 184 known digenean trematode species of marine fish in Brazil have been genetically characterised. The Hemiuridae Looss, 1899 is the second most speciose trematode family in marine fishes from Brazil but, in many ways, it remains a neglected group. Forty-three trematode specimens from nine fish species were collected from the coastal zone off Rio de Janeiro, Brazil. Trematodes were found in the stomach of 14 specimens of 9 fish species belonging to 8 families (Carangidae, Clupeidae, Haemulidae, Muraenidae, Percophidae, Pinguipedidae, Trichiuridae, and Triglidae). Trematode specimens were studied using morphological and molecular genetic analyses. A total of eight hemiurid species from four genera, Ectenurus, Lecithochirium, Myosaccium, and Parahemiurus were identified. This paper reports on new host records for four species of hemiurids, adds a new record on the geographical distribution for one species, and provides the first DNA sequence data supplemented with the detailed description of morphology for five species. Phylogenetic analyses supported that the subfamily classifications of the Hemiuridae-based entirely on morphological characters-needs to be reconsidered, taking into account a wider range of information sources.

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Rough-toothed dolphins, Steno bredanensis, are closely associated with coastal waters in the Southwestern Atlantic Ocean, increasing the exposure to multiple stressors, such as chemical pollution. Persistent organic pollutants (POPs) are known to affect the health of cetacean species. To comprehend the potential impacts of POPs on populations' viability, it is necessary to distinguish populations and predict their risk of long-term exposure. Blubbers of rough-toothed dolphins (n = 28) collected along the southeastern (SE) and southern (S) Brazilian coast were screened for polychlorinated biphenyls (PCBs) and pesticides in a gas chromatograph coupled to a mass spectrometer. Based on the contamination profile, a discriminant function analysis separated the rough-toothed dolphins into three ecological populations: two coastal and one offshore. POP concentrations were the highest reported for the species worldwide and highest among the delphinids in Brazilian waters, reaching 647.9 µg g-1 lw for PCBs. The SE population presented 212.9 ± 163.0, S population presented 101.0 ± 96.7, and OCS/S population presented 183.3 ± 85.3 µg g-1 lw (mean ± SD) of PCBs. The potential risk of effects triggered by elevated PCB concentrations was assessed in an individual-based model. A risk of severe decline in population size is projected for the three populations in the next 100 years, especially in SE Brazil, varying between 67 and 99%.

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Deep-sea carbonate mounds can harbor a wide variety of heterotrophic and chemosynthetic microbial communities, providing biodiversity hotspots among the deep-sea benthic ecosystems. This study examined the bacterial and archaeal diversity and community structure in the water column and sediments associated with a recently described giant carbonate mound named Alpha Crucis Carbonate Ridge (ACCR), located in the Southwestern Atlantic Ocean. Because of the acoustic evidence of gas chimneys from a previous study, we further evaluated the chemosynthetic primary production through in situ-simulated dark carbon fixation rates. Pelagic microbial communities varied significantly with depth, showing a high abundance of photosynthetic groups in surface waters and taxa related to nitrification in intermediate and deep waters. The benthic communities from the top of the ACCR were very similar along with the sediment depth, while those from the base of the ACCR showed a clear stratification pattern, with members in the deep strata mainly related to anoxic and chemosynthetic ecosystems. Dark carbon fixation rates were of the same order of magnitude as those of deep-sea cold seeps and hydrothermal vents. Our study provides the first description of the ACCR microbiome and adds new information to help formulate and implement future conservation and management strategies for vulnerable marine ecosystems.

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Specimens representing two new species of Guidus Ivanov, 2006 were collected from the Magellan skate (Bathyraja magellanica [Philippi]) in the Patagonian Continental Shelf of Argentina, Southwestern Atlantic Ocean. Guidus francoi sp. n. and Guidus magellanicus sp. n. differ from their congeners by a particular combination of features, including type of bothridia, worm length, number of testes, and distribution of vitelline follicles. Guidus francoi sp. n. is distinguished from G. magellanicus sp. n. by having fewer proglottids, fewer testes and a higher ratio between the cirrus sac length and the proglottid width. The microthrix pattern of species of Guidus from the Southwestern Atlantic is described, based on specimens of G. francoi sp. n., Guidus magellanicus sp. n., and newly collected specimens of Guidus argentinense Ivanov, 2006. These three species share the presence of wide aristate gladiate spinitriches on the proximal bothridial surface, narrow gladiate spinitriches on the bothridial rim, and filitriches on the distal bothridial surface. The diagnosis of Guidus is revised to include several features exhibited by the new species (i.e., presence of bothridial indentations and bothridial stalks, distribution of vitelline follicles, and eggs grouped in cocoons). The discovery of G. francoi sp. n. and G. magellanicus sp. n. from B. magellanica increases the number of species of Guidus collected from batoids in the Southwestern Atlantic from one to three. The specificity exhibited by the species herein described reinforces the tight association between rays in the genera Guidus and Bathyraja.

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Spirobranchus are abundant and diverse serpulids in tropical regions, with three species reported in Brazil, which occurrence is questionable, due to their distant type localities. In the present work, we describe a new species of Spirobranchus from the Brazilian coast and report the other species of the genus occurring off Brazilian shoreline, based on specimens from different locations. Specimens were collected in the states of Alagoas, Rio de Janeiro, and Santa Catarina, sorted and analyzed under a stereoscopic microscope. Then, the animals were anesthetized and subsequently fixed and prepared for the scanning electron microscopy. Specimens from the Caribbean and other Brazilian states were loaned from Museu Nacional of Universidade Federal do Rio de Janeiro, Universidade Estadual do Rio de Janeiro and Universidade Federal de Alagoas. Morphological analyzes differentiated the three species and provided details of the morphology that can be used in the future taxonomy of the family. The species S. giganteus and S. tetraceros are more similar to each other, but can be readily separated based on the spiral radiolar crown in the former; S. minutus differs from the other species for the tube, operculum, and type of uncini. Spirobranchus lirianeae sp. nov. nests within S. kraussii-complex, with a concave operculum, absence of collar chaetae and paired compound eyes on the radioles, differing by being a solitary rather than a gregarious species, by the funnel-shaped operculum, fringed tonguelets and tube with single keel, distally pointed.(AU)

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This study presents the first report on the concentration of trace elements (Al, As, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn) in the blood and egg fractions of green turtles from Rocas Atoll, a pristine nesting site in NE Brazil. The highest concentrations of all elements were in the blood or shell samples. In order, iron, Zn, Cu, Al and As presented the highest concentrations in all tissues. The nonessential trace elements were below the limit of detection for more than 50% of the yolk (Al, Cd and Pb) and albumen samples (Al, As, Ba, Cd and Pb). This study will serve as a baseline reference for future monitoring of the ecotoxicology of breeding green turtles in the southwestern Atlantic Ocean.

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Spirobranchus are abundant and diverse serpulids in tropical regions, with three species reported in Brazil, which occurrence is questionable, due to their distant type localities. In the present work, we describe a new species of Spirobranchus from the Brazilian coast and report the other species of the genus occurring off Brazilian shoreline, based on specimens from different locations. Specimens were collected in the states of Alagoas, Rio de Janeiro, and Santa Catarina, sorted and analyzed under a stereoscopic microscope. Then, the animals were anesthetized and subsequently fixed and prepared for the scanning electron microscopy. Specimens from the Caribbean and other Brazilian states were loaned from Museu Nacional of Universidade Federal do Rio de Janeiro, Universidade Estadual do Rio de Janeiro and Universidade Federal de Alagoas. Morphological analyzes differentiated the three species and provided details of the morphology that can be used in the future taxonomy of the family. The species S. giganteus and S. tetraceros are more similar to each other, but can be readily separated based on the spiral radiolar crown in the former; S. minutus differs from the other species for the tube, operculum, and type of uncini. Spirobranchus lirianeae sp. nov. nests within S. kraussii-complex, with a concave operculum, absence of collar chaetae and paired compound eyes on the radioles, differing by being a solitary rather than a gregarious species, by the funnel-shaped operculum, fringed tonguelets and tube with single keel, distally pointed.

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Abstract Spirobranchus are abundant and diverse serpulids in tropical regions, with three species reported in Brazil, which occurrence is questionable, due to their distant type localities. In the present work, we describe a new species of Spirobranchus from the Brazilian coast and report the other species of the genus occurring off Brazilian shoreline, based on specimens from different locations. Specimens were collected in the states of Alagoas, Rio de Janeiro, and Santa Catarina, sorted and analyzed under a stereoscopic microscope. Then, the animals were anesthetized and subsequently fixed and prepared for the scanning electron microscopy. Specimens from the Caribbean and other Brazilian states were loaned from Museu Nacional of Universidade Federal do Rio de Janeiro, Universidade Estadual do Rio de Janeiro and Universidade Federal de Alagoas. Morphological analyzes differentiated the three species and provided details of the morphology that can be used in the future taxonomy of the family. The species S. giganteus and S. tetraceros are more similar to each other, but can be readily separated based on the spiral radiolar crown in the former; S. minutus differs from the other species for the tube, operculum, and type of uncini. Spirobranchus lirianeae sp. nov. nests within S. kraussii-complex, with a concave operculum, absence of collar chaetae and paired compound eyes on the radioles, differing by being a solitary rather than a gregarious species, by the funnel-shaped operculum, fringed tonguelets and tube with single keel, distally pointed.

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The change towards intensive agriculture has led to an increase in the use of pesticides. In addition, legacy pesticides, such as organochlorines are still present in the environment. Ten Franciscana dolphins were accidentally killed by netting in a coastal area of Argentina in Buenos Aires province. From these animals, organochlorine, organophosphate and pyrethroid pesticides were analyzed in liver, bubbler and melon tissues. The concentrations of Σendosulfan ranged from not detectable values (nd) to 3539 ng g-1 lw, with the maximum level in melon tissue. DDE was present in 60% of all samples at concentrations from nd to 6672 ng g-1 lw, indicating historical DDT contamination. The presence of endosulfan and heptachlor in a nursling calf indicated a transfer of these pesticides through lactational and placental transport. The concentrations of organophosphates and pyrethroids were below the limit of detection, reflecting the low persistence of these compounds.

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The Remo flounder, Oncopterus darwinii Steindachner, 1874 is a small Pleuronectidae (~ 250 mm TL) distributed in the warm-temperate zone from Santa Catarina (28°S - Brazil) to the Gulf of San Matías (42°S - Argentina). We studied the occurrence and diet of juveniles of this flatfish (85% < 100 mm TL) for one year (August 2009 to July 2010) in a southern Brazilian sandy beach. Individuals were much more common in spring and early summer than in the other seasons. Of the 758 individuals analyzed, only 69 (9.1%) were found with empty stomachs. The Remo flounder fed predominantly on small crustaceans (gammarid amphipods, mysids and the hipiidae Emerita brasiliensis Schmitt, 1935) and no seasonal differences were found in the composition of the diet of this flatfish. However, variations in the Index of Relative Importance (IRI) were found among seasons, which most likely can be explained by a decrease in the availability of favored food items throughout the year. The pattern of distribution of O. darwinii indicates that southern Brazilian sandy beaches are used as nursery ground for this species.

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The Remo flounder, Oncopterus darwinii Steindachner, 1874 is a small Pleuronectidae (~ 250 mm TL) distributed in the warm-temperate zone from Santa Catarina (28°S - Brazil) to the Gulf of San Matías (42°S - Argentina). We studied the occurrence and diet of juveniles of this flatfish (85% < 100 mm TL) for one year (August 2009 to July 2010) in a southern Brazilian sandy beach. Individuals were much more common in spring and early summer than in the other seasons. Of the 758 individuals analyzed, only 69 (9.1%) were found with empty stomachs. The Remo flounder fed predominantly on small crustaceans (gammarid amphipods, mysids and the hipiidae Emerita brasiliensis Schmitt, 1935) and no seasonal differences were found in the composition of the diet of this flatfish. However, variations in the Index of Relative Importance (IRI) were found among seasons, which most likely can be explained by a decrease in the availability of favored food items throughout the year. The pattern of distribution of O. darwinii indicates that southern Brazilian sandy beaches are used as nursery ground for this species.(AU)

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The dataset contains 2007 records of occurrence of 39 species of fish and 2 species of squid distributed on the Patagonian continental shelf and slope. This dataset describes a new and revised version of the original data published through OBIS with individual morphometrics. Specimens are representative of pelagic, demersal, demersal-pelagic, demersal-benthic and benthic habits and they were collected by commercial fishing vessels in autumn (May-June, 2001, 51 catches), winter (July-August, 2001, 38 catches) and summer (January-February, 2002, 112 catches). The sampling was carried out with bottom trawls at a depth range of 73-370 m. The survey was located between 39°-52°S and 55°-65°W.

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Three new tardigrade species, Batillipes brasiliensis sp. nov., Batillipes dandarae sp. nov. and Batillipes potiguarensis sp. nov., are described from shallow subtidal sediments of the Brazilian coast. B. brasiliensis sp. nov. and B. dandarae sp. nov. have toes 3 and 4 on leg IV different in length, so they can be included in the D group of species, while B. potiguarensis sp. nov., with toes 3 and 4 on leg IV equal in length belong to the A group. Batillipes brasiliensis sp. nov. is characterized by having an ala-like caudal expansion; cuticular projections on the coxal region of legs I-III, and lateral projections. The lateral projection located between the third and fourth legs is fringed with digit-shaped expansions. Batillipes dandarae sp. nov. has a dorsal blunt enlargement in the scapular region; a pointed triangular caudal appendage, and no lateral projections. The new species exhibits a sensorial spine on legs I inserted posteriorly and turning forward, and anus surrounded by a peculiar cuticular structure constituted by six platelets. Batillipes potiguarensis sp. nov. is characterized by a unique combination of characters: scapular region well developed, protruding laterally at the level of the first pair of legs; lateral blunt processes between legs, and prominent roundish caudal protrusion. In addition, the new species exhibits cephalic appendages with swollen tips, evident secondary clavae, and very short sense organs on the legs IV.

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ABSTRACT The reef-building vermetid Petaloconchus varians occurs in the western Atlantic Ocean, from the Caribbean Sea to the southern coast of Brazil. The present study evaluated the abundance of P. varians on intertidal rocky shores in Ilha Grande Bay (Rio de Janeiro State), and characterized their reefs, describing the species density, besides the weight and the belt width of the reefs. Petaloconchus varians reefs were recorded at 25 sites, with rocky shores exposed to different wave action (very sheltered, sheltered, semi-exposed and exposed) and slopes (10° to 46°). Clusters of individuals constructed large reefs along the middle intertidal zone, creating a wide belt (38 cm to 2 m). The density of P. varians and the weight of the reefs ranged from 620 to 2,559 ind.100 cm-2 and from 100 to 1,500 g.100 cm-2, respectively. Considering that the species was last reported from the area in the mid-20th century, the present study suggests that P. varians reefs are becoming dominant in the intertidal zone of rocky shores in Ilha Grande Bay. This is a contribution to knowledge of this ecosystem in Ilha Grande Bay, in view of local or global ecological changes.

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Franciscana dolphins are the most impacted small cetacean in the Southwestern Atlantic Ocean, classified as Vulnerable A3d by IUCN. Essential (Fe, Mo, Mn, Cr, Ni, Co) and non-essential (Ag, Pb, Sn) trace elements (TEs) were measured in liver, kidney, and brain samples of by-catch Franciscana dolphins that were living in estuarine (n = 21) and marine (n = 21) habitats (1) to assess whether TEs posed a threat and (2) to evaluate the suitability of TEs for discriminating ecological populations of this species in Argentinean waters. Essential TEs showed little variation in tissues from both groups in agreement with levels reported for other cetaceans and suggesting that these concentrations correspond to normal physiological levels. Non-essential TEs were higher in estuarine juveniles and adults dolphins than in marine specimens. These results suggest anthropogenic sources associated with estuarine area and that Franciscana dolphins are good sentinels of the impact of the environment. The difference in the concentrations of TEs beetwen ecological populations appeared to be related to distinct exposures in both geographical areas, and it is suggested that Ag and Sn concentrations in adults are good chemical tracers of anthropogenic input of TEs. These results provide additional information for improved management and regulatory policy.

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Parrotfish are fundamental species in controlling algal phase-shifts and ensuring the resilience of coral reefs. Nevertheless, little is known on their ecological role in the south-western Atlantic Ocean. The present study analysed the ontogenetic foraging activity and feeding selectivity of the Brazilian endemic parrotfish Scarus zelindae using behavioural observation and benthic composition analyses. We found a significant negative relationship between fish size and feeding rates for S. zelindae individuals. Thus, terminal phase individuals forage with lower feeding rates compared to juveniles and initial phase individuals. The highest relative foraging frequency of S. zelindae was on epilithic algae matrix (EAM) with similar values for juveniles (86.6%), initial phase (88.1%) and terminal phase (88.6%) individuals. The second preferred benthos for juveniles was sponge (11.6%) compared with initial (4.5%) and terminal life phases (1.3%). Different life phases of S. zelindae foraged on different benthos according to their availability. Based on Ivlev's electivity index, juveniles selected EAM and sponge, while initial phase and terminal phase individuals only selected EAM. Our findings demonstrate that the foraging frequency of the endemic parrotfish S. zelindae is reduced according to body size and that there is a slight ontogenetic change in feeding selectivity. Therefore, ecological knowledge of ontogenetic variations on resource use is critical for the remaining parrotfish populations which have been dramatically reduced in the Southwestern Atlantic Ocean.

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With the aim of evaluating the utility of marine parasites as indicators of ecotonal regions in the marine environment, we analysed data on assemblages of long-lived larval parasites of Zenopsis conchifer inhabiting the region of convergence of three masses of water in the southwestern Atlantic Oceans. These masses of water with different origins are expected to affect the structure of parasite communities by acting as sources of infective stages of helminth species typical of adjacent zoogeographical regions. Multivariate analyses at both infracommunity and component community levels, including data of four other species recognised as harbouring parasite assemblages representatives of these zoogeographical regions, were carried out to corroborate the existence of repeatable distribution patterns and to provide further evidence of the utility of parasites as zoogeographic indicators in the region. Results showed a tight correspondence with the existing zoogeographical classification in the study region, namely two zoogeographical provinces, one of which is subdivided into two districts demonstrating the ecotonal nature of parasite assemblages from the convergence region, which were characterised by a species rich component community but depauperate and heterogeneous infracommunities. The borders of biological communities have been suggested as priority areas for conservation where a fully functioning ecosystem can be protected and parasite communities can be considered as reliable indicators to define such transitional regions.

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