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Maternal offloading of polycyclic aromatic hydrocarbons (PAHs) poses a significant exposure route for developing embryos, with implications for subsequent generations. Despite known developmental effects regarding fish physiology and behavior, maternal PAH transfer assessments in elasmobranchii are still lacking. This study investigated PAH contamination and maternal transfer in one female Lesser Numbfish (Narcine brasiliensis) electric ray and seven embryos for the first time. Naphthalene was identified as the predominant low molecular weight PAH, and dibenzo[a,h]anthracene was the most abundant high molecular weight compound. Most embryos exhibited some level of PAH exposure, with varying accumulation patterns potentially influenced by size, developmental stage, and yolk absorption rates. Further investigation is warranted to understand the impacts of PAH maternal offloading on elasmobranchii uterine contents and embryos.

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The Rio de Janeiro Marine Aquarium (AquaRio) is the first to successfully maintain and reproduce the spiny butterfly ray (Gymnura altavela), providing unique information about the species' biology. Seven rays were kept in captivity between 2018 and 2023, two captured on the southeastern coast of Brazil and five born in the aquarium. The applied abiotic conditions and nutrition allowed for the survival, growth, and reproduction of these individuals. Growth parameters (asymptotic disk width-DW∞ and growth coefficient-k) were estimated based on the von Bertalanffy model using the Fabens method for males and females separately. The best models estimated DW∞ = 106.47 cm and k = 0.396 for males and DW∞ = 172.2 cm and k = 0.190 for females. Sexual dimorphism was corroborated, with females reaching larger sizes and presenting slower growth rates than males. The estimated k values were higher than those estimated for rays of similar size to G. altavela in the natural environment, probably due to the constant water temperature (around 25.5°C), food abundance, low population density, reduced predation rates, and high water quality in the captive environment. A comparison of the captivity findings with other studies on G. altavela age and growth in the Atlantic and Mediterranean indicates a broad phenotypic plasticity regarding growth. Three G. altavela reproductions were recorded, with size at birth appearing to be a key factor for pup's survival. Behavioral pattern observations associated with reproduction are also described, encompassing chasing and copulation, whereas the species' internal morphology is described through coelomic cavity ultrasound scanning.

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Cocaine (COC) and benzoylecgonine (BE), the main COC metabolite, have been detected in aquatic ecosystems. Studies focusing on wild fish are, however, very limited, and no reports concerning elasmobranchs are available. This study investigated COC and BE levels in Brazilian Sharpnose sharks (Rhizoprionodon lalandii) (n = 13) using LC-MS/MS. All samples (13/13) tested positive for COC, with 92 % (12/13) testing positive for BE. COC concentrations (23.0 µg kg-1) were over 3-fold higher than BE (7.0 µg kg-1). COC levels were about three-fold significantly higher in muscle (33.8 ± 33.4 g kg-1) compared to liver (12.2 ± 14.2 µg kg-1). Females presented higher COC concentrations in muscle (40.2 ± 35.8 µg kg-1) compared to males (12.4 ± 5.9 µg kg-1). Several positive statistical correlations were noted between COC and BE (rho = 0.84) in females, indicating systemic COC transport and metabolization, as well as between BE and weight (rho = 0.62), and between COC and the Condition Factor (rho = 0.73). A strong correlation was noted between BE and COC in the muscle of non-pregnant females (rho = 1.00). This study represents the first COC and BE report in free-ranging sharks, and the findings point to the potential impacts of the presence of illicit drugs in environments.

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Studies on the occurrence of POPs and other persistent compounds in pristine areas are extremely valuable, as they offer insights on the long-range transportation of POPs and the occurrence of natural compound producers' areas. In this regard, this study aimed to report data of both anthropogenic (polychlorinated biphenyls, PCBs, and polybrominated diphenyl ethers, PBDEs) and natural (methoxylated PBDEs, MeO-BDEs) compounds in tissues of the black triggerfish, Melichthys niger (Tetraodontiformes, Balistidae), specimens (n = 30) sampled in 2018 during a scientific expedition conducted at Trindade Island. Concentrations of ∑28PCBs ranged from 73 to 1052 ng g-1 lw in liver, 334 to 1981 ng g-1 lw in gonads, and 20 to 257 ng g-1 lw in muscle, with the predominance of PCB-180 in liver and PCB-52 in gonad and muscle. Concentrations of ∑7PBDEs ranged from

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Metal contamination poses a significant threat to elasmobranchs, underscoring the need for targeted conservation approaches. The critically endangered Brazilian guitarfish, Pseudobatos horkelii, confronts an array of challenges, notably overexploitation, putting its survival at risk. Our study investigated the potential toxicity arising from arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) contamination across various adult guitarfish tissues from southeastern Brazil. Serological stress indicators, nutritional metabolites, and creatinine, an organ function marker, were also assessed, and Selenium (Se) levels were also investigated for possible protective effects. Our investigation unveiled significant correlations between metal concentrations and the determined physiological markers, shedding light on potential adverse effects. Remarkably, six correlations were indicative of how Hg and Pb negatively impact hepatic metabolite assimilation, while As was shown to influence renal phosphorus dynamics, Cd to affect rectal gland phosphorus regulation, and Pb to influence creatinine production in muscle tissue. Furthermore, Se demonstrated protective properties against Cd, Hg, and Pb, suggesting a role in alleviating the toxicity of these elements. Despite probable protective Se influences, the detected elemental interactions still suggest potential for organ impairment. These findings gain heightened significance within the context of the cumulative stressors faced by the Brazilian guitarfish, with metal contamination exhibiting the capacity to erode this species resilience against both anthropogenic and environmental pressures, thereby disrupting systemic equilibrium and jeopardizing wild populations. By investigating the intricate balance between metal accumulation and physiological consequences, our study contributes with crucial insights into potential conservation strategy formulations towards pollution for this critically endangered elasmobranch species.

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Polycyclic aromatic hydrocarbon (PAH) contamination is ubiquitous and comprises a significant worldwide concern in ecological and Public Health frameworks. Many aquatic biota representatives have been reported as contaminated by these toxic compounds, including one of the most threatened vertebrate groups, elasmobranchs (sharks and rays). Although elasmobranchs play important ecological roles and provide significant ecosystem services, they are highly consumed and comprise a cheap source of protein for humans globally. Studies concerning elasmobranch PAH contamination are, however, notably lacking. A systematic review was, thus, conducted herein to assess PAH elasmobranch contamination and discuss potential human health risks following the Preferred Reporting Item Statement Guidelines for Systematic Reviews and Meta-analyses (PRISMA) guidelines applying the Population (P), Intervention (I), Comparison I, and Outcome (O) (PICO) strategy. A total of 86 published papers were retrieved by this method and analyzed. Only nine studies of this total concerned PAH elasmobranch contamination, assessed in 10 shark species and one ray species, with only one study calculating human health risks. A significant knowledge gap is, thus, noted for this subject, indicating the need to monitor PAH elasmobranch contamination in consumed shark and ray species worldwide.

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Biodiversity baselines are essential subsidies to evaluate how environmental changes and human impacts affect the special and temporal patterns of communities. This information is paramount to promote proper conservation and management for historically impacted environments such as Guanabara Bay, in southeastern Brazil. Here, we propose an ichthyofaunal baseline for this bay using gathered past data from 1889 to 2020, including literature records, scientific collections, biological sampling, and fisheries landing monitoring. A total of 220 species (203 teleosts and 17 elasmobranchs), distributed in 149 genera (136 teleosts and 13 elasmobranchs) and 72 families (61 teleosts and 11 elasmobranchs) were recorded, including the first record of a tiger-shark, Galeocerdo cuvier, in Guanabara Bay. Although the employed sampling effort was sufficient to represent the ichthyofauna in the middle and upper estuary, the Chao2 estimator indicates an even greater richness regarding the bay as a whole. Evidence of reduced abundance and probable local extinction over the decades was found, supporting the importance of implementing management and conservation strategies in the area. The ichthyofaunal distribution analyses revealed that areas close to conservation units are richer compared to their surroundings, indicating that this is an effective strategy to mitigate human impacts in the bay.(AU)

Esforços de caracterização da biodiversidade são subsídios essenciais para avaliar como mudanças ambientais e impactos antrópicos afetam os padrões espaciais e temporais das comunidades. Essas informações são essenciais para promover conservação e manejo adequados em ambientes historicamente impactados como a Baía de Guanabara, no sudeste do Brasil. Aqui, nós propomos uma linha de referência da ictiofauna dessa baía utilizando dados pretéritos de 1889 a 2020, incluindo registros de literatura, coleções científicas, coletas biológicas e monitoramento de desembarque pesqueiro. Um total de 220 espécies (203 teleósteos e 17 elasmobrânquios), distribuídas em 149 gêneros (136 teleósteos e 13 elasmobrânquios) e 72 famílias (61 teleósteos e 11 elasmobrânquios) foram registradas, incluindo o primeiro registro de tubarão-tigre, Galeocerdo cuvier, na Baía de Guanabara. Apesar do esforço amostral empregado ter sido suficiente para representar a ictiofauna do médio e alto estuário, o estimador Chao2 indicou uma riqueza ainda maior para a baía como um todo. Evidências de redução de abundância e de provável extinção local de táxons ao longo das décadas foram encontradas, corroborando a importância da implantação de medidas de manejo e conservação para a área. A análise da distribuição da ictiofauna revelou que áreas próximas a unidades de conservação são mais ricas em comparação ao seu entorno, indicando que essa é uma estratégia efetiva para mitigar os impactos antrópicos na baía.(AU)

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A global movement towards decreases in elasmobranch overfishing has been noted in the last decades. However, discussion concerning the effects of POP contamination on the health and survival of these organisms is still recent. These compounds can affect the immune and endocrine systems of both sharks and batoids, impairing reproduction and impacting species recruitment, acting synergistically alongside overfishing effects. In this context, this study investigated the concentration of organochlorine compounds in liver of 29 individuals of Rioraja agassizii, a commercially exploited skate classified as Vulnerable by IUCN and as Endangered in Brazil. Contaminant concentrations were higher in adults compared to juveniles. Distinct contamination profiles were observed, suggesting different groups within the investigated population and revealing contaminants as a potential tool to assess population ecology. PCB levels were considered a concern as they resemble concentrations in ecosystems from the northern hemisphere, where deleterious effects on elasmobranchs have been observed.

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Metal contamination has never been assessed in Ampullae of Lorenzini. This study employed Rhizoprionodon lalandii, as an ecotoxicological model to investigate potential metal accumulation in Ampullae of Lorenzini jelly. No differences between sexes were observed regarding jelly metal concentrations at Rio das Ostras (RJ) or Santos (SP). Statistically significant correlations were noted between total lengths (TL) and condition factors and several metals at both sampling sites, demonstrating the potential for Chondrichthyan sensory capacity disruption and possible effects on foraging success. Maternal metal transfer to Ampullae jelly was confirmed. Rhizoprionodon lalandii is thus, a good model to assess Ampullae of Lorenzini contamination, as this electrosensory organ seems to be highly vulnerable to metal contamination.

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This study comprises a novel report on subcellular metal partitioning and metallothionein (MT) metal detoxification efforts in lesser numbfish (Narcine brasiliensis) electric ray specimens, as well as the first assessment on MT contents in any ray electric organ. Individuals sampled from an area in Southeastern Brazil affected by the Mariana dam rupture disaster were assessed concerning subcellular metal partitioning and MT metal-detoxification in the liver, gonads, electric organ and muscle of both adults and embryos. Yolk was also assessed when available. Relative total and heat-stable (bioavailable) metal and metalloid comparisons between adults and embryos in different developmental stages demonstrates maternal transfer of both total and bioavailable metals and significant MT associations demonstrate the detoxification of As, Ag, Mn, Ni, Cd, Co, Cu, Se and V through this biochemical pathway. Our findings expand the lacking ecotoxicological assessments for this near-threatened species and indicates significant ecological concerns, warranting further biomonitoring efforts.

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Araruama Lagoon (Rio de Janeiro) is the largest hypersaline lagoon in South America. The aim of this study was to survey fishing landings, capture areas and production at this lagoon, in addition to analyzing data from the Pescarte Census. Fishing landings were monitored daily by community agents from March to August/2009, through the Petrobras Mosaico Program. Thirteen landing points were identified in five municipalities, totaling 8,096 recorded landings, and accumulating 469.1 tonnes. São Pedro da Aldeia (39.6%), Arraial do Cabo (27.7%) and areas in the central region (37.6%) and the south coast (29.1%) of the lagoon presented the highest landings and catch volumes. Twelve species were identified, mainly Pogonias courbina (48.9%) and Penaeus spp. (33.8%), and gillnets were the most important fishing gear. Very few studies have addressed fishing at Araruama Lagoon, leading to current planning measures supported by little data. We advocate a participatory review of current regulations, to better address gillnet fishing and the capture of different fish species. This study is the result of research financed by the Pescarte Environmental Education Project, a mitigation measure required by the Federal Environmental Licensing, conducted by IBAMA.(AU)

A Lagoa de Araruama (Rio de Janeiro) é a maior lagoa hipersalina da América do Sul. O objetivo do estudo foi levantar os pontos de desembarque pesqueiro, áreas de captura e a produção da lagoa, além de analisar dados do Censo Pescarte. Por meio do Programa Petrobras Mosaico foi acompanhado o desembarque pesqueiro de março a agosto/2009, por agentes comunitários, com monitoramento diário da pesca. Foram identificados 13 pontos de desembarque, em cinco municípios, sendo registrados 8.096 desembarques, com 469,1 toneladas. São Pedro da Aldeia (39,6%), Arraial do Cabo (27,7%) e áreas da região central (37,6%) e litoral sul (29,1%) da lagoa apresentaram os maiores desembarques e capturas. Foram identificadas 12 espécies, sendo Pogonias courbina (48,9%) e Penaeus spp. (33,8%) as principais, com a rede de emalhar sendo o petrecho mais importante. Pouquíssimos estudos abordaram à pesca na Lagoa de Araruama; logo, as medidas de ordenamento vigentes estão respaldadas em poucos dados. Defendemos uma revisão participativa da regulamentação, de forma a abordar melhor a pesca de emalhe e a captura de peixes diversos. Este estudo é resultado de pesquisa financiada pelo Projeto de Educação Ambiental Pescarte, que é uma medida de mitigação exigida pelo Licenciamento Ambiental Federal, conduzido pelo IBAMA.(AU)

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Araruama Lagoon (Rio de Janeiro) is the largest hypersaline lagoon in South America. The aim of this study was to survey fishing landings, capture areas and production at this lagoon, in addition to analyzing data from the Pescarte Census. Fishing landings were monitored daily by community agents from March to August/2009, through the Petrobras Mosaico Program. Thirteen landing points were identified in five municipalities, totaling 8,096 recorded landings, and accumulating 469.1 tonnes. São Pedro da Aldeia (39.6%), Arraial do Cabo (27.7%) and areas in the central region (37.6%) and the south coast (29.1%) of the lagoon presented the highest landings and catch volumes. Twelve species were identified, mainly Pogonias courbina (48.9%) and Penaeus spp. (33.8%), and gillnets were the most important fishing gear. Very few studies have addressed fishing at Araruama Lagoon, leading to current planning measures supported by little data. We advocate a participatory review of current regulations, to better address gillnet fishing and the capture of different fish species. This study is the result of research financed by the Pescarte Environmental Education Project, a mitigation measure required by the Federal Environmental Licensing, conducted by IBAMA.

A Lagoa de Araruama (Rio de Janeiro) é a maior lagoa hipersalina da América do Sul. O objetivo do estudo foi levantar os pontos de desembarque pesqueiro, áreas de captura e a produção da lagoa, além de analisar dados do Censo Pescarte. Por meio do Programa Petrobras Mosaico foi acompanhado o desembarque pesqueiro de março a agosto/2009, por agentes comunitários, com monitoramento diário da pesca. Foram identificados 13 pontos de desembarque, em cinco municípios, sendo registrados 8.096 desembarques, com 469,1 toneladas. São Pedro da Aldeia (39,6%), Arraial do Cabo (27,7%) e áreas da região central (37,6%) e litoral sul (29,1%) da lagoa apresentaram os maiores desembarques e capturas. Foram identificadas 12 espécies, sendo Pogonias courbina (48,9%) e Penaeus spp. (33,8%) as principais, com a rede de emalhar sendo o petrecho mais importante. Pouquíssimos estudos abordaram à pesca na Lagoa de Araruama; logo, as medidas de ordenamento vigentes estão respaldadas em poucos dados. Defendemos uma revisão participativa da regulamentação, de forma a abordar melhor a pesca de emalhe e a captura de peixes diversos. Este estudo é resultado de pesquisa financiada pelo Projeto de Educação Ambiental Pescarte, que é uma medida de mitigação exigida pelo Licenciamento Ambiental Federal, conduzido pelo IBAMA.

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The guitarfishes Pseudobatos horkelii and Pseudobatos percellens meet the criteria for threatened status as Critically Endangered (CR) and Endangered (EN), respectively. Both species occur in the Southern Atlantic Ocean. Considering the lack of data on the genetic structure of these species, the present study evaluated the genetic variability and population structure of the P. horkelii and P. percellens in the southern region of Brazil and the northern coast of Argentina, based on sequences of mitochondrial DNA, Control Region (D-loop). Samples of P. horkelii (n = 135) were analyzed in six localities situated in Northern Argentina, along the Brazilian states' coast. The mean of nucleotide diversity was 0.0053, the ΦST was 0.4277 and demographic analysis of P. horkelii suggests the existence of stability of the populations, with D = 0.9929, FS = 2.0155, SSD = 0.0817, R = 0.2153. In P. percellens (n = 101) were analyzed from six Brazilian localities along the coast of Santa Catarina, Paraná, and São Paulo. The mean nucleotide diversity was 0.0014 and ΦST value of 0.2921, the demographic analysis indicates a high migration rate of P. percellens among the localities evaluated, with D = 0.5222, FS = 0.3528, SSD = 0.01785, R = 0.3890.(AU)

As raias violas Pseudobatos horkelii e Pseudobatos percellens, são listados como "Criticamente em Perigo" (CR) e "Em Perigo" (EN), respectivamente. Ambas as espécies ocorrem no Sul do Oceano Atlântico. Considerando a falta de dados sobre a estrutura genética dessas espécies, o presente estudo avaliou a variabilidade genética e a estrutura populacional de P. horkelii e P. percellens na região sudeste do Brasil e litoral norte da Argentina, com base em sequências de DNA mitocondrial, região de controle (D-loop). Amostras de 135 indivíduos de P. horkelii analisados em seis localidades, situadas no norte da Argentina e ao longo da costa dos estados brasileiros. A média da diversidade nucleotídica foi de 0.0053, o índice ΦST foi de 0.4277 e a análise demográfica de P. horkelii, indicou a existência de estabilidade das populações, com D = 0.9929, Fus = 2.0155, SSD = 0.0817, R = 0.2153. Em 101 exemplares de P. percellens, foram analisados em seis localidades brasileiras ao longo do litoral de Santa Catarina, Paraná e São Paulo. A diversidade nucleotídica média foi de 0.0014 e o valor ΦST de 0.2921, a análise demográfica indicou uma alta taxa de migração de P. percellens entre as localidades analisadas, com D = 0.5222, FS = 0.3528, SSD = 0.01785, R = 0.3890.(AU)

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The guitarfishes Pseudobatos horkelii and Pseudobatos percellens meet the criteria for threatened status as Critically Endangered (CR) and Endangered (EN), respectively. Both species occur in the Southern Atlantic Ocean. Considering the lack of data on the genetic structure of these species, the present study evaluated the genetic variability and population structure of the P. horkelii and P. percellens in the southern region of Brazil and the northern coast of Argentina, based on sequences of mitochondrial DNA, Control Region (D-loop). Samples of P. horkelii (n = 135) were analyzed in six localities situated in Northern Argentina, along the Brazilian states' coast. The mean of nucleotide diversity was 0.0053, the ΦST was 0.4277 and demographic analysis of P. horkelii suggests the existence of stability of the populations, with D = 0.9929, FS = 2.0155, SSD = 0.0817, R = 0.2153. In P. percellens (n = 101) were analyzed from six Brazilian localities along the coast of Santa Catarina, Paraná, and São Paulo. The mean nucleotide diversity was 0.0014 and ΦST value of 0.2921, the demographic analysis indicates a high migration rate of P. percellens among the localities evaluated, with D = 0.5222, FS = 0.3528, SSD = 0.01785, R = 0.3890.(AU)

As raias violas Pseudobatos horkelii e Pseudobatos percellens, são listados como "Criticamente em Perigo" (CR) e "Em Perigo" (EN), respectivamente. Ambas as espécies ocorrem no Sul do Oceano Atlântico. Considerando a falta de dados sobre a estrutura genética dessas espécies, o presente estudo avaliou a variabilidade genética e a estrutura populacional de P. horkelii e P. percellens na região sudeste do Brasil e litoral norte da Argentina, com base em sequências de DNA mitocondrial, região de controle (D-loop). Amostras de 135 indivíduos de P. horkelii analisados em seis localidades, situadas no norte da Argentina e ao longo da costa dos estados brasileiros. A média da diversidade nucleotídica foi de 0.0053, o índice ΦST foi de 0.4277 e a análise demográfica de P. horkelii, indicou a existência de estabilidade das populações, com D = 0.9929, Fus = 2.0155, SSD = 0.0817, R = 0.2153. Em 101 exemplares de P. percellens, foram analisados em seis localidades brasileiras ao longo do litoral de Santa Catarina, Paraná e São Paulo. A diversidade nucleotídica média foi de 0.0014 e o valor ΦST de 0.2921, a análise demográfica indicou uma alta taxa de migração de P. percellens entre as localidades analisadas, com D = 0.5222, FS = 0.3528, SSD = 0.01785, R = 0.3890.(AU)

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ABSTRACT Rhinoptera bonasus is a bento-pelagic and highly migratory species occurring from southern United States to northern Argentina. Due to overfishing effects, R. bonasus is currently at risk, classified by the IUCN Red List as vulnerable. Considering the lack of molecular data available for R. bonasus, this study aimed to describe the genetic variability and population structure of specimens sampled from three Brazilian coast ecoregions (Amazon ecoregion, Pará; Northeastern ecoregion, Pernambuco and Southeastern ecoregion, Rio de Janeiro, São Paulo and Santa Catarina), through five polymorphic microsatellite markers. Here testing the panmixia hypothesis for Brazilian ecoregions and test natal philopathy. A total of 69 analyzed specimens revealed individual and significant genetic differentiation between the sampled locations. ST (0.12), PCA, DAPC and Bayesian analyses of the genetic population structure revealed at least two distinct genetic R. bonasus groupings. IBD tests were significant, indicating a correlation between genetic and geographical distance among populations, which can be explained by reproductive philopatric behavior. Philopatric behavior associated with R. bonasus mobility may influence the differentiation values observed for all loci in the investigated samples.

RESUMO Rhinoptera bonasus é uma espécie bento-pelágica e altamente migratória, que ocorre do sul dos Estados Unidos ao norte da Argentina. Devido aos efeitos da sobrepesca, R. bonasus está atualmente em risco, classificada pela Lista Vermelha da IUCN como vulnerável. Considerando a falta de dados moleculares disponíveis para R. bonasus, este estudo teve como objetivo descrever a variabilidade genética e estrutura populacional de espécimes amostrados em três ecorregiões do litoral brasileiro (Ecorregião Amazônica, Pará; Ecorregião Nordeste, Pernambuco e Ecorregião Sudeste, Rio de Janeiro, São Paulo e Santa Catarina), por meio de cinco marcadores microssatélites polimórficos. Assim, testaremos as hipóteses de panmixia e filopatria natal. Um total de 69 espécimes analisados revelou diferenciação genética individual e significativa entre os locais amostrados. As análises de ST (0,12), PCA, DAPC e Bayesiana revelaram pelo menos dois agrupamentos genéticos distintos de R. bonasus. Os testes de IBD foram significativos, indicando uma correlação entre a distância genética e geográfica entre as populações, o que pode ser explicado pelo comportamento filopátrico reprodutivo. O comportamento filopátrico associado à mobilidade de R. bonasus pode influenciar os valores de diferenciação observados para todos os loci nas amostras investigadas.

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Bacterial communities of two critically endangered rays from the South Atlantic, the butterfly ray (Gymnura altavela) and the groovebelly ray (Dasyatis hypostigma), were described using 16S rRNA gene metabarcoding. The study characterized the bacterial communities associated with (i) G. altavela in natural (in situ) and aquarium (ex situ) settings, (ii) skin and stinger of G. altavela, and D. hypostigma in aquaria, and (iii) newborns and adults of D. hypostigma. The results revealed potentially antibiotic-producing bacterial groups on the skin of rays from the natural environment, and some taxa with the potential to benefit ray health, mainly in rays from the natural environment, as well as possible pathogens to other animals, including fish and humans. Differences were observed between the G. altavela and D. hypostigma bacteria composition, as well as between the skin and stinger bacterial composition. The bacterial community associated with D. hypostigma changed with the age of the ray. The aquarium environment severely impacted the G. altavela bacteria composition, which changed from a complex bacterial community to one dominated almost exclusively by two taxa, Oceanimonas sp. and Sediminibacterium sp. on the skin and stinger, respectively.

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Understanding elasmobranch reproductive biology is necessary for species conservation. Multiple paternity (MP) has been reported for elasmobranchs, and this study investigates the reproductive aspects and mating system (paternity genetic analyses) for Squalus albicaudus. Thirteen pregnant females were analysed concerning reproductive parameters, and the mating system was assessed for nine females and their litters. The study found a mean fecundity of 2.84 pups per litter without correlation between total female length and the number of embryos per litter. One litter showed evidence of MP, indicating the presence of polyandrous behaviour of the species.

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The recently described Squalus albicaudus is a mesopredator shark and, as such, exposed to mercury biomagnification processes. Therefore, this study aimed to assess total Hg (THg) concentrations in S. albicaudus, a deep-water species, sampled off Southeastern Brazil and discuss ecological, reproductive, human consumption and conservation implications. Thirty-two individuals were sampled off the coast of Rio de Janeiro, including 13 gravid females carrying 34 embryos. Muscle THg concentrations were higher in all sex classes compared to liver, gonads and brain. The last three, in turn, presented THg concentrations above toxic biota thresholds. Significant correlations were observed between muscle and brain and liver, indicating systemic Hg contamination and inter-organ transport and distribution. In addition, correlations observed between organs strongly support efficient Hg blood-brain barrier crossing and maternal transfer. Maternal THg transfer was observed, with embryo THg also above toxic thresholds for fish. THg levels in muscle and liver, as well as embryos, were higher compared to other Squalus species worldwide. Hg contamination off the coast of Rio de Janeiro is of significant concern and should be further assessed. Potential human consumption risks are noted, as muscle THg concentrations were above maximum permissible levels set by regulatory agencies.

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RESUMO

Genidens genidens is a species susceptible to population declines in view of their reproductive biology peculiarities. Morphometric differences between sexes are observed in the literature, and these differences should also be evident in otolith development. Growth patterns are one of the most important biological characteristics regarding population dynamics and management. In this context, the aim of the present study is to describe this species relative growth and identify differences between sex life cycles. Somatic growth-otolith growth relationships and somatic length-weight relationships were estimated based on two methodologies; the Huxley and the polyphasic allometric models. Both models demonstrated different growth patterns between sexes. The three axes of otolith growth were adequate descriptors of growth, and the results of the Huxley model demonstrated distinct growth patterns between sexes, with male otoliths larger in all three measured axes. In the polyphase model, male otoliths were thicker, while female otoliths were longer and higher. Both sexes presented similar length-weight relationships, which may indicate that oocyte production and parental care lead to similar costs for this species.(AU)

Genidens genidens é uma espécie suscetível a declínios populacionais, tendo em vista as peculiaridades de sua reprodução. Diferenças morfométricas entre os sexos são observadas na literatura, e essas diferenças também devem ser evidentes no desenvolvimento dos otólitos. O padrão de crescimento é uma das características biológicas mais importantes no que diz respeito à dinâmica populacional e manejo. Assim, nosso objetivo é descrever o crescimento relativo da espécie e identificar diferenças entre os ciclos de vida dos sexos. A relação crescimento somático-crescimento do otólito e a relação comprimento-peso somáticos foram estimados com base em duas metodologias, os modelos alométricos de Huxley e polifásico. Ambos os modelos demonstraram diferentes padrões de crescimento entre sexos. Os três eixos dos otólitos descreveram adequadamente o crescimento, e os resultados do modelo de Huxley demonstraram padrões de crescimento distintos entre os sexos, com os otólitos dos machos sendo maiores em todos os três eixos medidos. No modelo polifásico os otólitos dos machos foram maiores em espessura, enquanto os otólitos das fêmeas exibiram maior comprimento e altura. Ambos os sexos apresentaram relações de comprimento-peso semelhantes, o que pode indicar que a produção de ovócitos e o cuidado parental apresentam custos semelhantes para essa espécie.(AU)

Assuntos

RESUMO

Abstract: A total of 1,471 specimens of 16 species of flatfishes (Pleuronectiformes) were caught during 48 sampling campaigns between July 2005 and June 2007 at ten stations in Guanabara Bay, Rio de Janeiro, Brazil. Paralichthyidae was the dominant family, with Etropus crossotus as the dominant species. The outer stations, especially those on the western side of the lower estuary, were distinguished as a result of their higher abundance of flatfishes and number of species. The spatial distribution of E. crossotus and its population structure indicate that this species is an estuarine resident despite the apparent reduction in its area of occupation within the estuarine complex. Among the other species, nine were classified as marine stragglers (Achirus declivis, Bothus ocellatus, Cyclopsetta chittendeni, Etropus longimanus, Paralichthys orbignyanus, P. patagonicus, Syacium micrurum, Symphurus diomedeanus and Trinectes paulistanus) and three as estuarine opportunists (Bothus robinsi, Citharichthys macrops and Syacium papillosum); another three could not be classified due to the small number of captures or lack of previous data (S. tessellatus, A. lineatus and C. spilopterus).

Resumo: Um total de 1.471 espécimes de 16 espécies de linguados (Pleuronectiformes) foram capturados durante 48 campanhas de amostragem entre julho de 2005 e junho de 2007 em dez estações na Baía de Guanabara, Rio de Janeiro, Brasil. Paralichthyidae foi a família dominante, com Etropus crossotus como a espécie dominante. As estações externas, especialmente aquelas no lado ocidental do baixo estuário, foram distinguidas como resultado de sua maior abundância de linguados e número de espécies. A distribuição espacial de E. crossotus e sua estrutura populacional indicam que esta espécie é uma residente estuarina, apesar da aparente redução em sua área de ocupação dentro do complexo estuarino. Dentre as outras espécies, nove foram classificadas como migrantes marinhos (Achirus declivis, Bothus ocellatus, Cyclopsetta chittendeni, Etropus longimanus, Paralichthys orbignyanus, P. patagonicus, Syacium micrurum, Symphurus diomedeanus e Trinectes paulistanus) e três como oportunistas estuarinos (Bothus robinsi, Citharichthys macrops e Syacium papillosum); outras três não puderam ser classificados devido ao pequeno número de capturas ou falta de dados prévios (S. tessellatus, A. lineatus e C. spilopterus).