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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. [ABSTRACT FROM AUTHOR]

Migratory patterns of the catfish Genidens genidens in four estuaries along the Brazilian Atlantic coast are reconstructed from otolith Sr/Ca, a salinity proxy, to test estuarine‐dependency. To facilitate interpretation of this proxy in otolith core‐to‐edge profiles, a Sr/Ca Reference Value for High Salinity (RVHSSr/Ca) of 4.88 mmol/mol was established experimentally, from fish specimens reared in water with a salinity level (33 psu) between estuarine and high salinity (marine) water. All wild specimens exhibited otolith Sr/Ca values higher than RVHSSr/Ca, suggesting that G. genidens utilizes environments with marine salinity. Our results reveal highly variable environmental histories, with at least five major habitat usage patterns. Most distinctive among these, we find that (a) fish from Paranaguá Estuarine Complex (PEC) exhibit high intraindividual heterogeneity; (b) most fish (57%) from Guanabara Bay (GB) exhibit prolonged exposure to very high salinities, often exceeding 36.5 psu levels found in some shelf sectors; and (c) some fish from Paraiba do Sul River, GB and PEC exhibit Sr/Ca values below RVHSSr/Ca consistent with estuarine residence. These results suggest that G. genidens is not strictly estuarine‐dependent. [ABSTRACT FROM AUTHOR]

Molecular analysis is a powerful tool for assessing and developing conservation strategies for endangered species. Elasmobranchs comprise one of the most threatened groups of vertebrates, with about one‐third of the species subject to some degree of threat. This is the case for Pseudobatos horkelii, the Brazilian guitarfish, which has suffered severe population reductions (>80%) in recent decades, mainly through coastal overfishing. Understanding the genetic diversity of this species is paramount to applying adequate management and conservation strategies.In this context, the present study evaluated the genetic diversity of P. horkelii, employing single‐nucleotide polymorphism (SNP) nuclear markers obtained by double‐digest restriction site‐associated DNA sequencing (ddRADseq). Samples collected in three areas along the Brazilian Coast (Rio de Janeiro, São Paulo, and Rio Grande do Sul) provided an average of 1,565,339 reads and 2,846 SNPs.The results indicate the presence of at least two genetically distinct populations along the Brazilian Coast, with molecular diversity differences noted among clusters. The heterozygosity excess observed in all populations is likely the result of a bottleneck, probably resulting from overfishing and habitat fragmentation. Moreover, the upwelling phenomenon in Cabo Frio, in the state of Rio de Janeiro, may have a significant influence over the observed genetic structure.The gene flow between the clusters was estimated and was noted as asymmetric between the populations studied. The observed patterns may be the result of the combination of biological characteristics and overfishing pressure in the past decades. The evidence of structured populations presenting genetic diversity differences provides insightful information for the development of stock management and conservation strategies for the Brazilian guitarfish. [ABSTRACT FROM AUTHOR]

The whitemouth croaker, Micropogonias furnieri, is a long-lived fish of high commercial importance in the western Atlantic Ocean. Here, we used stable isotope ratios of carbon, sulfur, and nitrogen and isotopic niche metrics (SIBER) to study feeding habits and track habitat use by whitemouth croakers in Guanabara Bay, an estuary in Rio de Janeiro state, Brazil. Our results highlighted size-related habitat segregation, with small juvenile fishes (60 cm) feeding mainly in Continental Shelf waters. Medium adult fishes (30-60 cm) appear to feed in multiple coastal and Continental Shelf habitats. Moreover, their feeding ecology showed strong temporal differences, linked with seasonal and, to a lesser extent, interannual variation in oceanographic features of the ecosystem in which they live. Overall, these differences in ecological features suggest that (1) adult and juvenile whitemouth croakers should be treated as different components of the food web and (2) the conservation of these habitats should be prioritized to better manage and sustain the coastal fisheries in Guanabara Bay. Le tambour raye, Micropogonias furnieri, est un poisson longevif de grande importance commerciale dans l'ocean Atlantique occidental. Nous avons utilise les rapports d'isotopes stables du carbone, du soufre et de l'azote et des parametres associes a la niche isotopique (SIBER) pour etudier les habitudes d'alimentation et suivre l'utilisation de l'habitat de tambours rayes dans la baie de Guanabara, un estuaire dans l'Etat de Rio de Janeiro (Bresil). Nos resultats font ressortir une segregation de l'habitat associee a la taille, les petits poissons juveniles (60 cm) s'alimentent principalement dans les eaux du plateau continental. Les poissons adultes de taille moyenne (30-60 cm) semblent s'alimenter dans divers habitats littoraux et du plateau continental. L'ecologie de leur alimentation montre en outre de fortes variations temporelles associees a des variations saisonnieres et, dans une moindre mesure, interannuelles de caracteristiques oceanographiques de l'ecosysteme dans lequel ils vivent. Dans l'ensemble, ces variations des caracteristiques ecologiques indiqueraient que (1) les tambours rayes adultes et juveniles devraient etre traites comme representant differentes composantes du reseau trophique et (2) la priorite devrait etre accordee a la conservation de ces habitats pour une meilleure gestion a long terme des peches cotieres dans la baie de Guanabara. [Traduit par la Redaction], Introduction The Sciaenidae, popularly known as croakers or drums due to the sound they produce using muscles associated with the swim bladder, are a widely distributed fish family throughout the [...]

Resource depletion and climate change have fostered sustainable initiatives in the waste management sector. Pyrolysis (Py) has emerged as an option for valorizing spent coffee grounds (SCG). In addition, inorganic compounds can have catalytic effects on the pyrolytic reaction of organic materials, increasing the char yield and porosity of biochar. This study investigates the slow pyrolysis of SCG using concentrated landfill leachate residue (CLLR) (1:1 wt%) as a pyrolitic additive due to its high salinity. Biochars were characterized based on their thermal behavior to discuss environmental benefits and potential applications. Slow-py experiments were conducted using a lab-scale pyrolizer, and thermal characterization was performed using TA Instruments, specifically the SDTQ600 model. Biochars were characterized by higher water contents and heating rates than those experienced by their feedstocks. It is suggested that the high metal content of CLLR could change the biochar's thermal stability, decreasing its decomposition temperature. Values were 9.18 wt% and 18.11 MJ kg−1 and 23.25 wt% and 22.05 MJ kg−1 for biochars produced using SCG and SCG and CLLR (1:1 wt%), respectively. Future studies will include biochar ecotoxicity analyses and measure carbon–energy balance. [ABSTRACT FROM AUTHOR]