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A strategy for vaccine design involves identifying proteins that could be involved in pathogen-host interactions. The aim of this proteomic study was to determine how iron limitation affects the protein expression of Tenacibaculum dicentrarchi, with a primary focus on virulence factors and proteins associated with iron uptake. The proteomic analysis was carried out using two strains of T. dicentrarchi grown under normal (control) and iron-limited conditions, mimicking the host environment. Our findings revealed differences in the proteins expressed by the type strain CECT 7612T and the Chilean strain TdCh05 of T. dicentrarchi. Nonetheless, both share a common response to iron deprivation, with an increased expression of proteins associated with iron oxidation and reduction metabolism (e.g., SufA, YpmQ, SufD), siderophore transport (e.g., ExbD, TonB-dependent receptor, HbpA), heme compound biosynthesis, and iron transporters under iron limitation. Proteins involved in gliding motility, such as GldL and SprE, were also upregulated in both strains. A negative differential regulation of metabolic proteins, particularly those associated with amino acid biosynthesis, was observed under iron limitation, reflecting the impact of iron availability on bacterial metabolism. Additionally, the TdCh05 strain exhibited unique proteins associated with gliding motility machinery and phage infection control compared to the type strain. These groups of proteins have been identified as virulence factors within the Flavobacteriaceae family, including the genus Tenacibaculum. These results build upon our previous report on iron acquisition mechanisms and could lay the groundwork for future studies aimed at elucidating the role of some of the described proteins in the infectious process of tenacibaculosis, as well as in the development of potential vaccines.

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Groupers (Epinephelidae and Serranidae) have attracted special attention to fish farming, and their species offer good opportunities for successful hybridizations. Cytogenetic data allow a better understanding of the role of karyotypic diversification in the acquisition of post-zygotic reproductive isolation (RI). Thus, chromosomal analyses were performed on E. striatus (Caribbean Sea), E. coioides and E. tauvina (Indo-Pacific Region), using standard procedures and mapping of six repetitive DNA classes by the in situ hybridization. The three species have 2n=48 chromosomes. The karyotypes of E. coioides and E. striatus are composed only of acrocentric chromosomes (FN=48), while E. tauvina has 8 submetacentric chromosomes (FN=56). Heterochromatin has a preferential centromeric distribution, and the microsatellite repeats are dispersed throughout the chromosomes of all species. The 18S and 5S rDNA sites are unique but show a colocalization arrangement in E. tauvina and E. striatus. The chromosomal organization suggests that the three species still maintain a significant amount of syntenic regions. The range of the karyotype divergence and the RI levels showed low, but goes turn proportionally greater in relation to the divergence time between the parental species. The slow acquisition of postzygotic RI is consistent with the high karyotype homogeneity presented by Epinephelidae family.

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Estuarine mangroves are often considered nurseries for the Atlantic Goliath grouper juveniles. Yet, the contributions of different estuarine primary producers and habitats as sources of organic matter during early ontogenetic development remain unclear. Given the species' critically endangered status and protection in Brazil, obtaining biological samples from recently settled recruits in estuaries is challenging. In this study, we leveraged a local partnership with fishers and used stable isotope (C and N) profiles from the eye lenses of stranded individuals or incidentally caught by fishery to reconstruct the trophic and habitat changes of small juveniles. The eye lens grows by the apposition of protein-rich layers. Once these layers are formed, they become inert, allowing to make inferences on the trophic ecology and habitat use along the development of the individual until its capture. We used correlations between fish size and the entire eye lens size, along with estuarine baselines, to reconstruct the fish size and trophic positions for each of the lens layers obtained. We then used dominant primary producers and basal sources from mangrove sheltered, exposed estuarine and marine habitats to construct an ontogenetic model of trophic and habitat support changes since maternal origins. Our model revealed marine support before the juveniles reached 25 mm (standard length), followed by a rapid increase in reliance on mangrove sheltered sources, coinciding with the expected size at settlement. After reaching 60 mm, individuals began to show variability. Some remained primarily supported by the mangrove sheltered area, while others shifted to rely more on the exposed estuarine area around 150 mm. Our findings indicate that while mangroves are critical for settlement, as Goliath grouper juveniles grow, they can utilize organic matter produced throughout the estuary. This underscores the need for conservation strategies that focus on seascape connectivity, as protecting just one discrete habitat may not be sufficient to preserve this endangered species and safeguard its ecosystem functions.

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The purpose of this study was to investigate the relationships between the abundance and occurrence of juvenile Atlantic goliath grouper and physicochemical variables in a tropical mangrove ecosystem, employing a non-lethal methodology. Juvenile Atlantic goliath grouper individuals were captured biweekly, using blue crab traps, across three locations within the São Mateus estuary (18°36'S, 39°44'W), from August 2021 to July 2022. Simultaneously, the physicochemical water variables were assessed during each trap inspection. The physicochemical water variables influence on the abundance and occurrence of Atlantic goliath grouper juveniles were assessed using the Zero-Inflated Binomial (ZIB) and the Poisson (ZIP) generalized linear mixed-effects models (GLMMs). A total of 66 Atlantic goliath grouper juveniles were sampled (Pontal do Sul = 50, Lagoa Creek = 13, and Pitangueiras Creek = 3), ranging from 32 to 319 mm in total length. The best model fitted to presence-absence data (AIC = 278.6) consisted of location, depth, and salinity, with only location having a significant influence on the likelihood of species occurrence. Regarding abundance data, the best model (AIC = 336.4) included location, depth, and turbidity, with only location and depth showing a significant impact on abundance variation, with lower abundance at deeper areas. Although our results indicate a weak significant influence of physicochemical variables on juvenile Atlantic goliath grouper distribution, it is imperative to continue this monitoring effort, considering that additional data may be required to gain a deeper understanding of these patterns.

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BACKGROUND: Seafood consumers are widely exposed to diclofenac due to the high contamination levels often present in aquatic organisms. It is a potential risk to public health due its endocrine disruptor properties. Limited information is available about diclofenac behavior after food digestion to enable a more realistic scenario of consumer exposure. This study aimed to evaluate cooking effects on diclofenac levels, and determine diclofenac bioaccessibility by an in vitro digestion assay, using commercial fish species (seabass and white mullet) as models. The production of the main metabolite 4'-hydroxydiclofenac was also investigated. Fish hamburgers were spiked at two levels (150 and 1000 ng g-1) and submitted to three culinary treatments (roasting, steaming and grilling). RESULTS: The loss of water seems to increase the diclofenac levels after cooking, except in seabass with higher levels. The high bioaccessibility of diclofenac (59.1-98.3%) observed in both fish species indicates that consumers' intestines are more susceptible to absorption, which can be worrisome depending on the level of contamination. Contamination levels did not affect the diclofenac bioaccessibility in both species. Seabass, the fattest species, exhibited a higher bioaccessibility of diclofenac compared to white mullet. Overall, cooking decreased diclofenac bioaccessibility by up to 40% in seabass and 25% in white mullet. The main metabolite 4'-hydroxydiclofenac was not detected after cooking or digestion. CONCLUSION: Thus, consumption of cooked fish, preferentially grilled seabass and steamed or baked white mullet are more advisable. This study highlights the importance to consider bioaccessibility and cooking in hazard characterization studies. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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During January 2013, a mining spill occurred in the Santa Maria mining region, releasing around 300,000 m3 of tailings on Los Remedios river, which was transported through the San Lorenzo river and finally to El Comedero (EC) dam. Twenty months later, we examined the concentrations of Hg and Se in the muscle, liver, gills, and guts of three fish species (Cyprinus carpio, Oreochromis aureus, Micropterus salmoides) captured in the EC dam to assess the performance of the cleaning operations. A high Se concentration in the liver of all species (carp, 1.2 ± 0.4; tilapia, 3.9 ± 2.1; bass, 3.5 ± 1.1 µg g-1 ww) was consistently observed, while this behavior was only found in the blue tilapia for Hg (0.15 ± 0.11 µg g-1 ww). Tilapia (benthic-detritivorous) exhibited the highest Se concentrations compared to the carp (omnivore) and the largemouth bass (piscivore). In contrast, the largemouth bass had the highest Hg levels in the muscle compared with the other fishes. Such differences could be related to the different metabolism and feeding habits among species. Compared to a tilapia study carried out three months after the mine spill during a mortality event, a decrease was evident in the liver for Se and Hg by 7.2 and 4.7 times, respectively. This reveals that cleaning operations were more efficient for Se and less for Hg, and that a prolonged period was required for the partial recovery of the element levels in fish from sites impacted by mining. Considering the Mexican consumption scenarios for each fish species, it could be concluded that there will be no non-cancer risk by exposure to Hg or Se.

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Domoic acid (DA) produces neurotoxic damage in seabirds and marine mammals when they are exposed to this potent neurotoxin. Other vertebrates are also susceptible to DA intoxication including humans. However, neurobehavioral affectations have not been detected in fish when naturally exposed to DA but only when it is administered intraperitoneally. Therefore, the current idea is that fish are less sensitive to DA acquired under ecologically relevant routes of exposure. Here, we show that oral consumption of DA induces neurobehavioral and histopathological alterations in the brain and heart of totoaba (Totoaba macdonaldi) and striped bass (Morone saxatilis). Lesions were found in both species in the optic tectum and cerebellum after exposure for 7 days to a diet containing 0.776 µgDA g-1. The affectations prevailed chronically. Also, we found that cardiac tissue exhibits lesions and focal atrium melanism. Although affectations of the brain and heart tissue were evident, excitotoxic signs like those described for other vertebrates were not observed. However, the use of standardized behavioral tests (dark/light and antipredator avoidance tests) permitted the detection of behavioral impairment of fish after DA exposure. Pathological and associated behavioral alterations produced by DA can have relevant physiological consequences but also important ecological implications.

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The most important fisheries are recording catches below their historical averages despite increased effort. This level of overfishing is worrying and requires the establishment of feasible and precise measures to prevent a continuing decrease in biomass. Determining the factors that lead to changes in the abundance and distribution of overfished resources would allow us to identify the strengths and weaknesses of management schemes; this approach would also make it possible to estimate more accurate parameters for their evaluation. We hypothesize that environmental, temporal, spatial, and operational components contribute to the variation in the relative abundance. Thus, we analyzed the red grouper fishery, the most important demersal fishery in the southeastern Gulf of Mexico (SGM); it is locally known as escama. We employed the catch per unit effort (CPUE) as an index of relative abundance recorded by the semi-industrial fleet (kilogram per effective fishing day) and the small-scale fleet (kilogram per effective fishing hour) during the overexploitation phase (from 1996 to 2019). We fitted several variables of the components using generalized additive models (GAM) and used multi-model inference to determine the best GAM for each fleet. For both fleets, the operational and temporal components (fishing gear and year) have had a greater impact on the distribution and abundance of red grouper in the SGM than the spatial and environmental components (the place of origin and sea surface temperature). These findings encourage the exploration of métier schemes for more efficient fishery management. In addition, we have identified several strategies that would support the recovery of the resource, such as restricting fishing in the quadrants located to the northeast or regulating scuba diving. We recommend that in the future, researchers use the indices we have generated in the present study to evaluate the red grouper fishery.

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The dusky grouper (Epinephelus marginatus) is an overfished and threatened fish species with coastal distribution. In the Southwestern Atlantic, it occurs across a broad region influenced by two major oceanographic features: the Cabo Frio (23°S) and the Cabo Santa Marta (28°S) upwelling systems. Along the Brazilian coast, the species may present continuous or discrete populations, depending on the methodological approach used. In this study we combined otolith chemistry and muscle stable isotope analyses to examine the population structure of dusky groupers and its association with the two upwelling systems. Fish were collected in shallow coastal waters of the Southwest Atlantic Ocean, covering the southeastern and southern Brazilian coasts, among Macaé (22°S), Santos (24°S), Florianópolis (27°S), and in Rio Grande (32°S). The results show three statistically well-separated population groups along the region. We named these population groups as North (north of Cabo Frio); Center (between upwelling regions); and South (south of the Cabo Santa Marta system). Our findings allow to suggest that the upwelling systems may influence the distribution of E. marginatus stocks along the Brazilian south-western coast, even though a causal effect may not be attributed at this point. Overall, this combined approach, leveraging information from distinct natural tags, and reflecting variability of water chemistry and food webs with latitude, allowed us to enhance our understanding on how major upwelling systems influence the structuring of fish populations along the southwestern Atlantic Ocean.

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Density-dependent mechanisms and habitat use are important drivers of marine spatial distribution in complex ecosystems such as coral or rocky reefs. In the last decade, a few studies have assessed habitat use by reef fishes in nearshore and coastal environments along the Brazilian coast. Serranidae (groupers and sea basses) are regarded as excellent models for understanding habitat use patterns due to their diversity, long lifespan, wide distribution, morphological and functional diversity, and behavioural complexity. Their trophic position in the food web, from meso- to top-predators, grants them critical roles as top-down population controllers. Herein, we present the first assessment of habitat use by five sympatric Serranidae in a Brazilian oceanic island, Trindade. The model species selected for this assessment were the coney (Cephalopholis fulva), the rock hind (Epinephelus adscensionis), the greater soapfish (Rypticus saponaceus), the Creole-fish (Paranthias furcifer) and the hybrid between C. fulva and P. furcifer. Our findings revealed that the species showed specific associations with topographic characteristics related to shelter from predation, reproduction and feeding. Habitat use in Trindade was similar to that observed in nearshore coastal environments (where the hybrid is absent). The present work contributes to the knowledge of habitat use and niche partitioning among key species, which is a valuable tool to subsidize effective conservation initiatives such as designing marine protected areas focusing on the behaviour and habitat use of key ecological players.

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Epinephelidae fishes are important to reef ecosystems, as well as for commercial fishing and cultural heritage. Additionally, most of these species are at some risk of extinction, as Epinephelus marginatus and Hyporthodus nigritus. This study aimed to determine total mercury (THg) concentrations and burden on eight tissues of E. marginatus and H. nigritus. A Cold Vapor/Atomic Absorption Spectrometer was used for the THg determination. THg concentrations and burden varied significantly between tissues in both species. The highest concentrations were determined in the liver, and the greatest burden was in muscle. The gonad concentrations were higher than the toxicological threshold. General trends of increase in THg concentrations and burden along growth were observed. Mercury is a threat for both species evaluated, raising this concern for other Epinephelidae species.

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Aquatic ecosystems have been suffering deleterious effects due to the development of different economic activities. Metal(loid)s are one of the most persistent chemicals in environmental reservoirs, and may produce adverse effects on different organisms. Since fishes have been largely used in studies of metal(loid)s exposure, tilapia and largemouth bass were collected in three ecosystems from the Yaqui River Basin to measure the concentrations of metal(loid)s (chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), zinc (Zn) arsenic (As), mercury (Hg), and selenium (Se)) and some biomarkers (somatic indices, metallothionein expression and histopathological analysis) in tissues of both species. Metal(loid) concentrations varied seasonally among ecosystems in tissues of both species. The elements varied seasonally and spatially in tissues of both species, with a general distribution of liver > gills > gonads. Also, biomarkers showed variations indicative that the fish species were exposed to different environmental stressor conditions. The highest values of some biomarkers were in largemouth bass, possibly due to differences in their biological characteristics, mainly feeding habits. The multivariate analysis showed positive associations between metal(loid)s and biomarkers, which are usually associated to the use of these elements in metabolic and/or regulatory physiological processes. Both fish species presented histological damage at different levels, from SI types (changes that are reversible for organ structure) to SII types (changes that are more severe but may be repairable). Taken together, the results from this study suggest that the Yaqui River Basin is moderately impacted by metals and metalloids.

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Here, the authors investigate the evolution of scientific literature on the Atlantic goliath grouper (Epinephelus itajara), the largest grouper species in the Atlantic. This species was considered threatened according to the IUCN for nearly three decades due to overfishing and has been protected from fishing in a large part of its range. For the purpose of evaluating the scientific production on an endangered species banned from fishing, the authors present a scientometry and synthesis review analysing the literature produced in the timeline and the content of their studies. To this end, they set up an almost 60-year literary database through the Scopus, Web of Science and Google Scholar platforms. They analyse the publication and knowledge area patterns over the time in the world and in Brazil. They also feature the main areas, locations, ecosystems and types of those research studies and briefly describe the main records found in each decade. An increase in the number of publications was observed from the 1990s onwards worldwide, and particularly in Brazil from the 2000s, coinciding with the pioneering legislations for species protection. Most of the studies were classified within ecology and conservation and took place in countries that implemented moratoriums and had extensive areas of mangroves. Thus, fishing moratorium, classification as endangered, mangroves distribution and conservation all play a role in the studies distribution and contribute positively to the knowledge, as well as support conservation strategies for the species and its ecosystems of occurrence.

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Mercury (Hg) is a contaminant of global concern due to its damaging toxicological effects on organisms. For the vulnerable Dusky Grouper (Epinephelus marginatus) off the coast of Brazil, we investigated: i) spatial patterns in muscle tissue total mercury (THg) contamination; ii) the relationship between muscle THg concentrations and total length iii) the relationship between muscle THg and stable isotopes; and iv) THg concentrations among muscle, liver, and ovary tissues. Out of 134 fish sampled, 21.8 % were higher than 0.5 mg/kg wet weight (above the safe limit for human consumption). THg concentrations increased toward lower latitudes, but an opposite pattern was observed for δ13C and δ15N with decreased values toward lower latitudes. There were significant differences in THg concentration among the three tissues. Results of Hg concentrations are useful for understanding the potential adverse effects on the health of this vulnerable species and to serve as a guide to human consumers.

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Members of the order Trypanorhyncha are cestode parasites that are frequently found infecting the muscles of several marine fish species, affecting fish health, and resulting in consumers' rejection of fish. Fifty-two specimens of marine fish were freshly caught throughout the year 2020 from boat landing sites at the Alexandria coast along the Mediterranean Sea in Egypt, including the grey trigger fish Balistes carolinensis (F: Balistidae); the mottled grouper Mycteroperca rubra (F: Serranidae) and the common sole Solea vulgaris (F: Soleidae). Blastocysts were isolated and ruptured; the generated pleurocerci were described morphologically and morphometrically by light and scanning electron microscopy. Also, multiple-sequence alignment was performed, and a phylogenetic tree was constructed following maximum likelihood analysis of the 18s and 28s ribosomal RNA sequences of the recovered worms. Thirty fish were infected; the infection was recorded as blastocysts embedded in fish flesh. Three different parasitic species were recovered and classified morphologically as Gymnorhynchus isuri, Pseudotobothrium dipsacum and Heteronybelinia estigmena. The taxonomic position of these parasites was justified by molecular analysis of their 18s and 28s rRNAs, which revealed high percentages of homology with species recovered from the GenBank. The accession numbers ON157059, ON139663 and ON139662 were respectively assigned to the recovered parasites after their deposition in GenBank. The results obtained from the molecular analyses confirmed the morphological records of the recovered parasites. Since metacestodes are found in the musculature of infected fish specimens, it is necessary to remove these areas in the commercialization of fish.

Os membros da ordem Trypanorhyncha são parasitas de cestóides que são freqüentemente encontrados infectando os músculos de várias espécies de peixes marinhos, afetando a saúde dos peixes e resultando na rejeição do peixe por parte dos consumidores. Cinqüenta e dois espécimes de peixes marinhos foram capturados recentemente durante todo o ano de 2020 nos locais de desembarque de barcos na costa de Alexandria ao longo do Mar Mediterrâneo, no Egito, incluindo o peixe de gatilho cinzento Balistes carolinensis (F: Balistidae); a garoupa mosqueada Mycteroperca rubra (F: Serranidae) e o linguado comum Solea vulgaris (F: Soleidae). Os blastocistos foram isolados e rompidos; os pleurocistos gerados foram descritos morfologicamente e morfometricamente por microscopia eletrônica de luz e varredura. Além disso, foi realizado o alinhamento de sequências múltiplas e uma árvore filogenética foi construída seguindo a análise de máxima probabilidade das sequências de RNA ribossômico de 18s e 28s dos vermes recuperados. Trinta peixes foram infectados; a infecção foi registrada como blastocistos embutidos na carne do peixe. Três espécies diferentes de parasitas foram recuperadas e classificadas morfologicamente como Gymnorhynchus isuri, Pseudotobothrium dipsacum e Heteronybelinia estigmena. A posição taxonômica desses parasitas foi justificada pela análise molecular de seus rRNAs de 18 e 28 anos, que revelou altas porcentagens de homologia com espécies recuperadas do GenBank. Os números de acesso ON157059, ON139663 e ON139662 foram respectivamente atribuídos aos parasitas recuperados após sua deposição no GenBank. Os resultados obtidos a partir das análises moleculares confirmaram os registros morfológicos dos parasitas recuperados. Como as metacestodes são encontradas na musculatura dos espécimes de peixes infectados, é necessário remover estas áreas na comercialização dos peixes.

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Members of the order Trypanorhyncha are cestode parasites that are frequently found infecting the muscles of several marine fish species, affecting fish health and resulting in consumers' rejection. Seventy-five specimens of marine fish were freshly caught from boat landing sites at the Alexandria coast along the Mediterranean Sea in Egypt, including two Carangids, the greater amberjack Seriola dumerili and the gulley jack Pseudocarans dentex; two Serranids, the Haifa grouper Epinephelus haifensis and the mottled grouper Mycteroperca rubra. Forty-five fish were infected; the infection was recorded as blastocysts embedded in fish flesh. Blastocysts were isolated and ruptured; the generated plerocerci were described morphologically, where, four different species were recovered; Callitetrarhynchus gracilis, Callitetrarhynchus speciosus, Protogrillotia zerbiae, and Grillotia brayi. The taxonomic position of these parasites was justified by multiple-sequence alignment and a phylogenetic tree was constructed following maximum likelihood analysis of the 18s rRNA sequences of the recovered worms. The accession numbers MN625168, MN625169, MN611431and MN611432 were respectively assigned to the recovered parasites. The results obtained from the molecular analyses confirmed the morphological records of the recovered parasites. Since metacestodes are found in the musculature of infected fish specimens, it is necessary to remove these areas in the commercialization of fish.

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This work investigates the possibility of using scales of sea bass Dicentrarchus labrax as a low-cost material for the adsorptive removal of methylene blue (MB) cationic dye in aqueous solutions. The physical-chemical characterizations of fish scales in natura (FS-in natura) revealed through thermogravimetry that they are composed of inorganic (hydroxyapatite) and organic (collagen) phases in relatively similar amounts. Spectroscopy analyses show that the interactions of MB with FS-in natura occur mainly in the organic phase layer of the adsorbent. The effects of initial MB concentration (5.0 × 10-4 and 5.0 × 10-3 mol L-1) and temperature (25-55 °C) on the adsorption efficiency of FS-in natura were evaluated. FS-in natura at MB concentration (5.0 × 10-3 and 5.0 × 10-4 mol L-1) exhibited the maximum adsorption capacities of 2.2 × 10-3 mol g-1 at 25 °C and 2.8 × 10-5 mol g-1 at 55 °C, respectively. The pseudo-second-order model represented the adsorption kinetics well, and the equilibrium isotherm data were better correlated using the Langmuir equation. The newly developed neural model demonstrated a high predictive capacity with an R-value greater than 0.99 and reduced values for mean squared error, root mean squared error, and mean absolute error equal to 0.003, 0.055, and 0.0348, respectively. The genetic algorithm was used to optimize the experimental conditions of the process. In conclusion, the sea bass scales have promising prospects as a low-cost alternative material for removing cationic dyes from aqueous solutions.

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The three most important grouper fishery species in southern Gulf of Mexico, Epinephelus morio, Mycteroperca bonaci and Mycteroperca microlepis, do not have life history parameters data reported such as growth, age and natural mortality essential to management. Individuals from the three species were captured in the Campeche Bank (CB) at different times from 1988 to 2001. Sagittae were thin-sectioned to count annuli: n = 1081 for E. morio, n = 920 for M. bonaci and n = 251 for M. microlepis. Otoliths from the three species exhibited successive opaque and translucent bands deposited with an annual frequency, occurring between January and April for E. morio and M. bonaci, and between January and March for M. microlepis. Estimated age in the three grouper species ranged from 0+ to 20 years. The most frequent ages were 7-10 years for E. morio and 8-12 years for M. bonaci and M. microlepis. The von Bertallanfy Growth Function model parameters (L∞ , K and t0 ) were consistent with reported growth patterns for Epinephelidae family species, as established by growth performance Ф' (near 3). The CB groupers appear to reach maximum ages over 13 years with K values between 0.09 and 0.12 year-1 , indicating all three studied species displayed relatively slow growth rate and medium longevity. Lifespan values ranged from 13 to 33 years for E. morio, from 18 to 30 years for M. bonaci and from 17 to 33 years for M. microlepis. A50 was 6.1 years for E. morio and 5.5 years for both M. bonaci and M. microlepis. Age at which all females were mature was 8 years for M. bonaci and 10 years for E. morio and M. microlepis. P50 was 9.3 years for E. morio, 13.6 years for M. bonaci and 11.6 years for M. microlepis. Age at which 100% of individuals were male was 13 years for E. morio, 19 years for M. bonaci and 15 years for M. microlepis. Values of M at age exhibited an exponential decrease with age for all three species, but overall values were 0.13 year-1 for E. morio, 0.14 year-1 for M. bonaci and 0.17 year-1 for M. microlepis. For the three species size at age varied by geographical distribution area, but particularly for E. morio the discrepancy in average size between published studies may be the consequence of the fishing effort exerted on the stock and/or the lack of regulation for the fishery prior to 2001; after this stock biomass fell below the reference limit point and was declared overexploited. Resource managers could use the information provided in this study as a reference, representing pre-overexploitation values, to evaluate the current status of these populations and ensure sustainable management actions for the CB grouper fisheries.

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Mycteroperca bonaci (black grouper) is one of the most sought species of grouper along its entire distribution, being a prime target for demersal line fisheries because of its high commercial value. Nonetheless, because of population declines the species is considered near threatened according to the IUCN red list. The present study aimed to determine the population parameters of M. bonaci, including growth, reproduction and mortality, and thus contributes to measures towards its conservation and management in the southwestern Atlantic. The sampling area is in the North Brazil Shelf, off Maranhão State, an area of intense fisheries development and yet poorly known. The large continental shelf harbours unique coral reef formations and has been declared an ecologically or biologically significant marine area (EBSA). Sampling on landing sites was carried out monthly between May 2017 and January 2019. A total of 137 black grouper specimens were sampled from commercial landings of artisanal fisheries. The size of the specimens ranged from 44 to 157 cm, and the weight varied from 0.976 to 54 kg. The length-weight was established: log(TW) = -11.26 + 3.01log(TL). Histological analysis of the gonads confirmed only the presence of female individuals, and the occurrence of individuals in the sexual transition was not recorded. Higher GSI values and higher frequency of spawning capable staged individuals occurred during the months of June to August, indicating spawning peaks. The estimated age of sexual maturity A50 for females was 4.62 years ( x _ 93 cm-TL). The growth parameters for the Von Bertalanffy model were TL∞ (cm): 185.5, k: 0.04, t0 (year): -4.75 (t0 not fixed) and TL∞ (cm): 141, k: 0.11 (t0  = 0 fixed). The total estimated mortality rate (Z) according to catch length presented a Z value = 0.11, and the natural mortality was M = 0.04 year-1 . This is the first study on the age and growth of M. bonaci in the SWA, a region where the species is considered as endangered according to Brazil's red list regional assessment. Only females were present in the samples, results that suggest either differential capturability of sexes because of distinct patterns of behaviour or distribution or an effect of selective mortality upon larger and older individuals, as the species is described as a protogynous hermaphrodite. This indicates the need to closely manage this population to avoid collapses. Recovery plans that have been planned by the Brazilian government but not yet implemented for the species must be put into practice to avoid progressive decline as fisheries target more remote areas.

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Wastes from iron ore mining activities are potentially damaging to adjacent aquatic ecosystems. We aimed to determine biomarkers of environmental exposure to this xenobiotic in the dusky grouper Epinephelus marginatus by differential gene expression analysis. For this, fish were exposed to iron ore (15.2 mg/L) and gene expression in liver was assessed by RNA-Seq and compared to the control group. A total of 124 differentially expressed genes were identified, from which 52 were upregulated and 72 were downregulated in response to iron ore. From these, ferritin (medium subunit), cytochrome b reductase and epoxide hydrolase genes were selected for validation by RT-qPCR that confirmed the upregulation of epoxide hydrolase in fish exposed to iron ore.