The consumption of shark meat in the Amazon region and its implications for human health and the marine ecosystem

Smelly shark, smelly ray: what is infecting you?

AIMS

Although elasmobranchs are consumed worldwide, bacteriological assessments for this group are still sorely lacking. In this context, this study assessed bacteria of sharks and rays from one of the most important landing ports along the Rio de Janeiro coast.

METHODS AND RESULTS

Bacteria were isolated from the cloacal swabs of the sampled elasmobranchs. They were cultured, and Vibrio, Aeromonas, and Enterobacterales were isolated and identified. The isolated bacteria were then biochemically identified and antimicrobial susceptibility assays were performed. Antigenic characterizations were performed for Salmonella spp. and Polymerase Chain Reaction (PCR) assays were performed to identify Escherichia coli pathotypes. Several bacteria of interest in the One Health context were detected. The most prevalent Enterobacterales were Morganella morganii and Citrobacter freundii, while Vibrio harveyi and Vibrio fluvialis were the most prevalent among Vibrio spp. and Aeromonas allosacharophila and Aeromonas veronii bv. veronii were the most frequent among Aeromonas spp. Several bacteria also displayed antimicrobial resistance, indicative of Public Health concerns. A total of 10% of Vibrio strains were resistant to trimethoprim-sulfamethoxazole and 40% displayed intermediate resistance to cefoxitin. Salmonella enterica strains displayed intermediate resistance to ciprofloxacin, nalidixic acid and streptomycin. All V. cholerae strains were identified as non-O1/non-O139. The detected E. coli strains did not exhibit pathogenicity genes. This is the first study to perform serology assessments for S. enterica subsp. enterica isolated from elasmobranchs, identifying the zoonotic Typhimurium serovar. Salmonella serology evaluations are, therefore, paramount to identify the importance of elasmobranchs in the epidemiological salmonellosis chain.

CONCLUSIONS

The detection of several pathogenic and antibiotic-resistant bacteria may pose significant Public Health risks in Brazil, due to high elasmobranch consumption rates, indicating the urgent need for further bacteriological assessments in this group.

Ecotoxicology applied to conservation: Potential negative metal and metalloid contamination effects on the homeostatic balance of the critically endangered Brazilian guitarfish, Pseudobatos horkelii (Elasmobranchii: Rhinobatidae)

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.

Assessment of potential risks to human health associated with trace elements in three commercially important shark species captured in the Central Mexican Pacific

Shark meat is a popular protein source worldwide. However, existing national control policies for ensuring the safety and quality of shark meat are minimal. There are concerns about the sustainability of shark populations, which bioaccumulate and biomagnify potentially toxic elements at higher rates than non-predatory fish, posing a risk to human health. In this study, the contributions of essential elements to the Recommended Dietary Allowance (RDA) and potentially toxic elements to the Reference Dose (RfD) linked to shark consumption (200 g per week) were investigated for three shark species in the Central Mexican Pacific. We estimated risks and benefits for women, children, and men. Our results suggest that the three shark species are sources of Se, Co, Cr, Cu, Fe, and Zn, but poor sources of Mn for women and men aged 19-50 years. A weekly ingestion of 200 g of shark meat exceeded the RfD-As by 4-14 times and the RfD-Pb by 1.1-1.7 times for adults, indicating a potential risk to human health. The three shark species were also significant sources of potentially toxic elements for children, including Hg, Cd, Cr, and Pb. An excessive intake of Se was observed, with levels at 8.4-10.6 and 4.3-5.3 times the RDA for children aged 1-8 and 9-13 years, respectively. Although shark meat can be a good source of essential nutrients, the lack of controls in the commercialization process indicates that it should be consumed in moderation due to the potential risks associated with excessive exposure to potentially toxic elements. This caution is particularly important for children and pregnant women, who are at higher risk of health complications from consuming contaminated food.

Total mercury and fatty acids content in selected fish marketed in Quito - Ecuador. A benefit-risk assessment

Total mercury and fatty acids contents were determined in muscles of croaker, snapper, dolphinfish, blue marlin, and shark, from different markets in the Metropolitan District of Quito, Ecuador. Fifty-five samples were collected and analyzed for total mercury using cold vapor atomic fluorescence spectrometry, and the fatty acids were analyzed using gas chromatography equipped with a flame ionization detector. The lowest total mercury levels were found in snapper [0.041 µg·g^-1 wet weight (ww)] while blue marlin showed the highest (5.883 µg·g^-1 ww). EPA + DHA ranged from 1.0 mg·g^-1 in snapper to 2.4 mg·g^-1 in shark. A high omega-3/omega-6 ratio was found for all fish types; however, the HQ_EFA for the benefit-risk ratio was above 1, suggesting an evident risk to human health. Based on our results, consumption of croaker and dolphinfish is recommended up to one serving per week, considering the importance of EFAs intake and avoiding fish with elevated MeHg content. Therefore, Ecuadorian authorities could enhance public standards for seafood safety and develop consumer advice for pregnant women and young children to determine good fish choices or those to avoid.

Spatial analysis of mercury and stable isotopes in the vulnerable Dusky Grouper Epinephelus marginatus along the Brazilian coast

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.

Determination of metals in estuarine fishes in a metropolitan region of the coastal zone of the Brazilian Amazon

The aim of the present study was to determine concentrations of cadmium, copper, chromium, manganese and iron in fishes in the São Marcos (SMB), São Jose (SJB) and Arraial (AB) Bays. Metal concentrations were determined using inductively coupled plasma optical emission spectrometry. Mean Cd and Cr levels were above the permissible limits set by different international or national guidelines in all three bays, whereas copper levels were well below the maximum acceptable limit. High concentrations of iron were found in all species analyzed, whereas high concentrations of manganese were found, especially in specimens caught in SJB. Spatial analysis indicated significant differences among the elements investigated. Copper was correlated more with SMB and AB as well as the species Macrodon ancylodon (carnivore) and Sciades herzbergii (omnivore). Cadmium and iron were strongly associated with AB and SJB, while manganese was only associated with SJB, mainly in carnivorous and herbivorous species.

Trace elements in the silky shark Carcharhinus falciformis in the Central Pacific Mexican Shelf

Mercury (Hg), cadmium (Cd) and copper (Cu) concentrations were determined in muscle, liver and fin of the silky shark (Carcharhinus falciformis) caught in the Central Pacific Mexican Shelf. Liver tissue presented the highest concentrations of Cd (2.83 μg g^-1 wet weight (ww)) and Cu (2.34 μg g^-1 ww). For muscle and fin, Cu presented the highest concentrations (0.97 and 1.80 μg g^-1 ww, respectively). Liver concentrations were influenced by the maturation stages for the three elements. Immature organisms exhibited lower trace element concentrations than adults. No significant differences were found between sexes, except for Cu concentrations in muscle, where adult females present higher levels than adult males. One muscle sample (2.3 %) exceeded the Mexican Legislation for Hg (1.0 μg g^-1 ww) and five muscles samples (11.6 %) exceeded the Mexican limit for Cd (0.5 μg g^-1 ww). Meat consumption of this species can be a risk to human health if it is ingested regularly.

Human risk assessment of toxic elements (As, Cd, Hg, Pb) in marine fish from the Amazon

The present study evaluated As, Hg, Pb and Cd burdens in both ecologically and commercially important 314 marine fishes belonging to 47 species sampled along the Amazon Coast. We specifically investigated variations in these four elements among different habitats and their relationships with trophic position and estimated potential human health risk by calculating the hazard quotient (HQ), hazard index (HI), and target cancer risk (TR). Our analyses revealed that Hg concentrations in reef-associated fish were over 2-fold those recorded in demersal fish (p < 0.001). A stable isotope analysis indicated that most of the fish species analyzed herein are secondary consumers (i.e., TP > 2.9) and their trophic positions exhibited a significant negative correlation to As, Pb and Cd. Positive significant relationships were noted between As-Cd, As-Pb, As-Hg, Hg-Cd and Cd-Pb, suggesting that these elements exhibit similar dispersion properties and bioaccumulation homology, probably arising from natural fluvial inputs from the Amazon basin system. Detected As concentrations were higher than established guidelines and legal limits in 63.8% of the examined species (n = 30), whereas Cd, Hg and Pb levels were generally very low. Estimated daily intake (EDI) of iAs, Hg and Pb were above reference dose (RfD) in more almost half of species analyzed and HQ values were each found to pose potential non-carcinogenic health risks if high amounts are consumed over time. HI indicates that the determined elements attained levels considered as potential human health hazards trough consumption of eight cartilaginous fish. The TR values of iAs and Pb were higher than the guideline value and given this, individuals who continuously consume cartilaginous fish contaminated with the toxic elements determined here will likely be under increased cancer risks in the long term.

First report on metal and metalloid contamination of Ampullae of Lorenzini in sharks: A case study employing the Brazilian sharpnose shark Rhizoprionodon lalandii from Southeastern Brazil as an ecotoxicological model

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.

Arsenic contamination in widely consumed Caribbean sharpnose sharks in southeastern Brazil: Baseline data and concerns regarding fisheries resources

Although shark meat is consumed worldwide, elevated arsenic (As) concentrations have been increasingly reported. The Caribbean sharpnose shark (Rhizoprionodon porosus) is a widely consumed fishing resource in Brazil, with scarce information on As burdens to date. Herein, commercial-sized juvenile Caribbean sharpnose sharks from Rio de Janeiro (Brazil) were assessed in this regard, presenting significantly higher hepatic As concentrations in males (8.24 ± 1.20 mg kg^-1 wet weight; n = 12) compared to females (6.59 ± 1.87 mg kg^-1 w.w.; n = 8), and a positive correlation (r = 0.74) was noted between female muscle and liver As concentrations, indicating systemic inter-tissue transport not evidenced in males. Arsenic concentrations were over the maximum permissible As limit established in Brazilian legislation for seafood and calculated Target Hazard Quotients suggest consumption risks, although cancer risks were not evidenced. Therefore, Public Health concerns with regard to Caribbean sharpnose shark As burdens deserve careful attention.

Negative metal bioaccumulation impacts on systemic shark health and homeostatic balance

Contamination by metals is among the most pervasive anthropogenic threats to the environment. Despite the ecological importance of marine apex predators, the potential negative impacts of metal bioaccumulation and biomagnification on the health of higher trophic level species remains unclear. To date, most toxicology studies in sharks have focused on measuring metal concentrations in muscle tissues associating human consumption and food safety, without further investigating potential impacts on shark health. To help address this knowledge gap, the present study evaluated metal concentrations in the gills, muscle, liver and rectal gland of coastal sharks opportunistically sampled from Brazilian waters and tested for potential relationships between metal bioaccumulation and general shark health and homeostatic balance metrics. Results revealed high metal concentrations in all four tissue types, with levels varying in relation to size, sex, and life-stage. Metal concentrations were also associated with serum biomarkers (urea, lactate, ALT, triglycerides, alkaline phosphatase, and phosphorus) and body condition, suggesting potential negative impacts on organismal health.

The Behavior of Consumers and Producers of Food of Animal Origin and Their Impacts in One Health

Most people consume animal foods, for example meats, but few are concerned with the quality and origin of these products. Many studies point out hygiene problems of these foods after production; however, the lack of knowledge of the consumers of animal products about the importance of hygienic-sanitary control during the production process can lead them to a bad choice when buying these products and, consequently, expose themselves to the risk of acquiring many diseases, such as zoonosis. In this perspective, the objective of this work is to reflect about the consumers' role in the production of safe food of animal origin and to show that the population's health education is necessary and urgent. Only by helping the consumers to obtain knowledge about the production of animal products origin will there be a change in consumption habits, preventing the ingestion of contaminated foods that can cause damage to human health and to the environment, consequently, promoting one's health.

Research trends on elasmobranchs from the Brazilian Amazon Coast: a four-decade review

Abstract: Elasmobranchs exhibit the biggest population declines among vertebrates, being considered one of the groups with the highest risk of extinction. The Brazilian Amazon Coast (BAC) is considered a priority area for elasmobranch conservation, as many species are endemic to the region, and most of them are threatened with extinction. The present study made a scientometric analysis using the IRAMUTEQ method (Interface de R pour les Analyses Multidimensionnelles de Textes et de Questionnaires) to evaluate the trends of research with elasmobranchs in BAC in the last four decades. Ten research trends were identified, highlighting “Biodiversity”, “Reproduction”, “Trophic Ecology” and “Conservation”. However, most of the publications found are aimed at understanding the diversity and abundance of species in the region, with the number of studies focused on reproduction, feeding and other aspects of the biology and ecology of elasmobranchs in the BAC being less expressive. Although the research area “Conservation” stood out in the search, the amount of relevant information so that management and conservation measures can be implemented is still low. Lastly, despite following the global trend of studies with elasmobranchs between 2000 and 2010, investigations into the BAC need to advance, especially considering the poor level of basic information on most species (Biology and population dynamics) and the incomplete knowledge of specific composition of elasmobranch species in the entire area, aspects relevant to conservation and more applied studies that rely on more recent methodologies and technologies.