Rachel Ann Hauser-Davis

This study provides the first age and growth assessment of the endangered spiny butterfly ray, Gymnura altavela (Linnaeus, 1758), in the Southwest Atlantic, while also updating the growth parameters (asymptotic disc width—DW _∞ and growth coefficient— k ) estimated in an ex situ a marine aquarium setting. In situ growth was assessed by analyzing the vertebrae of 95 individuals captured off the southeastern coast of Brazil. The Centrum Edge and Marginal Increment analyses indicated an annual annuli formation cycle. After applying a multi‐model approach, the Gompertz model was selected as the most appropriate for describing the in situ growth of both females (DW _∞ = 201.0 cm and k = 0.100 year ⁻¹ ) and males (DW _∞ = 139.4 cm and k = 0.170 year ⁻¹ ). In turn, ex situ growth was assessed by periodically measuring seven individuals kept in a marine aquarium for 8 years (2018–2025). The von Bertalanffy model modified by Fabens was used to estimate ex situ growth parameters for females (DW _∞ = 212.1 cm and k = 0.132 year ⁻¹ ) and males (DW _∞ = 120.1 cm and k = 0.255 year ⁻¹ ). A well‐marked sexual size dimorphism was observed in both in situ and ex situ, with females growing more slowly but reaching larger sizes than males. G. altavela grew faster in the controlled environment (ex situ). However, reaching the maturity size earlier may not necessarily result in anticipated reproduction events and it may also have a negative effect on longevity. Comparing the growth parameters and curves estimated in situ and ex situ provides valuable insight into how this population may respond to future environmental changes and impacts.

Seafood is an important component of human nutrition worldwide but also represents a major dietary pathway of arsenic (As) exposure. Assessing seafood-related health risks remains challenging because As toxicity depends strongly on chemical speciation rather than total concentration alone. Although seafood often contains high total arsenic (tAs), most occurs as organic compounds such as arsenobetaine, generally regarded as low in toxicity and rapidly excreted in humans. In contrast, inorganic arsenic (iAs), primarily arsenite [As(III)] and arsenate [As(V)], is highly toxic and carcinogenic. Emerging evidence further challenges the traditional assumption that organic arsenicals are uniformly harmless, as methylated intermediates have demonstrated cytotoxic and genotoxic properties, and some arsenolipid subclasses, particularly arsenic-containing hydrocarbons, have demonstrated cytotoxicity. Despite the importance of As speciation assessments, routine species-specific analysis remains limited in seafood monitoring due to the limited availability of validated methods and certified reference materials, as well as relatively high operational costs, and limited laboratory accessibility. Consequently, many exposure assessments rely on tAs concentrations and generalized assumptions regarding iAs fractions, despite substantial variability among seafood taxa, habitats, and geographic regions. Human exposure assessments are further complicated by marked differences in seafood consumption patterns and demographic susceptibility, with coastal and fishing-dependent communities often experiencing substantially greater dietary exposure than population averages suggest. This review synthesizes current knowledge on As occurrence and speciation in seafood, analytical approaches, toxicological implications of different arsenic species, and human exposure and risk assessment frameworks, including Estimated Daily Intake (EDI), Estimated Weekly Intake (EWI), Target Hazard Quotient (THQ), Hazard Index (HI), and Target Cancer Risk (TCR). Particular emphasis is placed on taxonomic variability in iAs occurrence, localized seafood consumption, demographic heterogeneity, and emerging toxicological evidence. Collectively, the evidence supports a transition from tAs-based screening toward more realistic, speciation-informed and context-dependent seafood risk assessment.

The 2019 oil spill in Guanabara Bay, among the most significant in Brazilian history, has reinforced how persistently PAHs move through food webs significant to artisanal fishing communities. However, low-cost tools for tracking these contaminants in key sentinel species, such as bivalves, remain scarce, especially for matrices that resist conventional extraction protocols. In this sense, this study developed a dual-extraction method combining Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) and solid-phase extraction (SPE) clean-up to quantify multiple PAHs in Perna perna mussels sampled from Guanabara Bay, Brazil overcoming matrix interference to deliver faster, cheaper and more actionable contamination data for a subsistence food source. A total of 210 mussels were collected across four artisanal fishing communities in Guanabara Bay, a socially and ecologically critical estuary, 2 to 3 years after the spill. The method achieved strong linearity ( r ² > 0.995) and acceptable recovery (51.1–109.0%) for 15 of 18 target PAHs. Only five compounds were quantified above the Limit of Quantification, with special focus on benzo(a)pyrene, with a high-molecular-weight and predominantly pyrogenic signature pointing to a diffuse, combustion-derived background rather than a lingering trace of the spill. This finding highlights the value of the proposed method, of a practical, affordable tool that is extensible to oil-impacted tropical estuaries worldwide for routine PAH biomonitoring.

Metal accumulation in batoids reflects both environmental exposure and physiological regulation, although studies concerning this group are still scarce. The Smooth butterfly ray (Gymnura cf. micrura) is consumed in northeastern Brazil, yet information on metal contamination and associated health risks are unavailable to date. This study assessed metal and metalloid concentrations, muscle metallothionein (MT) levels, elemental associations, and human health risks in specimens collected off the Maranhão coast. No significant sex-related differences were observed in element concentrations or MT levels, and MT showed no significant correlations with metals, suggesting limited muscle involvement in detoxification or exposure levels below induction thresholds. Multivariate and correlation analyses indicated distinct accumulation patterns, with rare earth elements associated with lithogenic inputs and some essential-toxic element relationships suggesting possible antagonistic interactions, particularly involving Se and Hg. A risk assessment showed that estimated daily and weekly intake values remained below guidance limits under realistic inorganic As assumptions. However, non-carcinogenic and carcinogenic risks increased under conservative scenarios, especially for infants at higher consumption frequencies. Although a positive HBVSe value suggests possible Se-mediated protection against Hg toxicity, this effect does not eliminate overall contaminant-related health risks. Graphical abstract

Estuarine fishes are exposed to multiple contaminants, yet metal(loid) partitioning in skeletal tissues remains poorly understood. In this context, this study assessed As, Cd, Ca, Cu, Hg, Pb, Sr, and Zn concentrations in adult fat snook (Centropomus parallelus) soft tissues and skeletal structures from southeastern Brazil (n = 12). Soft tissues comprised muscle, liver, gills, eyes, and gonads, and skeletal tissues included the cranium, cleithrum, neural and hemal spines, and dorsal and anal pterygiophores. Associations with biometric parameters and the compliance of muscle concentrations with regard to food-safety reference values were also evaluated. Distinct element- and tissue-specific distribution patterns were observed, in which Cd and Cu were mainly associated with the liver, Hg was highest in muscle, Zn was highest in the eyes and gonads, and Ca and Sr were predominantly concentrated in skeletal tissues. Associations with biometric variables varied among elements and tissues, indicating size-related differences in elemental accumulation. Muscle As, Cd, Hg, Pb, Cu, and Zn concentrations remained below regulatory limits and/or reference values. These findings demonstrate that muscle alone does not adequately represent whole-body metal(loid) distribution and support the inclusion of skeletal tissues in biomonitoring and ecotoxicological assessments of C. parallelus.

Although caudal spines are present in most Myliobatiformes species, their biology and ecological function, beyond self-defense, are still poorly understood. Novel information on the development and replacement of the species’ caudal spines was obtained herein by examining the caudal spines of 63 Gymnura altavela specimens. Our data suggest that G. altavela in the southwestern Atlantic undergoes an annual caudal spine replacement cycle, with new spines forming in spring and summer. This replacement may be anticipated by spine breakage, as double-spined stingrays with broken lower spines were observed in winter. Unlike previously studied stingrays, new spines in G. altavela developed on the dorsal region of old spines. Furthermore, this study is the first to investigate the possible use of caudal spines for assessing stingray age. Although spine width growth follows body morphometry, growth bands were not observed along the length of the caudal spines or in their interior. Therefore, these calcified structures do not appear to be suitable for age assessment, at least when considering the classical approach of counting annuli composed of growth bands.

Polycyclic aromatic hydrocarbons (PAHs) are toxic, carcinogenic organic contaminants widely distributed throughout the marine environment, directly affecting marine life and human health. Surveying these compounds in sentinel organisms, such as seabirds, is an effective way to assess environmental quality. In this sense, this research aimed to (i) develop and validate a high-performance liquid chromatography (HPLC) analytical method for the quantification of the 16 priority PAHs in blood plasma; (ii) establish an easy and quick protocol to reduce sample handling and potential contamination; and (iii) apply the method to Brown booby ( Sula leucogaster ) blood samples from specimens collected along the coast of the state of Rio de Janeiro in 2025. The performance parameters of the developed method met well-established criteria and the Limits of Quantification (LOQ) achieved herein (0.06 - 4.48 ng mL ^-1 ) are consistent with the main goal and comparable to recent literature. The analyzed samples (n=13) presented low PAH concentrations (from -1 ), consistent with chronic background exposure and no evidence of acute events. The contamination profile suggests exposure to low molecular weight PAH, possibly due to Brown booby trophic position and habitat. This research delivers an initial database of an ongoing monitoring project for future assistance in the event of oil spills or other acute contamination sources.