Zapteryx Brevirostris Research Articles

Post‐capture recovery is mediated by shifts in allostatic and metabolic dynamics in a threatened and endemic rhino ray

AbstractUnderstanding how animals respond to stressors is critical for effective conservation. The present study aimed to evaluate the physiological recovery of the Shortnose Guitarfish, Zapteryx brevirostris after being incidentally captured by artisanal fleets and compared it to guitarfish with delayed mortality. Moreover, the study aimed to test the efficiency of a rehabilitation protocol for the species. To this end, individuals landed alive were transported to the rehabilitation facilities and kept in tanks under monitoring for 3 days. Physiological markers indicative of allostatic overload (i.e., lactate and phosphorus) and energy metabolism (i.e., glucose and β‐hydroxybutyrate) were assessed in the serum of the studied guitarfish: right after gillnet capture (i.e., post‐capture) and on rehabilitation (i.e., pre‐monitoring, post‐monitoring, as well as guitarfish that deceased during monitoring – post‐mortem). Results showed that the transportation and additional handling employed in the rehabilitation protocol did not increase the stress response, pointing to its potential efficacy in recovering debilitated, incidentally caught guitarfish before release. As for recovery success of monitored guitarfish, lactic acidosis was fully reverted after a 3‐day rest period, as was allostatic overload. The same was not observed in recovery failure. Correlation tests revealed key relationships between physiological markers, shedding light on how physiological pathways help guitarfish cope with capture and handling stress. This study highlights the valuable application of conservation physiology principles to fisheries management of this endemic and threatened guitarfish species.

Secondary sexual dimorphism and ontogenetic shifts in habitat use by the lesser guitarfish Zapteryx brevirostris.

Sexual dimorphisms are generated by divergent processes, such as natural or sexual selection and niche convergence. Males and females of the lesser guitarfish, Zapteryx brevirostris, present morphological differences in their discs, and the relationships with the species biology and ecology were unrecognized. Analysing the morphometry of 201 specimens and the influence of bottom features on the frequencies of 188 specimens among life stages and sexes, we found strong evidence that gonadal maturation leads to dimorphisms on discs, validating a concavity on male pectoral fins as a secondary sexual dimorphism and rejecting the hypothesis that such dimorphisms were related to ecological pressures. The principal component analysis (PCA) and permutational MANOVA (PERMANOVA) analyses revealed that males and females shared similar body aspects until they reached maturity, mainly due to lower variations in WD, WR, LD, DPRO, and LSC at younger life stages. The relationships of these variables with LT corroborate the former results, showing a changing point around LT > 30 cm where females started to attain larger measurements than males. Moreover, we revealed ontogenetic shifts, with adults from both sexes exploring different habitats than juveniles and subadults. Differences in frequencies of each life stage were best explained by organic matter (OM) with the adults exploring bottom habitats of higher concentrations of OM than juveniles and subadults, strengthening the assumption that body differences between sexes are not related to ecological pressures. These results bring not only new insights about the possible advantages that those morphometric differences provide to males while mating but also information about the abiotic influences on species distribution, which, along with knowledge of local oceanographic dynamics and benthic community patterns, would inform actions for species conservation.

Comparative morphology of the oropharyngeal denticles in the order Rhinopristiformes and its functional implications (Chondrichthyes: Batoidea).

Guitarfishes and sawfishes are included in the order Rhinopristiformes, which currently encompasses five families: Pristidae, Rhinobatidae, Trygonorrhinidae, Rhinidae and Glaucostegidae. Considering the low number of studies focused on oral structures in Rhinopristiformes and the need to better understand their internal morphology, this study aimed to(1) evaluate and describe the morphological variation of the oropharyngeal denticles of guitarfishes and sawfish; (2) evaluate and describe the ontogenetic and sexual variation of the oropharyngeal denticles of Zapteryx brevirostris; (3) propose characters potentially useful for taxonomic and systematic purposes and (4) discuss the possible functions and advantages of these structures. Tissue samples were taken from the oropharyngeal region of specimens preserved in 70% alcohol and then prepared for visualization in scanning electron microscopy. A new method for sampling the pharynx region is proposed herein. Considerable morphological variation between families and genera was observed. However, no variation between conspecifics was found. Regional variations of denticles when examining a single individual were observed in shape, ornamentation, and orientation. In Zapteryx brevirostris, males had a significantly higher density of denticles in the ventral region than females and lower densities were observed in juveniles. The four characters discussed here are based on the presence of keels, number of cusps, distal end elongation and width/length ratio of the oropharyngeal denticles. Among the possible functions and advantages of these structures are the improvement of food adherence, tissue protection against food abrasion and parasitism, and attenuation of hydrodynamic drag in the oropharyngeal cavity during food ingestion.

Dual‐method survey of recreational fishing for guitarfishes in Southern and Southeastern Brazil

AbstractWe comprehensively assessed marine recreational fishing of threatened guitarfishes (Pseudobatos percellens, Pseudobatos horkelii, and Zapteryx brevirostris) in Southern and Southeastern regions of Brazil. A dual‐method approach integrated social media reports and in‐person interviews to explore practices, challenges, and conservation implications of recreational fishing for these species. Seasonal capture of guitarfishes required the promotion of catch‐and‐release, especially during gestational periods, and the development of best angling practices manuals and accessible identification guides. With a focus on land‐based activities and engagement with fishers, our findings underscored the importance of collaboration among researchers, recreational fishers, and conservationists to map and monitor recreational capture and contribute to guitarfish research and conservation.

Andrology of Shortnose Guitarfish Zapteryx brevirostris (Müller & Henle, 1841) (Chondrichthyes, Trygonorrhinidae).

The andrological study of a species comprises from the macro- and microscopic analysis of the internal reproductive organs to the evaluation of seminal parameters and ultrastructural characteristics of the spermatozoa. As in other vertebrates, the male reproductive tract in chondrichthyans is composed of testes and reproductive ducts (efferent duct, epididymis, Leydig's gland, ductus deferens and seminal vesicle). In this study we used three adult specimens of Zapteryx brevirostris from wild capture and kept at the Ubatuba Aquarium, Brazil. Semen collection was performed by abdominal massage, over the location of the seminal vesicle, preceded by ultrasonographic evaluation. The semen collected was diluted 1:200 and submitted to quantitative and morphological analysis. Ultrastructural analysis was performed by transmission and scanning electron microscopy. Correlation was observed between successful collection and ultrasonographic image of an engorged seminal vesicle, as well as testicles with easily delimitable margins and higher echogenicity. It was possible to identify free spermatozoa with helical filiform appearance, as well as spermatozeugmata. The average sperm concentration resulted in 5 million packets per ml and 140 million spermatozoa per ml. The sperm nucleus showed cone shape, parachromatin sheath less dense than the chromatin of the nucleus, smooth depression of the nuclear fossa, abaxial axoneme 9+2 and accessory axonemal columns in position 3 and 8 and oval shaped, with flattened inner surface in cross section. These results broaden the knowledge about the andrology of this species, contributing to ex situ breeding programs.

Bioaccumulation and potential impacts of persistent organic pollutants and contaminants of emerging concern in guitarfishes and angelsharks from Southeastern Brazil

The present study aimed to determine persistent organic pollutants (POPs) and contaminants of emerging concern in endangered angelshark and guitarfish species from southeastern Brazil, and to investigate potential impacts of these compounds on morphometric indexes. Pesticides of emerging concern, pharmaceutical and personal care products (PPCPs), polycyclic aromatic hydrocarbons (PAHs), and polybrominated diphenyl ethers (PBDEs) were determined in hepatic and muscular tissues of Pseudobatos horkelii, P. percellens, Squatina guggenheim, and Zapteryx brevirostris obtained from artisanal and industrial fisheries operating in southeastern Brazil. Accumulation profiles and effects of contaminants on condition factor and hepatosomatic index were investigated. No differences were detected regarding species contaminant concentration, potentially due to similarities in habits, occurrence and trophic position shared by guitarfishes and angelsharks. Polycyclic aromatic hydrocarbons (23.2–495.3 ng g −1), and PPCPs such as diclofenac (<LOQ – 448.4 ng g−1) and methylparaben (<LOQ – 645.5 ng g−1) presented the highest concentrations, regardless of the species. Effects of elasmobranch size were not significant on contaminant levels, indicating the lack of bioaccumulation over time. We suggest that the exposure to contaminants in elasmobranchs inhabiting this region is highly dependent on the economic activities and high urban development in southeastern Brazil. Regarding potential impacts of such exposure, the condition factor was only negatively influenced by PBDEs concentrations, whereas the hepatosomatic index was not influenced by any contaminant. Despite this, our results indicate that guitarfishes and angelsharks are exposed to POPs and contaminants of emerging concern potentially toxic to aquatic organisms. In this context, more refined biomarkers should be used to predict potential impacts of these contaminants on elasmobranch's health.

Side effects for batoids’ conservation in the vacuum of fishery management

A shift verified in batoid landings by artisanal fisheries during 2017-2021 is interpreted as a potential consequence of legal measures set by the Brazilian government in 2014. In this five-year period, the increasing landings of stingrays concomitant with a decrease in the landings of guitarfish might be a result of fishing bans established for the Brazilian guitarfish Pseudobatos horkelii and the Shortnose guitarfish Zapteryx brevirostris, which are both endemic to the coasts of Southern Brazil, Uruguay, and Argentina and listed as threatened at national and global levels. In 2022, more batoids became protected, so it is expected that shifts in captures will continue, reaching species whose stocks have not yet been evaluated and for which conservation measures are not foreseen. Considering the sociocultural and economic relevance of artisanal fisheries in the country, the observed shift is discussed here as it relates to batoids’ effective conservation and adherence to legal measures by the fishery sector in Southern Brazil.

Birth and growth of the shortnose guitarfish Zapteryx brevirostris (Müller & Henle, 1841) (Chondrichthyes, Rhinobatidae) in captivity.

Endemic to the south-west Atlantic Ocean, the shortnose guitarfish (Zapteryx brevirostris) is a small species, classified as endangered by the IUCN. Although reproduction in captivity has been successful for some species, a range of factors can limit the success of captive breeding programmes for elasmobranchs. In Brazil, the Ubatuba Aquarium was the first public aquarium to reproduce small-sized elasmobranchs. Since 2018, at least five parturition events have been recorded for Z. brevirostris at the institution. From a total of 13 live neonates that rearing was attempted, the mean ± standard error of weight, total length (TL) and disc width at birth were 17.47 ± 1.6g, 13.25 ± 0.7cm and 6.53 ± 0.2cm, respectively. The mean weight as well as mean TL were higher for females at all births, with 26.15 g and 15.07 cm for females in comparison with 17.09 g and 13.94 cm for males. Considering the increasing risk of extinction that the species is facing, age and growth studies are fundamental for the success of conservation, improving the knowledge of Z. brevirostris life cycle so that a more efficient and sustainable management can be carried out. This study provides important data, as well as directions for captive breeding of the species.

Occurrence of Nerocila acuminata (Schiödte &amp; Meinert, 1881) (Crustacea, Cymothoidae) parasitic on the shortnose guitarfish Zapteryx brevirostris (Rhinobatiformes, Rhinobatidae) off Brazil

The isopods of the family Cymothoidae are ectoparasites crustaceans that infest a wide variety of saltwater fish. This paper documented the first occurrence of Nerocila acuminata (Schiödte &amp; Meinert, 1881) parasitizing the shortnose guitarfish Zapteryx brevirostris (Müller &amp; Henle, 1841) (Rhinobatiformes, Rhinobatidae) in the southern Atlantic Ocean. This report can be an available tool to create a parasitology database for a species of conservation interest. It will also provide scientific data that can help the understanding of the biological factors acting in healthy populations and thus support the efforts made to preserve and conserve the species.

Isotopic niche of coastal fish and cephalopods off the Campos Basin, southeastern Brazil

The stable isotopes of carbon (δ13C) and nitrogen (δ15N) of three demersal guilds (benthic feeders, benthic/nekton feeders and nekton feeders) were assessed to understand their trophic relationships on the southeastern Brazilian coast. The organic matter (OM) pool that fuels the demersal food web is composed of a mixture of autochthonous (marine) and allochthonous (terrigenous) sources, highlighting the Paraíba do Sul River (PSR) influence in the shallow coastal waters, regardless of seasonality. Of the studied guilds, the nekton feeder guild (Doryteuthis plei, Lophius gastrophysus, Percophis brasiliensis and Saurida caribbaea) in the demersal food web had the highest δ15N’ values in the dry and rainy seasons. The benthic feeder guild (Atlantoraja platana, Dactylopterus volitans, Dules auriga, Etropus longimanus, Prionotus nudigula and Zapteryx brevirostris) presented the widest isotopic niche breadth (highest total niche area and trophic diversity) due to the assimilation of a variety of benthic crustaceans, with different isotope signatures. The assimilation of benthic and pelagic crustaceans by the benthic feeder and benthic/nekton feeder (Atlantoraja cyclophora, Octopus vulgaris and Priacanthus arenatus) guilds resulted in isotopic overlap (28.1–50.6%). Seasonal trends from benthic and inshore to pelagic and offshore associated food webs were observed for the benthic feeder and benthic/nekton feeder guilds. Our results highlight the importance of terrestrial OM sources from PSR to shallow coastal demersal food webs off inner and medium continental shelf in southeastern Brazil. In addition, the trophic relationships of megafauna from benthic to nekton feeders were discussed.

Capture‐induced vulnerability in male Shortnose guitarfish during their reproductive period

AbstractThe assessment of physiological responses to capture provides useful information for elasmobranch conservation. In particular, understanding these impacts in species caught as bycatch that are released after capture can predict their “post‐release” fate and aid in management plans. Although well studied in several species, capture‐stress is nonetheless frequently assessed without considering putative variability between sexes. Given the high mortality of pregnant Zapteryx brevirostris females reported in the literature, the present study aimed at determining greatest vulnerability period for males. Our results demonstrate that, when caught during the reproductive period, males display higher mortality (68%) than when caught outside the reproductive period (zero mortality). Seven out of 11 markers (i.e. sodium, chloride, potassium, lactate, phosphorus, triglycerides and condition factor) differed significantly following capture‐induced stress between males caught during the reproductive period and those caught outside this period. Results demonstrate the need for specific protocols during the reproductive period, also considering the influence of sex on physiological responses to stress for effective management.

Production Performance and hematological analysis of Zapteryx brevirostris in a Closed System / Desempenho Produtivo e Hemograma da Zapteryx brevirostris em Sistema Fechado

The shortnose guitarfish ray, Zapteryx brevirostris , is constantly hauled by seven-beard-shrimp trawl nets are currently within the endangered species category. One means of preserving some aquatic species is to maintain them in a captive system such as tanks and aquariums, where it is possible to know their behaviors, as well as hematology and their well-being. The objective of this study was to analyze the productive performance and hematological analysis of Zapteryx brevirostris when submitted to different sediments in a captive system of water recirculation. For this, four treatments were used: Treatment 1 (gravel), treatment 2 (coarse sand), treatment 3 (medium sand) and treatment 4 (control) without sediment. At the end of the experiment, growth and weight data were taken for calculations of productive performance. Further, the hematological analysis was performed. The results showed that the species showed no significant difference for productive performance and hematological analysis in all treatments. However, treatment 3 (medium sand) was the only one to demonstrate weight gain, but the hematological analysis proved that the rays of all treatments were with hypochromic microcytic anemia. Thus, none of the treatments contributed to the productive performance and well-being of the rays.

Metal contamination in threatened elasmobranchs from an impacted urban coast

Guitarfishes and angelsharks are two of the most endangered elasmobranch groups. Despite this, limited knowledge exists regarding the effects of environmental contamination in these groups. For this reason, this study assessed the concentrations of metals in liver and muscle of three guitarfishes (Pseudobatos horkelii, P. percellens, and Zapteryx brevirostris) and one angelshark species (Squatina guggenheim) captured during the year of 2019 in one of the most impacted areas in South America: the São Paulo State coast, Brazil, Southwest Atlantic. Cadmium (Cd) Chromium (Cr) Cupper (Cu) Iron (Fe), Mercury (Hg), and Lead (Pb) were determined by atomic spectrometry, with samples being previously acid digested. Among the non-essential metals, Cd had the highest mean concentrations for all species, followed by Pb and Hg, whereas Fe had the highest mean levels among the essential metals analyzed, followed by Cu and Cr. Liver and muscle samples had different concentrations, with liver presenting the highest concentrations. Except for Cd, non-essential metals had relatively low concentrations when compared to other elasmobranch species reported in the literature, which could be explained by the efficiency in metabolizing these compounds or differential life history patterns among the species studied herein and other. Considering that all species analyzed herein are typically consumed, human health impacts must be considered, especially concerning Cd concentrations. Furthermore, Cd, Cr and Pb were above the safety limits, indicating potential hazard for human consumption. In conclusion, our results suggest that these species are exposed to metals and that concentrations above the safety limits observed for these species must be taken into consideration regarding human consumption.

TUBARÕES E RAIAS COMO CAPTURA INCIDENTAL NA PESCA ARTESANAL DO LITORAL DO PARANÁ: CONDIÇÃO REPRODUTIVA E VARIAÇÕES SAZONAIS EM COMPOSIÇÃO E ABUNDÂNCIA

Monitoraram-se os desembarques de elasmobrânquios no litoral do Paraná nos anos 2009 e 2010. Descrevem-se atributos de frota e petrechos empregados. As espécies foram caracterizadas quanto ao tamanho dos indivíduos e à condição reprodutiva. Acessaram-se 4.941 indivíduos, 51% tubarões e 49% raias. Foram desembarcados inteiros 82% dos indivíduos, 3,68 t de tubarões e 2,35 t de raias. Identificaram-se 14 espécies de tubarões, peso médio de 1,46 kg (0,067-16,0 kg; DP = 3,83), predominando em número Rhizoprionodon lalandii e Sphyrna zygaena. Os tubarões foram mais capturados na primavera/verão, com maior frequência de neonatos ou imaturos. Registraram-se 12 espécies de raias, peso médio de 0,971 kg (0,394-10,0 kg; DP = 2,80), predominando em número Zapteryx brevirostris e Pseudobatos percellens. As raias foram mais capturadas no outono, em pescarias dirigidas a camarões e pequenos teleósteos, com maior frequência de imaturas ou maduras. Onze das 26 espécies são classificadas como vulneráveis, em perigo ou criticamente ameaçadas. Para fins de conservação, recomendam-se ações educativas pró-descarte de: animais vivos – neonatos em geral, Narcine brasiliensis no arrasto camaroeiro, e jovens e adultos de espécies com captura proibida; e priorização à proteção de Carcharias taurus, P. percellens acompanhante da pesca de linguado, e jovens de Squatina sp., cujos adultos são alvo em redes de emalhe.&#x0D; Palavras-chave: reprodução, neonatos, arrasto, captura incidental, Rhizoprionodon lalandii, Sphyrna zygaena, Zapteryx brevirostris.

Age and growth of three endemic threatened guitarfishes Pseudobatos horkelii, P. percellens and Zapteryx brevirostris in the western South Atlantic Ocean.

The age and growth of three endemic threatened guitarfish species were analysed using vertebrae of Pseudobatos horkelii, P. percellens and Zapteryx brevirostris. Edge and marginal-increment analyses were used to evaluate the periodicity of the formation of the band-pairs, suggesting deposition of one band-pair per year, from late winter to late spring. The von Bertalanffy growth model was used to describe the growth of these species with the following parameters, for pooled sexes: P. horkelii L∞ = 126.93, k = 0.19 and t0 = -1.51; P. percellens L∞ = 109.31, k = 0.16 and t0 = -1.78; Z. brevirostris L∞ = 60.37, k = 0.24 and t0 = -1.42. Our results are essential to understanding the resilience and vulnerability of these species to harvest, which can contribute to management and conservation actions of these species.

Use of eugenol for anesthesia of lesser guitarfish Zapteryx brevirostris (Rhinobatidae)

Anesthesia can be utilized as a non-lethal procedure to allow easy handling of teleosts and elasmobranchs in captivity or in the wild. For this, anesthetic protocols need to be established according to the species. The aim of this study was to determine the ideal concentration of eugenol for anesthesia of Zapteryx brevirostris. Four concentrations were tested: 21.25, 42.50, 85.00 and 170.00 mg L-1 (ratio of 1:5 with absolute ethanol). The perfect concentration of eugenol for this species was 85.0 mg L-1 , which enabled up to 300 seconds of work on the fish, without any response to handling.

Evidence of tide pool use by a viviparous elasmobranch as a parturition site

Despite the frequent occurrence of elasmobranchs in surf zones, the use of tidal pools by these animals is unknown, with only one incidental observation reported in the literature. Here we present a possible birth observation in a tide pool for the shortnose guitarfish, Zapteryx brevirostris (M&uuml;ller et Henle, 1841). We discuss this occurrence as it relates to the possible use of this micro-habitat to take advantage of its ecological characteristics during parturition, the moment of extreme vulnerability to viviparous elasmobranchs.

Quantification of liver lipid deposition and melano-macrophages in lesser guitarfish Zapteryx brevirostris submitted to different feeding cycles

The objective of this study was to evaluate and quantify the fat storage in the liver of lesser guitarfish Zapteryx brevirostris submitted to different periods of restriction and refeeding. In a water recirculation system, 21 animals were divided into three groups: control (n=7), fed every day; W1 (n=7), with one week of restriction and two of refeeding and W2 (n=7), with two weeks of restriction and two of refeeding. After 76 days, the animals were euthanized and liver samples were collected, paraffin embedded, stained with PAS and evaluated with stereological procedures and histopatological changes were recorded. The area occupied by fat in the liver of control group was higher than that found in groups W1 and W2 (p<0.001). Melano-macrophage center areas and diameters have risen with increased fasting period while there were swollen and necrotic hepatocytes. These results pointed to physiological adaptations and liver lesions caused by free radicals during fasting periods. Similarly to teleost fish, there was a consumption of lipid reserves while enhancing the gluconeogenesis during fasting.

RESILIENCE OF THE SHORTNOSE GUITARFISH (Zapteryx brevirostris): COMPLETE COMPENSATORY GAIN, HEMATOLOGY AND HISTOPATHOLOGY

Compensatory gain has been used to evaluate the plasticity of species, in adverse situations such as food deprivation. The aim of the present study was to identify the type of compensatory gain achieved by the shortnose guitarfish (Zapteryx brevirostris), in situations of reduction of food resources. Three treatments were used: seven days of food deprivation and fourteen days of refeeding (T7x14); fourteen days of food deprivation and fourteen days of refeeding (T14x14); and feeding every day (TControl). Zootechnical performance, blood samples and histological samples were evaluated. We demonstrated that this species presented complete compensatory gain and that some blood parameters and histological alterations were associated with fasting.

Embryonic malformations in an offspring of the shortnose guitarfish

Embryonic malformations can be a result of exposure toxic substances (pollution), lack of nutrients, physical restraint, genetic disorders, or infections and diseases. Such malformations can be classified according to severity and offspring survival outside the uterus. Moreover, abnormalities are normally restricted to a small portion of the litter, mostly, to only one embryo. Here, we report a case of congenital malformation dominance in an offspring of the shortnose guitarfish and compare it with other abnormalities commonly reported in batoids in addition to discussing the possible causes involved in the observed deformities.