Extending records of albinism and skin disorders in American cownose rays to southeastern Brazil.

Albinism is a genetic condition expressed as a lack of integumentary and retinal melanin. Although documented across many vertebrate species, albinism and other skin disorders are rarely observed in elasmobranchs (sharks and rays). The present study describes the first confirmed case of albinism in American cownose ray (Rhinoptera bonasus), and three other juveniles of the species with undetermined skin disorders observed in São Paulo, southeastern Brazil. Pigmentation disorders have already been observed in American cownose rays from the North Atlantic, including two cases of leucism and a possible albinism. Based on the results, it was discussed the possible consequences of albinism for the ray survival as well as the possible causes for the undetermined skin disorders.

First record of mating behaviour and induced parturition of the Brazilian endemic Lutz's stingray Hypanus berthalutzae.

The recently described Lutz's stingray Hypanus berthalutzae is endemic to the Brazilian Province, including oceanic islands. Although it is expected to have life-history traits similar to the southern stingray H. americanus, little is known about its reproductive biology. Here we present the first observations of courtship behaviour (n = 4), copulation (n = 3) and an induced parturition of H. berthalutzae at the Fernando de Noronha Archipelago, an insular Marine Protected Area from the Equatorial Atlantic Ocean. The mating event records included (1) 'chasing/close following', (2) 'biting/precopulatory biting', (3) 'insertion/copulation' and (4) 'separation'. These results are especially relevant considering that records of reproductive behaviour in the wild are rare for elasmobranchs in general. Mating events occurred in different months, suggesting that the reproductive cycle of H. berthalutzae in this insular system is asynchronous, as observed for other stingray species in regions with favourable environmental conditions and abundant food throughout the year. The opportunistic documentation of the induced parturition allowed for direct nonlethal observation of the two pups at or near full term in late May. Although preliminary, these observations should be considered in future management plans as they provide relevant data about the life-history traits and mating behaviour of this endemic and threatened species.

Female wound records suggest mating periods for the Caribbean reef shark at an insular marine protected area from the Equatorial Atlantic Ocean.

Despite being one of the most abundant, economically significant, reef-associated shark species, little is known about the reproductive aspects of the Caribbean reef shark (Carcharhinus perezi). In the present study the authors report the first evidence of mating wounds and scars in female Caribbean reef sharks at the Fernando de Noronha Archipelago, a remote marine protected area in the South Atlantic Ocean. Data from four females suggest this species mates mainly during the austral summer, between February and March. Given that the archipelago has been previously described as a nursery ground for the Caribbean reef shark, these results add information about the reproductive cycle of this species in the equatorial Atlantic Ocean.

Effects of urbanization on the nutritional ecology of a highly active coastal shark: Preliminary insights from trophic markers and body condition.

The synergistic effects of coastal urbanization have dramatically impacted biological communities. Yet, few studies have investigated how urbanization can influence the diet quality and trophic ecology of coastal sharks. In a preliminary study, we examined for spatial variation in the nutritional ecology of a highly active marine predator, the blacktip (Carcharhinus limbatus) exposed to regional differences in coastal urbanization in southeast Florida. We used medium-term nutritional indicators (i.e., body condition and whole blood stable isotopes [δ15N and δ13C]) and short-term dietary markers (i.e., plasma fatty acid profiles) to test the hypothesis that blacktip sharks sampled within highly urbanized areas (hereafter, 'urban sharks') would exhibit higher body condition, but lower diet quality, compared to conspecifics sampled in areas exposed to relatively low levels of urbanization (hereafter, 'urban sharks'). Our initial results showed that urban blacktip sharks exhibited relatively higher body condition, blood δ15N levels, and percentages of saturated fatty acids compared to non-urban sharks. Collectively, these results suggest a possible positive alteration in the amount of food consumed by blacktip sharks in the study region and/or in the caloric value of their prey. We also found lower percentages of bacterial markers and higher values of dinoflagellate markers in urban sharks. Accordingly, we did not detect an expected reduction in diet quality (in terms of essential fatty acids) in this highly active species exposed to urbanization, as has been previously reported in a resident shark species (Ginglymostoma cirratum). Therefore, it is possible that lifestyle and feeding behavior influence the quality of food consumed by urban sharks. We suspect that impacts of urbanization are more pronounced in resident, sedentary and benthic species.

Eye healing in a free-ranging whitespotted eagle ray (Aetobatus narinari) following shark-inflicted bite injuries.

Here we provide the first photographic records of the eye healing of a free-ranging whitespotted eagle ray (Aetobatus narinari) following shark-inflicted bite injuries on the cephalic region. The whitespotted eagle ray with fresh wounds on the cephalic region close to its right orbit, upper jaw and the anterior margin of its right pectoral fin was photographed on 19 July 2017 at the Fernando de Noronha Archipelago. Two subsequent photographs of the whitespotted eagle ray with a blind right eye were taken on 29 March 2018 and 18 April 2018. These records show the whitespotted eagle ray had the capacity to recover from the wounds, although they have led to the blindness of the eye. These findings also demonstrate this individual was able to survive for at least 9 months with a nonfunctional eye.

Microscopic aspects of electrosensory system on the partially euryhaline lesser guitarfish

ABSTRACT The electrosensory system on elasmobranchs consists of subcutaneous electroreceptor organs known as ampullae of Lorenzini. The present study investigated the ampullae of Lorenzini morphology of the lesser guitarfish Zapteryx brevirostris, using light microscopy and scanning electron microscopy. The pore number found in the ventral skin surface is much higher than that found in the dorsal portion, characteristic of species that inhabit the euphotic zone. Under light microscopy it was possible to observe that the wall canal consists of a single layer of squamous epithelial cells. The canal features distal expansion, where the ampullae are located with up to six alveoli. The sensory epithelium of ampullae is composed by cubic cells, with oval nucleus, restricted to the interior of the alveoli. With analysis the clusters under scanning electron microscopy, it was possible to observe the structure and the random arrangement of individual ampullae, canals and nerves. The distribution of dorsal and ventral pores and ampullae in Z. brevirostris resembled those of the same family. The number of alveoli per ampullae was similar to that found in euryhaline elasmobranchs species, suggesting that the morphological organization in Z. brevirostris is linked to its possible evolutionary transitory position among batoids.

Microscopic aspects of electrosensory system on the partially euryhaline lesser guitarfish.

The electrosensory system on elasmobranchs consists of subcutaneous electroreceptor organs known as ampullae of Lorenzini. The present study investigated the ampullae of Lorenzini morphology of the lesser guitarfish Zapteryx brevirostris, using light microscopy and scanning electron microscopy. The pore number found in the ventral skin surface is much higher than that found in the dorsal portion, characteristic of species that inhabit the euphotic zone. Under light microscopy it was possible to observe that the wall canal consists of a single layer of squamous epithelial cells. The canal features distal expansion, where the ampullae are located with up to six alveoli. The sensory epithelium of ampullae is composed by cubic cells, with oval nucleus, restricted to the interior of the alveoli. With analysis the clusters under scanning electron microscopy, it was possible to observe the structure and the random arrangement of individual ampullae, canals and nerves. The distribution of dorsal and ventral pores and ampullae in Z. brevirostris resembled those of the same family. The number of alveoli per ampullae was similar to that found in euryhaline elasmobranchs species, suggesting that the morphological organization in Z. brevirostris is linked to its possible evolutionary transitory position among batoids.

Use of a nursery area by cownose rays (Rhinopteridae) in southeastern Brazil

Using non-lethal methods for data collection of individuals and participatory monitoring by fishermen, we provide the first empirical evidence of the use of a nursery area by neonate and young-of-the-year cownose rays Rhinoptera bonasus and R. brasiliensis in southeastern Brazil. Two methods were used to collect data: (1) information provided by fishermen (reports, pictures, and videos) and (2) field sampling by researchers. A total of 746 cownose rays were captured; 113 have been identified as R. bonasus, 15 as R. brasiliensis, and 618 were reported by fishermen and could not be identified to the species. Records of newborns were made only in late spring and summer in 2015, 2016, and 2017, which suggests an annual reproductive cycle, with birth in late spring, extending to summer. A repeated use of this area by R. bonasus suggests that it is potentially important to the reproduction of this species. However, R. brasiliensis requires more studies. Small increases in mortality, resulting from increased fishing or other anthropogenic stressors, can have a disproportionately large effect on population viability. Thus, management of areas used during critical stages of the life cycle of rays is crucial to their conservation.(AU)

Usando métodos não-letais para levantamento de dados dos indivíduos e o monitoramento participativo dos pescadores fornecemos a primeira evidência empírica do uso de uma área de berçário por neonatos e jovens do ano de raias Ticonha Rhinoptera bonasus e R. brasiliensis no sudeste do Brasil. Dois métodos foram utilizados para coletar dados: (1) informações fornecidas pelos pescadores (relatórios, fotos e vídeos) e (2) amostragem de campo pelos pesquisadores. Um total de 746 raias Ticonha foram capturadas; 113 foram identificadas como R. bonasus, 15 como R. brasiliensis e 618 foram registrados pelos pescadores e não puderam ser identificadas em nível específico. Os registros de recém-nascidos foram feitos apenas no final da primavera e no verão de 2015, 2016 e 2017, o que sugere um ciclo reprodutivo anual, com nascimento no final da primavera, se estendendo até o verão. O uso repetido desta área por R. bonasus sugere sua potencial importância para a reprodução destas espécies. No entanto, R. brasiliensis requer mais estudos. Pequenos aumentos na mortalidade, resultantes do aumento da pesca ou outros estressores antropogênicos, podem ter um efeito desproporcionalmente grande na viabilidade populacional. Assim, o gerenciamento das áreas usadas durante os estágios críticos do ciclo de vida das raias é crucial para sua conservação.(AU)

Morphological analysis of the oviduct, oviducal gland and isthmus of the blue shark Prionace glauca (Linnaeus, 1758) (Elasmobranchii: Carcharhiniformes)

Oviducal gland present in elasmobranchs is correlated to the organism's reproductive strategy, and its functions are to produce mucus, to form the egg's tertiary envelope and to store sperm. The gland contains four zones: club, papillary,baffle and terminal. The structures of the oviduct, oviducal gland and isthmus of blue shark Prionace glauca were described using macroscopic, light microscopy and scanning electron microscopy techniques. The epithelium of the oviduct and isthmus is folded and is a simple, columnar, ciliated lining epithelium with glandular cells. In the oviducal gland, the lining tissues in the four zones are similar to the oviduct and isthmus lining. The terminal zone shows the presence of sperm in the lumen of the secretory tubules, which remains stored even in the absence of recent copulation. Here, these organs were studied and their connections in an attempt to elucidate the mechanisms of reproduction in the blue shark, showing the three-dimensional aspects, thus adding morphological information important for the understanding of the structure and functioning of these organs of fundamental importance in the life of the majority of elasmobranchs.

A glândula oviducal presente nos elasmobrânquios está correlacionada com a estratégia reprodutiva, cuja função é de produzir o muco, formar o envelope terciário do ovo e armazenar espermatozóides. A glândula contém quatro zonas: club, papilar, baffle e terminal. Foi descrita a estrutura do oviduto, glândula oviducal e istmo do tubarão-azul, Prionace glauca , pelas técnicas macroscópica, microscópica de luz e eletrônica de varredura. Foi observado que no oviduto e istmo o epitélio é pregueado de revestimento simples, colunar, ciliado com células glandulares. Na glândula oviducal o tecido de revestimento é semelhante ao oviduto e istmo nas quatro zonas. Na zona terminal observou-se a presença de espermatozoides no lúmen dos túbulos secretores que permanecem estocados mesmo na ausência de copula recente. Aqui, estudaram-se esses órgãos e suas conexões na tentativa de elucidar os mecanismos da reprodução no tubarão azul, apresentando os aspectos tridimensionais, desta forma agregando informações morfológicas importantes para o entendimento da estrutura e funcionamento desses órgãos de fundamental importância na vida da maioria dos elasmobrânquios.