Gymnura Altavela Research Articles

Skin and stinger bacterial communities in two critically endangered rays from the South Atlantic in natural and aquarium settings.

Bacterial communities of two critically endangered rays from the South Atlantic, the butterfly ray (Gymnura altavela) and the groovebelly ray (Dasyatis hypostigma), were described using 16S rRNA gene metabarcoding. The study characterized the bacterial communities associated with (i) G. altavela in natural (in situ) and aquarium (ex situ) settings, (ii) skin and stinger of G. altavela, and D. hypostigma in aquaria, and (iii) newborns and adults of D. hypostigma. The results revealed potentially antibiotic‐producing bacterial groups on the skin of rays from the natural environment, and some taxa with the potential to benefit ray health, mainly in rays from the natural environment, as well as possible pathogens to other animals, including fish and humans. Differences were observed between the G. altavela and D. hypostigma bacteria composition, as well as between the skin and stinger bacterial composition. The bacterial community associated with D. hypostigma changed with the age of the ray. The aquarium environment severely impacted the G. altavela bacteria composition, which changed from a complex bacterial community to one dominated almost exclusively by two taxa, Oceanimonas sp. and Sediminibacterium sp. on the skin and stinger, respectively.

“Urbanite” rays and sharks: Presence, habitat use and population structure in an urban semi-enclosed lagoon

There is a vital necessity to provide more biological data on rays and sharks to promote efficient conservation. In this study, we assembled a database of weekly sightings to describe temporal (seasonal) patterns in the presence of elasmobranchs within an urban, semi-enclosed, landscape (Las Canteras beach, Gran Canaria Island, eastern Atlantic). Data also provided insight into their habitat use and population structure. From October 2015 to October 2018, eight species, either endangered or “data deficient” according to the IUCN red list, were reported, including: the common eagle ray, Myliobatis aquila, the common stingray, Dasyatis pastinaca, the round stingray, Taeniurops grabatus, the spiny butterfly ray, Gymnura altavela, the bull ray, Aetomylaeus bovinus, the angel shark, Squatina squatina, the marbled electric ray, Torpedo marmorata and the hammerhead shark, Sphyrna zygaena. All species were predominantly observed at night. The species varied in their habitat use; D. pastinaca, G. altavela and S. squatina dominated in sandy and mixed bottoms, while M. aquila and T. grabatus were mostly found in rocky and mixed bottoms. Both D. pastinaca and T. grabatus did not show any seasonal pattern, with consistent records all year around. In contrast, M. aquila, G. altavela and S. squatina showed some degree of seasonality. For five species, small-sized individuals were observed. If semi-enclosed embayments at oceanic islands, under intense human presence, are used by juveniles of endangered rays and sharks, proper management, e.g. limitation of putative human interactions, need to be considered to avoid disturbances.

MEDLEM database, a data collection on large Elasmobranchs in the Mediterranean and Black seas

The Mediterranean Large Elasmobranchs Monitoring (MEDLEM) database contains over 3000 records (more than 4000 individuals) of large elasmobranch species from 20 different countries around the Mediterranean and Black seas, observed from 1666 to 2017. The main species included in the archive are the devil fish (1 813 individuals), the basking shark (939 individuals), the blue shark (585 individuals) and the great white shark (337 individuals).In the last decades other species such as the shortfin mako (166 individuals), the spiny butterfly ray (138) and the thresher shark (174 individuals) were reported with an increasing frequency. This was possibly due to an increased public awareness on the conservation status of sharks, and a consequent development of new monitoring programmes. MEDLEM does not have a homogeneous reporting coverage throughout the Mediterranean and Black seas and it should be considered as a database of observed species presence. Scientific monitoring efforts in the south-eastern Mediterranean and Black seas are generally lower than in the northern sectors and the absence in our database of some species does not imply their actual absence in these regions. Some considerations are made on the frequency and spatial distribution of records, size structure of the observed individuals for selected species, general area coverage and species involved as by-catch by fishing gear.

DNA barcode reveals the illegal trade of rays commercialized in fishmongers in Brazil

Sequences of the mitochondrial gene COI (DNA Barcode) were used to identify species of rays and skates commercialized in fishmongers in Brazil. The comparisons of the obtained sequences with previously published data available in NCBI and BOLD showed that the fish products corresponded to four species, Hypanus dipterurus, Potamotrygon motoro, Paratrygon ajereba and Gymnura altavela, the last of which is classified as vulnerable according to the IUCN Red List and therefore should not be marketed in accordance with the MMA ordinance 445/2015.

Diet and reproductive aspects of the endangered butterfly ray Gymnura altavela raising the discussion of a possible nursery area in a highly impacted environment

Diet and reproductive aspects of the endangered butterfly ray Gymnura altavela raising the discussion of a possible nursery area in a highly impacted environment

<b>Rostral anomaly in a juvenile Spiny Butterfly Ray <I>Gymnura altavela</I> (Linnaeus, 1758) (Elasmobranchii: Myliobatiformes: Gymnuridae) from the Canary Islands</b>

The present communication documents the first observation of a morphologic anomaly in a juvenile Spiny Butterfly Ray Gymnura altavela. This observation is interesting for its similarity with a rostral abnormality in an adult G. altavela from the Canary Islands 10 years earlier and with the one from a juvenile Long-tailed Butterfly Ray G. poecilura from the Western Indo-Pacific. Although no firm conclusions can be drawn from these records, it reinforces the hypothesis of a congenital disorder for this type of malformation within the genus. The individual appeared to have successfully adapted for its anomaly, suggesting that these instances are not of major conservation concern. Hence, long-term studies are required to monitor anomaly occurrences and to evaluate their potential threats.

First description of the embryos of the stingray Gymnura altavela (Linnaeus, 1758) (Myliobatiformes: Gymnuridae), a species at risk of extinction

This contribution presents a brief morphometric description of adult females and embryos of the ray Gymnura altavela. Two females, pregnant with a total of five embryos, were captured in Rio de Janeiro, southeastern Brazil, and their morphometry was compared to their respective embryos. The embryos showed higher body proportions (%DW) than adults, regardless of sex, which may be an effect of ontogeny.

Estimating some population parameters and stock assesment of spiny butterfly ray, Gymnura altavela (Linnaeus, 1758) the Levant Basin coast (Northeastern Mediterranean)

The purpose of this study was to investigate the morphometric characteristics, growth, mortality and exploitation rate of the spiny butterfly ray (Gymnura altavela Linnaeus, 1758). The study was conducted using 284 specimens from the coastal waters of the Levant Basin (the northeastern Mediterranean). Samples were collected monthly between July 2014 and June 2015 using a bottom trawl from the following depth strata: 0-10m, 10-20m, and 20-50m. The following measurements were taken total length (TL), disc length (DL), disc width (DW) distance from nose tip to eye (NE), nose tip to mouth (NM, cm), width of mouth (MW, cm) where Y is the various dimensions (TL; W; DL; DW; NE; NM; MW, respectively) and X is the total length estimated by linear regression analysis. Length-weight and disc width-weight relationships were W = 0.097 * TL3.2070 and W = 0.084 * DW3.169 for total individuals. The von Bertalanffy growth function contained in DW was DW¥ = 136.50cm K = 0.230 year-1 t0= -0.492year-1 for total individuals. The total mortality (Z) was 0.91year-1, the natural mortality (M) was 0.41year-1, and the fishing mortality (F) was estimated to be 0.51year-1. The exploitation rate (E) was calculated as 0.55 year-1 for all obtained individuals.

Age and growth assessment of western North Atlantic spiny butterfly ray Gymnura altavela (L. 1758) using computed tomography of vertebral centra

Life history strategies of batoid fishes have evolved within dynamic marine ecosystems. Adaptations in reproductive and developmental biology are paramount to the survival of species, and therefore knowledge of growth rates to maturity is fundamental for identifying constraints on the conservation of populations. The butterfly rays (Myliobatiformes: Gymnuridae) are highly derived batoids with generally low reproductive potentials for which age and growth information remains unknown. In this study we applied high-resolution X-ray computed tomography (HRXCT) to vertebral centra from a stingray for the first time to estimate age, and used a multimodel approach to investigate growth of spiny butterfly ray, Gymnura altavela. Estimated ages of the oldest male and female were 11 and 18 yrs. at disk widths (WD) 1355 mm and 2150 mm, respectively. Disk width-at-age data were analyzed using three growth models (von Bertalanffy, logistic, Gompertz), and the most parsimonious and empirically supported model was the logistic function with sex treated as a fixed effect on asymptotic disk width (WD ∞ ) and k parameters. Model parameter estimates were (males) WD ∞ = 1285.46 ± 67.27 mm, k = 0.60 ± 0.10, and (females) WD ∞ = 2173.51 ± 129.78 mm, k = 0.27 ± 0.04. Results indicated sexually dimorphic growth patterns, with males growing faster and reaching asymptotic size at earlier ages than females. These age and growth results are the first reported for the genus, and suggest that G. altavela grows at a similar rate as some teleosts and batoids, and relatively fast among chondrichthyans.

Feeding habits of three Batoids in the Levantine Sea (north-eastern Mediterranean Sea) based on stomach content and isotopic data

Understanding the diet of marine predators is essential to defining their trophic role in an ecosystem. Elasmobranchs (sharks and batoids) are considered pivotal components of marine food webs, and are often included in the top predator or mesopredator groups. However, in comparison with other Mediterranean areas, research focusing on marine predators inhabiting the Levantine Sea (eastern Mediterranean Sea) is very limited. Here, we examined the feeding habits (diet, trophic width and trophic position) of three endangered batoids (Gymnura altavela (Linnaeus, 1758), Raja asterias Delaroche, 1809 and Raja clavata, Linnaeus, 1758) coexisting in Iskenderun Bay (north-eastern Levantine Sea, Mediterranean Basin) by combining stomach content and stable isotope analyses. The results revealed clear differences in the trophic habits between them. Stomach contents showed differences in the diet between species, showing a clear feeding preference for teleosts in the case ofG. altavelaand a diet composed of fish and crustaceans in the case ofR. asteriasandR. clavata. In line with stomach content results, interspecific differences in the isotopic values and trophic levels were found. In particular,G. altavelawas isotopically segregated fromR. asteriasandR. clavata, showing lower isotopic trophic width and higher trophic level. The results of this study provide new insights into the ecological role of these three endangered batoid species in the Levantine Sea and are of crucial importance for management and conservation of these species.

Morphological and functional abnormality in the spiny butterfly ray Gymnura altavela

A variety of abnormalities have been described for sharks, rays and skates across different ecoregions. Morphological and functional anomalies in these species, however, were not yet documented in distributions from the Canary Islands, the spiny butterfly ray Gymnura altavela (Linnaeus, 1758) and from in situ observations. The aim of the present study is to fill these knowledge gaps. A female spiny butterfly ray G. altavela with an unfused anterior part of the right pectoral fin to the neurocranium was observed in the port of Sardina del Norte (Gran Canaria Island) during a visual scuba diving census. The size and the observation of the activities swimming, burying and preying confirmed the adaption of the specimen for the anomaly and underdeveloped electrosensory system in its survival. The limited knowledge of teratogens and their triggering factors, and the striking similarity with an anomaly reported for G. poecilura (Shaw, 1804) from South India, suggest genetic expression aberrations or mechanical obstructions during gestation as origin for the disorder.

Comparative anatomy of the extraocular muscles in four Myliobatoidei rays (Batoidea, Myliobatiformes).

Extraocular muscles are classically grouped as four rectus and two oblique muscles. However, their description and potential associations with species behavior are limited. The objective was to characterize extraocular muscles in four Myliobatoidei rays from diverse habitats with divergent behaviors. Heads (10 per species) of Dasyatis hypostigma, Gymnura altavela, Mobula thurstoni and Pteroplatytrygon violacea were decalcified and dissected to characterize and describe extraocular muscles. Principal component analysis (PCA) was used to evaluate relationships between muscle length and species; for P.violacea, D.hypostigma and G.altavela, these were qualitatively and quantitatively consistent with the general pattern of extraocular muscles in vertebrates. In contrast, for M.thurstoni, the two oblique muscles were completely fused and there was a seventh extraocular muscle, named m. lateral rectus β (both were apparently novel findings in this species). There were also significant differences in eye disposition in the chondrocranium. The PCA axis 1 (rectus muscles) and PCA axis 2 (oblique muscles) accounted for 98.47% of data variability. Extraocular muscles had significant differences in length and important anatomical differences among sampled species that facilitated grouping species according to their life history. In conclusion, extraocular muscles are not uniform in all vertebrate species, thereby providing another basis for comparative studies.

New Mediterranean Biodiversity Records (April 2015)

The Collective Article ‘New Mediterranean Biodiversity Records’ of the Mediterranean Marine Science journal offers the means to publish biodiversity records in the Mediterranean Sea. The current article is divided in two parts, for records of native and alien species respectively. The new records of native fish species include: the slender sunfish Ranzania laevis and the scalloped ribbonfish Zu cristatus in Calabria; the Azores rockling Gaidropsarus granti in Calabria and Sicily; the agujon needlefish Tylosurus acus imperialis in the Northern Aegean; and the amphibious behaviour of Gouania willdenowi in Southern Turkey. As regards molluscs, the interesting findings include Ischnochiton usticensis in Calabria and Thordisa filix in the bay of Piran (Slovenia). The stomatopod Parasquilla ferussaci was collected from Lesvos island (Greece); the isopod Anilocra frontalis was observed parasitizing the alien Pteragogus trispilus in the Rhodes area. The asteroid Tethyaster subinermis and the butterfly ray Gymnura altavela were reported from several localities in the Greek Ionian and Aegean Seas. The new records of alien species include: the antenna codlet Bregmaceros atlanticus in Saronikos Gulf; three new fish records and two decapods from Egypt; the establishment of the two spot cardinal fish Cheilodipterus novemstriatus and the first record of the Indo-Pacific marble shrimp Saron marmoratus in semi-dark caves along the Lebanese coastline; the finding of Lagocephalus sceleratus, Sargocentron rubrum, Fistularia commersonii and Stephanolepis diaspros around Lipsi island (Aegean Sea, Greece); the decapod Penaeus hathor in Aegean waters; the decapod Penaeus aztecus and the nudibranch Melibe viridis in the Dodecanese islands; the finding of Pinctada imbricata radiata in the Mar Grande of Taranto (Ionian Sea, Italy) and the Maliakos Gulf (Greece).

Temporal changes in some Rajiformes species of cartilaginous fish (Chondrichthyes) from the west coast of İskenderun Bay (northeastern Mediterranean)

Some Rajiformes species among the cartilaginous fish (Chondrichthyes) that are distributed on the west coast of the Gulf of Iskenderun were seasonally obtained by bottom trawling from 2 different depth layers between the years 2004 and 2011. The spatiotemporal changes in catch per unit effort (CPUE) values were investigated by considering 2 depth contours (10 and 20 m). Six species belonging to 6 different Rajiformes families were identified during the sampling period, including Dasyatis pastinaca (common stingray), Gymnura altavela (spiny butterfly ray), Rhinobatos rhinobatos (common guitarfish), Raja radula (rough ray), Myliobatis aquila (common eagle ray), and Torpedo marmorata (marbled electric ray). A general linear model was used to analyze the changes in the total and separate weights of cartilaginous fish. For this purpose, the logarithms of CPUE values in weight were classed according to the depth, season, and years. Seasonal variations and year–season 2-way interactions were found to be highly significant for total cartilaginous CPUE values (P < 0.01). The annual changes in R. rhinobatos were the only significant annual difference (P < 0.05), while the year–season interactions of D. pastinaca were found to be significant (P < 0.01). The seasonal variations of D. pastinaca and G. altavela were also highly significant (P < 0.01).

Thorough analysis of polyhalogenated compounds in ray liver samples off the coast of Rio de Janeiro, Brazil

Five liver samples of two different ray species (Gymnura altavela and Zapteryx brevirostris) off the coast of Rio de Janeiro, Brazil, were analyzed for their pollution with anthropogenic and naturally occurring organohalogen compounds. The samples were extracted with accelerated solvent extraction, and after a clean-up procedure, organohalogen compounds were separated by a modified group separation on activated silica. Subsequent analyses were done by targeted and non-targeted gas chromatography-mass spectrometry in the electron capture negative ion mode. "Classic" organohalogen compounds such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and technical 1,1,1-trichloro-2,2-di(4-chlorophenyl)ethane (DDT) were detected and quantified. PCBs generally exceeded the parts per million level and represented up to 90% of the total contamination of the ray livers. High concentrations were also detected for p,p'-DDE. Non-targeted full scan investigations lead to the detection of an abundant trichlorinated compound which was identified as a new DDT metabolite in biota. Different PBDE congeners and several halogenated natural products were quantified as well. In addition, polychlorinated terphenyls were identified and analyzed in the two species. Moreover, both ray species showed different fatty acid patterns and stable carbon isotope signatures. The two ray species showed high concentrations of organohalogen compounds in their liver tissue. Varied δ (13)C values by up to 3.1‰ indicated that the two ray species were living in different habitats.

Length–weight relationship for five elasmobranch species from the Cilician Basin shelf waters (Northeastern Mediterranean)

Summary In this study, elasmobranch length–weight relationships were estimated for five species caught between June 1999 and May 2003 from the Cilician Basin shelf waters (Northeastern Mediterranean): Raja clavata, Raja radula, Raja asterias, Dasyatis pastinaca, and Gymnura altavela. There were no significant differences between males and females, and only Raja clavata females showed isometric growth.

Elasmobrânquios capturados pela pesca artesanal na costa sul do Paraná e norte de Santa Catarina, Brasil

O presente estudo foi realizado no litoral entre a divisa dos Estados do Paraná e Santa Catarina, em duas comunidades pesqueiras artesanais que integram os municípios de Guaratuba (PR) e Itapoá (SC). Foram acompanhadas as atividades pesqueiras das comunidades, entre julho de 2001 e março de 2003, com o objetivo de: listar as espécies de elasmobrânquios capturadas pelas comunidades em questão; avaliar o uso comercial das espécies; observar a ocorrência sazonal das espécies nos desembarques; estimar a freqüência relativa de captura por aparelho de pesca; e inferir sobre a biologia reprodutiva das espécies. Durante o período estudado foram capturados: Carcharhinus falciformis, Galeocerdo cuvier, Rhizoprionodon lalandii, R. porosus, Sphyrna lewini, S. zygaena, Squatina guggenheim, Narcine brasiliensis, Rhinobatos percellens, Zapteryx brevirostris, Rioraja agassizii, Dasyatis americana, D. guttata, D. hipostigma, Gymnura altavela, Myliobatis goodei, Rhinoptera bonasus e R. brasiliensis. Quanto à comercialização das espécies, foi observado que todos os tubarões capturados na área de estudo são comercializados, dentre as raias, apenas Rhinobatos percellens e Zapteryx brevirostris. Nos desembarques, a ocorrência de elasmobrânquios foi maior durante o inverno e a primavera. A maioria das capturas ocorreu com redes de emalhe, o arrasto camaroneiro pouco capturou. Os dados do presente trabalho indicaram a utilização da área estudada para o parto das espécies G. cuvier, R. lalandii, R. porosus, S. lewini, N. brasiliensis e R. agassizii; para o crescimento de todas as espécies amostradas; e para a gestação de R. percellens e Z. brevirostris. É sugerido que medidas que visem a proteger as espécies sejam tomadas, sem trazer prejuízos e conflitos para as comunidades de pescadores.

The roughtail stingray Dasyatis centroura (Pisces: Dasyatidae) and spiny butterfly ray Gymnura altavela (Pisces: Gymnuridae) from the southern Adriatic

A roughtail stingray, Dasyatis centroura, and a spiny buterfly ray, Gymnura altavela, were caught near Kolocčep Island (Elafiti Archipelago, southern Adriatic) and the settlement Crkvice (Pelješac Peninsula, southern Adriatic) in October 2002 and November 2000, respectively. The roughtail stingray is the largest specimen recorded. Morphometric data of spiny butterfly ray are the first for this species in the Adriatic Sea.

Anthobothrium altavelae sp. n. (Cestoda: Tetraphyllidea) from the spiny butterfly ray Gymnura altavela (Elasmobranchii: gymnuridae) in Tunisia.

Seven Gymnura altavela (Linnaeus, 1758) (Elasmobranchii, Myliobatiformes) caught off the Tunisian coast were examined for endoparasites during a three-year period (1995-1998). A phyllobothriid cestode new to science was found in the spiral intestine of all host specimens. The presence of a tetrabothridiate scolex, bothridia lacking an apical sucker, laciniate strobila, and possession of postvaginal testes are sufficient to place this species in the genus Anthobothrium Van Beneden, 1850. In this genus, we consider that only two species, both previously reported from carcharhiniform sharks, are valid: Anthobothrium cornucopia Van Beneden, 1850 and A. laciniatum Linton, 1890. Anthobothrium altavelae sp. n. can be distinguished from its congeners by its length, strobila morphology, and the number of testes. The taxonomic position of the species attributed to Anthobothrium parasitic in gymnurids is discussed.

Pterobothrioides, a new genus of tapeworms (Cestoda: Trypanorhyncha: Pterobothriidae) from dasyatid stingrays in the Eastern Atlantic and Pacific Oceans

Two new species of pterobothriid trypanorhynch cestodes representing a new genus are described from dasyatid stingrays taken in Pacific coastal waters off Mexico and Costa Rica and from Atlantic waters off Senegal, West Africa. Pterobothrioides carvajali n. g., n. sp. is described from Dasyatis longus (Garman) from Pacific coastal waters off Mexico and Costa Rica. P. petterae n. g., n. sp. is described from Gymnura altavela (Linnaeus) from Atlantic coastal waters off West Africa. Both species resemble other pterobothriids in their possession of four pedicellate bothridia in a cruciform arrangement, elongated scolex and bulbs, heteroacanthous armature with five hooks per principal row, one or more intercalary rows and a band consisting of irregular files of microhooks on the external tentacular surface. Both new species are unique in the possession of a simple chainette of hooks in addition to a band of microhooks in the tentacle armature. The chainette hooks of P. carvajali are robust, rose-thorn-shaped hooks with large rounded bases. The chainette of P. petterae consists of smaller uncinate hooks that are most distinct in the basal region of the tentacle armature and progressively decrease in size until they become almost indistinguishable from the band microhooks in the distal metabasal region. A new genus, Pterobothrioides, is proposed to accommodate these two new species, combining a chainette, considered characteristic of poeciloacanths, with the band of hooks characteristic of atypical heteroacanths. It is suggested that through changes in hook number and arrangement the typical heteroacanths, having bands of hooks, evolved into poeciloacanths with chainettes and that clades are now apparent in the family Pterobothriidae.