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Diane P. Barton - One of the best experts on this subject based on the ideXlab platform.

  • Description and genetic characterisation of Pulchrascaris australis n. sp. in the scalloped hammerhead shark, Sphyrna lewini (Griffin & Smith) in Australian waters
    Parasitology Research, 2020
    Co-Authors: Shokoofeh Shamsi, Diane P. Barton
    Abstract:

    Being listed in the IUCN Red List of Threatened Species, knowledge on the biology, health and diseases of the scalloped hammerhead, Sphyrna lewini (Griffith & Smith) is limited; this is especially true for its parasites. In this paper, a new species, Pulchrascaris australis , is morphologically described followed by genetic characterisation based on the sequence of the ITS region. The new species can be easily differentiated from its congeners based on the morphology of the mouthpart, spicules, plectanes, eggs and vulva. Phylogenetic analyses clearly distinguish specimens in the present study from other parasitic nematodes found in the Australasian waters and elsewhere. The sequencing data also suggest that Terranova larval type I found previously in various fish from New Caledonian and Australian (Queensland) waters also belong to Pulchrascaris australis n. sp.

  • description and genetic characterisation of pulchrascaris australis n sp in the scalloped hammerhead shark Sphyrna lewini griffin smith in australian waters
    Parasitology Research, 2020
    Co-Authors: Shokoofeh Shamsi, Diane P. Barton
    Abstract:

    : Being listed in the IUCN Red List of Threatened Species, knowledge on the biology, health and diseases of the scalloped hammerhead, Sphyrna lewini (Griffith & Smith) is limited; this is especially true for its parasites. In this paper, a new species, Pulchrascaris australis, is morphologically described followed by genetic characterisation based on the sequence of the ITS region. The new species can be easily differentiated from its congeners based on the morphology of the mouthpart, spicules, plectanes, eggs and vulva. Phylogenetic analyses clearly distinguish specimens in the present study from other parasitic nematodes found in the Australasian waters and elsewhere. The sequencing data also suggest that Terranova larval type I found previously in various fish from New Caledonian and Australian (Queensland) waters also belong to Pulchrascaris australis n. sp.

  • Acanthocephalans from Australian elasmobranchs (Chondrichthyes) with a description of a new species in the genus Gorgorhynchus Chandler, 1934 (Rhadinorhynchidae)
    Systematic Parasitology, 2019
    Co-Authors: Lesley R. Smales, Diane P. Barton, Leslie A. Chisholm
    Abstract:

    Gorgorhynchus occultus n. sp. is described from Sutorectus tentaculatus (Peters) (Orectolobidae) collected off Bunbury, Western Australia in 1986. The new species differs from all other species of Gorgorhynchus Chandler, 1934 by having a suite of characters including a proboscis hook formula of 18–20 rows of 8–9 hooks, a well-developed neck, irregular circles of small spines in a single anterior field, the male reproductive system limited to the posterior quarter of the trunk and three cement glands. In a survey of 284 sharks collected between 2015 and 2018 from 10 localities in Australian waters, 11 individuals were infected with acanthocephalan cystacanths. One individual of Sphyrna mokarran (Rupell) (Sphyrnidae) was infected with Corynosoma cetaceum Johnston & Best, 1931. Serrasentis sagittifer (Linton, 1889) (Rhadinorhynchidae) was found in five individuals of S. mokarran , four individuals of Syphyrna lewini (Griffith & Smith) and one individual of Carcharhinus coatesi (Whitley) (Carcharhinidae ). These infections may be accidental because it has been suggested that acanthocephalans cannot tolerate the high levels of urea used by marine and esturine elasmobranchs for osmoregulation. The two most common host species examined, S. mokarran and S. lewini had the highest intensities and prevalences of infection with S. sagittifer . Although more individuals of S. lewini were examined, S. mokarran had the higher prevalence of infection.

  • Description of Piscicapillaria bursata sp. nov. (Capillariidae) and Redescription of Parascarophis Sphyrnae Campana-Rouget, 1955 (Cystidicolidae), Two Nematode Parasites of Hammerhead Sharks (Sphyrna spp.) off Australia
    Acta Parasitologica, 2019
    Co-Authors: František Moravec, Diane P. Barton
    Abstract:

    Purpose Data on helminth parasites in hammerhead sharks are scarce and, therefore, new examinations of these hosts are needed to recognize the species composition of their parasites, including nematodes. Methods Helminthological examinations of hammerhead sharks, Sphyrna lewini (Griffith et Smith) (209 specimens) and Sphyrna mokarran (Rüppell) (57 specimens) (Sphyrnidae, Carcharhiniformes), from off the northern coast of Australia revealed one new and one insufficiently known species of intestinal nematode parasites. These were studied with the use of light and scanning electron microscopy. Results Both nematode species are described. Piscicapillaria bursata sp. nov. (Capillariidae) from S . mokarran (type host) and S . lewini differs from its congeners mainly in the spicule length (330 µm), body length of gravid females 12.80–21.26 mm and in possessing a subterminal female anus. The specimens of Parascarophis Sphyrnae Campana-Rouget, 1955 (Cystidicolidae) (type species of Parascarophis Campana-Rouget, 1955) collected from S . lewini made it possible to redescribe the female and, for the first time, to describe the male; the same species was also found in S . mokarran . Amended diagnosis of Parascarophis is provided. Parascarophis is mainly characterized by the presence of lateral alae, a unique feature within the Cystidicolidae, and by the cephalic structures (presence of a cuticular hood and a pair of anterolateral plate-like structures in the mouth). Conclusions In addition to the discovery of a new nematode species, Pi . bursata sp. nov., the finding of Pa . Sphyrnae in Australian waters represents a new geographical record of this parasite outside the Atlantic Ocean. The species of Parascarophis previously described from teleosts, P . bharatii Agrawal, 1965, P . oteroi Arya, 1992 and P . mulloidi Imam, Tawfik et Abdel Hady, 1982, are designated as species inquirendae and incertae sedis . The finding of P . Sphyrnae in Australian waters represents a new geographical record of this parasite outside the Atlantic Ocean. Pa . Sphyrnae had not been reported previously from beyond the Atlantic Ocean.

  • description and characterisation of terranova pectinolabiata n sp nematoda anisakidae in great hammerhead shark Sphyrna mokarran ruppell 1837 in australia
    Parasitology Research, 2019
    Co-Authors: Shokoofeh Shamsi, Diane P. Barton
    Abstract:

    Terranova pectinolabiata n. sp. is described from the great hammerhead, Sphyrna mokarran, from Australian waters. This represents the first report of a species of Terranova from the host species. The new species is characterised by the morphology of the caudal plates and labia. ITS sequences were obtained for 20 specimens which were identical, despite morphological variation that has traditionally been indicative of separation of species. Additionally, genetic analyses confirmed the identification of the larval Terranova Type II previously reported in Australian and New Caledonian waters as Terranova pectinolabiata n. sp.

Shokoofeh Shamsi - One of the best experts on this subject based on the ideXlab platform.

Stephen M Kajiura - One of the best experts on this subject based on the ideXlab platform.

  • Enhanced visual fields in hammerhead sharks.
    The Journal of experimental biology, 2020
    Co-Authors: D M Mccomb, Timothy C Tricas, Stephen M Kajiura
    Abstract:

    Several factors that influence the evolution of the unusual head morphology of hammerhead sharks (family Sphyrnidae) are proposed but few are empirically tested. In this study we tested the 'enhanced binocular field' hypothesis (that proposes enhanced frontal binocularity) by comparison of the visual fields of three hammerhead species: the bonnethead shark, Sphyrna tiburo, the scalloped hammerhead shark, Sphyrna lewini, and the winghead shark, Eusphyra blochii, with that of two carcharhinid species: the lemon shark, Negaprion brevirostris, and the blacknose shark, Carcharhinus acronotus. Additionally, eye rotation and head yaw were quantified to determine if species compensate for large blind areas anterior to the head. The winghead shark possessed the largest anterior binocular overlap (48 deg.) and was nearly four times larger than that of the lemon (10 deg.) and blacknose (11 deg.) sharks. The binocular overlap in the scalloped hammerhead sharks (34 deg.) was greater than the bonnethead sharks (13 deg.) and carcharhinid species; however, the bonnethead shark did not differ from the carcharhinids. These results indicate that binocular overlap has increased with lateral head expansion in hammerhead sharks. The hammerhead species did not demonstrate greater eye rotation in the anterior or posterior direction. However, both the scalloped hammerhead and bonnethead sharks exhibited greater head yaw during swimming (16.9 deg. and 15.6 deg., respectively) than the lemon (15.1 deg.) and blacknose (15.0 deg.) sharks, indicating a behavioral compensation for the anterior blind area. This study illustrates the larger binocular overlap in hammerhead species relative to their carcharhinid sister taxa and is consistent with the 'enhanced binocular field' hypothesis.

  • Adult blacktip sharks (Carcharhinus limbatus) use shallow water as a refuge from great hammerheads (Sphyrna mokarran).
    Journal of Fish Biology, 2020
    Co-Authors: Melanie D. Doan, Stephen M Kajiura
    Abstract:

    : A refuge can be any space that keeps an organism safe from danger. Prey usually seek protection in the closest refuge available to minimize cost while maximizing survival. Aerial drone footage of blacktip sharks, Carcharhinus limbatus, along the coast of southeast Florida, USA shows adult blacktips fleeing to the shallow water adjacent to the beach when confronted or chased by a predatory great hammerhead shark, Sphyrna mokarran. To our knowledge, this is the first evidence of adult Carcharhinus limbatus using shallow water as a refuge. This article is protected by copyright. All rights reserved.

  • electroreception in neonatal bonnethead sharks Sphyrna tiburo
    Marine Biology, 2003
    Co-Authors: Stephen M Kajiura
    Abstract:

    The ability of sharks to orient to weak electric fields is well documented, but a detailed analysis of orientation pathways is lacking. Digital video analysis was used to quantify the behavioral response of naive neonatal bonnethead sharks, Sphyrna tiburo, to prey-simulating weak electric fields. Sharks less than 24 h post-parturition failed to demonstrate a positive feeding response to the electrodes whereas vigorous biting at the electrodes was observed in all sharks greater than 32 h post-parturition. Orientation behaviors were classified as one of five types: "straight" approach, "single turn," "overshoot," "spiral tracking," and "orient without biting." One-third of all orientations were elicited at stimulus intensities of less than 20 nV cm−1. The median electric stimulus threshold for initiation of orientation was 47 nV cm−1 and the minimum was less than 1 nV cm−1. Most orientations to the dipole were from a distance of less than 10 cm with a maximum orientation distance of 22 cm. The innate feeding response to electric stimuli is demonstrated for the first time in a chondrichthyan fish.

  • maneuvering in juvenile carcharhinid and sphyrnid sharks the role of the hammerhead shark cephalofoil
    Zoology, 2003
    Co-Authors: Stephen M Kajiura, Jesica B Forni, Adam P Summers
    Abstract:

    Summary The peculiar head morphology of hammerhead sharks has spawned a variety of untested functional hypotheses. One of the most intu itively appealing ideas is that the anterior foil acts, as in canard-winged aircraft, to increase maneuverability. We tested this hypothesis by determining whether juveniles of two hammerhead species (Sphyrna tiburo and S. lewini) turn more sharply, more often, and with greater velocity than a juvenile carcharhinid shark ( Carcharhinus plumbeus). Although the hammerheads were more maneuverable, further investigation revealed that they do not roll their body during turns, suggesting that the cephalofoil does not act as a steering wing. We also show that hammerhead sharks demonstrate greater lateral flexure in a turn than carcharhinids, and that this flexibility may be due to cross sectional shape rather than number of vertebrae.

  • notes on the long term transport of the scalloped hammerhead shark Sphyrna lewini
    Zoo Biology, 2002
    Co-Authors: Forrest Young, Stephen M Kajiura, Gerard J Visser, Joao P S Correia, Mark F L Smith
    Abstract:

    The capture and transport of scalloped hammerhead sharks (Sphyrna lewini Griffith and Smith, 1834) historically has represented a difficult, expensive, and uncertain undertaking for the public aquarium community. In this study, techniques were developed to improve the successful long-term transport of S. lewini by mitigating some of the deleterious effects associated with hyperactivity and impaired swimming patterns. The relationship between the transport vessel size and shark sizes, numbers, and swimming behavior was considered when formulating the transport regime. By balancing these factors and adopting a comprehensive water treatment method, it was possible to extend the duration of a successful transport by up to 60 hr. Implications for the future transport of S. lewini and other free-swimming sharks are discussed. Zoo Biol 21:243–251, 2002. © 2002 Wiley-Liss, Inc.

Mahmood S Shivji - One of the best experts on this subject based on the ideXlab platform.

  • Restricted connectivity and population genetic fragility in a globally endangered Hammerhead Shark
    Reviews in Fish Biology and Fisheries, 2020
    Co-Authors: Danillo Pinhal, Otto Bismarck Fazzano Gadig, Rodrigo R. Domingues, Christine C. Bruels, Bruno L. S. Ferrette, Mahmood S Shivji, Cesar Martins
    Abstract:

    Vagile, large-bodied marine organisms frequently have wide range dispersion but also dependence on coastal habitats for part of their life history. These characteristics may induce complex population genetic structure patterns, with resulting implications for the management of exploited populations. The scalloped hammerhead, Sphyrna lewini , is a cosmopolitan, migratory shark in tropical and warm temperate waters, inhabiting coastal bays during parturition and juvenile development, and the open ocean as adults. Here, we investigated the genetic connectivity and diversity of S. lewini in the western Atlantic using large sample coverage (N = 308), and data from whole mitochondrial control region (mtCR) sequences and ten nuclear microsatellite markers We detected significant population genetic structure with both mtCR and microsatellites markers (mtCR: Φ_ST = 0.60; p  

  • Complete mitogenome sequences of smooth hammerhead sharks, Sphyrna zygaena, from the eastern and western Atlantic
    Mitochondrial DNA Part B, 2017
    Co-Authors: Cassandra L Ruck, Jose V. Lopez, Mahmood S Shivji
    Abstract:

    AbstractWe report the first mitogenome sequences of the circumglobally distributed, highly mobile, smooth hammerhead shark, Sphyrna zygaena, from the eastern and western Atlantic. Both genomes were...

  • the complete mitochondrial genome of the endangered great hammerhead shark Sphyrna mokarran
    Mitochondrial DNA Part B, 2017
    Co-Authors: Cassandra L Ruck, Nicholas J Marra, Mahmood S Shivji, Michael J. Stanhope
    Abstract:

    AbstractWe present the first mitochondrial genome sequence of the great hammerhead shark, Sphyrna mokarran. This species is of considerable conservation concern throughout its global distribution, and currently listed as Endangered on the IUCN Red List. The mitochondrial genome is 16,719 bp in length with 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes and a non-coding control region. The gene arrangement is congruent with other shark and most vertebrate species. This S. mokarran mitogenome provides a genomic resource for assisting with population studies and conservation efforts for this highly depleted species.

  • virgin birth in a hammerhead shark
    Biology Letters, 2007
    Co-Authors: Demian D Chapman, Ed Louis, Julie Sommer, Hugh L Fletcher, Mahmood S Shivji, Paulo A Prodohl
    Abstract:

    Parthenogenesis has been documented in all major jawed vertebrate lineages except mammals and cartilaginous fishes (class Chondrichthyes: sharks, batoids and chimeras). Reports of captive female sharks giving birth despite being held in the extended absence of males have generally been ascribed to prior matings coupled with long-term sperm storage by the females. Here, we provide the first genetic evidence for chondrichthyan parthenogenesis, involving a hammerhead shark (Sphyrna tiburo). This finding also broadens the known occurrence of a specific type of asexual development (automictic parthenogenesis) among vertebrates, extending recently raised concerns about the potential negative effect of this type of facultative parthenogenesis on the genetic diversity of threatened vertebrate species.

Felipe Galván-magaña - One of the best experts on this subject based on the ideXlab platform.

  • Feeding habits and trophic level of the smooth hammerhead shark, Sphyrna zygaena (Carcharhiniformes: Sphyrnidae), off Ecuador
    Journal of the Marine Biological Association of the United Kingdom, 2018
    Co-Authors: Colombo Estupiñán-montaño, Luis G. Cedeño-figueroa, José F. Estupiñán-ortiz, Alejandro Sandoval-londoño, David Castañeda-suarez, Felipe Galván-magaña, Carlos Polo-silva
    Abstract:

    As apex predators, sharks are known to play an important role in marine food webs. Detailed information on their diet and trophic level is however needed to make clear inferences about their role in the ecosystem. A total of 335 stomachs of smooth hammerhead sharks, Sphyrna zygaena, were obtained from commercial fishing vessels operating in the Ecuadorian Pacific between January and December 2004. A total of 53 prey items were found in the stomachs. According to the Index of Relative Importance (%IRI), cephalopods were the main prey (Dosidicus gigas, Sthenoteuthis oualaniensis, Ancistrocheirus lesueurii and Lolliguncula [Loliolopsis] diomedeae). Sphyrna zygaena was thus confirmed to be a teutophagous species. The estimated trophic level of S. zygaena was between 4.6 and 5.1 (mean ± SD: 4.7 ± 0.16; males: 4.7; females: 4.8). Levin's index (BA) was low (overall: 0.07; males: 0.08; females: 0.09), indicating a narrow trophic niche. We found that sharks <150 cm in total length consumed prey of coastal origin, whereas sharks ≥150 cm foraged in oceanic waters and near the continental shelf. The analyses indicate that S. zygaena is a specialized predator consuming mainly squids.

  • Population and individual foraging patterns of two hammerhead sharks using carbon and nitrogen stable isotopes
    Rapid Communications in Mass Spectrometry, 2015
    Co-Authors: Peggy Loor-andrade, Fernando R. Elorriaga-verplancken, Carlos Polo-silva, Felipe Galván-magaña, Antonio Delgado-huertas
    Abstract:

    Rationale Individual foraging behavior is an important variable of predators commonly studied at the population level. Some hammerhead shark species play a significant role in the marine ecosystem as top consumers. In this context, stable isotope analysis allows us to infer some ecological metrics and patterns that cannot usually be obtained using traditional methods. Methods We determined the isotopic composition (δ13C and δ15N values) of dorsal muscle and vertebrae of Sphyrna lewini and Sphyrna zygaena using a continuous-flow system consisting of an elemental analyzer combined with a Delta Plus XL mass spectrometer. Foraging variability by sex and by individual was inferred from the isotopic values. Results There were no significant differences in the isotopic values of muscle samples between sexes, but there were differences between species. The trophic niche breadth of the two species was similar and overlap was low. A low niche overlap was observed between S. lewini individual vertebrae. We found differences in the δ15N values of S. zygaena vertebrae, with lower values in the first group of samples. Conclusions Despite these hammerhead shark species inhabiting the same area, there was low trophic niche overlap between species and individuals, due to different individual foraging strategies, according to the carbon and nitrogen isotopic profiles obtained. The use of tissues that retain lifetime isotopic information is useful to complement studies on trophic ecology. Copyright © 2015 John Wiley & Sons, Ltd.

  • Bioaccumulation and Biomagnification of Total Mercury in Four Exploited Shark Species in the Baja California Peninsula, Mexico
    Bulletin of Environmental Contamination and Toxicology, 2012
    Co-Authors: A. Maz-courrau, Ofelia Escobar-sánchez, Rene Rosiles-martínez, Felipe Galván-magaña, C. López-vera, A. Sanjuán-muñoz
    Abstract:

    The present study determined the average mercury bioaccumulation in the muscle tissue of four shark species ( Carcharhinus falciformis , Prionace glauca , Sphyrna zygaena and Isurus oxyrinchus ) captured in the Baja California Peninsula. We also evaluated biomagnification of some prey consumed by sharks. All sharks’ species had mercury levels over the limit specified by the Mexican government for human consumption. Blue shark ( P. glauca ) presented highest mercury values (1.96 ± 1.48 μg/g Hg d.w.) and it was the unique specie that showed a negative correlation with mercury content (Rs = −0.035, p  = 0.91). Scomber japonicus was the prey with high content of mercury (0.57 ± 0.02 μg/g).

  • Mercury and selenium bioaccumulation in the smooth hammerhead shark, Sphyrna zygaena Linnaeus, from the Mexican Pacific Ocean.
    Bulletin of Environmental Contamination and Toxicology, 2010
    Co-Authors: Ofelia Escobar-sánchez, Felipe Galván-magaña, Rene Rosiles-martínez
    Abstract:

    We analyzed total mercury and selenium bioaccumulation in muscle tissue and cartilage fibers (fins) from smooth hammerhead shark, Sphyrna zygaena, caught off Baja California Sur, Mexico. In muscle tissue, the mercury concentration ranged from 0.005 to 1.93 μg g−1 ww (wet weight), which falls within the safety limits for food set by international agencies (Hg > 1.0 μg g−1 ww). Only one specimen showed a mercury value that exceeded this limit. In fins, the mercury bioaccumulation was lower (

  • Stomach content analysis of juvenile, scalloped hammerhead shark Sphyrna lewini captured off the coast of Mazatlán, Mexico
    Aquatic Ecology, 2009
    Co-Authors: Yassir Eden Torres-rojas, Agustín Hernández-herrera, Felipe Galván-magaña, Vanessa Alatorre-ramírez
    Abstract:

    We quantified the diet of juvenile, scalloped hammerhead shark Sphyrna lewini in the area off Mazatlan, Sinaloa, Mexico, to understand their feeding ecology this shark. The prey species of Sphyrna lewini were identified and quantified from stomach content analysis. In addition, we determined the variations between genders. During two fishing seasons (2000–2001 and 2001–2002), we analyzed 232 stomachs, of which 85% contained food. The trophic spectrum was composed of three species of cephalopods, six of crustaceans and 19 species of fish from mainly pelagic and benthic habitats. According to the Index of Relative Importance (%IRI), the cephalopod Loliolopsis diomedeae with IRI = 18%, fish of the family Carangidae IRI = 25% and family Synodontidae IRI = 19% constituted the main prey in general. The trophic niche width was

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