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Andrea J Morash, Sara R C Mackellar, Louise Tunnah, David A Barnett, Kilian M Stehfest, Jayson M Semmens, Suzanne Currie
Estuarine habitats are frequently used as nurseries by elasmobranch species for their protection and abundant resources; however, global climate change is increasing the frequency and severity of environmental challenges in these estuaries that may negatively affect elasmobranch physiology. Hyposmotic events are particularly challenging for marine sharks that osmoconform, and species-specific tolerances are not well known. Therefore, we sought to determine the effects of an acute (48 h) ecologically relevant hyposmotic event (25...
2016: Conservation Physiology
K B Burgess, M B Bennett
Ethanol storage and lipid and urea extraction had no effect on bluespotted maskray Neotrygon kuhlii muscle δ(13) C values whereas urea-removal and ethanol storage increased δ(15) N values. Results presented here show a significant δ(15) N increase post-urea removal and provide additional support for this approach in future elasmobranch stable-isotope analysis (SIA) studies. Further experimental work on other elasmobranch species is needed to assess extraction and preservation effects on stable-isotope (SI) values...
October 12, 2016: Journal of Fish Biology
J R Ovenden, G M Leigh, D C Blower, A T Jones, A Moore, C Bustamante, R C Buckworth, M B Bennett, C L Dudgeon
Sustainable exploitation of fisheries populations is challenging to achieve when the size of the population prior to exploitation and the actual numbers removed over time and across fishing zones are not clearly known. Quantitative fisheries' modeling is able to address this problem, but accurate and reliable model outcomes depend on high quality input data. Much of this information is obtained through the operation of the fishery under consideration, but while this seems appropriate, biases may occur. For example, poorly quantified changes in fishing methods that increase catch rates can erroneously suggest that the overall population size is increasing...
October 11, 2016: Journal of Fish Biology
Julie Larsen, Peter Bushnell, John Steffensen, Morten Pedersen, Klaus Qvortrup, Richard Brill
We assessed the functional properties in atrial and ventricular myocardium (using isolated cardiac strips) of smooth dogfish (Mustelus canis), clearnose skate (Raja eglanteria), and sandbar shark (Carcharhinus plumbeus) by blocking Ca(2+) release from the sarcoplasmic reticulum (SR) with ryanodine and thapsigargin and measuring the resultant changes in contraction-relaxation parameters and the force-frequency relationship at 20 °C and 30 °C. We also examined ultrastructural differences with electron microscopy...
September 29, 2016: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
Georgina K Cox, Richard W Brill, Kaitlin A Bonaro, Anthony P Farrell
The coronary circulation first appeared in the chordate lineage in cartilaginous fishes where, as in birds and mammals but unlike most teleost fishes, it supplies arterial blood to the entire myocardium. Despite the pivotal position of elasmobranch fishes in the evolution of the coronary circulation, the determinants of coronary blood flow have never been investigated in this group. Elasmobranch fishes are of special interest because of the morphological arrangement of their cardiomyocytes. Unlike teleosts, the majority of the ventricular myocardium in elasmobranch fishes is distant to the venous blood returning to the heart (i...
September 27, 2016: Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology
Jayne M Gardiner, Jelle Atema, Robert E Hueter, Philip J Motta
The ability of predators to modulate prey capture in response to the size, location, and behavior of prey is critical to successful feeding on a variety of prey types. Modulating in response to changes in sensory information may be critical to successful foraging in a variety of environments. Three shark species with different feeding morphologies and behaviors were filmed using high-speed videography while capturing live prey: the ram-feeding blacktip shark, the ram-biting bonnethead, and the suction-feeding nurse shark...
August 25, 2016: Zoology: Analysis of Complex Systems, ZACS
B Finucci, C Bustamante, E G Jones, M R Dunn
The reproductive biology and diet of prickly dogfish Oxynotus bruniensis, a deep-sea elasmobranch, endemic to the outer continental and insular shelves of southern Australia and New Zealand, and caught as by-catch in demersal fisheries, are described from specimens caught in New Zealand waters. A total of 53 specimens were obtained from research surveys and commercial fisheries, including juveniles and adults ranging in size from 33·5 to 75·6 cm total length (LT ). Estimated size-at-maturity was 54·7 cm LT in males and 64·0 cm LT in females...
September 8, 2016: Journal of Fish Biology
A T Fields, K A Feldheim, J Gelsleichter, C Pfoertner, D D Chapman
Population structure and lineage diversification within a small, non-dispersive hammerhead shark species, the bonnethead shark Sphyrna tiburo, was assessed. Sphyrna tiburo is currently described as one continuously distributed species along the Atlantic continental margins of North, Central and South America, but recent genetic analysis of an insular population (Trinidad) suggests the possibility of cryptic speciation. To address this issue S. tiburo were sampled at six sites along c. 6200 km of continuous, continental coastline and from one island location (Grand Bahama) across a discontinuity in their distribution (the Straits of Florida), in order to test if they constitute a single lineage over this distribution...
September 7, 2016: Journal of Fish Biology
Julia Wiens, Ryan Ho, Dinesh Fernando, Ayush Kumar, Peter C Loewen, Ann Karen C Brassinga, W Gary Anderson
We report here a genome sequence for Rhodococcus sp. isolate UM008 isolated from the renal/interrenal tissue of the winter skate Leucoraja ocellata Genome sequence analysis suggests that Rhodococcus bacteria may act in a novel mutualistic relationship with their elasmobranch host, serving as biocatalysts in the steroidogenic pathway of 1α-hydroxycorticosterone.
2016: Genome Announcements
Ronald Seidel, Kady Lyons, Michael Blumer, Paul Zaslansky, Peter Fratzl, James C Weaver, Mason N Dean
The endoskeleton of elasmobranchs (sharks and rays) is comprised largely of unmineralized cartilage, differing fundamentally from the bony skeletons of other vertebrates. Elasmobranch skeletons are further distinguished by a tessellated surface mineralization, a layer of minute, polygonal, mineralized tiles called tesserae. This 'tessellation' has defined the elasmobranch group for more than 400 million years, yet the limited data on development and ultrastructure of elasmobranch skeletons (e.g. how tesserae change in shape and mineral density with age) have restricted our abilities to develop hypotheses for tessellated cartilage growth...
November 2016: Journal of Anatomy
A T Oliveira, M L G Araújo, J Pantoja-Lima, P H R Aride, M Tavares-Dias, R P Brinn, J L Marcon
Intraerythrocytic parasites are frequently found in fish, including elasmobranchs. The Amazonian rivers present well defined annual hydrological cycles that results in drastic modifications of the environmental conditions with deep implications in the life cycle of the whole associated biota in those fluvial systems. The freshwater stingray Potamotrygon wallacei (stingray cururu) is a new species restricted to the Middle Rio Negro basin and it is subject to strong alterations in their natural habitats (igapós) a result of the constant variations in the water level of Rio Negro...
August 15, 2016: Brazilian Journal of Biology, Revista Brasleira de Biologia
Cat A Gordon, Ali R Hood, Jim R Ellis
Updated descriptions and measurements for the eggcases of 10 rajiform and three scyliorhinid species occurring in the shelf seas around the British Isles are given, based on museum material, specimens collected during the 'Great Eggcase Hunt' (a Shark Trust recording project), and specimens obtained from fishery surveys. Quantitative data are given for Amblyraja radiata (n = 94), Dipturus batis (n = 24), D. cf. intermedia (n = 33), Leucoraja naevus (n = 94), Raja brachyura (n = 53), R. clavata (n = 52), R. microocellata (n = 57), R...
2016: Zootaxa
Luca Bolognini, Simone Leoni, Piero Polidori, Fabio Grati, Giuseppe Scarcella, Giulio Pellini, Filippo Domenichetti, Carmen FerrÃ, Gianna Fabi
The present study provides a parasitological analysis of the elasmobranch species caught in the northern and central Adriatic Sea. A total of 62 marine leeches were recorded on 747 individuals of Raja clavata Linnaeus, 1758 (thornback ray), Myliobatis aquila Linnaeus, 1758 (common eagle ray), and Torpedo marmorata Risso, 1810 (marbled torpedo ray) caught in 56 hauls over a 5 yr period. All leeches were identified as Pontobdella muricata, which is a typical ectoparasite of benthic elasmobranchs. The prevalence of infection ranged from 7...
August 10, 2016: Journal of Parasitology
Lara Cusack, Cara L Field, Lisa Hoopes, Alexa McDermott, Tonya Clauss
Though one of the most widely kept elasmobranchs in human care, the cownose ray (CNR; Rhinoptera bonasus ), remains a species with minimal published information on hematologic reference intervals. As part of a larger study investigating the health and nutrition of the CNR, this study established a preliminary data set of plasma chemistry and hematology values specific to animals recently caught from the wild and compared this data set (intake sample) to values obtained following a period of quarantine (27-40 days) in an aquarium (exit sample)...
June 2016: Journal of Zoo and Wildlife Medicine: Official Publication of the American Association of Zoo Veterinarians
Karin H Olsson, Henrik Gislason, Ken Haste Andersen
Offspring size reflects the optimal balance between female fecundity and allocation of energy to each offspring. Most fish, in particular teleost species, produce many small eggs, while others, notably elasmobranch species, have low fecundity and large offspring. No general explanation has yet been put forwards to explain these different strategies between species which occupy similar habitats. We approach the problem by (1) examining the differences between life history parameters of teleost fish and elasmobranchs and (2) an evolutionary model...
October 21, 2016: Journal of Theoretical Biology
T Fatima Mitterboeck, Alexander Y Chen, Omar A Zaheer, Eddie Y T Ma, Sarah J Adamowicz
The major branches of life diversified in the marine realm, and numerous taxa have since transitioned between marine and freshwaters. Previous studies have demonstrated higher rates of molecular evolution in crustaceans inhabiting continental saline habitats as compared with freshwaters, but it is unclear whether this trend is pervasive or whether it applies to the marine environment. We employ the phylogenetic comparative method to investigate relative molecular evolutionary rates between 148 pairs of marine or continental saline versus freshwater lineages representing disparate eukaryote groups, including bony fish, elasmobranchs, cetaceans, crustaceans, mollusks, annelids, algae, and other eukaryotes, using available protein-coding and noncoding genes...
September 2016: Evolution; International Journal of Organic Evolution
L-A Henry, M F W Stehmann, L De Clippele, H S Findlay, N Golding, J M Roberts
Highly localized concentrations of elasmobranch egg capsules of the deep-water skate Bathyraja richardsoni were discovered during the first remotely operated vehicle (ROV) survey of the Hebrides Terrace Seamount in the Rockall Trough, north-east Atlantic Ocean. Conductivity-temperature-depth profiling indicated that the eggs were bathed in a specific environmental niche of well-oxygenated waters between 4·20 and 4·55° C, and salinity 34·95-35·06, on a coarse to fine-grained sandy seabed on the seamount's eastern flank, whereas a second type of egg capsule (possibly belonging to the skate Dipturus sp...
August 2016: Journal of Fish Biology
N P A Bezerra, P Travassos, F H V Hazin
Catch and effort data from 29 418 longline sets from Brazilian tuna longline vessels operating in the south-western and equatorial Atlantic Ocean between 2004 and 2011 were analysed to investigate the distribution, catch rate and size of three species of hammerhead sharks (Sphyrna lewini, Sphyrna mokarran and Sphyrna zygaena). During that period, 6172 hammerhead sharks were caught. Among the elasmobranchs, the highest percentage of hammerhead sharks were caught in 2007, when they accounted for 3·90% of the group, while the lowest value of 0·40% was recorded in 2010...
August 2016: Journal of Fish Biology
Martin Stelfox, Jillian Hudgins, Michael Sweet
This review focuses on the effect that ghost gear entanglement has on marine megafauna, namely mammals, reptiles and elasmobranchs. A total of 76 publications and other sources of grey literature were assessed, and these highlighted that over 5400 individuals from 40 different species were recorded as entangled in, or associated with, ghost gear. Interestingly, there appeared to be a deficit of research in the Indian, Southern, and Arctic Oceans; and so, we recommend that future studies focus efforts on these areas...
October 15, 2016: Marine Pollution Bulletin
Martijn S Johnson, Daniel W Kraver, Gillian M C Renshaw, Jodie L Rummer
Atmospheric CO2 is increasing due to anthropogenic causes. Approximately 30% of this CO2 is being absorbed by the oceans and is causing ocean acidification (OA). The effects of OA on calcifying organisms are starting to be understood, but less is known about the effects on non-calcifying organisms, notably elasmobranchs. One of the few elasmobranch species that has been studied with respect to OA is the epaulette shark, Hemiscyllium ocellatum. Mature epaulette sharks can physiologically and behaviourally tolerate prolonged exposure to elevated CO2, and this is thought to be because they are routinely exposed to diurnal decreases in O2 and probably concomitant increases in CO2 in their coral reef habitats...
2016: Conservation Physiology
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