Freshwater elasmobranchs: a review of their physiology and biochemistry

Ballantyne, James S.; Robinson, J. W.

doi:10.1007/s00360-010-0447-0

Cited by 58 publications

(54 citation statements)

References 159 publications

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“…Given these euryhaline characteristics and the data presented herein, it seems that the life cycle of Glyphis sharks includes periods of marine dispersal in conjunction with some dependence on rivers and estuaries. In contrast to teleost fishes, 40% of which live in freshwater, only very few (about 5%) of elasmobranch species are able to survive in freshwater (28). Most of these belong to the potamotrygonid stingray family, which is fully adapted to freshwater and no longer capable of surviving in saltwater, as well as a few additional species of rays, some of which are capable of surviving in both freshwater and saltwater (29).…”

Section: Discussionmentioning

confidence: 99%

DNA capture reveals transoceanic gene flow in endangered river sharks

Corrigan

Yang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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For over a hundred years, the "river sharks" of the genus Glyphis were only known from the type specimens of species that had been collected in the 19th century. They were widely considered extinct until populations of Glyphis-like sharks were rediscovered in remote regions of Borneo and Northern Australia at the end of the 20th century. However, the genetic affinities between the newly discovered Glyphis-like populations and the poorly preserved, original museum-type specimens have never been established. Here, we present the first (to our knowledge) fully resolved, complete phylogeny of Glyphis that includes both archival-type specimens and modern material. We used a sensitive DNA hybridization capture method to obtain complete mitochondrial genomes from all of our samples and show that three of the five described river shark species are probably conspecific and widely distributed in Southeast Asia. Furthermore we show that there has been recent gene flow between locations that are separated by large oceanic expanses. Our data strongly suggest marine dispersal in these species, overturning the widely held notion that river sharks are restricted to freshwater. It seems that species in the genus Glyphis are euryhaline with an ecology similar to the bull shark, in which adult individuals live in the ocean while the young grow up in river habitats with reduced predation pressure. Finally, we discovered a previously unidentified species within the genus Glyphis that is deeply divergent from all other lineages, underscoring the current lack of knowledge about the biodiversity and ecology of these mysterious sharks.freshwater sharks | DNA | museum specimens

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Section: Discussionmentioning

confidence: 99%

DNA capture reveals transoceanic gene flow in endangered river sharks

Corrigan

Yang

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…It is believed to be related to the rectal gland activity plasticity (Pillans et al, 2005), urea and trimethylamine oxide (TMAO) reabsorption by the kidney (Pillans et al, 2008), and ion uptake by the gills (Ballantyne & Robinson, 2010), which is enhanced when in freshwater. With all this put together, according to these authors, C. leucas can maintain its body hyperosmotic in freshwater environments, but loses much more water and ions due to large amounts of urine produced.…”

Section: Discussionmentioning

confidence: 99%

New record of Carcharhinus leucas (Valenciennes, 1839) in an equatorial river system

2016

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Bull sharks are a cosmopolitan shark species frequently found in shallow shelf ocean waters and, occasionally, in several tropical river systems around the world. Due to bull shark's capability to enter riverine systems, the documentation of its occurrence is essential for future fisheries inspections and studies. In this way, this study aims to report the presence of a medium sized specimen of C. leucas in an equatorial river system. The specimen was caught by fishermen at Mearim River, located in Northern Brazil and well known for the occurrence of tidal bores during the highest spring tides of the dry season. The event coincided with the occurrence of one of the strongest spring tides of 2015. The captured female specimen measured approximately 1300 mm and weighted 35 kg. The occurrence of this species was not known in this river basin until now. We recommend and support future ichthyologic studies in the Mearim River basin in order to provide data for the delimitation of the territory used by C. leucas in Maranhão State, specially looking into its age, growth, diet, spatial, and temporal movement patterns in this area.

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“…Ballantyne and Robinson, 2010;Ballantyne and Fraser, 2013;Pillans and Franklin, 2004;Thorson, 1962); current hypotheses suggest that metabolic organisation of elasmobranchs is responsible for their poor penetration into fresh water, resulting in metabolic costs associated with osmoregulation (Ballantyne and Robinson, 2010;Meloni et al, 2002). Whereas the difference in solute concentrations has a significant impact on the physiological biochemistry of elasmobranchs, the potential impact of the changing density of sea water and fresh water has not been adequately considered.…”

Section: Introductionmentioning

confidence: 99%

“…The close relationship between the locomotor performance and body density may represent a fundamental influence on the lifestyle of elasmobranchs (Bone and Roberts, 1969;Gleiss et al, 2011a) and a key aspect to understanding how the constraints of water density and buoyancy shape the lives of those species that occur in fresh water. However, this has received no attention in the literature thus far (Ballantyne and Robinson, 2010). In this paper, we aim to clarify the impact of changing water density on the buoyancy and energetics of elasmobranchs.…”

Section: Introductionmentioning

confidence: 99%

Mechanical challenges to freshwater residency in sharks and rays

Gleiss

Potvin

Keleher

et al. 2015

Journal of Experimental Biology

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Major transitions between marine and freshwater habitats are relatively infrequent, primarily as a result of major physiological and ecological challenges. Few species of cartilaginous fish have evolved to occupy freshwater habitats. Current thought suggests that the metabolic physiology of sharks has remained a barrier to the diversification of this taxon in freshwater ecosystems. Here, we demonstrate that the physical properties of water provide an additional constraint for this species-rich group to occupy freshwater systems. Using hydromechanical modeling, we show that occurrence in fresh water results in a two-to three-fold increase in negative buoyancy for sharks and rays. This carries the energetic cost of lift production and results in increased buoyancy-dependent mechanical power requirements for swimming and increased optimal swim speeds. The primary source of buoyancy, the lipidrich liver, offers only limited compensation for increased negative buoyancy as a result of decreasing water density; maintaining the same submerged weight would involve increasing the liver volume by very large amounts: 3-to 4-fold in scenarios where liver density is also reduced to currently observed minimal levels and 8-fold without any changes in liver density. The first data on body density from two species of elasmobranch occurring in freshwater (the bull shark Carcharhinus leucas, Mü ller and Henle 1839, and the largetooth sawfish Pristis pristis, Linnaeus 1758) support this hypothesis, showing similar liver sizes as marine forms but lower liver densities, but the greatest negative buoyancies of any elasmobranch studied to date. Our data suggest that the mechanical challenges associated with buoyancy control may have hampered the invasion of freshwater habitats in elasmobranchs, highlighting an additional key factor that may govern the predisposition of marine organisms to successfully establish in freshwater habitats.

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Freshwater elasmobranchs: a review of their physiology and biochemistry

Cited by 58 publications

References 159 publications

DNA capture reveals transoceanic gene flow in endangered river sharks

DNA capture reveals transoceanic gene flow in endangered river sharks

New record of Carcharhinus leucas (Valenciennes, 1839) in an equatorial river system

Mechanical challenges to freshwater residency in sharks and rays

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