| elasmobranch tissue culture: in vitro growth of brain explants from a shark (rhizoprionodon) and dogfish (squalus). | brain explants from a caribbean sharpnose shark (rhizoprionodon porosus) and six spiny dogfish (squalus acanthias) were cultured at 22 degrees c in leibovitz l-15 medium, 1000 mosmol, with 350 mm urea, 20 mm added nacl, and either 2% fetal bovine serum, 2% bull shark (carcharhinus leucas) serum, or 2% spiny dogfish serum. cell outgrowth from explants appeared after 1 month. cells were subcultured once with 20% survival, and were viable at termination of the trials 6 months later. cell morphology ... | 1988 | 3232143 |
| sequence, circulating levels, and expression of c-type natriuretic peptide in a euryhaline elasmobranch, carcharhinus leucas. | the present study has examined expression and circulating levels of c-type natriuretic peptide (cnp) in the euryhaline bull shark, carcharhinus leucas. complementary dna and deduced amino acid sequence for cnp in c. leucas were determined by race methods. homology of cnp amino acid sequence in c. leucas was high both for procnp and for mature cnp when compared with previously identified elasmobranch cnps. mature cnp sequence in c. leucas was identical to that in triakis scyllia and scyliorhinus ... | 2005 | 15979619 |
| essential and toxic metals in nine fish species for human consumption from two coastal lagoons in the eastern gulf of california. | with the aim of knowing concentrations of cd, cu, fe, mn, pb and zn; percentage of daily mineral intake (pmi) for essential elements and percentage of weekly intake (pwi) of toxic metals in commercial fish from 2 coastal lagoons in the eastern gulf of california, analyses were carried out in 9 species. highest values of cd were detected in the liver of the sharks sphyrna lewini and carcharhinus leucas, pb was mostly detected in the liver of s. lewini; cu and mn in the liver and gills of the mull ... | 2007 | 17680479 |
| total and organic mercury in ten fish species for human consumption from the mexican pacific. | total mercury and organic mercury were measured in ten fish species from the mexican pacific ocean to have a general view on the ratio of total mercury-organic mercury and potential implications on human health. highest concentration of total mercury was recorded in muscle tissue of carcharhinus leucas (0.62 μg g(-1) wet weight). organic mercury was more concentrated in haemulon sexfasciatum (0.4 μg g(-1) wet weight). percentages of organic mercury ranged from 33 to 100%. hazard indices associat ... | 2011 | 21516459 |
| [fishery of oceanic and coastal sharks in colima, jalisco and michoacán]. | shark fishery is one of the most important activities in the mexican pacific coast, nevertheless, there is few data available about the specific captures done by the fleet along the coast. this study describes fishery biology aspects of the shark species catched by the semi-industrial long-line fleet of manzanillo. monthly samplings were made on board of these vessels during an annual period from april 2006 to april 2007. captured species composition (n = 1 962 organisms) was represented by nine ... | 2011 | 21721232 |
| isolation and characterization of eight microsatellite loci from galeocerdo cuvier (tiger shark) and cross-amplification in carcharhinus leucas, carcharhinus brevipinna, carcharhinus plumbeus and sphyrna lewini. | the tiger shark galeocerdo cuvier (carcharhinidae) is a large elasmobranch suspected to have, as other apex predators, a keystone function in marine ecosystems and is currently considered near threatened (red list iucn). knowledge on its ecology, which is crucial to design proper conservation and management plans, is very scarce. here we describe the isolation of eight polymorphic microsatellite loci using 454 gs-flx titanium pyrosequencing of enriched dna libraries. their characteristics were t ... | 2016 | 27231661 |
| morphology of the ampullae of lorenzini in juvenile freshwater carcharhinus leucas. | ampullae of lorenzini were examined from juvenile carcharhinus leucas (831-1,045 mm total length) captured from freshwater regions of the brisbane river. the ampullary organ structure differs from all other previously described ampullae in the canal wall structure, the general shape of the ampullary canal, and the apically nucleated supportive cells. ampullary pores of 140-205 µm in diameter are distributed over the surface of the head region with 2,681 and 2,913 pores present in two sharks that ... | 2015 | 25515416 |
| residency patterns and migration dynamics of adult bull sharks (carcharhinus leucas) on the east coast of southern africa. | bull sharks (carcharhinus leucas) are globally distributed top predators that play an important ecological role within coastal marine communities. however, little is known about the spatial and temporal scales of their habitat use and associated ecological role. in this study, we employed passive acoustic telemetry to investigate the residency patterns and migration dynamics of 18 adult bull sharks (195-283 cm total length) tagged in southern mozambique for a period of between 10 and 22 months. ... | 2014 | 25295972 |
| evidence for reproductive philopatry in the bull shark carcharhinus leucas. | reproductive philopatry in bull sharks carcharhinus leucas was investigated by comparing mitochondrial (nadh dehydrogenase subunit 4, 797 base pairs and control region genes 837 base pairs) and nuclear (three microsatellite loci) dna of juveniles sampled from 13 river systems across northern australia. high mitochondrial and low microsatellite genetic diversity among juveniles sampled from different rivers (mitochondrial φ(st) = 0·0767, p < 0·05; microsatellite f(st) = -0·0022, p > 0·05) support ... | 2012 | 22551174 |
| feeding biomechanics and theoretical calculations of bite force in bull sharks (carcharhinus leucas) during ontogeny. | evaluations of bite force, either measured directly or calculated theoretically, have been used to investigate the maximum feeding performance of a wide variety of vertebrates. however, bite force studies of fishes have focused primarily on small species due to the intractable nature of large apex predators. more massive muscles can generate higher forces and many of these fishes attain immense sizes; it is unclear how much of their biting performance is driven purely by dramatic ontogenetic inc ... | 2012 | 23040789 |
| to madagascar and back: long-distance, return migration across open ocean by a pregnant female bull shark carcharhinus leucas. | a large, pregnant, female bull shark carcharhinus leucas was tracked migrating from seychelles across open ocean to south-east madagascar, c. 2000 km away, and back again. in madagascar, the shark spent a prolonged period shallower than 5 m, consistent with entering estuarine habitat to pup, and upon return to seychelles the shark was slender and no longer gravid. this represents an unprecedented return migration across the open ocean for a c. leucas and highlights the need for international col ... | 2015 | 26511427 |
| patterns of occurrence of sharks in sydney harbour, a large urbanised estuary. | information about spatial and temporal variability in the distribution and abundance of shark-populations are required for their conservation, management and to update measures designed to mitigate human-shark interactions. however, because some species of sharks are mobile, migratory and occur in relatively small numbers, estimating their patterns of distribution and abundance can be very difficult. in this study, we used a hierarchical sampling design to examine differences in the composition ... | 2016 | 26824349 |
| an unusual blood sequestering tapeworm (sanguilevator yearsleyi n. gen., n. sp.) from borneo with description of cathetocephalus resendezi n. sp. from mexico and molecular support for the recognition of the order cathetocephalidea (platyhelminthes: eucestoda). | sanguilevator yearsleyi n. gen., n. sp. and cathetocephalus resendezi n. sp. are described from the broadfin shark, lamiopsis temmincki, in malaysian borneo and carcharhinus leucas in mexico, respectively. the new genus is unusual in its possession of internal chambers and channels in its scolex that appear to house extensive quantities of host white and red blood cells, respectively. histology reveals an extremely intimate association between host tissue and the surface of the apical pad of the ... | 2005 | 16019004 |
| a comparison of spatial and movement patterns between sympatric predators: bull sharks (carcharhinus leucas) and atlantic tarpon (megalops atlanticus). | predators can impact ecosystems through trophic cascades such that differential patterns in habitat use can lead to spatiotemporal variation in top down forcing on community dynamics. thus, improved understanding of predator movements is important for evaluating the potential ecosystem effects of their declines. | 2012 | 23049904 |
| natural or artificial? habitat-use by the bull shark, carcharhinus leucas. | despite accelerated global population declines due to targeted and illegal fishing pressure for many top-level shark species, the impacts of coastal habitat modification have been largely overlooked. we present the first direct comparison of the use of natural versus artificial habitats for the bull shark, carcharhinus leucas, an iucn 'near-threatened' species--one of the few truly euryhaline sharks that utilises natural rivers and estuaries as nursery grounds before migrating offshore as adults ... | 2012 | 23166772 |
| opportunistic visitors: long-term behavioural response of bull sharks to food provisioning in fiji. | shark-based tourism that uses bait to reliably attract certain species to specific sites so that divers can view them is a growing industry globally, but remains a controversial issue. we evaluate multi-year (2004-2011) underwater visual (n = 48 individuals) and acoustic tracking data (n = 82 transmitters; array of up to 16 receivers) of bull sharks carcharhinus leucas from a long-term shark feeding site at the shark reef marine reserve and reefs along the beqa channel on the southern coast of v ... | 2013 | 23516496 |
| habitat use and movement patterns of bull sharks carcharhinus leucas determined using pop-up satellite archival tags. | habitat use, movement and residency of bull sharks carcharhinus leucas were determined using satellite pop-up archival transmitting (pat) tags throughout coastal areas in the u.s., gulf of mexico and waters off the south-east u.s. from 2005 to 2007, 18 fish (mean size = 164 cm fork length, l(f)) were tagged over all seasons. fish retained tags for up to 85 days (median = 30 days). based on geolocation data from initial tagging location to pop-off location, c. leucas generally travelled c. 5-6 km ... | 2010 | 20701646 |
| halogenated bipyrroles and methoxylated tetrabromodiphenyl ethers in tiger shark (galeocerdo cuvier) from the southern coast of japan. | naturally produced halogenated bipyrroles (hbps) and methoxylated tetrabdes (meo-tetrabdes) are lipophilic and persistent, and therefore may bioaccumulate with higher trophic levels. in this study, the livers of tiger shark (galeocerdo cuvier) collected from the southern coast of japan were investigated for size-related bioaccumulation of natural hbps and meo-tetrabdes in comparison with anthropogenic pcbs and pbdes. heptachloro-1'-methyl-1,2'-bipyrrole (cl7-mbp) and hexahalogenated 1,1'-dimethy ... | 2009 | 19452876 |
| first record of dicephalia in a bull shark carcharhinus leucas (chondrichthyes: carcharhinidae) foetus from the gulf of mexico, u.s.a. | the first recorded incidence of dicephalia in a bull shark carcharhinus leucas is reported from a foetus collected by a fisherman in the gulf of mexico near florida, u.s.a. external examination, radiography and magnetic resonance imaging revealed a case of monosomic dicephalia where the axial skeleton and internal organs were found to divide into parallel systems anterior to the pectoral girdle resulting in two well-developed heads. | 2013 | 23557317 |
| uptake of human pharmaceuticals in bull sharks (carcharhinus leucas) inhabiting a wastewater-impacted river. | the presence of human pharmaceuticals in sewage-impacted ecosystems is a growing concern that poses health risks to aquatic wildlife. despite this, few studies have investigated the uptake of active pharmaceutical ingredients (apis) in aquatic organisms. in this study, the uptake of 9 apis from human drugs was examined and compared in neonate bull sharks (carcharhinus leucas) residing in pristine (myakka river) and wastewater-impacted (caloosahatchee river) tributaries of florida's charlotte har ... | 2013 | 23602972 |
| multi-tissue stable isotope analysis and acoustic telemetry reveal seasonal variability in the trophic interactions of juvenile bull sharks in a coastal estuary. | understanding how natural and anthropogenic drivers affect extant food webs is critical to predicting the impacts of climate change and habitat alterations on ecosystem dynamics. in the florida everglades, seasonal reductions in freshwater flow and precipitation lead to annual migrations of aquatic taxa from marsh habitats to deep-water refugia in estuaries. the timing and intensity of freshwater reductions, however, will be modified by ongoing ecosystem restoration and predicted climate change. ... | 2014 | 23927728 |
| comparative feeding ecology of bull sharks (carcharhinus leucas) in the coastal waters of the southwest indian ocean inferred from stable isotope analysis. | as apex predators, sharks play an important role shaping their respective marine communities through predation and associated risk effects. understanding the predatory dynamics of sharks within communities is, therefore, necessary to establish effective ecologically based conservation strategies. we employed non-lethal sampling methods to investigate the feeding ecology of bull sharks (carcharhinus leucas) using stable isotope analysis within a subtropical marine community in the southwest india ... | 2013 | 24205168 |
| age-related polychlorinated biphenyl dynamics in immature bull sharks (carcharhinus leucas). | polychlorinated biphenyls (pcbs) were quantified in liver tissues of bull sharks (carcharhinus leucas) ranging in age from <4 wk to >3 yr. summed values of pcbs (σpcbs) ranged from 310 ng/g to 22 070 ng/g (lipid wt) across age classes with σpcb concentrations for the youngest sharks in the present study (<4 wk; 5230 ± 2170 ng/g lipid wt) determined to not significantly differ from those quantified in >3-yr-old sharks, highlighting the extent of exposure of this young life stage to this class of ... | 2014 | 24357032 |
| ampullary organs and electroreception in freshwater carcharhinus leucas. | the ampulla of lorenzini of juvenile carcharhlinus leucas differ histologically from those previously described for other elasmobranchs. the wall of the ampullary canal consists of protruding hillock-shaped epidermal cells that appear to secrete large quantities of a mucopolysaccharide gel. the ampullary organs comprise a long canal sheathed in collagen terminating in an ampulla. each ampulla contains six alveolar sacs, with each sac containing hundreds of receptor cells. the receptor cells are ... | 2008 | 14692487 |
| urea based osmoregulation and endocrine control in elasmobranch fish with special reference to euryhalinity. | since the landmark contributions of homer smith and co-workers in the 1930s there has been a considerable advance in our knowledge regarding the osmoregulatory strategy of elasmobranch fish. smith recognised that urea was retained in the body fluids as part of the 'osmoregulatory ballast' of elasmobranch fish so that body fluid osmolality is raised to a level that is iso- or slightly hyper-osmotic to that of the surrounding medium. from studies at that time he also postulated that many marine dw ... | 2003 | 14662294 |
| mitochondrial genome of the bull shark carcharhinus leucas (carcharhiniformes: carcharhinidae). | the bull shark carcharhinus leucas is a large elasmobranch species widespread in tropical and warm oceans, rivers and lakes. we first determine the complete mitogenome of c. leucas in this article. it is 16,704 bp in length, consists 37 genes and one control region with the typical gene order in vertebrates. the nd6 gene used the rare agg as stop codon. the 22 trna genes ranged from 67 to 75 bp. the trna-ser2 lacks the dihydrouridine arm and cannot form the typical cloverleaf structure. the cont ... | 2015 | 24409857 |
| long-term changes in species composition and relative abundances of sharks at a provisioning site. | diving with sharks, often in combination with food baiting/provisioning, has become an important product of today's recreational dive industry. whereas the effects baiting/provisioning has on the behaviour and abundance of individual shark species are starting to become known, there is an almost complete lack of equivalent data from multi-species shark diving sites. in this study, changes in species composition and relative abundances were determined at the shark reef marine reserve, a multi-spe ... | 2014 | 24466197 |
| multiple prismatic calcium phosphate layers in the jaws of present-day sharks (chondrichthyes; selachii). | jaws of large individuals, over 2 m in total length, of the shark species carcharodon carcharias (great white shark) and isurus oxyrinchus (mako shark) of the family lamnidae, and galeocerdo cuvieri (tiger shark) and carcharhinus leucas (bull shark) of the family carcharhinidae were found to have multiple, up to five, layers of prismatic calcium phosphate surrounding the cartilages. smaller individuals of these species and other known species of living chondrichthyans have only one layer of pris ... | 1991 | 1999241 |
| granulinema gen. n. a new dracunculoid genus with two new species (g. carcharhini sp. n. and g. simile sp. n.) from the bull shark, carcharhinus leucas (valenciennes), from louisiana, usa. | two new species of dracunculoid nematodes, g. carcharhini sp. n. and g. simile sp. n., representing a new genus granulinema gen. n. (dracunculoidea: micropleuridae) are described from the bull shark, carcharhinus leucas, from louisiana (lake borgne), usa; the site of their localization in the host is unknown (probably abdominal cavity). the nematodes of both species were found in tissue juice and only males, juvenile females and body fragments of more advanced but nongravid females were obtained ... | 1988 | 3169642 |
| comparison of some parameters of serum and uterine fluid of pregnant, viviparous sharks (carcharhinus leucas) and serum of their near-term young. | | 1972 | 4402718 |
| rectal glands of marine and fresh-water sharks: comparative histology. | the rectal glands of elasmobranchs perform the function of salt-excreting organs. these glands are smaller and show regressive changes in specimens of the bull shark, carcharhinus leucas found in fresh-water environment, compared with specimens of this and other species from a marine habitat. | 1964 | 17814499 |
| calcium and other ions in blood and skeleton of nicaraguan fresh-water shark. | the bull shark, carcharhinus leucas, employing archaic but effective means of regulating the physical-chemical composition of its body fluids, thrives in tropical fresh-water rivers and lakes. the ionic strength of the serum and the concentrations of total solutes, calcium, urea, and other ions are below the levels found in marine elasmobranchs but higher than the levels in teleosts. the patterns of the calcium deposits of the vertebrae are identical in marine and fresh-water subspecies. | 1962 | 13923921 |
| the complete mitochondrial dna of the bull shark (carcharhinus leucas). | the bull shark mitochondrial structure is similar to that of other elasmobranchs; it has a total length of 16,100 bp, the base composition of the genomes was as follows: a (31.35%), t (31.35%), c (24.38%) and g (12.90%). it contains 13 protein-coding genes and 23 trna genes. the trna genes range from 70-72 bp. gene order is the same as in other vertebrates and teleosts. | 2016 | 24810063 |
| distribution and dynamic habitat use of young bull sharks carcharhinus leucas in a highly stratified northern gulf of mexico estuary. | understanding how animals alter habitat use in response to changing abiotic conditions is important for effective conservation management. for bull sharks (carcharhinus leucas), habitat use has been widely examined in the eastern and western gulf of mexico; however, knowledge of their movements and the factors influencing them is lacking for populations in the more temperate north-central gulf of mexico. to examine how changes in hydrographic conditions affected the presence of young bull sharks ... | 2014 | 24841925 |
| a new metric for measuring condition in large predatory sharks. | a simple metric (span condition analysis; sca) is presented for quantifying the condition of sharks based on four measurements of body girth relative to body length. data on 104 live sharks from four species that vary in body form, behaviour and habitat use (carcharhinus leucas, carcharhinus limbatus, ginglymostoma cirratum and galeocerdo cuvier) are given. condition shows similar levels of variability among individuals within each species. carcharhinus leucas showed a positive relationship betw ... | 2014 | 25130454 |
| mechanical challenges to freshwater residency in sharks and rays. | 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 g ... | 2015 | 25573824 |
| individual variation in ontogenetic niche shifts in habitat use and movement patterns of a large estuarine predator (carcharhinus leucas). | ontogenetic niche shifts are common among animals, yet most studies only investigate niche shifts at the population level, which may overlook considerable differences among individuals in the timing and dynamics of these shifts. such divergent behaviors within size-/age-classes have important implications for the roles a population-and specific age-classes-play in their respective ecosystem(s). using acoustic telemetry, we tracked the movements of juvenile bull sharks in the shark river estuary ... | 2015 | 25669454 |
| evidence of partial migration in a large coastal predator: opportunistic foraging and reproduction as key drivers? | understanding animal movement decisions that involve migration is critical for evaluating population connectivity, and thus persistence. recent work on sharks has shown that often only a portion of the adult population will undertake migrations, while the rest may be resident in an area for long periods. defining the extent to which adult sharks use specific habitats and their migratory behaviour is essential for assessing their risk of exposure to threats such as fishing and habitat degradation ... | 2016 | 26841110 |
| contrasting movements and connectivity of reef-associated sharks using acoustic telemetry: implications for management. | understanding the efficacy of marine protected areas (mpas) for wide-ranging predators is essential to designing effective management and conservation approaches. the use of acoustic monitoring and network analysis can improve our understanding of the spatial ecology and functional connectivity of reef-associated species, providing a useful approach for reef-based conservation planning. this study compared and contrasted the movement and connectivity of sharks with different degrees of reef asso ... | 2015 | 26910942 |
| a comparison of the heart and muscle total lipid and fatty acid profiles of nine large shark species from the east coast of south africa. | we have assessed the fatty acid profiles of the hearts and different muscle tissues from nine large shark species (carcharhinus limbatus (blacktip), carcharhinus obscurus (dusky), carcharhinus brevipinna (spinner), carcharhinus leucas (zambezi/bull), galeocerdo cuvier (tiger), sphyrna lewini (scalloped hammerhead), sphyrna zygaena (smooth hammerhead), carcharodon carcharias (great white) and carcharias taurus (raggedtooth/grey nurse/sand tiger)) found off the east coast of south africa. while th ... | 2011 | 20694746 |
| relative abundance and size of coastal sharks derived from commercial shark longline catch and effort data. | in the north-west atlantic ocean, stock assessments conducted for some commercially harvested coastal sharks indicate declines from 64 to 80% with respect to virgin population levels. while the status of commercially important species is available, abundance trend information for other coastal shark species in the north-west atlantic ocean are unavailable. using a generalized linear modelling (glm) approach, a relative abundance index was derived from 1994 to 2009 using observer data collected i ... | 2012 | 22497406 |
| mode of attachment and lesions associated with trypanorhynch cestodes in the gastrointestinal tracts of two species of sharks collected from coastal waters of borneo. | lesions associated with two species of tapeworms within the digestive tract of wild-caught specimens of the bull shark, carcharhinus leucas, and the sicklefin weasel shark, hemigaleus microstoma, from malaysian borneo are described. portions of the glandular stomach and pyloric gut with parasites were removed and fixed in 10% formalin buffered in sea water. whole mounts, histological sections of tissues with and without worms in situ, and scanning electron microscopy images of detached worms wer ... | 2006 | 16866923 |
| comparative retinal anatomy in four species of elasmobranch. | using both light and transmission electron microscopy, we examined the retinal anatomy of four elasmobranch species with differing ecologies: the bull shark carcharhinus leucas, port jackson shark heterodontus portusjacksoni, epaulette shark hemiscyllium ocellatum and pink whipray himantura fai. their retinas are typical of other vertebrates, having three nuclear and two synaptic layers, but are characterised by very large horizontal cells, low densities of ganglion cells (many of which are disp ... | 2012 | 22114011 |
| branchial osmoregulation in the euryhaline bull shark, carcharhinus leucas: a molecular analysis of ion transporters. | bull sharks, carcharhinus leucas, are one of only a few species of elasmobranchs that live in both marine and freshwater environments. osmoregulation in euryhaline elasmobranchs is achieved through the control and integration of various organs (kidney, rectal gland and liver) in response to changes in environmental salinity. however, little is known regarding the mechanisms of ion transport in the gills of euryhaline elasmobranchs and how they are affected by osmoregulatory challenges. this stud ... | 2011 | 21832131 |
| oceans apart? short-term movements and behaviour of adult bull sharks carcharhinus leucas in atlantic and pacific oceans determined from pop-off satellite archival tagging. | adult bull sharks carcharhinus leucas were monitored with electronic tags to investigate horizontal and vertical movements in the atlantic and pacific oceans. in both locations, c. leucas showed some fidelity to specific coastal areas with only limited horizontal movements away from the tagging sites after tag attachment. fish tagged in the bahamas were detected mostly in the upper 20 m of the water column in water 25-26° c, whereas c. leucas tagged in fiji spent most of their time below 20 m in ... | 2010 | 21039509 |
| contrasting patterns of individual specialization and trophic coupling in two marine apex predators. | 1. apex predators are often assumed to be dietary generalists and, by feeding on prey from multiple basal nutrient sources, serve to couple discrete food webs. but there is increasing evidence that individual level dietary specialization may be common in many species, and this has not been investigated for many marine apex predators. 2. because of their position at or near the top of many marine food webs, and the possibility that they can affect populations of their prey and induce trophic casc ... | 2011 | 20831730 |
| the effects of freshwater to seawater transfer on circulating levels of angiotensin ii, c-type natriuretic peptide and arginine vasotocin in the euryhaline elasmobranch, carcharhinus leucas. | this study examined the effect of transfer to increased environmental salinity on the circulating levels of angiotensin ii (ang ii), c-type natriuretic peptide (cnp), and arginine vasotocin (avt) in the euryhaline elasmobranch, carcharhinus leucas. plasma levels of ang ii and cnp were significantly increased in c. leucas chronically acclimated to seawater (sw) in comparison to freshwater (fw) acclimated fish. there was no difference in plasma avt levels. acute transfer of fw fish to 75% sw induc ... | 2006 | 16181629 |
| hepatic urea biosynthesis in the euryhaline elasmobranch carcharhinus leucas. | plasma urea levels and hepatic urea production in the euryhaline bull shark, carcharhinus leucas, acclimated to freshwater and seawater environments were measured. it was found that plasma urea concentration increased with salinity and that this increase was, in part, the result of a significant increase in hepatic production of urea. this study provides direct evidence that hepatic production of urea plays an important role in the osmoregulatory strategy of c. leucas. | 2005 | 16161010 |
| bite motivation of sharks reflected by the wound structure on humans. | bite wounds on humans have rarely been comparatively analyzed, and the behavior leading to such bites is virtually unknown. nevertheless, the behavior of a shark is reflected in the bite structure and should be an essential part of shark-accident analysis. this paper compares 3 nonfatal accidents on humans, caused by bull sharks, carcharhinus leucas, that occurred within a 12-month period in the same area of the bahamas. examination focused on wound analysis and accident reconstruction to determ ... | 2005 | 15894846 |
| freshwater to seawater acclimation of juvenile bull sharks (carcharhinus leucas): plasma osmolytes and na+/k+-atpase activity in gill, rectal gland, kidney and intestine. | this study examined the osmoregulatory status of the euryhaline elasmobranch carcharhinus leucas acclimated to freshwater (fw) and seawater (sw). juvenile c. leucas captured in fw (3 mosm l(-1) kg(-1)) were acclimated to sw (980-1,000 mosm l(-1) kg(-1)) over 16 days. a fw group was maintained in captivity over a similar time period. in fw, bull sharks were hyper-osmotic regulators, having a plasma osmolarity of 595 mosm l(-1) kg(-1). in sw, bull sharks had significantly higher plasma osmolaritie ... | 2005 | 15565307 |
| plasma osmolyte concentrations and rectal gland mass of bull sharks carcharhinus leucas, captured along a salinity gradient. | bull sharks (carcharhinus leucas) were captured across a salinity gradient from freshwater (fw) to seawater (sw). across all salinities, c. leucas were hyperosmotic to the environment. plasma osmolarity in fw-captured animals (642 +/- 7 mosm) was significantly reduced compared to sw-captured animals (1067 +/- 21 mosm). in fw animals, sodium, chloride and urea were 208 +/- 3, 203 +/- 3 and 192 +/- 2 mmol l(-1), respectively. plasma sodium, chloride and urea in sw-captured c. leucas were 289 +/- 3 ... | 2004 | 15313492 |
| a revision of platybothrium linton, 1890 (tetraphyllidea: onchobothriidae), with a phylogenetic analysis and comments on host-parasite associations. | a revision of platybothrium linton, 1890 is presented, based on available type and voucher material, as well as extensive new collections from elasmobranchs belonging to the carcharhinidae (requiem sharks) and sphyrnidae (hammerhead sharks). all 10 nominal platybothrium species are treated or redescribed herein. four of these 10 nominal species, in addition to one former member of dicranobothrium euzet, 1953, are considered valid members of platybothrium. five new platybothrium species are descr ... | 2003 | 14574090 |
| fatal mass poisoning in madagascar following ingestion of a shark (carcharhinus leucas): clinical and epidemiological aspects and isolation of toxins. | in november 1993, 188 people were admitted to hospital after eating the meat from a single shark (carcharhinus leucas) in manakara, a medium-sized town on the south-east coast of madagascar. this shark and its meat had no unusual characteristics. the attack rate was about 100%. the first clinical signs appeared within 5-10 hr after ingestion. the patients presented with neurological symptoms almost exclusively, the most prominent being a constant, severe ataxia. gastrointestinal troubles, like d ... | 1995 | 8599186 |
| assessment of acid-base derangements among bonnethead (sphyrna tiburo), bull (carcharhinus leucas), and lemon (negaprion brevirostris) sharks from gillnet and longline capture and handling methods. | blood gasses of wild bonnethead, bull, and lemon sharks were measured with the i-stat clinical analyzer with the cg4+ cartridge immediately after capture; and again immediately prior to release after tagging, handling and morphometric measurements were taken. relative reference ranges of post-capture status were established. among species, stress response to capture was similar for all parameters; however, ph declined and lactate concentrations rose over time, indicating continued insult from ca ... | 2012 | 21600297 |
| maternal meddling in neonatal sharks: implications for interpreting stable isotopes in young animals. | stable isotopes of neonatal vertebrates reflect those of their mother's diet and foraging location. evaluating feeding strategies and habitat use of neonates is consequently complicated by the maternal isotopic signal and its subsequent elimination with growth. thus, methods that measure the loss of the maternal signal, i.e. when the isotopic signal of a neonate reflects its own diet, are needed. values of δ(13)c and δ(15)n were measured in liver and muscle tissues of <1 year old bull (carcharhi ... | 2011 | 21452377 |
| seasonal and long-term changes in relative abundance of bull sharks from a tourist shark feeding site in fiji. | shark tourism has become increasingly popular, but remains controversial because of major concerns originating from the need of tour operators to use bait or chum to reliably attract sharks. we used direct underwater sampling to document changes in bull shark carcharhinus leucas relative abundance at the shark reef marine reserve, a shark feeding site in fiji, and the reproductive cycle of the species in fijian waters. between 2003 and 2009, the total number of c. leucas counted on each day rang ... | 2011 | 21346792 |
| provisional audiogram for the shark, carcharhinus leucas. | in an operant-conditioning study, a bull shark responded to signals at frequencies between 100 and 1500 cy/sec. in its band of greatest sensitivity (400 to 600 cy/sec), it discriminated, from high-level ambient noise, signals of amplitudes which the apparatus could not measure. | 1961 | 13754400 |