Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 4.583
Filtrar
1.
Adv Mar Biol ; 90: 1-49, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34728053

RESUMO

Sharks are iconic and ecologically important predators found in every ocean. Because of their ecological role as predators, some considered apex predators, and concern over the stability of their populations due to direct and indirect overfishing, there has been an increasing amount of work focussed on shark conservation, and other elasmobranchs such as skates and rays, around the world. Here we discuss many aspects of current shark science and conservation and the path to the future of shark conservation in the Northeastern and Eastern Central Pacific. We explore their roles in ecosystems as keystone species; the conservation measures and laws in place at the international, national, regional and local level; the conservation status of sharks and rays in the region, fisheries for sharks in the Northcentral Pacific specifically those that target juveniles and the implications to shark conservation; a conservation success story: the recovery of Great White Sharks in the Northeast Pacific; public perceptions of sharks and the roles zoos and aquariums play in shark conservation; and the path to the future of shark conservation that requires bold partnerships, local stakeholders and innovative measures.


Assuntos
Tubarões , Animais , Conservação dos Recursos Naturais , Ecossistema , Pesqueiros , Oceano Pacífico
2.
BMC Ecol Evol ; 21(1): 192, 2021 10 21.
Artigo em Inglês | MEDLINE | ID: mdl-34674635

RESUMO

BACKGROUND: The evolutionary processes that shape patterns of species richness in marine ecosystems are complex and may differ between organismal groups. There has been considerable interest in understanding the evolutionary processes that led to marine species richness being concentrated in specific geographical locations. In this study we focus on the evolutionary history of a group of small-to-medium sized sharks known as carpet sharks. While a few carpet shark species are widespread, the majority of carpet shark species richness is contained within a biodiversity hotspot at the boundary of the Indian and Pacific oceans. We address the significance of this biodiversity hotspot in carpet shark evolution and speciation by leveraging a rich fossil record and molecular phylogenetics to examine the prehistoric distribution of carpet sharks. RESULTS: We find that carpet sharks species richness was greatest in shallow seas connected to the Atlantic Ocean during the Late Cretaceous, but that there was a subsequent loss of biodiversity in Atlantic waters. Fossil evidence from sites in close geographic proximity to the current center of carpet shark diversity are generally restricted to younger geologic strata. CONCLUSIONS: From this data we conclude that (1) center of carpet shark biodiversity has shifted during the last 100 million years, (2) carpet sharks have repeatedly dispersed to nascent habitat (including to their current center of diversity), and (3) the current center of carpet shark biodiversity conserves lineages that have been extirpated from this prehistoric range and is a source of new carpet shark species. Our findings provide insights into the roles of marine biodiversity hotspots for higher-tropic level predators and the methods applied here can be used for additional studies of shark evolution.


Assuntos
Tubarões , Animais , Biodiversidade , Ecossistema , Oceanos e Mares , Oceano Pacífico , Tubarões/genética
3.
FASEB J ; 35(11): e21970, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34637549

RESUMO

Single domain shark variable domain of new antigen receptor (VNAR) antibodies can offer a viable alternative to conventional Ig-based monoclonal antibodies in treating COVID-19 disease during the current pandemic. Here we report the identification of neutralizing single domain VNAR antibodies selected against the severe acute respiratory syndrome coronavirus 2 spike protein derived from the Wuhan variant using phage display. We identified 56 unique binding clones that exhibited high affinity and specificity to the spike protein. Of those, 10 showed an ability to block both the spike protein receptor binding domain from the Wuhan variant and the N501Y mutant from interacting with recombinant angiotensin-converting enzyme 2 (ACE2) receptor in vitro. In addition, three antibody clones retained in vitro blocking activity when the E484K spike protein mutant was used. The inhibitory property of the VNAR antibodies was further confirmed for all 10 antibody clones using ACE2 expressing cells with spike protein from the Wuhan variant. The viral neutralizing potential of the VNAR clones was also confirmed for the 10 antibodies tested using live Wuhan variant virus in in vitro cell infectivity assays. Single domain VNAR antibodies, due to their low complexity, small size, unique epitope recognition, and formatting flexibility, should be a useful adjunct to existing antibody approaches to treat COVID-19.


Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , COVID-19 , SARS-CoV-2/imunologia , Anticorpos de Domínio Único/imunologia , Glicoproteína da Espícula de Coronavírus/imunologia , Animais , COVID-19/imunologia , COVID-19/prevenção & controle , Chlorocebus aethiops , Humanos , Ligação Proteica , Tubarões/imunologia , Células Vero
4.
J R Soc Interface ; 18(183): 20210533, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34699727

RESUMO

Shark bites on humans are rare but are sufficiently frequent to generate substantial public concern, which typically leads to measures to reduce their frequency. Unfortunately, we understand little about why sharks bite humans. One theory for bites occurring at the surface, e.g. on surfers, is that of mistaken identity, whereby sharks mistake humans for their typical prey (pinnipeds in the case of white sharks). This study tests the mistaken identity theory by comparing video footage of pinnipeds, humans swimming and humans paddling surfboards, from the perspective of a white shark viewing these objects from below. Videos were processed to reflect how a shark's retina would detect the visual motion and shape cues. Motion cues of humans swimming, humans paddling surfboards and pinnipeds swimming did not differ significantly. The shape of paddled surfboards and human swimmers was also similar to that of pinnipeds with their flippers abducted. The difference in shape between pinnipeds with abducted versus adducted flippers was bigger than between pinnipeds with flippers abducted and surfboards or human swimmers. From the perspective of a white shark, therefore, neither visual motion nor shape cues allow an unequivocal visual distinction between pinnipeds and humans, supporting the mistaken identity theory behind some bites.


Assuntos
Mordeduras e Picadas , Tubarões , Animais , Humanos , Natação
5.
Parasitol Res ; 120(11): 3739-3747, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34611723

RESUMO

The biology, including accompanying ectoparasitic fauna, remains unstudied for several elasmobranchs off the Canary Islands in spite of concerns over their conservation. Within this region, this is the first report of copepod associations with these fishes. Twenty smooth hammerhead sharks, Sphyrna zygaena, and one common stingray, Dasyatis pastinaca, were inspected for symbionts on their body surface. Symbiotic siphonostomatoids were collected from 18 S. zygaena hosts and represent two different species, i.e., Alebion crassus (Caligidae) and Pandarus cranchii (Pandaridae). A high prevalence of 90% and a mean infection of 8.3 individuals per infected host were exhibited by A. crassus, while only a single P. cranchii was collected. Both these findings represent new geographical records. Additionally, one free-ranging common stingray Dasyatis pastinaca was opportunistically inspected and 11 Pseudocharopinus pillaii (Lernaeopodidae) collected which constitutes a new host record and a new geographical record. A re-description with detail regarding the morphology of the appendages is provided for the first time. Due to the morphological similarity between P. pillaii and P. malleus, a molecular analysis of the partial mitochondrial DNA cytochrome oxidase I gene was done in an attempt to determine if there is molecular divergence between the two species. This provided an estimate of the phylogenetic relationships amongst four Pseudocharopinus species (P. bicaudatus, P. pteromylaei, P. malleus, and P. pillaii) with Charopinus dubius as an outgroup as an alternative hypothesis to compare with the previous morphological topology estimated for all Pseudocharopinus species.


Assuntos
Copépodes , Pastinaca , Tubarões , Rajidae , Animais , Humanos , Filogenia , Espanha
6.
Nutrients ; 13(10)2021 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-34684329

RESUMO

Fatty acid (FA) balance is strictly related to human health. The composition of fatty acids in lipid membranes seems to be influenced by diet. Shark liver oil (SLO) supplementation has been widely used recently in the prevention and treatment of human diseases. We analyzed the impact of short-term SLO supplementation on certain biochemical parameters and erythrocyte FA composition in a group of young healthy women. Our results showed that 6 weeks of SLO supplementation led to a significant decrease in C-reactive protein levels in sera and intracellular cholesterol levels in peripheral blood mononuclear cells. SLO supplementation caused a significant increase in the content of the polyunsaturated omega-3 FAs: docosahexaenoic acid, docosapentaenoic acid and α-linolenic acid. In the group of omega-6 FAs, we observed a significant elevation of arachidonic and dihomo-gamma-linoleic acid content. Due to these alterations, the omega-3 index increased significantly from 3.6% (before) to 4.2% (after supplementation). We also observed the impact of SLO supplementation on the membrane fluidity index. The ratio between saturated and unsaturated FAs decreased significantly from 13.1 to 9.9. In conclusion, our results show that even short-term SLO supplementation can improve human erythrocyte fatty acid composition and other parameters that may have health-promoting consequences.


Assuntos
Suplementos Nutricionais , Membrana Eritrocítica/metabolismo , Ácidos Graxos/metabolismo , Óleos de Peixe/farmacologia , Fígado/química , Adulto , Animais , LDL-Colesterol/sangue , Membrana Eritrocítica/efeitos dos fármacos , Ácidos Graxos Ômega-3/sangue , Humanos , Leucócitos Mononucleares/efeitos dos fármacos , Leucócitos Mononucleares/metabolismo , Fluidez de Membrana/efeitos dos fármacos , Tubarões , Adulto Jovem
7.
PLoS One ; 16(10): e0253867, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34610033

RESUMO

Sharks have declined worldwide and remote sanctuaries are becoming crucial for shark conservation. The southwest Indian Ocean is a hotspot of both terrestrial and marine biodiversity mostly impacted by anthropogenic damage. Sharks were observed during surveys performed from April to June 2013 in the virtually pristine coral reefs around Europa Island, a remote Marine Protected Area located in the southern Mozambique Channel. Observation events comprised 67 1-hour scientific dives between 5 - 35m depth and 7 snorkeling inspections, as well as 4 dinghy-based observations in the shallow lagoon. In a period of 24 days, 475 sharks were tallied. Carcharhinus galapagensis was most encountered and contributed 20% of the abundance during diving, followed by C. albimarginatus (10%). Both species were more abundant between 11-14h, and on the exposed sides of the island. Numbers of Sphyrna lewini were highest with 370 individuals windward and leeward, mostly schooling. S. lewini aggregations in the area are hypothesized to be attracted to the seamount archipelago offering favorable conditions for deep incursions and of which Europa Island forms part. C. amblyrhynchos, Galeocerdo cuvier and S. mokarran were uncommon, while there was an additional observation of Rhincodon typus. The lagoon of Europa was a nursery ground for C. melanopterus where it was the only species present. A total of 8 species was recorded, contributing to the shark diversity of 15 species reported from Europa since 1952 in the scientific and gray literature. Overall, with the occurrence of several species of apex predators in addition to that of R. typus, large schools of S. lewini, fair numbers of reef sharks and a nursery of C. melanopterus, Europa's sharks constitute a significant reservoir of biodiversity, which contributes to preserve the functioning of the ecosystem. Our observations highlight the relevance of Europa Island for shark conservation and the need for shark-targeted management in the EEZ of both Europa and Bassas da India.


Assuntos
Tubarões/fisiologia , Animais , Biodiversidade , Conservação dos Recursos Naturais/métodos , Recifes de Corais , Ecossistema , Oceano Índico , Moçambique , Densidade Demográfica , Especificidade da Espécie
8.
Mar Environ Res ; 172: 105489, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34619503

RESUMO

Aquatic ecosystems face numerous anthropogenic threats associated with coastal urbanization, with boat activity being among the most prevalent. The present study aimed to evaluate a potential relationship between boat activity and shark space use in Biscayne Bay, Florida (USA), a coastal waterway exposed to high levels of boating. Spatiotemporal patterns in boat density and traffic were determined from aerial surveys and underwater acoustic recorders, respectively. These data were then compared with residency patterns of bull (Carcharhinus leucas), nurse (Ginglymostoma cirratum) and great hammerhead (Sphyrna mokarran) sharks quantified through passive acoustic telemetry. Results were mixed, with no detectable relationship between boat density and shark residency for any of the species. Hourly presence of G. cirratum decreased with increasing boat traffic, a relationship not seen in the other two species. Explanations for these results include habituation of sharks to the high levels of chronic boat activity in the study area and interspecific differences in hearing sensitivity.


Assuntos
Tubarões , Animais , Ecossistema , Florida , Navios , Telemetria
9.
Nat Commun ; 12(1): 5557, 2021 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-34548488

RESUMO

Precise cis-regulatory control of gene expression is essential for normal embryogenesis and tissue development. The BMP antagonist Gremlin1 (Grem1) is a key node in the signalling system that coordinately controls limb bud development. Here, we use mouse reverse genetics to identify the enhancers in the Grem1 genomic landscape and the underlying cis-regulatory logics that orchestrate the spatio-temporal Grem1 expression dynamics during limb bud development. We establish that transcript levels are controlled in an additive manner while spatial regulation requires synergistic interactions among multiple enhancers. Disrupting these interactions shows that altered spatial regulation rather than reduced Grem1 transcript levels prefigures digit fusions and loss. Two of the enhancers are evolutionary ancient and highly conserved from basal fishes to mammals. Analysing these enhancers from different species reveal the substantial spatial plasticity in Grem1 regulation in tetrapods and basal fishes, which provides insights into the fin-to-limb transition and evolutionary diversification of pentadactyl limbs.


Assuntos
Nadadeiras de Animais/metabolismo , Elementos Facilitadores Genéticos , Regulação da Expressão Gênica no Desenvolvimento , Peptídeos e Proteínas de Sinalização Intercelular/genética , Botões de Extremidades/metabolismo , Nadadeiras de Animais/citologia , Nadadeiras de Animais/crescimento & desenvolvimento , Animais , Sequência de Bases , Evolução Biológica , Boidae , Bovinos , Galinhas , Embrião de Mamíferos , Embrião não Mamífero , Iguanas , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Botões de Extremidades/citologia , Botões de Extremidades/crescimento & desenvolvimento , Camundongos , Camundongos Transgênicos , Filogenia , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Coelhos , Genética Reversa/métodos , Alinhamento de Sequência , Homologia de Sequência do Ácido Nucleico , Tubarões , Transdução de Sinais , Suínos
10.
Nano Lett ; 21(19): 8080-8085, 2021 10 13.
Artigo em Inglês | MEDLINE | ID: mdl-34585939

RESUMO

Structural versatility and multifunctionality of biological materials have resulted in countless bioinspired strategies seeking to emulate the properties of nature. The nanostructured egg case of swell sharks is one of the toughest permeable membranes known and, thus, presents itself as a model system for materials where the conflicting properties, strength and porosity, are desirable. The egg case possesses an intricately ordered structure that is designed to protect delicate embryos from the external environment while enabling respiratory and metabolic exchange, achieving a tactical balance between conflicting properties. Herein, structural analyses revealed an enabling nanolattice architecture that constitutes a Bouligand-like nanoribbon hierarchical assembly. Three distinct hierarchical architectural adaptations enhance egg case survival: Bouligand-like organization for in-plane isotropic reinforcement, noncylindrical nanoribbons maximizing interfacial stress distribution, and highly ordered nanolattices enabling permeability and lattice-governed toughening mechanisms. These discoveries provide fundamental insights for the improvement of multifunctional membranes, fiber-reinforced soft composites, and mechanical metamaterials.


Assuntos
Nanoestruturas , Tubarões , Animais , Permeabilidade , Porosidade
11.
ACS Nano ; 15(9): 15316-15327, 2021 09 28.
Artigo em Inglês | MEDLINE | ID: mdl-34533924

RESUMO

Intelligent management beyond therapeutic drug treating holds significant prospects in facilitating the recovery of intractable chronic wounds. Here, inspired by the flat and inclined structure of shark teeth, we present a shark tooth-inspired microneedle patch for intelligent wound management. By simply replicating negative molds fabricated by laser engraving and using origami, such a biomimetic microneedle patch can be fabricated easily and rapidly. The biomimetic structures endow the microneedle patch with stable adhesion during the long-term recovery process of chronic wounds. Porous ordered structures and a temperature-responsive hydrogel are utilized to construct a controllable drug release system on the microneedle patch. The microfluidic channel composed of microneedle arrays and porous ordered structures enables a microneedle patch with the capacity to analyze several inflammatory factors. In addition, MXene electronics was patterned on the microneedle patch in order to achieve sensitive motion monitoring. Also, it was demonstrated from in vivo diabetic rat experiments that recovery of full-thickness cutaneous wounds including stripe-shaped and circular wounds can be facilitated by employing the drug-loaded biomimetic microneedle patch.


Assuntos
Biomimética , Tubarões , Animais , Bandagens , Eletrônica , Microfluídica , Ratos
12.
BMC Ecol Evol ; 21(1): 166, 2021 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-34488638

RESUMO

BACKGROUND: Sharks and rays are some of the most threatened marine taxa due to the high levels of bycatch and significant demand for meat and fin-related products in many Asian communities. At least 25% of shark and ray species are considered to be threatened with extinction. In particular, the density of reef sharks in the Pacific has declined to 3-10% of pre-human levels. Elasmobranchs are thought to be sparse in highly urbanised and turbid environments. Low visibility coupled with the highly elusive behaviour of sharks and rays pose a challenge to diversity estimation and biomonitoring efforts as sightings are limited to chance encounters or from carcasses ensnared in nets. Here we utilised an eDNA metabarcoding approach to enhance the precision of elasmobranch diversity estimates in urbanised marine environments. RESULTS: We applied eDNA metabarcoding on seawater samples to detect elasmobranch species in the hyper-urbanised waters off Singapore. Two genes-vertebrate 12S and elasmobranch COI-were targeted and amplicons subjected to Illumina high-throughput sequencing. With a total of 84 water samples collected from nine localities, we found 47 shark and ray molecular operational taxonomic units, of which 16 had species-level identities. When data were compared against historical collections and contemporary sightings, eDNA detected 14 locally known species as well as two potential new records. CONCLUSIONS: Local elasmobranch richness uncovered by eDNA is greater than the seven species sighted over the last two decades, thereby reducing phantom diversity. Our findings demonstrate that eDNA metabarcoding is effective in detecting shark and ray species despite the challenges posed by the physical environment, granting a more consistent approach to monitor these highly elusive and threatened species.


Assuntos
DNA Ambiental , Tubarões , Animais , Código de Barras de DNA Taxonômico , Ecossistema , Humanos , Água do Mar , Tubarões/genética
13.
Biochem Biophys Res Commun ; 577: 139-145, 2021 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-34517211

RESUMO

The lantern shark genus Etmopterus contains approximately 40 species of deep-sea bioluminescent cartilaginous fishes. They emit blue light mainly from the ventral body surface. The biological functions of this bioluminescence have been discussed based on the luminescence patterns, but the bioluminescence mechanism remains uncertain. In this study, we detected both coelenterazine and coelenterazine-dependent luciferase activity in the ventral photophore tissue of Etmopterus molleri. The results suggested that bioluminescence in lantern sharks is produced using coelenterazine as the substrate for the luciferin-luciferase reaction, as some luminous bony fishes.


Assuntos
Proteínas de Peixes/metabolismo , Imidazóis/metabolismo , Luciferases/metabolismo , Luminescência , Medições Luminescentes/métodos , Pirazinas/metabolismo , Tubarões/metabolismo , Animais , Cromatografia Líquida/métodos , Proteínas de Peixes/química , Concentração de Íons de Hidrogênio , Imidazóis/química , Luciferases/química , Metanol/química , Pirazinas/química , Tubarões/classificação , Pele/química , Especificidade da Espécie , Especificidade por Substrato , Espectrometria de Massas em Tandem/métodos
14.
Chin J Traumatol ; 24(6): 401-403, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34518065

RESUMO

Shark attacks are rare unique pathological processes. Some of them represent devastating injuries with a high morbidity and significant mortality. Related published articles are limited. The increased human interaction within the environment of sharks is the cause of rising incidence of such attacks. This study reported a case of level 4 shark injuries (shark-induced trauma scale) in a 33-year-old male patient, who presented with an extensive injury of the right lower limb with the characteristic features of shark bite. At admission the patient was in a state of shock with profuse bleeding that was controlled by tourniquet. The patient was resuscitated according to the advanced trauma life support. Clinical examination showed hard signs of vascular injury with absent pedal pulse, associated neurological deficits and severance at the knee joint. Prompt vascular intervention after resuscitation was performed to manage the major vascular injuries, together with proper washout and debridement of all the necrotic tissues under strong antibiotic coverage to prevent infection. After that, the patient underwent sequenced plastic, orthopedic, and neurological interventions. Strict follow-up was conducted, which showed that the patient was saved and achieved a functioning limb. This study aims to highlight the management of level 4 shark injuries, which are considered serious and challenging with a high fatality rate and a great risk of amputation due to the associated major vascular injuries. Immediate well organized management plan is crucial. Prompt resuscitation and surgical intervention by a highly-skilled medical team are required to improve the chance of patient survival and limb salvage.


Assuntos
Mordeduras e Picadas , Tubarões , Lesões do Sistema Vascular , Adulto , Animais , Mordeduras e Picadas/complicações , Humanos , Salvamento de Membro , Masculino , Estudos Retrospectivos , Lesões do Sistema Vascular/cirurgia
15.
PLoS One ; 16(9): e0256146, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34499686

RESUMO

Sharks and rays are at risk of extinction globally. This reflects low resilience to increasing fishing pressure, exacerbated by habitat loss, climate change, increasing value in a trade and inadequate information leading to limited conservation actions. Artisanal fisheries in the Bay of Bengal of Bangladesh contribute to the high levels of global fishing pressure on elasmobranchs. However, it is one of the most data-poor regions of the world, and the diversity, occurrence and conservation needs of elasmobranchs in this region have not been adequately assessed. This study evaluated elasmobranch diversity, species composition, catch and trade within the artisanal fisheries to address this critical knowledge gap. Findings show that elasmobranch diversity in Bangladesh has previously been underestimated. In this study, over 160000 individual elasmobranchs were recorded through landing site monitoring, comprising 88 species (30 sharks and 58 rays) within 20 families and 35 genera. Of these, 54 are globally threatened according to the IUCN Red List of Threatened Species, with ten species listed as Critically Endangered and 22 species listed as Endangered. Almost 98% juvenile catch (69-99% for different species) for large species sand a decline in numbers of large individuals were documented, indicating unsustainable fisheries. Several previously common species were rarely landed, indicating potential population declines. The catch pattern showed seasonality and, in some cases, gear specificity. Overall, Bangladesh was found to be a significant contributor to shark and ray catches and trade in the Bay of Bengal region. Effective monitoring was not observed at the landing sites or processing centres, despite 29 species of elasmobranchs being protected by law, many of which were frequently landed. On this basis, a series of recommendations were provided for improving the conservation status of the elasmobranchs in this region. These include the need for improved taxonomic research, enhanced monitoring of elasmobranch stocks, and the highest protection level for threatened taxa. Alongside political will, enhancing national capacity to manage and rebuild elasmobranch stocks, coordinated regional management measures are essential.


Assuntos
Conservação dos Recursos Naturais , Ecossistema , Espécies em Perigo de Extinção/estatística & dados numéricos , Pesqueiros/estatística & dados numéricos , Tubarões/fisiologia , Rajidae/fisiologia , Animais , Bangladesh , Mudança Climática , Oceanos e Mares , Dinâmica Populacional , Tubarões/classificação , Rajidae/classificação
16.
PLoS One ; 16(9): e0255673, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34525094

RESUMO

Bycatch mortality is a major factor contributing to shark population declines. Post-release mortality (PRM) is particularly difficult to quantify, limiting the accuracy of stock assessments. We paired blood-stress physiology with animal-borne accelerometers to quantify PRM rates of sharks caught in a commercial bottom longline fishery. Blood was sampled from the same individuals that were tagged, providing direct correlation between stress physiology and animal fate for sandbar (Carcharhinus plumbeus, N = 130), blacktip (C. limbatus, N = 105), tiger (Galeocerdo cuvier, N = 52), spinner (C. brevipinna, N = 14), and bull sharks (C. leucas, N = 14). PRM rates ranged from 2% and 3% PRM in tiger and sandbar sharks to 42% and 71% PRM in blacktip and spinner sharks, respectively. Decision trees based on blood values predicted mortality with >67% accuracy in blacktip and spinner sharks, and >99% accuracy in sandbar sharks. Ninety percent of PRM occurred within 5 h after release and 59% within 2 h. Blood physiology indicated that PRM was primarily associated with acidosis and increases in plasma potassium levels. Total fishing mortality reached 62% for blacktip and 89% for spinner sharks, which may be under-estimates given that some soak times were shortened to focus on PRM. Our findings suggest that no-take regulations may be beneficial for sandbar, tiger, and bull sharks, but less effective for more susceptible species such as blacktip and spinner sharks.


Assuntos
Acidose/fisiopatologia , Mortalidade/tendências , Potássio/sangue , Tubarões/fisiologia , Estresse Fisiológico , Animais , Pesqueiros , Medição de Risco , Tubarões/sangue , Tubarões/crescimento & desenvolvimento
17.
Mar Pollut Bull ; 172: 112905, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34523430

RESUMO

Although shark meat is consumed worldwide, elevated arsenic (As) concentrations have been increasingly reported. The Caribbean sharpnose shark (Rhizoprionodon porosus) is a widely consumed fishing resource in Brazil, with scarce information on As burdens to date. Herein, commercial-sized juvenile Caribbean sharpnose sharks from Rio de Janeiro (Brazil) were assessed in this regard, presenting significantly higher hepatic As concentrations in males (8.24 ± 1.20 mg kg-1 wet weight; n = 12) compared to females (6.59 ± 1.87 mg kg-1 w.w.; n = 8), and a positive correlation (r = 0.74) was noted between female muscle and liver As concentrations, indicating systemic inter-tissue transport not evidenced in males. Arsenic concentrations were over the maximum permissible As limit established in Brazilian legislation for seafood and calculated Target Hazard Quotients suggest consumption risks, although cancer risks were not evidenced. Therefore, Public Health concerns with regard to Caribbean sharpnose shark As burdens deserve careful attention.


Assuntos
Arsênio , Tubarões , Animais , Brasil , Feminino , Pesqueiros , Masculino , Alimentos Marinhos
19.
Mar Pollut Bull ; 172: 112853, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34425367

RESUMO

We provided the first multi-species study investigating the presence and organotropism of trace elements in three tissues of 12 elasmobranch species. Shark species showed comparable TE loads, although milk sharks and juvenile scalloped hammerhead sharks exhibited the highest Cd and Hg levels, respectively. Fins accumulated higher levels of Pb, Co, and Cr; muscles higher V, As, and Hg; livers higher Se and Cd levels. The organotropism of TEs calls for cautious when choosing a tissue to be sampled since certain tissues, like fin clips, do not provide reliable surrogate for the internal loads of some TEs. Strong correlations between essential and toxic TEs indicated detoxification mechanisms, while the TMF provided evidence for Hg, As and Se biomagnification along the food-web. Considering the difficulties in assessing elasmobranchs contamination from different areas, the proposed multi-species approach represents a valuable way to estimate the species-specific accumulation and transfer of pollutants in sharks.


Assuntos
Tubarões , Oligoelementos , Poluentes Químicos da Água , Animais , Bioacumulação , Monitoramento Ambiental , Cadeia Alimentar , Oceano Índico , Oligoelementos/análise , Poluentes Químicos da Água/análise
20.
J Forensic Sci ; 66(6): 2493-2498, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34418091

RESUMO

Understanding why sharks bite humans is essential for developing strategies to prevent these incidents. Here, we use bite wound characteristics and eye witness descriptions of shark behavior to determine the likely motivation for several bites perpetrated by an oceanic whitetip (OWT) shark Carcharhinus longimanus on an adult female snorkeler off Moorea island (French Polynesia) in October 2019. The victim was snorkeling with others in pelagic waters as part of an organized whale-watching tour when the shark-without any warning behavior-bit her at least three times resulting in severe injuries with substantial loss of soft tissue from the chest and both forearms. The victim survived these injuries thanks to rapid and effective first aid provided by her companions. The sudden, unprovoked and repeated bites with substantial tissue removal are consistent with predatory behavior although the dominance hypothesis cannot be fully ruled out. This would be the first case of a predatory shark bite ever documented in French Polynesia in over 70 years of data collection. Given the routine association of OWT sharks with cetaceans, in-water whale watching activities should adopt appropriate risk management strategies in regions hosting this species of shark.


Assuntos
Mordeduras e Picadas/patologia , Comportamento Predatório , Tubarões , Animais , Feminino , Humanos , Polinésia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...