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1.
Environ Pollut ; 263(Pt A): 114480, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32283460

RESUMO

Bioaccumulation of Hg and Cd from food is a complex ecological process that has been oversimplified in the past. Common dolphins (Delphinus delphis) provide a powerful model to biomonitor metal concentrations in marine environments worldwide. We combined proportions-based nutritional geometry with metal analysis, stomach content analysis and the proximate composition of prey, to yield novel insights into the accumulation of Hg and Cd. Our analysis showed an age-related accumulation trend for Cd and Hg in kidney and liver, with highest concentrations found at 18 years of age. When viewed through the lens of nutritional ecology, Argentine anchovy (58.1 Mass %) and South American long-finned squid (22.7 Mass %), provided most of the dietary intake of protein (P) and lipids (L) (P:L ratio = 2.6:1.0) and also represented the main source for Cd and Hg levels accumulated in their bodies. This study presents unprecedented evidence on metal accumulation in relation to age and nutritional intake in a marine predator.


Assuntos
Golfinhos Comuns , Golfinhos , Mercúrio/análise , Poluentes Químicos da Água/análise , Animais , Argentina , Cádmio , Monitoramento Ambiental
2.
Dis Aquat Organ ; 136(3): 265-271, 2019 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-31724559

RESUMO

Bilateral nephrolithiasis with a concurrent vaginal calculus was identified in a stranded free-ranging long-beaked common dolphin Delphinus capensis. Necropsy and radiologic examinations of the sexually mature D. capensis revealed multiple small irregularly round nephroliths and a 6.4 × 4.1 × 9.2 cm vaginal calculus weighing 182 g. Nephroliths numbered 68 and 71 in the left and right kidneys, respectively, and ranged from 1.7 to 6.9 mm in diameter. Nephroliths were composed of 100% ammonium urate, which has been found in captive dolphin populations. However, the vaginolith consisted of struvite and calcium carbonate suggesting an alternate etiology. The composition of the vaginolith suggests that bacterial vaginitis could have served as the predisposing condition. Renal lesions included chronic tubulointerstitial nephritis with tubular degeneration and loss, likely secondary to the nephroliths. The pathogenesis of ammonium urate nephrolithiasis in managed care is suspected to be linked to diet and age but in this case may be due to metabolic disruption. However, if environmental changes cause a shift in prey species, the risk of nephrolithiasis in free-ranging cetaceans could increase. Careful surveillance for nephroliths in free-ranging populations should be considered by researchers.


Assuntos
Cálculos , Golfinhos Comuns , Animais , Feminino , Rim , Nefrolitíase , Vagina
3.
Bull Environ Contam Toxicol ; 103(4): 521-527, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31473774

RESUMO

We determinated Hg and Se concentrations in liver, kidney, brain, lung and muscle of five bottlenose dolphin (Tursiops truncatus), four common dolphins (Delphinus delphis) and four Risso's dolphin (Grampus griseus) stranded along the Murcia coast, Southeast Spain, in order to evaluate the risk of Hg toxicity. Hg concentrations showed similar concentrations to other individuals in the Mediterranean Sea with the same length in the same period. We observed a positive correlation of Hg and Se in liver (r = 0.948, p < 0.001) and kidney (r = 0.939; p = 0.001) and ratio the Se/Hg molar was higher than 1 in most cases. Our results suggest that the protective effects of Se against Hg toxicity occur in cetaceans. However, we detected levels of Hg described as responsible liver damage and neurotoxicological effects so other tools, as biochemical markers, should be included. Besides, more studies are needed to evaluate the risk of Hg exposure in dolphins from Murcia coastline.


Assuntos
Golfinhos/metabolismo , Monitoramento Ambiental/métodos , Rim/química , Fígado/química , Mercúrio/análise , Selênio/análise , Animais , Golfinho Nariz-de-Garrafa/metabolismo , Golfinhos Comuns/metabolismo , Mar Mediterrâneo , Especificidade de Órgãos , Espanha
4.
Anim Cogn ; 22(5): 777-789, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31177344

RESUMO

Conveying identity is important for social animals to maintain individually based relationships. Communication of identity information relies on both signal encoding and perception. Several delphinid species use individually distinctive signature whistles to transmit identity information, best described for the common bottlenose dolphin (Tursiops truncatus). In this study, we investigate signature whistle use in wild common dolphins (Delphinus delphis). Acoustic recordings were analysed from 11 encounters from three locations in South Africa (Hout Bay, False Bay, and Plettenberg Bay) during 2009, 2016 and 2017. The frequency contours of whistles were visually categorised, with 29 signature whistle types (SWTs) identified through contour categorisation and a bout analysis approach developed specifically to identify signature whistles in bottlenose dolphins (SIGID). Categorisation verification was conducted using an unsupervised neural network (ARTwarp) at both a 91% and 96% vigilance parameter. For this, individual SWTs were analysed type by type and then in a 'global' analysis whereby all 497 whistle contours were categorised simultaneously. Overall the analysis demonstrated high stereotypy in the structure and temporal production of whistles, consistent with signature whistle use. We suggest that individual identity information may be encoded in these whistle contours. However, the large group sizes and high degree of vocal activity characteristic of this dolphin species generate a cluttered acoustic environment with high potential for masking from conspecific vocalisations. Therefore, further investigation into the mechanisms of identity perception in such acoustically cluttered environments is required to demonstrate the function of these stereotyped whistle types in common dolphins.


Assuntos
Golfinhos Comuns , Vocalização Animal , Acústica , Animais , Golfinho Nariz-de-Garrafa , Espectrografia do Som , África do Sul
5.
PLoS One ; 14(4): e0215020, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30990845

RESUMO

A case of intergeneric hybridization in the wild between a female bottlenose dolphin (Tursiops truncatus) and a short-beaked common dolphin (Delphinus delphis), considered members of 'vulnerable' and 'endangered' subpopulations in the Mediterranean, respectively, by the International Union of Conservation of Nature is described in this paper. The birth of the hybrid was registered in the Bay of Algeciras (southern Spain) in August 2016, and the animal has been tracked on frequent trips aboard dolphin-watching platforms. This unique occurrence is the result of an apparent ongoing interaction (10 years) between a female bottlenose dolphin and common dolphins. The calf has a robust body with length similar to Tursiops, while its lateral striping and coloration are typical of Delphinus. It displays the common dolphin's 'criss-cross' pattern. However, the thoracic patch is lighter than in D. delphis and its dorsal area is light grey, with a 'V' shape under the dorsal fin. This paper also provides a comprehensive mini-review of hybridizations of T. truncatus with other species.


Assuntos
Golfinho Nariz-de-Garrafa/fisiologia , Quimera/genética , Golfinhos Comuns/fisiologia , Hibridização Genética , Animais , Golfinho Nariz-de-Garrafa/genética , Golfinhos Comuns/genética , Feminino , Masculino
6.
Dis Aquat Organ ; 134(1): 75-87, 2019 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-31020950

RESUMO

Lobomycosis-like disease (LLD) is a chronic granulomatous skin disorder that affects Delphinidae worldwide. LLD has been observed in common bottlenose dolphins Tursiops truncatus from the Gulf of Guayaquil, Ecuador, since 1990. Although exogenous factors such as salinity and pollution may play a role in the pathogenesis of this disease in estuarine and coastal dolphin communities, we hypothesized that demography and social behaviour may also influence its epidemiology. To address this issue, the role of social behaviour in the distribution and prevalence of LLD was assessed through hierarchical cluster analysis and spatial distribution analysis in 7 dolphin communities inhabiting the inner estuary. Individuals with LLD lesions were observed in 5 of the 7 dolphin communities, with 13 of the 163 (8%) animals being positive, all adults. Among 8 dolphins of known sex, LLD affected mostly males (86%), who usually were found in pairs. Prevalence was low to moderate (5.1-13%) in dolphin communities where low-rank males had LLD. Conversely, it was high (44.4%, n = 9) in a small community where a high-rank male was infected. LLD affected both dolphins in 2 of the 4 male pairs for which large time series data were available, suggesting horizontal transmission due to contact. Thus, association with LLD-positive males seems to be an important risk factor for infections. Additionally, low-rank males had larger home ranges than high-rank males, indicating that low-status LLD-affected dolphins are likely responsible for the geographic dissemination of the disease in this population.


Assuntos
Golfinho Nariz-de-Garrafa , Golfinhos Comuns , Lobomicose , Animais , Equador , Feminino , Lobomicose/veterinária , Masculino , Comportamento Social
7.
PLoS One ; 14(3): e0213346, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30893348

RESUMO

Dolphin stranding events occur frequently in Florida and Massachusetts. Dolphins are an excellent sentinel species for toxin exposures in the marine environment. In this report we examine whether cyanobacterial neurotoxin, ß-methylamino-L-alanine (BMAA), is present in stranded dolphins. BMAA has been shown to bioaccumulate in the marine food web, including in the muscles and fins of sharks. Dietary exposure to BMAA is associated with the occurrence of neurofibrillary tangles and ß-amyloid plaques in nonhuman primates. The findings of protein-bound BMAA in brain tissues from patients with Alzheimer's disease has advanced the hypothesis that BMAA may be linked to dementia. Since dolphins are apex predators and consume prey containing high amounts of BMAA, we examined necropsy specimens to determine if dietary and environmental exposures may result in the accumulation of BMAA in the brains of dolphins. To test this hypothesis, we measured BMAA in a series of brains collected from dolphins stranded in Florida and Massachusetts using two orthogonal analytical methods: 1) high performance liquid chromatography, and 2) ultra-performance liquid chromatography with tandem mass spectrometry. We detected high levels of BMAA (20-748 µg/g) in the brains of 13 of 14 dolphins. To correlate neuropathological changes with toxin exposure, gross and microscopic examinations were performed on cortical brain regions responsible for acoustico-motor navigation. We observed increased numbers of ß-amyloid+ plaques and dystrophic neurites in the auditory cortex compared to the visual cortex and brainstem. The presence of BMAA and neuropathological changes in the stranded dolphin brain may help to further our understanding of cyanotoxin exposure and its potential impact on human health.


Assuntos
Diamino Aminoácidos/toxicidade , Encéfalo/metabolismo , Encéfalo/patologia , Cianobactérias/patogenicidade , Golfinhos/metabolismo , Neurotoxinas/toxicidade , Diamino Aminoácidos/análise , Animais , Golfinho Nariz-de-Garrafa/metabolismo , Encéfalo/efeitos dos fármacos , Golfinhos Comuns/metabolismo , Monitoramento Ambiental , Cadeia Alimentar , Proliferação Nociva de Algas , Humanos , Massachusetts , Neurotoxinas/análise , Placa Amiloide/patologia , Espécies Sentinelas
8.
Mar Pollut Bull ; 137: 526-532, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30503464

RESUMO

Plastic debris is currently recognised as one of the major global threats to marine life. However, few data exist on the presence and abundance of microplastics (plastics < 5 mm in size) in marine mammals. This is the first record of the presence of microplastics in the digestive tracts of marine mammals from the Iberian Peninsula. This study made use of 35 samples of common dolphin stomach contents. Microplastics were identified in all the samples analysed, an average of 12 items per stomach although abundance varied widely from one stomach to another. Most plastic items were small fibres although some fragments and a bead were also found. Excluding the smallest fibres as possible airborne contamination, the estimated occurrence of microplastics could drop to as low as 94%. Although factors affecting accumulation of microplastics and their effect on common dolphins are unknown, the fact that all stomachs analysed contained microplastics is a cause for concern.


Assuntos
Golfinhos Comuns , Conteúdo Gastrointestinal/química , Plásticos/análise , Poluentes Químicos da Água/análise , Animais , Tamanho Corporal , Exposição Ambiental/análise , Monitoramento Ambiental , Feminino , Masculino , Espanha , Resíduos/análise
9.
J Acoust Soc Am ; 144(4): 2213, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30404511

RESUMO

Mammals use binaural or monaural (spectral) cues to localize acoustic sources. While the sensitivity of terrestrial mammals to changes in source elevation is relatively poor, the accuracy achieved by the odontocete cetaceans' biosonar is high, independently of where the source is. Binaural/spectral cues are unlikely to account for this remarkable skill. In this paper, bone-conducted sound in a dolphin's mandible is studied, investigating its possible contribution to sound localization. Experiments are conducted in a water tank by deploying, on the horizontal and median planes of the skull, ultrasound sources that emit synthetic clicks between 45 and 55 kHz. Elastic waves propagating through the mandible are measured at the pan bones and used to localize source positions via either binaural cues or a correlation-based full-waveform algorithm. Exploiting the full waveforms and, most importantly, reverberated coda, it is possible to enhance the accuracy of source localization in the vertical plane and achieve similar resolution of horizontal- vs vertical-plane sources. The results noted in this paper need to be substantiated by further experimental work, accounting for soft tissues and making sure that the data are correctly mediated to the internal ear. If confirmed, the results would favor the idea that dolphin's echolocation skills rely on the capability to analyze the coda of biosonar echoes.


Assuntos
Golfinhos Comuns/fisiologia , Ecolocação , Mandíbula/fisiologia , Animais , Som , Localização de Som
10.
Mol Phylogenet Evol ; 129: 325-337, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30218775

RESUMO

Natural interspecific hybridization might be more important for the evolutionary history and speciation of animals than previously thought, considering several demographic and life history traits as well as habitat disturbance as factors that promote it. In this aspect, cetaceans comprise an interesting case in which the occurrence of sympatric species in mixed associations provides excellent opportunities for interspecific sexual interaction and the potential for hybridization. Here, we present evidence of natural hybridization for two cetacean species commonly occurring in the Greek Seas (Stenella coeruleoalba and Delphinus delphis), which naturally overlap in the Gulf of Corinth by analyzing highly resolving microsatellite DNA markers and mitochondrial DNA sequences in skin samples from 45 individuals of S. coeruleoalba, 12 D. delphis and three intermediate morphs. Employing several phylogenetic and population genetic approaches, we found 15 individuals that are potential hybrids including the three intermediate morphs, verifying the occurrence of natural hybridization between species of different genera. Their hybrids are fertile and able to reproduce not only with the other hybrids but also with each of the two-parental species. However, current evidence does not allow firm conclusions whether hybridization might constitute a step towards the generation of a new species and/or the swan song of an already existing species (i.e., D. delphis). Given that the focal species form mixed pods in several areas of Mediterranean, this study is an excellent opportunity to understand the mechanisms leading to hybridization in the context of gene flow and urges for the evaluation of the genetic status of common dolphins in the Mediterranean.


Assuntos
Golfinhos Comuns/genética , Hibridização Genética , Oceanos e Mares , Stenella/genética , Animais , Teorema de Bayes , DNA Mitocondrial/genética , Geografia , Grécia , Repetições de Microssatélites/genética , Filogenia , Processos de Determinação Sexual/genética
11.
Environ Sci Technol ; 52(5): 3101-3109, 2018 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-29397698

RESUMO

While environmental pollutants have been associated with changes in endocrine health in cetaceans, efforts to link contaminant exposure with hormones have largely been limited to a list of known, targeted contaminants, overlooking minimally characterized or unknown compounds of emerging concern. To address this gap, we analyzed a suite of potential endocrine disrupting halogenated organic compounds (HOCs) in blubber from 16 male short-beaked common dolphins ( Delphinus delphis) with known maturity status collected from fishery bycatch in the Southern California Bight. We employed a suspect screening mass spectrometry-based method to investigate a wide range of HOCs that were previously observed in cetaceans from the same region. Potential endocrine effects were assessed through the measurement of blubber testosterone. We detected 167 HOCs, including 81 with known anthropogenic sources, 49 of unknown origin, and 37 with known natural sources. The sum of 11 anthropogenic and 4 unknown HOC classes were negatively correlated with blubber testosterone. Evidence suggests that elevated anthropogenic HOC load contributes to impaired testosterone production in mature male D. delphis. The application of this integrative analytical approach to cetacean contaminant analysis allows for inference of the biological consequences of accumulation of HOCs and prioritization of compounds for future environmental toxicology research.


Assuntos
Golfinhos Comuns , Golfinhos , Poluentes Químicos da Água , Animais , California , Monitoramento Ambiental , Masculino , Testosterona
12.
Anat Histol Embryol ; 47(1): 3-10, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29052248

RESUMO

Magnetic resonance imaging (MRI) and computed tomography (CT) scans were used to analyse, respectively, the soft tissues and the bones of the heads of four common dolphins and three harbour porpoises. This imaging study was completed by an examination of anatomical sections performed on two odontocete heads (a subadult common dolphin and a subadult harbour porpoise). The three complementary approaches allowed to illustrate anatomical differences in the echolocation systems of the common dolphin and the harbour porpoise. We captured images confirming strong differences of symmetry of the melon and of its connexions to the MLDB (Monkeys Lips/Dorsal Bursae) between the common dolphin and the harbour porpoise. The melon of the common dolphin is asymmetrically directly connected to the right bursae cantantes at its right side, whereas the melon of the harbour porpoise is symmetrical, and separated from the two bursae cantantes by a set of connective tissues. Another striking difference comes from the bursae cantantes themselves, less deeply located in the head of the common dolphin than in the harbour porpoise.


Assuntos
Golfinhos Comuns/anatomia & histologia , Cabeça/anatomia & histologia , Cabeça/diagnóstico por imagem , Phocoena/anatomia & histologia , Crânio/anatomia & histologia , Tecido Adiposo/anatomia & histologia , Tecido Adiposo/diagnóstico por imagem , Animais , Autopsia/veterinária , Golfinhos Comuns/fisiologia , Ecolocação/fisiologia , Feminino , Audição/fisiologia , Imagem por Ressonância Magnética/veterinária , Phocoena/fisiologia , Crânio/diagnóstico por imagem , Tomografia Computadorizada Espiral/veterinária , Vocalização Animal/fisiologia
13.
J Acoust Soc Am ; 142(2): 863, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28863550

RESUMO

Passive acoustic monitoring is an efficient way to study acoustically active animals but species identification remains a major challenge. C-PODs are popular logging devices that automatically detect odontocete echolocation clicks. However, the accompanying analysis software does not distinguish between delphinid species. Click train features logged by C-PODs were compared to frequency spectra from adjacently deployed continuous recorders. A generalized additive model was then used to categorize C-POD click trains into three groups: broadband click trains, produced by bottlenose dolphin (Tursiops truncatus) or common dolphin (Delphinus delphis), frequency-banded click trains, produced by Risso's (Grampus griseus) or white beaked dolphins (Lagenorhynchus albirostris), and unknown click trains. Incorrect categorization rates for broadband and frequency banded clicks were 0.02 (SD 0.01), but only 30% of the click trains met the categorization threshold. To increase the proportion of categorized click trains, model predictions were pooled within acoustic encounters and a likelihood ratio threshold was used to categorize encounters. This increased the proportion of the click trains meeting either the broadband or frequency banded categorization threshold to 98%. Predicted species distribution at the 30 study sites matched well to visual sighting records from the region.


Assuntos
Acústica , Golfinhos/classificação , Golfinhos/psicologia , Ecolocação , Monitoramento Ambiental/métodos , Vocalização Animal/classificação , Animais , Golfinho Nariz-de-Garrafa/classificação , Golfinho Nariz-de-Garrafa/psicologia , Golfinhos Comuns/classificação , Golfinhos Comuns/psicologia , Processamento de Sinais Assistido por Computador , Espectrografia do Som , Especificidade da Espécie
14.
J Exp Biol ; 220(Pt 20): 3717-3723, 2017 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-28819052

RESUMO

Whale tracking tags often penetrate semi-rigid blubber, with intramuscular sharp tips and toggling barbs under the subdermal sheath to reduce premature shedding. Tag sites can show persistent regional swellings or depressions. Fibroelastic blubber grips a tag, so if muscle shears relative to blubber during locomotion, the tag tip could cavitate the muscle within overall shearing distance. We modeled shearing of blubber relative to muscle, within the dorsal-ventral peduncular movement range of four common dolphin (Delphinus delphis) cadavers (mean length 186 cm). The net change in angle and hence tip distance moved was calculated with dorsal and ventral flexion, and compared between 1.5 mm diameter needles inserted into blubber only and through blubber into muscle. The greatest shearing value was 3.6 cm, and shearing was most pronounced in the areas ventral and caudal to the dorsal fin. Scaled dummy tags were also inserted and the animal cyclically flexed dorsally and ventrally for 18 h. Tag sites were dissected and cavities around the tag tips documented. If this shearing is comparable in large whales, depressions and regional swellings observed with intramuscular tracking tags are likely the result of tissue loss and repair, respectively. Placing tags para-sagittally anterior to the dorsal fin would cause the least trauma, but pain from such tags remains a concern.


Assuntos
Tecido Adiposo/fisiologia , Golfinhos Comuns/fisiologia , Músculo Esquelético/fisiologia , Animais , Fenômenos Biomecânicos , Modelos Biológicos
15.
Brain Behav Evol ; 90(3): 193-210, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28768268

RESUMO

The present study focuses on the relationship between neocortical structures and functional aspects in three selected mammalian species. Our aim was to compare cortical layering and neuron density in the projection areas (somatomotor, M1; somatosensory, S1; auditory, A1; and visual, V1; each in a wider sense). Morphological and design-based stereological analysis was performed in the wild boar (Sus scrofa scrofa) as a representative terrestrial hoofed animal (artiodactyl) and the common dolphin (Delphinus delphis) as a highly derived related aquatic mammal (cetartiodactyl). For comparison, we included the human (Homo sapiens) as a well-documented anthropoid primate. In the cortex of many mammals, layer IV (inner granular layer) is the main target of specific thalamocortical inputs while layers III and V are the main origins of neocortical projections. Because the fourth layer is indistinct or mostly lacking in the primary neocortex of the wild boar and dolphins, respectively, we analyzed the adjacent layers III and V in these animals. In the human, all the three layers were investigated separately. The stereological data show comparatively low neuron densities in all areas of the wild boar and high cell counts in the human (as expected), particularly in the primary visual cortex. The common dolphin, in general, holds an intermediate position in terms of neuron density but exhibits higher values than the human in a few layers. With respect to the situation in the wild boar, stereological neuron counts in the dolphin are consistently higher, with a maximum in layer III of the visual cortex. The extended auditory neocortical field in dolphins and the hypertrophic auditory pathway indicate secondary neurobiological adaptations to their aquatic habitat during evolution. The wild boar, however, an omnivorous quadruped terrestrial mammal, shows striking specializations as to the sensorimotor neurobiology of the snout region.


Assuntos
Neocórtex/anatomia & histologia , Neocórtex/citologia , Adaptação Fisiológica , Animais , Córtex Auditivo/anatomia & histologia , Vias Auditivas/anatomia & histologia , Vias Auditivas/fisiologia , Contagem de Células , Golfinhos Comuns/anatomia & histologia , Humanos/anatomia & histologia , Mamíferos/anatomia & histologia , Neurônios/fisiologia , Especificidade da Espécie , Sus scrofa/anatomia & histologia , Córtex Visual/anatomia & histologia
16.
Rapid Commun Mass Spectrom ; 31(18): 1551-1557, 2017 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-28700111

RESUMO

RATIONALE: Isotope ratios from skin samples have been widely used to study cetacean trophic ecology. Usually, isotopic skin uniformity has been assumed, despite the heterogeneity of this tissue. This study aims to investigate (1) regional isotopic variation within the skin in cetaceans, and (2) isotopic variation among internal tissues. METHODS: Stable carbon (δ13 C values) and nitrogen (δ15 N values) isotope ratios were measured in 11 skin positions in 10 common dolphins (Delphinus delphis) and 9 striped dolphins (Stenella coeruleoalba). In addition, the isotope ratios in the muscle, liver and kidney of both species were determined and compared with those from the skin and from all tissues combined. The signatures were determined by means of elemental analyser/isotope ratio mass spectrometry (EA/IRMS). RESULTS: In both species, no differences between isotope ratios of the skin positions were found. Moreover, the isotope ratios of skin were similar to those of muscle. In contrast, liver and kidney showed higher isotope ratios than muscle and skin. CONCLUSIONS: Isotopic homogeneity within the skin suggests that the isotope ratios of a sample from a specific skin position can be considered representative of the ratios from the entire skin tissue in dolphins. This conclusion validates the results of previous stable isotope analyses in dolphins that used skin samples as representative of the whole skin tissue. Isotopic similarities or dissimilarities among tissues should be considered when analysing different tissues and comparing results from the same or different species.


Assuntos
Isótopos de Carbono/análise , Isótopos de Nitrogênio/análise , Pele/química , Animais , Golfinhos Comuns , Feminino , Fígado/química , Masculino , Espectrometria de Massas
17.
PLoS One ; 12(2): e0171000, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28192446

RESUMO

The nearest known population of common dolphins (Delphinus sp.) to the Colombian Caribbean occurs in a fairly restricted range in eastern Venezuela. These dolphins have not been previously reported in the Colombian Caribbean, likely because of a lack of study of the local cetacean fauna. We collected cetacean observations in waters of the Guajira Department, northern Colombia (~11°N, 73°W) during two separate efforts: (a) a seismic vessel survey (December 2009-March 2010), and (b) three coastal surveys from small boats (May-July 2012, May 2013, and May 2014). Here we document ten sightings of common dolphins collected during these surveys, which extend the known range of the species by ~1000 km into the southwestern Caribbean. We also collected nine skin biopsies in 2013 and 2014. In order to determine the taxonomic identity of the specimens, we conducted genetic barcoding and phylogenetic analyses using two mitochondrial markers, the Control Region (mtDNA) and Cytochrome b (Cytb). Results indicate that these specimens are genetically closer to the short-beaked common dolphin (Delphinus delphis) even though morphologically they resemble a long-beaked form (Delphinus sp.). However, the specific taxonomic status of common dolphins in the Caribbean and in the Western Atlantic remains unresolved. It is also unclear whether the distribution of the species between northern Colombia and eastern Venezuela is continuous or disjoined, or whether they can be considered part of the same stock.


Assuntos
Golfinhos Comuns/genética , Citocromos b/genética , Código de Barras de DNA Taxonômico/métodos , DNA Mitocondrial/genética , Filogenia , Animais , Região do Caribe , Cetáceos/classificação , Cetáceos/genética , Colômbia , Golfinhos Comuns/classificação , Golfinhos Comuns/fisiologia , DNA Mitocondrial/química , Geografia , Reação em Cadeia da Polimerase , Dinâmica Populacional , Análise de Sequência de DNA/métodos , Especificidade da Espécie , Venezuela
18.
Anat Histol Embryol ; 46(2): 204-212, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27990670

RESUMO

Magnetic resonance imaging (MRI) was used to scan the head of a common dolphin (Delphinus delphis) in order to visualize the different adipose tissues involved in echolocation functioning and to precisely delineate their anatomical topology. MRI scans were performed on the head taken from a freshly stranded carcass and repeated after a 2-week freezing time followed by thawing. The main fatty organs of the head, that is the melon, the mandibula bulba, the bursae cantantes, and their different connections with surrounding tissues were identified and labelled. The nasal sacs, other organs of echolocation, were also identified and labelled thanks to different MRI acquisitions. The shape, the location, the type of MRI signal of each organ and of their different connections were successfully analysed on all images, and then, the images of the head fresh or after thawing were compared. No impacts of the freezing/thawing cycle on the fatty tissues of the head were identified. Different parts were distinguished in the melon on the basis of the MRI signal emitted, corresponding most likely to the internal and external melon already identified by other analytical approaches, and linked to differences in lipid composition. MRI is shown here to be a useful tool to study the functional anatomy of the organs responsible for echolocation in odontocetes, with a particularly high level of precision.


Assuntos
Tecido Adiposo/anatomia & histologia , Golfinhos Comuns/anatomia & histologia , Cabeça/diagnóstico por imagem , Imagem por Ressonância Magnética/veterinária , Tomografia Computadorizada por Raios X/veterinária , Tecido Adiposo/diagnóstico por imagem , Animais , Ecolocação/fisiologia , Cabeça/anatomia & histologia , Imagem por Ressonância Magnética/métodos
19.
J Anat ; 230(2): 249-261, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27995620

RESUMO

Cetaceans face the challenge of maintaining equilibrium underwater and obtaining sensory input within a dense, low-visibility medium. The cetacean ear represents a key innovation that marked their evolution from terrestrial artiodactyls to among the most fully aquatic mammals in existence. Using micro-CT and histological data, we document shape and size changes in the cetacean inner ear during ontogeny, and demonstrate that, as a proportion of gestation time, the cetacean inner ear is precocial in its growth compared with that of suid artiodactyls. Cetacean inner ears begin ossifying and reach near-adult shape as early as at 32% of the gestation period, and near-adult dimensions as early as at 27% newborn total length. Our earliest embryos with measurable inner ears (13% newborn length) exhibit a flattened cochlea (i.e. smaller distance from cochlear apex to round window) compared with later and adult stages. Inner ears of Sus scrofa have neither begun ossifying nor reached near-adult dimensions at 55% of the gestation period, but have an adult-like ratio of cochlear diameters to each other, suggesting an adult-like shape. The precocial development of the cetacean inner ear complements previous work demonstrating precocial development of other cetacean anatomical features such as the locomotor muscles to facilitate swimming at the moment of birth.


Assuntos
Balaenoptera/crescimento & desenvolvimento , Golfinhos Comuns/crescimento & desenvolvimento , Orelha Interna/crescimento & desenvolvimento , Jubarte/crescimento & desenvolvimento , Animais , Balaenoptera/anatomia & histologia , Cetáceos/anatomia & histologia , Cetáceos/crescimento & desenvolvimento , Cóclea/anatomia & histologia , Cóclea/crescimento & desenvolvimento , Golfinhos Comuns/anatomia & histologia , Orelha Interna/anatomia & histologia , Jubarte/anatomia & histologia , Canais Semicirculares/anatomia & histologia , Canais Semicirculares/crescimento & desenvolvimento , Especificidade da Espécie , Sus scrofa
20.
PLoS One ; 11(11): e0164107, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27851763

RESUMO

Common dolphins (Delphinus delphis) are responsible for the large majority of interactions with the pole-and-line tuna fishery in the Azores but the underlying drivers remain poorly understood. In this study we investigate the influence of various environmental and fisheries-related factors in promoting the interaction of common dolphins with this fishery and estimate the resultant catch losses. We analysed 15 years of fishery and cetacean interaction data (1998-2012) collected by observers placed aboard tuna fishing vessels. Dolphins interacted in less than 3% of the fishing events observed during the study period. The probability of dolphin interaction varied significantly between years with no evident trend over time. Generalized additive modeling results suggest that fishing duration, sea surface temperature and prey abundance in the region were the most important factors explaining common dolphin interaction. Dolphin interaction had no impact on the catches of albacore, skipjack and yellowfin tuna but resulted in significantly lower catches of bigeye tuna, with a predicted median annual loss of 13.5% in the number of fish captured. However, impact on bigeye catches varied considerably both by year and fishing area. Our work shows that rates of common dolphin interaction with the pole-and-line tuna fishery in the Azores are low and showed no signs of increase over the study period. Although overall economic impact was low, the interaction may lead to significant losses in some years. These findings emphasize the need for continued monitoring and for further research into the consequences and economic viability of potential mitigation measures.


Assuntos
Golfinhos Comuns/fisiologia , Ecossistema , Pesqueiros , Atum/fisiologia , Animais , Açores , Modelos Teóricos , Probabilidade , Especificidade da Espécie
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