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1.
Environ Sci Technol ; 56(8): 5037-5048, 2022 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-35394783

RESUMO

Increasing human activities are altering marine ecosystems, which may have ramifications for predator feeding ecology and, thus, the degree of contaminant exposure. We conducted the first investigation of spatiotemporal trends for nine alternative halogenated flame retardants (AHFRs) and their relations with dietary variations in 128 humpback dolphins that were stranded along the northern South China Sea during 2003-2020. We detected the highest levels of seven major AHFRs in humpback dolphins compared with the results reported in cetaceans globally, indicating high AHFR contamination in coastal regions of South China. Dolphins that were stranded near urban regions generally contained higher AHFR concentrations than those that were stranded near rural areas, mirroring the environmental trends of AHFRs occurring in this area. Model-generated diet estimates suggested that humpback dolphins have reduced their consumption of high trophic-level prey in recent years, likely attributable to overfishing-induced prey decline in this region. After adjusting AHFR concentrations due to diet changes, the temporal trends of AHFR contamination in humpback dolphins were only slightly altered. Our results suggest that increasing discharges of AHFRs into the South China Sea during the 2000s and 2010s may have had a greater influence on AHFR trends in humpback dolphins than dietary shifts.


Assuntos
Golfinhos , Retardadores de Chama , Poluentes Químicos da Água , Animais , China , Conservação dos Recursos Naturais , Ecossistema , Pesqueiros , Poluentes Químicos da Água/análise
2.
PLoS One ; 17(4): e0266424, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35413068

RESUMO

Passive acoustic monitoring (PAM) has proven a powerful tool for the study of marine mammals, allowing for documentation of biologically relevant factors such as movement patterns or animal behaviors while remaining largely non-invasive and cost effective. From 2008-2019, a set of PAM recordings covering the frequency band of most toothed whale (odontocete) echolocation clicks were collected at sites off the islands of Hawai'i, Kaua'i, and Pearl and Hermes Reef. However, due to the size of this dataset and the complexity of species-level acoustic classification, multi-year, multi-species analyses had not yet been completed. This study shows how a machine learning toolkit can effectively mitigate this problem by detecting and classifying echolocation clicks using a combination of unsupervised clustering methods and human-mediated analyses. Using these methods, it was possible to distill ten unique echolocation click 'types' attributable to regional odontocetes at the genus or species level. In one case, auxiliary sightings and recordings were used to attribute a new click type to the rough-toothed dolphin, Steno bredanensis. Types defined by clustering were then used as input classes in a neural-network based classifier, which was trained, tested, and evaluated on 5-minute binned data segments. Network precision was variable, with lower precision occurring most notably for false killer whales, Pseudorca crassidens, across all sites (35-76%). However, accuracy and recall were high (>96% and >75%, respectively) in all cases except for one type of short-finned pilot whale, Globicephala macrorhynchus, call class at Kaua'i and Pearl and Hermes Reef (recall >66%). These results emphasize the utility of machine learning in analysis of large PAM datasets. The classifier and timeseries developed here will facilitate further analyses of spatiotemporal patterns of included toothed whales. Broader application of these methods may improve the efficiency of global multi-species PAM data processing for echolocation clicks, which is needed as these datasets continue to grow.


Assuntos
Golfinhos , Ecolocação , Baleia Comum , Acústica , Animais , Cetáceos , Hawaii , Ilhas , Aprendizado de Máquina , Espectrografia do Som , Vocalização Animal
3.
Braz J Biol ; 84: e254487, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35293542

RESUMO

Biological samples obtained from a small temporary pond of northern Colombia yielded the first record Coronatella undata Sousa, Elmoor-Loureiro and Santos, 2015 and of the male of C. monacantha (Sars, 1901) for Colombia. In this study, the morphology of female of Coronatella undata and female and male of C. monacantha was described and compared to other species within the genus. C. undata was originally described from Brazil and, among the species of the Coronatella monacantha complex, seems to be closely related to C. acuticostata (Sars, 1903). C. undata shows some similarities with C. monacantha, but it can be identified by important diagnostic characters such as: 1) posterior-ventral corner of valve with two denticles, 2) seta on exopodite of trunk limb II rudimentary, 3) filter comb of trunk limb II with six setae, 4) ODL seta of trunk limb I shorter than longest seta of IDL. C. monacantha is the most reported species in the Neotropical region and the male most resemble C. paulinae Sousa, Elmoor-Loureiro & Santos, 2015 in relation to (i), length/wide of postabdomen ratio (ii) basal spine almost straight and (iii)) long basal spine reaching the mid-length of basal spine. However, they can be separated by (i) number of lateral seta on the antennule, (ii) postanal angle, (iii) position of gonopore (iv) presence of a denticle on posterior-ventral corner of valve.


Assuntos
Cladóceros , Golfinhos , Distribuição Animal , Animais , Brasil , Colômbia , Feminino , Masculino
4.
Sci Rep ; 12(1): 4510, 2022 03 16.
Artigo em Inglês | MEDLINE | ID: mdl-35296695

RESUMO

Tracking species with expanding ranges is crucial to conservation efforts and some typically temperate marine species are spreading northward into the Arctic Ocean. Risso's (Gg) and Pacific white-sided (Lo) dolphins have been documented spreading poleward. Further, they make very similar sounds, so it is difficult for both human analysts and classification algorithms to tell them apart. Using automatic detectors and classifiers on large acoustic datasets would improve the efficiency of monitoring these species. variational mode decomposition (VMD) provides both an easier visualization tool for human analysts and exhibited robustness to background noise while extracting features in pulsed signals with very similar spectral properties. The goal of this work was to develop a new visualization tool using VMD and a statistics-based classification algorithm to differentiate similar pulsed signals. The proposed VMD method achieved 81% accuracy, even when using audio files with low SNR that did not have concurrent visual survey data. While many dolphins whistle, pulsed signals are one of the more useful vocalizations to use in detection and classification because of their species-specific acoustic features. Automating the VMD method and expanding it to other dolphin species that have very similar pulsed signals would complement current detection and classification methods and lead to a more complete understanding of ecosystem dynamics under a changing climate.


Assuntos
Golfinhos , Acústica , Animais , Ecossistema , Ruído , Especificidade da Espécie
5.
PLoS One ; 17(3): e0264988, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35324943

RESUMO

A combination of machine learning and expert analyst review was used to detect odontocete echolocation clicks, identify dominant click types, and classify clicks in 32 years of acoustic data collected at 11 autonomous monitoring sites in the western North Atlantic between 2016 and 2019. Previously-described click types for eight known odontocete species or genera were identified in this data set: Blainville's beaked whales (Mesoplodon densirostris), Cuvier's beaked whales (Ziphius cavirostris), Gervais' beaked whales (Mesoplodon europaeus), Sowerby's beaked whales (Mesoplodon bidens), and True's beaked whales (Mesoplodon mirus), Kogia spp., Risso's dolphin (Grampus griseus), and sperm whales (Physeter macrocephalus). Six novel delphinid echolocation click types were identified and named according to their median peak frequencies. Consideration of the spatiotemporal distribution of these unidentified click types, and comparison to historical sighting data, enabled assignment of the probable species identity to three of the six types, and group identity to a fourth type. UD36, UD26, and UD28 were attributed to Risso's dolphin (G. griseus), short-finned pilot whale (G. macrorhynchus), and short-beaked common dolphin (D. delphis), respectively, based on similar regional distributions and seasonal presence patterns. UD19 was attributed to one or more species in the subfamily Globicephalinae based on spectral content and signal timing. UD47 and UD38 represent distinct types for which no clear spatiotemporal match was apparent. This approach leveraged the power of big acoustic and big visual data to add to the catalog of known species-specific acoustic signals and yield new inferences about odontocete spatiotemporal distribution patterns. The tools and call types described here can be used for efficient analysis of other existing and future passive acoustic data sets from this region.


Assuntos
Golfinhos , Ecolocação , Acústica , Animais , Aprendizado de Máquina , Cachalote , Vocalização Animal , Baleias
6.
Curr Biol ; 32(7): 1664-1669.e3, 2022 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-35334228

RESUMO

Understanding determinants of differential reproductive success is at the core of evolutionary biology because of its connection to fitness. Early work has linked variation in reproductive success to differences in age,1 rank,2 or size,3,4 as well as habitat characteristics.5 More recently, studies in group-living taxa have revealed that social relationships also have measurable effects on fitness.6-8 The influence of social bonds on fitness is particularly interesting in males who compete over reproductive opportunities. In Shark Bay, Western Australia, groups of 4-14 unrelated male bottlenose dolphins cooperate in second-order alliances to compete with rival alliances over access to females.9-12 Nested within second-order alliances, pairs or trios of males, which can vary in composition, form first-order alliances to herd estrus females. Using 30 years of behavioral data, we examined how individual social factors, such as first-order alliance stability, social connectivity, and variation in social bond strength within second-order alliances, affect male fitness. Analyzing the reproductive careers of 85 males belonging to 10 second-order alliances, we found that the number of paternities a male achieved was positively correlated with his cumulative social bond strength but negatively correlated with his variation in bond strength. Thus, well-integrated males with more homogeneous social bonds to second-order allies obtained most paternities. Our findings provide novel insights into the fitness benefits of polyadic cooperation among unrelated males and highlight the adaptive value of social bonds in this context.


Assuntos
Comportamento Cooperativo , Golfinhos , Animais , Feminino , Masculino , Comportamento Social , Integração Social
8.
Sci Data ; 9(1): 51, 2022 02 14.
Artigo em Inglês | MEDLINE | ID: mdl-35165321

RESUMO

Fisheries bycatch is recognised as a global threat to vulnerable marine megafauna and historical data can contribute to quantify the magnitude of the impact. Here, we present a collection of three datasets generated between 2006 and 2019 by a monitoring programme on marine megafauna bycatch in one of the main Italian fisheries, the northern central Adriatic midwater pair trawl fishery. The three datasets consist of: (i) monitored fishing effort; (ii) bycatch and biological data of dolphins, sea turtles and elasmobranchs; (iii) and dolphin sightings. Some information included in these datasets has already proved to provide a unique opportunity to estimate total incidental capture of species of conservation concern and trends of their relative abundance over time in the northern - central Adriatic Sea. These datasets are expected to be considered by different end users to improve the conservation of species and fishery management approaches to assess the impact of a fishery on species of conservation concern.


Assuntos
Pesqueiros , Animais , Conservação dos Recursos Naturais , Golfinhos , Itália , Tartarugas
9.
Front Immunol ; 13: 786396, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35185884

RESUMO

Current research efforts require a broad range of immune reagents, but those available for pigs are limited. The goal of this study was to generate priority immune reagents for pigs and pipeline them for marketing. Our efforts were aimed at the expression of soluble swine cytokines and the production of panels of monoclonal antibodies (mAbs) to these proteins. Swine interleukin-17A (IL-17A) and Interferon-gamma (IFNγ) recombinant proteins were produced using yeast expression and used for monoclonal antibody (mAb) production resulting in panels of mAbs. We screened each mAb for cross-species reactivity with orthologs of IL-17A or IFNγ and checked each mAb for inhibition by other related mAbs, to assign mAb antigenic determinants. For porcine IL-17A, the characterization of a panel of 10 mAbs identified eight different antigenic determinants; interestingly, most of the mAbs cross-reacted with the dolphin recombinant ortholog. Likewise, the characterization of a panel of nine anti-PoIFNγ mAbs identified four different determinants; most of the mAbs cross-reacted with dolphin, bovine, and caprine recombinant orthologs. There was a unique reaction of one anti-PoIFNγ mAb that cross-reacted with the zebrafish recombinant ortholog. The αIL-17A mAbs were used to develop a quantitative sandwich ELISA detecting the yeast expressed protein as well as native IL-17A in stimulated peripheral blood mononuclear cell (PBMC) supernatants. Our analyses showed that phorbol myristate acetate/ionomycin stimulation of PBMC induced significant expression of IL-17A by CD3+ T cells as detected by several of our mAbs. These new mAbs expand opportunities for immunology research in swine.


Assuntos
Anticorpos Monoclonais/sangue , Interferon gama/imunologia , Interleucina-17/imunologia , Leucócitos Mononucleares/metabolismo , Suínos/imunologia , Animais , Bovinos/imunologia , Reações Cruzadas , Golfinhos/imunologia , Ensaio de Imunoadsorção Enzimática , Cabras/imunologia , Ionomicina/farmacologia , Leucócitos Mononucleares/efeitos dos fármacos , Proteínas Recombinantes , Suínos/sangue , Linfócitos T/imunologia , Acetato de Tetradecanoilforbol/farmacologia , Peixe-Zebra/imunologia
10.
Sci Total Environ ; 822: 153651, 2022 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-35124055

RESUMO

Stranding data can provide conservation-valuable information on cetaceans over long time and large space, representing a low-cost but useful approach to monitor these indicator species and their inhabiting environments. Here, we established a national dataset by collating all available records of cetacean strandings (CSs) along >30,000-km coastline of China over seven decades. Between 1950 and 2018, a total of 1763 CSs were recorded across 36 cetacean species from eight families. Importantly, 30.5% of the recorded species are currently recognized as threatened levels on the IUCN Red List. In quantity, Odontocete species accounted for 89.9% of total CSs. In 1763 CSs, 91.8% were events of single individual. Furthermore, 31.9% and 42.4% were events of alive and dead animals, respectively. The number of CSs increased gradually from 1950 to 2018, and more rapidly between 1990 and 2018. CSs occurred in all months, while a seasonal pattern could be observed with 38.5% reports between March and June. The most commonly recorded species were finless porpoises (Neophocaena spp., n = 492) and Indo-Pacific humpback dolphin (Sousa chinensis, n = 291). The highest number of CSs (n = 478) was documented in Hong Kong, while the greatest species richness (n = 28) and the highest stranding density (24.6 CSs per 100-km coastline) were observed in Taiwan. Several CS hotspots were identified in the southern and eastern China, while hotspots differed among taxonomic categories. To conclude, these findings provided a comprehensive understanding of cetacean communities in the coastal waters of China, which are beneficial for improving further research, conservation, and management on cetaceans.


Assuntos
Golfinhos , Toninhas , Animais , Cetáceos , China , Hong Kong , Humanos
11.
J Wildl Dis ; 58(2): 445-449, 2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35007319

RESUMO

We observed contusion-like lesions caused by live sharksucker (Echeneis naucrates) attachment in an Indo-Pacific humpback dolphin (Sousa chinensis). Our report assists in differentiating epidermal lesions for visual health assessment in this vulnerable species and other cetaceans, and this adds new host and epibiont records for E. naucrates and S. chinensis, respectively.


Assuntos
Contusões , Golfinhos , Animais , China , Contusões/veterinária
12.
Anim Cogn ; 25(2): 287-296, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-34406542

RESUMO

The detection and use of emitters' signals by unintended receivers, i.e., eavesdropping, represents an important and often low-cost way for animals to gather information from their environment. Acoustic eavesdropping can be a key driver in mediating intra- and interspecific interactions (e.g., cooperation, predator-prey systems), specifically in species such as cetaceans that use sound as a primary sensory modality. While most cetacean species produce context-specific sounds, little is known about the use of those sounds by potential conspecific eavesdroppers. We experimentally tested the hypothesis that a social cetacean, Risso's dolphin (Grampus griseus), is able to gather biologically relevant information by eavesdropping on conspecific sounds. We conducted playback experiments on free-ranging dolphins using three context-specific sounds stimuli and monitored their horizontal movement using visual or airborne focal follow observations. We broadcasted natural sequences of conspecific foraging sounds potentially providing an attractive dinner bell signal (n = 7), male social sounds simulating a risk of forthcoming agonistic interaction (n = 7) and female-calf social sounds representing no particularly threatening context (n = 7). We developed a quantitative movement response score and tested whether animals changed their direction of horizontal movement towards or away from the playback source. Dolphins approached the foraging and the social female-calf sounds whereas they avoided the social male sounds. Hence, by acoustically eavesdropping on conspecifics, dolphins can discriminate between social and behavioural contexts and anticipate potential threatening or beneficial situations. Eavesdropping and the ensuing classification of 'friend or foe' can thus shape intra-specific social interactions in cetaceans.


Assuntos
Golfinhos , Acústica , Animais , Feminino , Masculino
13.
Anat Rec (Hoboken) ; 305(3): 609-621, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34288543

RESUMO

Most cetaceans are born with vibrissae but they can be lost or reduced in adulthood, especially in odontocetes. Despite this, some species of odontocetes have been found to have functioning vibrissal follicles (including the follicle itself and any remaining vibrissal hair shaft) that play a role in mechanoreception, proprioception and electroreception. This reveals a greater diversity of vibrissal function in odontocetes than in any other mammalian group. However, we know very little about vibrissal follicle form and function across the Cetacea. Here, we qualitatively describe the gross vibrissal follicle anatomy of fetuses of three species of cetaceans, including two odontocetes: Atlantic white-sided dolphin (Lagenorhynchus acutus), harbour porpoise (Phocoena phocoena), and one mysticete: minke whale (Balaenoptera acutorostrata), and compared our findings to previous anatomical descriptions. All three species had few, short vibrissae contained within a relatively simple, single-part follicle, lacking in muscles. However, we observed differences in vibrissal number, follicle size and shape, and innervation distribution between the species. While all three species had nerve fibers around the follicles, the vibrissal follicles of Balaenoptera acutorostrata were innervated by a deep vibrissal nerve, and the nerve fibers of the odontocetes studied were looser and more branched. For example, in Lagenorhynchus acutus, branches of nerve fibers travelled parallel to the follicle, and innervated more superficial areas, rather than just the base. Our anatomical descriptions lend support to the observation that vibrissal morphology is diverse in cetaceans, and is worth further investigation to fully explore links between form and function.


Assuntos
Golfinhos , Vibrissas , Animais , Cetáceos , Folículo Piloso , Vibrissas/inervação
14.
Sci Total Environ ; 804: 150196, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34798738

RESUMO

One of the largest environmental disasters worldwide occurred on November 5th, 2015, when the Fundão dam collapsed in Mariana (Minas Gerais State, Southeast Brazil). The tailing mud flooded the Doce River basin and reached the sea in the coast of Espírito Santo State (ES), Southeast Brazil. This coastal region is the habitat of the most isolated population of franciscana dolphins (Pontoporia blainvillei), with the lowest populational census and lowest genetic diversity in Franciscana Management Area Ia (FMA Ia) - 18° 25'S and 21° 17'S. This study aimed to assess the bioaccumulation of trace-elements (As, Cd, Cu, Fe, Hg, Mn, and Zn) in muscle, liver and kidney of franciscana dolphins collected near the Doce River's mouth before (n = 32) and after (n = 19) the tailing mud reached the sea. The Generalized Additive Model (GAM) showed increasing temporal trends of Hg and Zn in muscle and liver after the dam failure, probably related to higher concentrations and bioavailability in the water column and sediments from the Doce River. Declining trends were found for As and Cu muscular and hepatic concentrations and Fe concentrations in kidney due to their lower bioavailability after the disaster, caused by association with tailings mud trapped in the riverbanks and suspended particulate material. Additionally, higher As and Hg concentrations found in the first period of sampling may be due to historical contamination by mining activities. The full extent of the impacts caused by the Fundão dam failure is still unknown. However, due to their rapid increase and remobilization process, toxic effects can be induced in the biota by these elements. Elements' bioaccumulation in this study contributes to the knowledge of franciscana dolphins from FMA Ia. Considering the conservation concern regarding this franciscana population and its scarce knowledge, the impact of this disaster can be alarming for species conservation.


Assuntos
Desastres , Golfinhos , Oligoelementos , Poluentes Químicos da Água , Animais , Bioacumulação , Brasil , Monitoramento Ambiental , Mineração , Rios , Oligoelementos/análise , Poluentes Químicos da Água/análise
15.
Mar Pollut Bull ; 174: 113194, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34902768

RESUMO

Human noise can be harmful to sound-centric marine mammals. Significant research has focused on characterizing behavioral responses of protected cetacean species to navy mid-frequency active sonar (MFAS). Controlled exposure experiments (CEE) using animal-borne tags have proved valuable, but smaller dolphins are not amenable to tagging and groups of interacting individuals are more relevant behavioral units for these social species. To fill key data gaps on group responses of social delphinids that are exposed to navy MFAS in large numbers, we describe novel approaches for the coordinated collection and integrated analysis of multiple remotely-sensed datasets during CEEs. This involves real-time coordination of a sonar source, shore-based group tracking, aerial photogrammetry to measure fine-scale movements and passive acoustics to quantify vocal activity. Using an example CEE involving long-beaked common dolphins (Delphinus delphis bairdii), we demonstrate how resultant quantitative metrics can be used to estimate behavioral changes and noise exposure-response relationships.


Assuntos
Golfinhos Comuns , Golfinhos , Acústica , Animais , Ruído , Tecnologia de Sensoriamento Remoto , Som
16.
Sci Total Environ ; 807(Pt 1): 150561, 2022 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-34624692

RESUMO

Hydroxylated polybrominated diphenyl ethers (OH-BDEs) are major transformation products of PBDEs that readily bioaccumulate in the marine food web. Although 6-OH-BDE-47 is frequently and abundantly detected in cetaceans, its potential toxic effects are largely unknown. We explored the toxicological pathways and mechanisms of OH-BDEs by exposing pygmy killer whale skin fibroblast cell lines (PKW-LWHT) to 6-OH-BDE-47 at concentrations ranging from 0.02, 0.2, 2 to 4 µM. The result showed that 6-OH-BDE-47 inhibited cell proliferation in a concentration- and time-dependent manner. The cell cycle data revealed that the cell cycle was arrest at the G0/G1 phase by 6-OH-BDE-47. Using qPCR and Western blot assay, we found that 6-OH-BDE-47 up-regulated the transcription and expression level of p21 and RB1 and down-regulated the expression level of Proliferating Cell Nuclear Antigen (PCNA), CDK2, CDK4, cyclin D1, cyclin E2, E2F1, and E2F3 and the cellular phosphorylated RB1. The results showed that 6-OH-BDE-47 was able to arrest the cell cycle of PKW-LWHT cells at G1 phase by changing the expression level of related regulatory genes in G1 stage, and finally inhibit cell proliferation.


Assuntos
Golfinhos , Animais , Pontos de Checagem do Ciclo Celular , Proliferação de Células , Fibroblastos , Bifenil Polibromatos
17.
Environ Sci Technol ; 56(2): 1069-1080, 2022 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-34965107

RESUMO

The detrimental effects of contaminant exposure and changes in the availability of food resources are still of concern for Indo-Pacific humpback dolphins (Sousa chinensis) of the Pearl River Estuary (PRE). Here, we validated and applied a blubber cortisol biomarker approach to assess the physiological responses of PRE dolphins to various pollutants and diet changes during 2008-2018 (n = 70). For calves, generalized additive models (GAMs) revealed that cortisol levels varied significantly by month and were positively correlated with the body length, owing to significant maternal transfer of hormones. The significantly positive correlation between length-adjusted cortisol levels in calf and the annual calf mortality ratios suggested that during years of high calf mortality, these animals were highly stressed before they die. For noncalves, blubber cortisol levels in diseased animals were significantly higher than those in "healthy" ones. Chromium (Cr) and dichlorodiphenyltrichloroethanes displayed a significant and positive relationship with blubber cortisol levels, suggesting that contaminant-mediated endocrine disruption effects may have occurred in noncalves. The GAMs indicated a decreasing trend of noncalf's blubber cortisol levels over an 11-year span, which can be explained by their declining contaminant accumulation levels due to a significant dietary shift from eating highly contaminated fishes to less polluted ones.


Assuntos
Golfinhos , Poluentes Químicos da Água , Animais , China , Dieta , Estuários , Hidrocortisona , Poluentes Químicos da Água/análise
18.
Science ; 374(6573): 1332-1333, 2021 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-34882455
19.
J Acoust Soc Am ; 150(5): 3861, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34852567

RESUMO

Whistle classification plays an essential role in studying the habitat and social behaviours of cetaceans. We obtained six categories of sweep whistles of two Tursiops aduncus individual signals using the passive acoustic mornitoring technique over a period of eight months in the Xiamen area. First, we propose a depthwise separable convolutional neural network for whistle classification. The proposed model adopts the depthwise convolution combined with the followed point-by-point convolution instead of the conventional convolution. As a result, it brings a better classification performance in sample sets with relatively independent features between different channels. Meanwhile, it leads to less computational complexity and fewer model parameters. Second, in order to solve the problem of an imbalance in the number of samples under each whistle category, we propose a random series method with five audio augmentation algorithms. The generalization ability of the trained model was improved by using an opening probability for each algorithm and the random selection of each augmentation factor within specific ranges. Finally, we explore the effect of the proposed augmentation method on the performance of our proposed architecture and find that it enhances the accuracy up to 98.53% for the classification of Tursiops aduncus whistles.


Assuntos
Golfinhos , Acústica , Algoritmos , Animais , Redes Neurais de Computação , Comportamento Social
20.
J Acoust Soc Am ; 150(5): 3399, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34852628

RESUMO

Acoustic line transect surveys are often used in combination with visual methods to estimate the abundance of marine mammal populations. These surveys typically use towed linear hydrophone arrays and estimate the time differences of arrival (TDOAs) of the signal of interest between the pairs of hydrophones. The signal source TDOAs or bearings are then tracked through time to estimate the animal position, often manually. The process of estimating TDOAs from data and tracking them through time can be especially challenging in the presence of multiple acoustically active sources, missed detections, and clutter (false TDOAs). This study proposes a multi-target tracking method to automate TDOA tracking. The problem formulation is based on the Gaussian mixture probability hypothesis density filter and includes multiple sources, source appearance and disappearance, missed detections, and false alarms. It is shown that by using an extended measurement model and combining measurements from broadband echolocation clicks and narrowband whistles, more information can be extracted from the acoustic encounters. The method is demonstrated on false killer whale (Pseudorca crassidens) recordings from Hawaiian waters.


Assuntos
Golfinhos , Ecolocação , Acústica , Animais , Som , Espectrografia do Som , Vocalização Animal
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