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  • 1
    In: Marine Mammal Science, Wiley, Vol. 37, No. 1 ( 2021-01), p. 98-110
    Abstract: The Gulf of Ambracia, in northwestern Greece, hosts a highly threatened community of about 150 common bottlenose dolphins ( Tursiops truncatus ). Until now, information on their feeding habits was derived exclusively from fish scale samples collected during surface‐feeding events targeting small schooling epipelagic fish. The aim of this study was to determine the diet of bottlenose dolphins living in the Gulf of Ambracia through the application of Bayesian isotopic mixing models. Skin biopsy samples of 16 dolphins were analyzed and no difference related to sex or age‐class was found in δ 13 C and δ 15 N values. Results suggested that the dolphin diet was mainly based on Trachurus trachurus , species belonging to the family Sparidae: Diplodus annularis , Lithognathus mormyrus , and Sepia officinalis , which represented together about 42% ± 15% of the biomass ingested, followed by species belonging to the order Clupeiformes ( Engraulis encrasicolus, Sardinella aurita, and Sardina pilchardus ) and the genus Gobius (37% ± 17%). A better understanding of the feeding habits of these dolphins sheds light on the feeding ecology of this highly threatened population by, for instance, evidencing interactions with artisanal fisheries sharing the same target species, and is key for identifying adequate management measures consistent with an ecosystem‐based approach.
    Type of Medium: Online Resource
    ISSN: 0824-0469 , 1748-7692
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
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  • 2
    Online Resource
    Online Resource
    Wiley ; 2020
    In:  Aquatic Conservation: Marine and Freshwater Ecosystems Vol. 30, No. 12 ( 2020-12), p. 2428-2440
    In: Aquatic Conservation: Marine and Freshwater Ecosystems, Wiley, Vol. 30, No. 12 ( 2020-12), p. 2428-2440
    Abstract: The fish‐eating, type‐C ecotype, killer whale is a top predator in the Ross Sea, Antarctica. Increasing knowledge of this animal's foraging habitats, diet and movement patterns is listed amongst the research priorities adopted under the framework of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). To contribute to this goal, satellite transmitters were deployed on 10 type‐C killer whales and skin biopsies were obtained from seven individuals in Terra Nova Bay (Ross Sea) during austral summer (January–February) 2015. Hierarchical switching state–space models (hSSSM) were applied to Argos satellite tracking data to describe the movements of tagged whales, which were then paired with available diving data. Stable isotopes analyses were performed on the biopsy samples to describe the diet. A total of 8,803 Argos locations were available to fit the hSSSM. All whales engaged in potential foraging activity in localized areas along the Ross Sea coastline, followed by uninterrupted travel (i.e. migration) outside Antarctic waters, with no evidence of foraging activity. The pattern of deeper dives matched the occurrence of encamped behaviour indicated by the hSSSM results. The stable isotopes analysis indicated that Antarctic toothfish comprised the largest component (35%) of the prey biomass, raising concerns since this species is targeted by commercial fishery in the Ross Sea Region. These results provide new insights into the ecology of type‐C killer whales in the Ross Sea Region, underlining a potential threat from commercial fishing in the area. Considering the recent establishment of the Ross Sea Region Marine Protected Area, these findings will contribute to the required Research and Monitoring Programme of the Marine Protected Area and provide new empirical evidence to inform conservation measures in the existing Terra Nova Bay Antarctic Special Protected Area.
    Type of Medium: Online Resource
    ISSN: 1052-7613 , 1099-0755
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2020
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  • 3
    Online Resource
    Online Resource
    Wiley ; 2011
    In:  Rapid Communications in Mass Spectrometry Vol. 25, No. 9 ( 2011-05-15), p. 1343-1347
    In: Rapid Communications in Mass Spectrometry, Wiley, Vol. 25, No. 9 ( 2011-05-15), p. 1343-1347
    Type of Medium: Online Resource
    ISSN: 0951-4198 , 1097-0231
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2011
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  • 4
    In: Rapid Communications in Mass Spectrometry, Wiley, Vol. 28, No. 6 ( 2014-03-30), p. 668-670
    Type of Medium: Online Resource
    ISSN: 0951-4198
    Language: English
    Publisher: Wiley
    Publication Date: 2014
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  • 5
    In: Rapid Communications in Mass Spectrometry, Wiley, Vol. 32, No. 15 ( 2018-08-15), p. 1257-1262
    Abstract: Baleen plates are anatomical structures composed of inert tissue that hang from the upper jaw in mysticetes. Baleen plates may differ in size and in coloration between different segments of the filtering row or between sides of the mouth. Concern has been raised that variation in baleen plate characteristics may reflect dissimilar structural composition and growth rates liable to affect stable isotope ratios and their oscillation patterns. Methods We measured stable carbon (δ 13 C values) and nitrogen (δ 15 N values) isotope ratios at intervals of 1 cm along the longitudinal axis of six baleen plates collected from different positions along the mouth of a fin whale. All samples were analysed using a continuous flow isotope ratio mass spectrometer. Generalized additive models were fitted to the data from each baleen plate and the results of the models were compared visually. Results A total of 206 samples were analysed. Visually, all baleen plates presented nearly identical oscillations, independent of the position or the coloration of the baleen plate. However, the variation in δ 13 C and δ 15 N values occurring between the different baleen plates was higher in the segments of oscillations exhibiting steeper slopes. Conclusions Differences in size between plates in an individual are due to differential erosion rates according to their position in the mouth. Therefore, the position of sampling along the baleen plate row should not be a reason for concern when conducting stable isotope studies.
    Type of Medium: Online Resource
    ISSN: 0951-4198 , 1097-0231
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2018
    detail.hit.zdb_id: 2002158-6
    detail.hit.zdb_id: 58731-X
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  • 6
    In: Rapid Communications in Mass Spectrometry, Wiley, Vol. 37, No. 10 ( 2023-05-30)
    Abstract: Stable isotope analysis of growth layers in sperm whale teeth dentine can provide valuable insight into individual long‐distance displacements and diet. Although treating teeth half‐sections with formic acid and rubbing their surface with a graphite pencil improves growth layer visibility and reduces sampling error, previous studies mostly used untreated half‐sections as the effect that this treatment may have on stable isotope ratios in dentine is unknown. The present study investigates the treatment effect on stable C and N isotope ratios in sperm whale teeth dentine. Methods In the teeth of 30 sperm whales, we analysed and compared samples of powdered dentine obtained from (a) untreated half‐sections, (b) half‐sections etched with formic acid and rubbed with a graphite pencil and (c) half‐sections etched with formic acid from which the graphite pencil rubbing had been cleansed off. C and N values were compared between the three sample groups. Results We found significant differences in values of both elements between untreated and etched samples, with a mean increase of 0.2% in δ 13 C and δ 15 N values in the etched samples. No significant differences were found between etched samples with graphite rubbing versus those without it. Significant linear regression models were calculated to predict untreated δ 13 C and δ 15 N values from the values obtained in the etched half‐sections with limited precision. Conclusions We show for the first time that formic acid etching has a clear effect on C and N values in sperm whale teeth dentine. The developed models permit the estimation of untreated values from etched half‐sections, thus enabling the use of the latter in stable isotope analysis. However, as treatment procedures may vary between studies, it is advisable that similar predictive models are developed case‐by‐case to ensure comparability of results.
    Type of Medium: Online Resource
    ISSN: 0951-4198 , 1097-0231
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2023
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  • 7
    Online Resource
    Online Resource
    Wiley ; 2016
    In:  Marine Mammal Science Vol. 32, No. 2 ( 2016-04), p. 535-551
    In: Marine Mammal Science, Wiley, Vol. 32, No. 2 ( 2016-04), p. 535-551
    Abstract: The North Atlantic fin whale was subject to heavy exploitation in the past and, despite partial recovery, it is still considered endangered. Recent research has questioned its currently accepted subpopulation structure and migratory movements, challenging management and conservation efforts. Here we contribute to this discussion by presenting results of stable isotope analysis of fin whale bones and krill samples collected from fin whale stomachs from two exploited areas, west Iceland and northwest Spain, and comparing these results with North Atlantic isoscapes. In krill, δ 15 N values were highly variable and no significant differences in δ 15 N and δ 13 C between areas emerged. δ 15 N and δ 13 C values in bone were higher than in krill, due to trophic enrichment, and were not significantly different between areas. Both krill and bone results were slightly inconsistent with the local isoscapes, maybe due to seasonal variations in local productivity and in krill diet and, in the case of bone, to its capability to integrate long‐term isotopic values, derived from food consumed in distant areas. Conversely, δ 18 O values, which reflect the basal signal of sea water, were consistent with isoscapes and significantly higher in whales from northwestern Spain, possibly indicating migration to breeding grounds located at lower latitudes.
    Type of Medium: Online Resource
    ISSN: 0824-0469 , 1748-7692
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2016
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  • 8
    Online Resource
    Online Resource
    Wiley ; 2017
    In:  Rapid Communications in Mass Spectrometry Vol. 31, No. 18 ( 2017-09-30), p. 1551-1557
    In: Rapid Communications in Mass Spectrometry, Wiley, Vol. 31, No. 18 ( 2017-09-30), p. 1551-1557
    Abstract: 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 (δ 13 C values) and nitrogen (δ 15 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.
    Type of Medium: Online Resource
    ISSN: 0951-4198 , 1097-0231
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2017
    detail.hit.zdb_id: 2002158-6
    detail.hit.zdb_id: 58731-X
    SSG: 11
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  • 9
    In: Molecular Ecology, Wiley, Vol. 23, No. 13 ( 2014-07), p. 3306-3321
    Abstract: Despite no obvious barriers to gene flow in the marine realm, environmental variation and ecological specializations can lead to genetic differentiation in highly mobile predators. Here, we investigated the genetic structure of the harbour porpoise over the entire species distribution range in western Palearctic waters. Combined analyses of 10 microsatellite loci and a 5085 base‐pair portion of the mitochondrial genome revealed the existence of three ecotypes, equally divergent at the mitochondrial genome, distributed in the Black Sea ( BS ), the European continental shelf waters, and a previously overlooked ecotype in the upwelling zones of Iberia and Mauritania. Historical demographic inferences using approximate Bayesian computation ( ABC ) suggest that these ecotypes diverged during the last glacial maximum ( c.  23–19 kilo‐years ago, kyr bp ). ABC supports the hypothesis that the BS and upwelling ecotypes share a more recent common ancestor ( c.  14 kyr bp ) than either does with the European continental shelf ecotype ( c.  28 kyr bp ), suggesting they probably descended from the extinct populations that once inhabited the Mediterranean during the glacial and post‐glacial period. We showed that the two Atlantic ecotypes established a narrow admixture zone in the Bay of Biscay during the last millennium, with highly asymmetric gene flow. This study highlights the impacts that climate change may have on the distribution and speciation process in pelagic predators and shows that allopatric divergence can occur in these highly mobile species and be a source of genetic diversity.
    Type of Medium: Online Resource
    ISSN: 0962-1083 , 1365-294X
    URL: Issue
    RVK:
    Language: English
    Publisher: Wiley
    Publication Date: 2014
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  • 10
    In: Rapid Communications in Mass Spectrometry, Wiley, Vol. 27, No. 15 ( 2013-08-15), p. 1801-1806
    Type of Medium: Online Resource
    ISSN: 0951-4198
    Language: English
    Publisher: Wiley
    Publication Date: 2013
    detail.hit.zdb_id: 2002158-6
    detail.hit.zdb_id: 58731-X
    SSG: 11
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