The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
David M Lavigne - One of the best experts on this subject based on the ideXlab platform.
-
distinguishing between populations of fresh and salt water harbour seals Phoca vitulina using stable isotope ratios and fatty acid profiles
Canadian Journal of Fisheries and Aquatic Sciences, 1996Co-Authors: Richard J Smith, Keith A Hobson, Heather N Koopman, David M LavigneAbstract:On a utilise des rapports d'isotopes stables et des profils d'acides gras pour determiner si les phoques communs (Phoca vitulina mellonae) du lac des Loups marins, sur la peninsule de l'Ungava, dans le nord du Quebec (a 160 km a l'est de la baie d'Hudson), pouvaient etre distingues de ceux d'autres populations marines de cet animal, Phoca vitulina concolor et Phoca vitulina richardsi. Chez les P. v. mellonae, on observe une valeur inferieure de δ 13 C par rapport a celle des P. v. concolor (p < 0,001). Chez les phoques d'une population des P. v. concolor du lac Kasegalik (T.N.-O.), qui ont acces a du carbone provenant de sources dulcicoles et marines, la valeur moyenne de δ 13 C etait intermediaire entre celle des P. v. mellonae et celle des P. v. concolor marins, et les premiers pouvaient etre distingues des deux derniers. La graisse de P. v. mellonae contenait des concentrations significativement plus elevees de 18:2n-6, de 18:3n-3, de 20:4n-4, d'acides gras polyinsatures en C 18 et d'acides gras polyinsatures totaux que celles de phoques communs des deux populations marines, et des concentrations significativement plus faibles de 20:1n-9 et de 22:1n-11. Le rapport n-3/n-6 des P. v. mellonae du lac etait egalement significativement plus faible que celui observe chez les specimens marins. Ces observations semblent toutes indiquer que les phoques communs du lac des Loups marins subsistent principalement grâce a un regime alimentaire a base d'especes dulcicoles.
L Van De Zande - One of the best experts on this subject based on the ideXlab platform.
-
Structure and amount of genetic variation at minisatellite loci within the subspecies complex of Phoca vitulina (the harbour seal)
Heredity, 1997Co-Authors: A L Kappe, R Bijlsma, A D M E Osterhaus, W Van Delden, L Van De ZandeAbstract:The structure and amount of genetic variation within and between three subspecies of the harbour seal Phoca vitulina was assessed by multilocus DNA fingerprinting. Bandsharing similarity indicates that the subspecies Phoca vitulina richardsi (Alaska, East Pacific) is clearly separated from the other two subspecies, Phoca vitulina concolor (Sable Island, West Atlantic) and Phoca vitulina vitulina (North Sea, East Atlantic). The subspecies also differ significantly in the estimated amount of heterozygosity. Phoca vitulina richardsi has by far the highest amount of genetic variation, whereas P. vitulina vitulina has very low levels of genetic variation. Within the subspecies P. vitulina vitulina , especially the Wadden Sea population is depauperate of genetic variation. The findings are discussed in a historical, biogeographical and a conservation biological context.
-
Genetic variation in Phoca vitulina (the harbour seal) revealed by DNA fingerprinting and RAPDs.
Heredity, 1995Co-Authors: A L Kappe, R Bijlsma, L Van De Zande, E J Vedder, W Van DeldenAbstract:Genetic variation in two harbour seal (Phoca vitulina) populations from the Dutch Wadden Sea and Scotland was examined by RAPD analysis and DNA fingerprinting. For comparison a population of grey seals (Halichoerus grypus) was studied. The RAPD method revealed a very low number of polymorphic bands. The multilocus DNA fingerprinting technique showed very low levels of variation both within and between populations of the harbour seals. For one probe a significant difference in variation between populations was demonstrated. The estimated average heterozygosity, however, diverged more strongly between the two harbour seal populations because of more frequent occurrence of rare alleles in the Scottish population. Low levels of genetic variation seem to be characteristic for the subspecies Phoca vitulina vitulina, but not for all marine mammals in the North Sea, as the grey seal population showed significantly higher variation.
Morten Tange Olsen - One of the best experts on this subject based on the ideXlab platform.
-
prevalence of skull pathologies in european harbor seals Phoca vitulina during 1981 2014
Acta Theriologica, 2018Co-Authors: Cino Pertoldi, Rune Dietz, Lasse Fast Jensen, Aage Kristian Olsen Alstrup, Ole Lajord Munk, Trine Bæk Pedersen, Christian Sonne, Hanne E. Kortegaard, Tobias Daugaardpetersen, Morten Tange OlsenAbstract:Harbor seals (Phoca vitulina) inhabit the seas surrounding Denmark and are an important top predator in the marine food chain. This trophic position exposes them to environmental contaminants with disease epidemics and hunting being additional threats to this population. It is therefore important to study how environmental pollution at the current order of magnitude affects the health of the population. Earlier studies have shown that occurrence of periodontitis could be linked to the amount of pollution the seals were subjected to. In order to investigate this further, 380 skulls and 141 mandibles of harbor seals (Phoca vitulina) from the Wadden Sea, the Limfjord, and Kattegat collected during the period 1970–2014 were examined. The skulls were examined for pathological lesions. The Hounsfield Units (HU) which are correlated to the bone mineral density (BMD) were measured in a subsample (n = 34) using CT scans. The macroscopic examination revealed (with the exception of the Swedish part of Kattegat) a significant increase of pathological lesions over the study period of 1981–2014. The examination of HU showed that median HU measured at multiple sites was highest in the healthy skulls compared to the skulls with one or more of the lesions. A discriminant analysis allowed high discriminatory capacity to separate healthy skulls from the skulls with pathologies, simply by the utilization of the HU data. Former studies of BMD in marine mammals have shown that exposure to environmental chemicals alter BMD and cause periodontitis. The present study, based on temporal and spatial trends in BMD, confirms the results of previous studies.
-
Prevalence of skull pathologies in European harbor seals (Phoca vitulina) during 1981–2014
Mammal Research, 2017Co-Authors: Cino Pertoldi, Rune Dietz, Lasse Fast Jensen, Aage Kristian Olsen Alstrup, Ole Lajord Munk, Trine Bæk Pedersen, Christian Sonne, Tobias Daugaard-petersen, Hanne E. Kortegaard, Morten Tange OlsenAbstract:Harbor seals (Phoca vitulina) inhabit the seas surrounding Denmark and are an important top predator in the marine food chain. This trophic position exposes them to environmental contaminants with disease epidemics and hunting being additional threats to this population. It is therefore important to study how environmental pollution at the current order of magnitude affects the health of the population. Earlier studies have shown that occurrence of periodontitis could be linked to the amount of pollution the seals were subjected to. In order to investigate this further, 380 skulls and 141 mandibles of harbor seals (Phoca vitulina) from the Wadden Sea, the Limfjord, and Kattegat collected during the period 1970–2014 were examined. The skulls were examined for pathological lesions. The Hounsfield Units (HU) which are correlated to the bone mineral density (BMD) were measured in a subsample (n = 34) using CT scans. The macroscopic examination revealed (with the exception of the Swedish part of Kattegat) a significant increase of pathological lesions over the study period of 1981–2014. The examination of HU showed that median HU measured at multiple sites was highest in the healthy skulls compared to the skulls with one or more of the lesions. A discriminant analysis allowed high discriminatory capacity to separate healthy skulls from the skulls with pathologies, simply by the utilization of the HU data. Former studies of BMD in marine mammals have shown that exposure to environmental chemicals alter BMD and cause periodontitis. The present study, based on temporal and spatial trends in BMD, confirms the results of previous studies.
Deane Renouf - One of the best experts on this subject based on the ideXlab platform.
-
Preliminary measurements of the sensitivity of the vibrissae of Harbour seals (Phoca vitulina) to low frequency vibrations
Journal of Zoology, 2009Co-Authors: Deane RenoufAbstract:The sensitivity of the vibrissae of three Harbour seals (Phoca vitulina) to vibrations ranging between 50 and 1000 Hz was estimated using standard psychophysical techniques. Their vibrissae are relatively insensitive at the lower frequencies tested, however, vibrations which displaced the animal's whiskers by less than one micron were perceptible at 1000 Hz. Further preliminary tests indicated that the animals can use their vibrissae to perceive vibrations beyond this frequency. It is hypothesized that marine mammals can use their whiskers to detect the large amplitude water displacements propagated by objects vibrating at low frequencies. This ability would permit the animal to determine various properties of objects moving underwater without having to touch them.
-
Changes in food intake, mass, and fat accumulation in association with variations in thyroid hormone levels of harbour seals (Phoca vitulina)
Canadian Journal of Zoology, 1991Co-Authors: Deane Renouf, Elizabeth NoseworthyAbstract:Food intake, mass, fat, locomotor activity, and thyroid hormones were monitored in five captive harbour seals (Phoca vitulina) over an 18-month period. Food intake ranged from anorexia to 11% body ...
W Van Delden - One of the best experts on this subject based on the ideXlab platform.
-
Structure and amount of genetic variation at minisatellite loci within the subspecies complex of Phoca vitulina (the harbour seal)
Heredity, 1997Co-Authors: A L Kappe, R Bijlsma, A D M E Osterhaus, W Van Delden, L Van De ZandeAbstract:The structure and amount of genetic variation within and between three subspecies of the harbour seal Phoca vitulina was assessed by multilocus DNA fingerprinting. Bandsharing similarity indicates that the subspecies Phoca vitulina richardsi (Alaska, East Pacific) is clearly separated from the other two subspecies, Phoca vitulina concolor (Sable Island, West Atlantic) and Phoca vitulina vitulina (North Sea, East Atlantic). The subspecies also differ significantly in the estimated amount of heterozygosity. Phoca vitulina richardsi has by far the highest amount of genetic variation, whereas P. vitulina vitulina has very low levels of genetic variation. Within the subspecies P. vitulina vitulina , especially the Wadden Sea population is depauperate of genetic variation. The findings are discussed in a historical, biogeographical and a conservation biological context.
-
Genetic variation in Phoca vitulina (the harbour seal) revealed by DNA fingerprinting and RAPDs.
Heredity, 1995Co-Authors: A L Kappe, R Bijlsma, L Van De Zande, E J Vedder, W Van DeldenAbstract:Genetic variation in two harbour seal (Phoca vitulina) populations from the Dutch Wadden Sea and Scotland was examined by RAPD analysis and DNA fingerprinting. For comparison a population of grey seals (Halichoerus grypus) was studied. The RAPD method revealed a very low number of polymorphic bands. The multilocus DNA fingerprinting technique showed very low levels of variation both within and between populations of the harbour seals. For one probe a significant difference in variation between populations was demonstrated. The estimated average heterozygosity, however, diverged more strongly between the two harbour seal populations because of more frequent occurrence of rare alleles in the Scottish population. Low levels of genetic variation seem to be characteristic for the subspecies Phoca vitulina vitulina, but not for all marine mammals in the North Sea, as the grey seal population showed significantly higher variation.