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Terry R Spraker - One of the best experts on this subject based on the ideXlab platform.
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a study of uncinariasis in northern fur seal pups Callorhinus ursinus on the rookeries of bering island 2011 2012
Russian Journal of Marine Biology, 2019Co-Authors: Sergey V Fomin, L I Konovalova, O A Belonovich, Terry R SprakerAbstract:Carcasses of northern fur seal pups, Callorhinus ursinus, collected from the rookeries of Bering Island (n = 133), were examined for hookworms Uncinaria spp. The parasite was found in 90% of the pups from the Severo-Zapadnoe rookery and in 45% of the pups from the Severnoe rookery. This difference in prevalence of nematode infection between the rookeries is associated with the type of substrate, as well as with the pattern of distribution of the seal reproductive groups on each of the rookeries.
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digeneans of northern fur seals Callorhinus ursinus pinnipedia otariidae from five subpopulations on st paul island alaska
Parasitology Research, 2018Co-Authors: Tatiana A Kuzmina, Terry R Spraker, Vladimirovich Vladimir Tkach, Olena KudlaiAbstract:A parasitological survey of 651 northern fur seals Callorhinus ursinus L. from five subpopulations was conducted on St. Paul Island, Alaska, during July–August 2012–2014. Digenean trematodes were found in 210 of 651 fur seals with a total prevalence of 32.3%. Intensity of infection varied from 1 to 1540 parasites with mean intensity 18.4 ± 111.1 SD and median intensity of 2 specimens per host. Significant differences in prevalence and intensity of infection in northern fur seals between separate rookeries was not observed (Mann–Whitney test; p > 0.05). Four species of digeneans belonging to the families Heterophyidae (Apophallus zalophi Price, 1932, Phocitrema fusiforme Goto and Ozaki, 1930, and Galactosomum ubelakeri (Dailey, 1969)) and Troglotrematidae (Nanophyetus salmincola (Chapin, 1926)) were found. Nanophyetus salmincola is reported from C. ursinus for the first time. We obtained partial 28S rDNA sequences for all digenean species and conducted molecular phylogenetic analysis to demonstrate their phylogenetic relationships.
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the cestode community in northern fur seals Callorhinus ursinus on st paul island alaska
International journal for parasitology. Parasites and wildlife, 2015Co-Authors: Tatiana A Kuzmina, Vadym V Kornyushyn, Jesus S Hernandezorts, Terry R Spraker, Roman KuchtaAbstract:The diversity and ecology of cestodes from the northern fur seals, Callorhinus ursinus (NFS), were examined using newly collected material from 756 humanely harvested subadult males between 2011 and 2014. NFSs were collected from five different haul-outs on St. Paul Island, Alaska. A total of 14,660 tapeworms were collected with a prevalence of 98.5% and intensity up to 107 cestodes per host (mean intensity 19.7 ± 16.5 SD). Three species of tapeworms were found: Adenocephalus pacificus (Diphyllobothriidea) was the most prevalent (prevalence 97.4%), followed by Diplogonoporus tetrapterus (49.7%), and 5 immature specimens of Anophryocephalus cf. ochotensis (Tetrabothriidea) (0.5%). Most of the cestodes found in the NFS were immature (69.7%). However, only 0.9% of cestodes were in larval (plerocercoid) stages. The species composition, prevalence and intensity of cestodes from these NFSs were not statistically different between the five separate haul-outs. Significant increases in the intensity of NFS infections were observed during the study period.
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bilaterally symmetrical lesions of the caudate nucleus in a northern fur seal pup Callorhinus ursinus
Veterinary Record Case Reports, 2015Co-Authors: Vanessa Fravel, Sophie Dennison, William Van Bonn, Terry R SprakerAbstract:A northern fur seal ( Callorhinus ursinus ) pup was stranded and brought to The Marine Mammal Center (TMMC) in Sausalito, California, USA, for rehabilitation. Upon admission, the animal was lethargic, underweight and ataxic. Clinical diagnostics, including complete blood cell count (CBC), serum chemistry, protozoal antibody titres, radiographs and cisterna magna ultrasonography, were completed and considered within normal limits. MRI of the brain revealed bilaterally symmetrical focal lesions of the rostrolateral caudate nucleus. Treatment for thiamine deficiency and immune-mediated disease was initiated, but the pup did not improve. The pup was euthanased and postmortem examination revealed no gross lesions. Histopathology revealed bilateral regions of oedema, and areas of early malacia, within the caudate nucleus. Although the aetiology is not identified, the distribution of the lesions suggests a toxic insult or could be related to a developmental neurodegenerative disease. This case also gives an insight into the potential role of the caudate nucleus in fur seals.
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anisakids nematoda anisakidae from stomachs of northern fur seals Callorhinus ursinus on st paul island alaska parasitological and pathological analysis
Parasitology Research, 2014Co-Authors: T A Kuzmina, E T Lyons, Terry R SprakerAbstract:Anisakid nematodes parasitize the alimentary tracts of aquatic vertebrates, including northern fur seals (Callorhinus ursinus) (NFS). The main purpose of this study was to estimate the prevalence, intensity, and species composition of anisakids in NFSs on St. Paul Island, Alaska, and to analyze changes in NFS infection with these nematodes during the last decades. The study was carried out on St. Paul Island, Alaska, in July–August 2011–2013. Stomachs of 443 humanely harvested NFS males were collected from five separate haul-out areas. A total of 4,460 anisakid specimens were collected and identified by morphological criteria. Gross and histological examinations of stomachs were also performed. The overall prevalence of NFS infection was 91.2 %; overall mean intensity 10.9, and overall median intensity 6. Five species, Anisakis simplex s. l., Contracaecum osculatum s. l., Pseudoterranova decipiens s. l., P. azarazi and Phocascaris cystophorae, were found. The prevalence of Anisakis was 46.5 %, its intensity 7.5. The prevalence and intensity of Contracaecum, Pseudoterranova, and Phocascaris were 33.6 % and 3.5, 81.9 % and 6.5, and 5.2 % and 1.7, respectively. Significant differences in the prevalence of NFS infection were observed between separate haul-outs. Comparison of the present data with the results of studies performed in the North Pacific in the 1960s, showed a significant decrease in the intensity of NFS infection with anisakids during the last decades. The prevalence of mucosal lesions in NFS stomachs caused by anisakids also decreased from 92 to 20.9 %. Possible reasons for the changes in NFS infection with anisakids are discussed.
Russel D. Andrews - One of the best experts on this subject based on the ideXlab platform.
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foraging behavior of lactating northern fur seals Callorhinus ursinus in the commander islands russia
Polar Biology, 2016Co-Authors: Olga Belonovich, Russel D. Andrews, Vladimir N Burkanov, Sergey V Fomin, Randall W DavisAbstract:We characterized the foraging behavior and habitat associations of lactating female northern fur seals (Callorhinus ursinus) from two of four rookeries comprising the stable population on the Commander Islands (CI). The CI females included in the study were from Severo-Zapadnoe rookery (SZR in 2008 and 2009) and Servernoe rookery (SR in 2009) which are 16 km apart on the northern tip of Bering Island (BI). We used satellite-linked tags and time–depth recorders to track the animals at sea and record dive behavior. For SZR females, the average foraging trip duration, mean dive depth, and maximum travel distance for both years were 3.4 ± 1.42 days, 16 ± 9.8 m, and 85 ± 59.6 km, respectively. The same measures for SR females were 4.4 ± 1.90 days, 20 ± 9.7 m, and 159 ± 70.8 km, respectively. The mean duration of foraging trips, mean number of bouts per trip and trip duration, mean direction of foraging trips, and size of foraging areas were significantly different between females from SR and SZR. Foraging trips of females from neither rookery were associated with high chl-a concentration. Overall, females on the CI appeared to expend less time and energy during foraging trips than females on the Pribilof Islands, and this may explain why the latter population is declining while the CI population is stable.
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development of the aerobic dive limit and muscular efficiency in northern fur seals Callorhinus ursinus
Journal of Comparative Physiology B-biochemical Systemic and Environmental Physiology, 2012Co-Authors: Michelle R Shero, Russel D. Andrews, Keri C Lestyk, Jennifer M BurnsAbstract:Northern fur seal (Callorhinus ursinus; NFS) populations have been declining, perhaps due to limited foraging ability of pups. Because a marine mammal’s proficiency at exploiting underwater prey resources is based on the ability to store large amounts of oxygen (O2) and to utilize these reserves efficiently, this study was designed to determine if NFS pups had lower blood, muscle, and total body O2 stores than adults. Pups (<1-month old) had a calculated aerobic dive limit only ~40% of adult females due to lower blood and, to a much greater extent, muscle O2 stores. Development of the Pectoralis (Pec) and Longissimus dorsi (LD) skeletal muscles was further examined by determining their myosin heavy chain (MHC) composition and enzyme activities. In all animals, the slow MHC I and fast-twitch IIA proteins typical of oxidative fiber types were dominant, but adult muscles contained more (Pec ~50%; LD ~250% higher) fast-twitch MHC IID/X protein characteristic of glycolytic muscle fibers, than pup muscles. This suggests that adults have greater ability to generate muscle power rapidly and/or under anaerobic conditions. Pup muscles also had lower aerobic and anaerobic ATP production potential, as indicated by lower metabolically scaled citrate synthase, β-hydroxyacyl CoA dehydrogenase, and lactate dehydrogenase activities (all P values ≤0.001). In combination, these findings indicate that pups are biochemically and physiologically limited in their diving capabilities relative to adults. This may contribute to lower NFS first year survival.
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prey competition between sympatric steller sea lions eumetopias jubatus and northern fur seals Callorhinus ursinus on lovushki island russia
Canadian Journal of Zoology, 2012Co-Authors: Russel D. Andrews, Jason N Waite, V. N. BurkanovAbstract:Approximately 1 000 Steller sea lions (Eumetopias jubatus (Schreber, 1776); SSL) and 14 000 northern fur seals (Callorhinus ursinus (L., 1758); NFS) breed sympatrically on Lovushki Island in the Russian Far East, creating the potential for interspecific competition for prey. An additional 13 000 - 14 000 juvenile NFS are present during the breeding season. The diets of breeding SSL and both breeding and juvenile NFS were examined through analysis of scats and spews col- lected during the breeding seasons of 2003, 2005, and 2007-2008. There were significant overlaps in the prey species and size selection of SSL and juvenile NFS. There were significant differences between the diets of SSL and breeding NFS. SSL and juvenile NFS fed primarily on Atka mackerel (Pleurogrammus monopterygius (Pallas, 1810)), while breeding NFS fed on cephalopods, salmon (genus Oncorhynchus Suckley, 1861), Atka mackerel, and northern smoothtongue (Leuroglossus schmidti Rass, 1955). The partitioning of resources between breeding animals has allowed both species to coexist within the same region and likely reflected differences in foraging abilities and provisioning strategies of the adults and the fasting abil- ities of their pups. However, continued growth of the NFS population may lead to the exclusion of SSL owing to interspe- cific competition for prey. Resume : Environ 1 000 lions de mer de Steller (Eumetopias jubatus (Schreber, 1776); SSL) et 14 000 otaries a fourrure du Nord (Callorhinus ursinus (L., 1758); NFS) se reproduisent en sympatrie sur l'ile Lovushki dans l'Extreme-Orient russe, creant une situation potentielle de competition pour les proies. De plus, 13 000 - 14 000 jeunes NFS sont aussi presents du- rant la saison de reproduction. Nous avons determine le regime alimentaire des SSL en reproduction et des NFS reproduc- teurs et jeunes par l'examen des defecations et des vomissements recoltes durant les saisons de reproduction de 2003, 2005 et 2007-2008. Il y a des chevauchements significatifs dans la selection des especes et des tailles de proies par les SSL et les jeunes NFS. Il existe des differences significatives de regime alimentaire entre les SSL et les NFS en reproduction. Les SSL et les jeunes NFS se nourrissent surtout de maquereaux d'Atka (Pleurogrammus monopterygius (Pallas, 1810)), alors que les NFS en reproduction s'alimentent de cephalopodes, de saumons (genre Oncorhynchus Suckley, 1861), de maque- reaux d'Atka et de leuroglosses luisants (Leuroglossus schmidti Rass, 1955). Le partage des ressources entre les animaux re- producteurs permet aux deux especes de cohabiter dans la meme region et refletent vraisemblablement des differences dans les habiletes de recherche de nourriture et les strategies d'approvisionnement des adultes et les capacites de leurs petits a jeuner. Cependant, une croissance continue de la population de NFS pourrait mener a l'exclusion de SSL a cause de la com- petition interspecifique pour les proies. (Traduit par la Redaction)
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hematology of free ranging lactating northern fur seals Callorhinus ursinus
Journal of Wildlife Diseases, 2011Co-Authors: Sarah E Norberg, Russel D. Andrews, Vladimir N Burkanov, Pam TuomiAbstract:Thirteen standard hematology values were determined for a healthy and growing population of free-ranging, lactating northern fur seals (Callorhinus ursinus) from Lovushki Island in the Kuril Islands of far-east Russia. Results are presented from 24 females sampled between June and August during the 3-yr period of 2006–08. Hematologic values have been made available for future comparisons with the declining population of northern fur seals on the Pribilof Islands, Alaska, and are compared with published values for other otariid species.
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differentiating between steller sea lion eumetopias jubatus and northern fur seal Callorhinus ursinus scats through analysis of faecal dna
Molecular Ecology Resources, 2011Co-Authors: Russel D. Andrews, Jason N Waite, Mary Bozza, Lisette P WaitsAbstract:: We describe a method to determine the species of pinniped from faeces collected from sympatric Steller sea lion (Eumetopias jubatus) and northern fur seal (Callorhinus ursinus) rookeries using newly developed species-specific primers that amplify a 667-669-base pair segment from the mitochondrial DNA (mtDNA) cytochrome B (cytB) gene region. The primers yielded the correct species in 100% of tissue samples from 10 known animals and 100% of faecal samples from 13 known animals. Species could be identified unequivocally for 87.7% of faecal samples from 122 unknown individuals. The ability to differentiate between scats of sympatrically breeding Steller sea lions and northern fur seals will contribute to the range-wide knowledge of the foraging strategies of both species as well as allow researchers to examine the niche partitioning and potential resource competition between the two predators.
Jason N Waite - One of the best experts on this subject based on the ideXlab platform.
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prey competition between sympatric steller sea lions eumetopias jubatus and northern fur seals Callorhinus ursinus on lovushki island russia
Canadian Journal of Zoology, 2012Co-Authors: Russel D. Andrews, Jason N Waite, V. N. BurkanovAbstract:Approximately 1 000 Steller sea lions (Eumetopias jubatus (Schreber, 1776); SSL) and 14 000 northern fur seals (Callorhinus ursinus (L., 1758); NFS) breed sympatrically on Lovushki Island in the Russian Far East, creating the potential for interspecific competition for prey. An additional 13 000 - 14 000 juvenile NFS are present during the breeding season. The diets of breeding SSL and both breeding and juvenile NFS were examined through analysis of scats and spews col- lected during the breeding seasons of 2003, 2005, and 2007-2008. There were significant overlaps in the prey species and size selection of SSL and juvenile NFS. There were significant differences between the diets of SSL and breeding NFS. SSL and juvenile NFS fed primarily on Atka mackerel (Pleurogrammus monopterygius (Pallas, 1810)), while breeding NFS fed on cephalopods, salmon (genus Oncorhynchus Suckley, 1861), Atka mackerel, and northern smoothtongue (Leuroglossus schmidti Rass, 1955). The partitioning of resources between breeding animals has allowed both species to coexist within the same region and likely reflected differences in foraging abilities and provisioning strategies of the adults and the fasting abil- ities of their pups. However, continued growth of the NFS population may lead to the exclusion of SSL owing to interspe- cific competition for prey. Resume : Environ 1 000 lions de mer de Steller (Eumetopias jubatus (Schreber, 1776); SSL) et 14 000 otaries a fourrure du Nord (Callorhinus ursinus (L., 1758); NFS) se reproduisent en sympatrie sur l'ile Lovushki dans l'Extreme-Orient russe, creant une situation potentielle de competition pour les proies. De plus, 13 000 - 14 000 jeunes NFS sont aussi presents du- rant la saison de reproduction. Nous avons determine le regime alimentaire des SSL en reproduction et des NFS reproduc- teurs et jeunes par l'examen des defecations et des vomissements recoltes durant les saisons de reproduction de 2003, 2005 et 2007-2008. Il y a des chevauchements significatifs dans la selection des especes et des tailles de proies par les SSL et les jeunes NFS. Il existe des differences significatives de regime alimentaire entre les SSL et les NFS en reproduction. Les SSL et les jeunes NFS se nourrissent surtout de maquereaux d'Atka (Pleurogrammus monopterygius (Pallas, 1810)), alors que les NFS en reproduction s'alimentent de cephalopodes, de saumons (genre Oncorhynchus Suckley, 1861), de maque- reaux d'Atka et de leuroglosses luisants (Leuroglossus schmidti Rass, 1955). Le partage des ressources entre les animaux re- producteurs permet aux deux especes de cohabiter dans la meme region et refletent vraisemblablement des differences dans les habiletes de recherche de nourriture et les strategies d'approvisionnement des adultes et les capacites de leurs petits a jeuner. Cependant, une croissance continue de la population de NFS pourrait mener a l'exclusion de SSL a cause de la com- petition interspecifique pour les proies. (Traduit par la Redaction)
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differentiating between steller sea lion eumetopias jubatus and northern fur seal Callorhinus ursinus scats through analysis of faecal dna
Molecular Ecology Resources, 2011Co-Authors: Russel D. Andrews, Jason N Waite, Mary Bozza, Lisette P WaitsAbstract:: We describe a method to determine the species of pinniped from faeces collected from sympatric Steller sea lion (Eumetopias jubatus) and northern fur seal (Callorhinus ursinus) rookeries using newly developed species-specific primers that amplify a 667-669-base pair segment from the mitochondrial DNA (mtDNA) cytochrome B (cytB) gene region. The primers yielded the correct species in 100% of tissue samples from 10 known animals and 100% of faecal samples from 13 known animals. Species could be identified unequivocally for 87.7% of faecal samples from 122 unknown individuals. The ability to differentiate between scats of sympatrically breeding Steller sea lions and northern fur seals will contribute to the range-wide knowledge of the foraging strategies of both species as well as allow researchers to examine the niche partitioning and potential resource competition between the two predators.
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differentiating between steller sea lion eumetopias jubatus and northern fur seal Callorhinus ursinus scats through analysis of faecal dna
Molecular Ecology Resources, 2011Co-Authors: Russel D. Andrews, Jason N Waite, Mary Bozza, Lisette P WaitsAbstract:: We describe a method to determine the species of pinniped from faeces collected from sympatric Steller sea lion (Eumetopias jubatus) and northern fur seal (Callorhinus ursinus) rookeries using newly developed species-specific primers that amplify a 667-669-base pair segment from the mitochondrial DNA (mtDNA) cytochrome B (cytB) gene region. The primers yielded the correct species in 100% of tissue samples from 10 known animals and 100% of faecal samples from 13 known animals. Species could be identified unequivocally for 87.7% of faecal samples from 122 unknown individuals. The ability to differentiate between scats of sympatrically breeding Steller sea lions and northern fur seals will contribute to the range-wide knowledge of the foraging strategies of both species as well as allow researchers to examine the niche partitioning and potential resource competition between the two predators.
E T Lyons - One of the best experts on this subject based on the ideXlab platform.
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anisakids nematoda anisakidae from stomachs of northern fur seals Callorhinus ursinus on st paul island alaska parasitological and pathological analysis
Parasitology Research, 2014Co-Authors: T A Kuzmina, E T Lyons, Terry R SprakerAbstract:Anisakid nematodes parasitize the alimentary tracts of aquatic vertebrates, including northern fur seals (Callorhinus ursinus) (NFS). The main purpose of this study was to estimate the prevalence, intensity, and species composition of anisakids in NFSs on St. Paul Island, Alaska, and to analyze changes in NFS infection with these nematodes during the last decades. The study was carried out on St. Paul Island, Alaska, in July–August 2011–2013. Stomachs of 443 humanely harvested NFS males were collected from five separate haul-out areas. A total of 4,460 anisakid specimens were collected and identified by morphological criteria. Gross and histological examinations of stomachs were also performed. The overall prevalence of NFS infection was 91.2 %; overall mean intensity 10.9, and overall median intensity 6. Five species, Anisakis simplex s. l., Contracaecum osculatum s. l., Pseudoterranova decipiens s. l., P. azarazi and Phocascaris cystophorae, were found. The prevalence of Anisakis was 46.5 %, its intensity 7.5. The prevalence and intensity of Contracaecum, Pseudoterranova, and Phocascaris were 33.6 % and 3.5, 81.9 % and 6.5, and 5.2 % and 1.7, respectively. Significant differences in the prevalence of NFS infection were observed between separate haul-outs. Comparison of the present data with the results of studies performed in the North Pacific in the 1960s, showed a significant decrease in the intensity of NFS infection with anisakids during the last decades. The prevalence of mucosal lesions in NFS stomachs caused by anisakids also decreased from 92 to 20.9 %. Possible reasons for the changes in NFS infection with anisakids are discussed.
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acanthocephalans in northern fur seals Callorhinus ursinus and a harbor seal phoca vitulina on st paul island alaska
2012Co-Authors: T A Kuzmina, Terry R Spraker, E T Lyons, Olga I Lisitsyna, S C TolliverAbstract:Monitoring studies of acanthocephalans in northern fur seals (Callorhinus ursinus Linnaeus, 1758) (NFSs) and a harbor seal (Phoca vitulina Linnaeus, 1758) were performed on St. Paul Island, Alaska, in July-August 2011. Gastrointes- tinal tracts of 105 humanely harvested NFS subadult males (SAMs) (3-4yearsold) werecollectedduringtheannual Aleut subsistence harvest at four haul-out areas (HOAS): Lukanin (n026 NFSs), Polovina (n028), Gorbatch (n030), and Morz- hovyi (n021). One gastrointestinal tract collected from a har- borseal (about3-4 years old)found deadat Morzhovyi HOAS was also examined. The total prevalenceof infection in NFSs with acanthocephalans was 29.52 % with variations from 7.69 % to 47.62 % between the four different HOAS. Eight acanthocephalan species of two genera—Coryno- soma Luhe, 1904 (Corynosoma strumosum, Corynosoma alaskensis, Corynosoma cameroni, Corynosoma semerme, Corynosoma similis, Corynosoma validum ,a ndCorynosoma villosum), and Bolbosoma Porta, 1908 (Bolbosoma nipponi- cum)—were found in the NFSs and a harbor seal. This is a new record of C. alaskensis for the NFSs. Short biological notes of the species found are presented. Differences in spe- cies composition as well as in prevalence of acanthocephalans parasitizing NFSs were observed in subpopulations from four differentHOASonSt. Paul Island. Thehighest biodiversityof acanthocephalans and infection were found in subpopulations on Polovina and Morzhovyj HOAS, the lowest was on Lukanin HOAS. From 3.2 % (for C. validum) to 19.4 % (for C. villosum) of NFSs were infected by one acanthocephalan species; two species were found in 22.6 %; three in 9.7 %; and four in 3.2 %. Further studies of NFS parasites are necessary to follow the trends in parasitic infection rates and diversity in NFS population on the Pribilov Islands and for monitoring the influence of various ecological factors on NFS populations in Alaska.
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historic importance of some aspects of research by o wilford olsen on hookworms uncinaria lucasi in northern fur seals Callorhinus ursinus and steller sea lions eumatopias jubatus in 1951 on st paul island alaska
Parasitology Research, 2005Co-Authors: E T LyonsAbstract:The purpose of this paper is to disseminate, more widely, certain historically important aspects of research by O. Wilford Olsen on hookworms (Uncinaria lucasi) in northern fur seals (Callorhinus ursinus) and Steller sea lions (Eumatopias jubatus) in 1951 on St. Paul Island, Alaska. Highly meaningful facets of the research were recorded only in a report with limited availability by Olsen in 1952. Portions of his research presented here include measurements of hookworm free-living infective third-stage larvae (L3) and adults, photographs of bursae, and the conclusion that the species of hookworms (U. lucasi) is probably the same in both pinniped hosts. This information is especially important because very little has been published on taxonomy of hookworms in E. jubatus.
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historic importance of some aspects of research by o wilford olsen on hookworms uncinaria lucasi in northern fur seals Callorhinus ursinus and steller sea lions eumatopias jubatus in 1951 on st paul island alaska
Parasitology Research, 2005Co-Authors: E T LyonsAbstract:The purpose of this paper is to disseminate, more widely, certain historically important aspects of research by O. Wilford Olsen on hookworms (Uncinaria lucasi) in northern fur seals (Callorhinus ursinus) and Steller sea lions (Eumatopias jubatus) in 1951 on St. Paul Island, Alaska. Highly meaningful facets of the research were recorded only in a report with limited availability by Olsen in 1952. Portions of his research presented here include measurements of hookworm free-living infective third-stage larvae (L3) and adults, photographs of bursae, and the conclusion that the species of hookworms (U. lucasi) is probably the same in both pinniped hosts. This information is especially important because very little has been published on taxonomy of hookworms in E. jubatus.
Rolf R Ream - One of the best experts on this subject based on the ideXlab platform.
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evaluating exposure of northern fur seals Callorhinus ursinus to microplastic pollution through fecal analysis
Marine Pollution Bulletin, 2019Co-Authors: Mary J Donohue, Jason D Baker, Julie Masura, Rolf R Ream, Kayleigh Faulhaber, Thomas S Gelatt, Darren T LernerAbstract:Abstract Environmental microplastics are widely documented in marine life and bioaccumulation may present risks to marine predators. Investigations of microplastics in marine mammals are increasing, though none have examined animals routinely consumed by humans. Here, we investigate microplastic exposure in the northern fur seal (Callorhinus ursinus), a species consumed by humans, using fecal material. We examined 44 feces (scat) at sites encompassing the seals' eastern Pacific range. Multiple contamination control measures were implemented, including field and laboratory controls. Fragments were the most common microplastic recovered, in 55% (24/44) of scat and no controls (range 1 to 86 fragments/scat, mean 16.6, sd 19.1). Microplastic fibers were recovered from 41% of scats (18/44), though some controls contained fibers confounding fiber results. Fecal analysis documented northern fur seal exposure to microplastics throughout their eastern Pacific range.
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stable isotope models predict foraging habitat of northern fur seals Callorhinus ursinus in alaska
PLOS ONE, 2015Co-Authors: Tonya K Zeppelin, Devin S Johnson, Carey E Kuhn, Sara J Iverson, Rolf R ReamAbstract:We developed models to predict foraging habitat of adult female northern fur seals (Callorhinus ursinus) using stable carbon (δ13C) and nitrogen (δ15N) isotope values from plasma and red blood cells. Binomial generalized linear mixed models were developed using blood isotope samples collected from 35 adult female fur seals on three breeding colonies in Alaska during July-October 2006. Satellite location and dive data were used to define habitat use in terms of the proportion of time spent or dives made in different oceanographic/bathymetric domains. For both plasma and red blood cells, the models accurately predicted habitat use for animals that foraged exclusively off or on the continental shelf. The models did not perform as well in predicting habitat use for animals that foraged in both on- and off-shelf habitat; however, sample sizes for these animals were small. Concurrently collected scat, fatty acid, and dive data confirmed that the foraging differences predicted by isotopes were associated with diet differences. Stable isotope samples, dive data, and GPS location data collected from an additional 15 females during August-October 2008 validated the effective use of the models across years. Little within year variation in habitat use was indicated from the comparison between stable isotope values from plasma (representing 1-2 weeks) and red blood cells (representing the prior few months). Constructing predictive models using stable isotopes provides an effective means to assess habitat use at the population level, is inexpensive, and can be applied to other marine predators.
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prey selection of subadult male northern fur seals Callorhinus ursinus and evidence of dietary niche overlap with adult females during the breeding season
Marine Mammal Science, 2012Co-Authors: Katherine A Call, Rolf R ReamAbstract:During the breeding season northern fur seals (Callorhinus ursinus) congregate on the Pribilof Islands in large numbers creating the potential for intraspecific competition. Due to the declining trend in the Pribilof Islands population of fur seals, it is important to understand how prey resources are partitioned among the population. Fur seals exhibit a high degree of sexual dimorphism resulting in energetic differences among age and sex classes. Therefore, we hypothesized that subadult male and adult female fur seals would differ in the type and size of prey consumed. We examined the diets of subadult male (age 2–8; mean mass 28– 176 kg) and adult female (age ≥ 3 yr; mean mass 13–50 kg) seals on St. Paul Island from 1992 to 2000. Prey remains found in fecal samples were compared using niche overlap indices. There was nearly complete dietary niche overlap between subadult male and adult female fur seals. Walleye pollock (Theragra chalcogramma), Pacific salmon (Oncorhynchus spp.), Pacific herring (Clupeia pallasi), and cephalopods were common prey items found in the diets of both groups. We found differences in the size of pollock consumed and that geographic location of sample collection may be important in determining diet differences. Our results indicate high levels of dietary overlap among subadult male and adult female fur seals.
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diving ontogeny and lunar responses in a highly migratory mammal the northern fur seal Callorhinus ursinus
Marine Ecology Progress Series, 2010Co-Authors: Devin S Johnson, Sharon R. Melin, Rolf R ReamAbstract:Diving ontogeny studies enable the examination of both the evolution of diving strate- gies and the physiological constraints and environmental factors determining foraging behaviour. Northern fur seal (NFS) Callorhinus ursinus pups that undertake far-ranging migrations in their first year are an ideal species for examining such factors. The diving behaviour of 64 NFS pups from 4 North American breeding sites was studied using satellite-dive recorders deployed on pups prior to weaning. Summarised diving activity (6 h histograms of dive depth and duration) was recorded dur- ing the pups' first 8 mo at sea and transmitted via satellite. During the first month at sea, pups adopted the nocturnal diving patterns characteristic of adults, with average maximum nightly and crepuscular dive depths and durations exceeding daytime values by a factor of from 4 to 4.5. Diving capacity in terms of maximum depths (112 m) and durations (285 s) attained also increased linearly with age until ~8 to 10 mo of age. Overlaid on diving capability development was the significant influence of environmental cues, such as lunar phase, on migratory diving behaviour. During full moons, pups dived deeper and for longer periods than during other lunar phases, as pups likely mim- icked the behaviour of their vertically migrating prey. These findings indicate that prey accessibility, particularly for younger pups with reduced diving capacity, may prove more challenging during higher lunar illumination periods.
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population structure as revealed by mtdna and microsatellites in northern fur seals Callorhinus ursinus throughout their range
PLOS ONE, 2010Co-Authors: Bobette Dickerson, Rolf R Ream, Sacha Vignieri, Paul BentzenAbstract:Background The northern fur seal (Callorhinus ursinus; NFS) is a widely distributed pinniped that has been shown to exhibit a high degree of philopatry to islands, breeding areas on an island, and even to specific segments of breeding areas. This level of philopatry could conceivably lead to highly genetically divergent populations. However, northern fur seals have the potential for dispersal across large distances and have experienced repeated rapid population expansions following glacial retreat and the more recent cessation of intensive harvest pressure. Methodology/Principal Findings Using microsatellite and mitochondrial loci, we examined population structure in NFS throughout their range. We found only weak population genetic structure among breeding islands including significant FST and ΦST values between eastern and western Pacific islands. Conclusions We conclude that insufficient time since rapid population expansion events (both post glacial and following the cessation of intense harvest pressure) mixed with low levels of contemporary migration have resulted in an absence of genetic structure across the entire northern fur seal range.
