Current trends toward warmer air temperatures and longer ice free seasons in Hudson Bay are expected to cause changes in Arctic marine ecosystem dynamics. Ringed seals (Phoca hispida) will likely experience changes in levels of predation, competition, and prey availability. The purpose of this thesis was to investigate seasonal, inter-annual, and spatial variation in Hudson Bay ringed seal feeding ecology. Fatty acid composition, δ15N, and δ13C varied significantly by season, suggesting seasonal changes in foraging habitat and diet. Spatial differences in ringed seal stable isotope ratios occurred between western and eastern Hudson Bay, and there was a strong relationship between spring air temperature and δ15N. Peak δ15N occurred within a range in spring air temperatures between approximately -5°C and -2°C. I propose that the high δ15N observed in ringed seals within this temperature range is indicative of relatively greater importance of capelin (Mallotus villosus) in the ringed seal diet.

Current trends toward warmer air temperatures and longer ice free seasons in Hudson Bay are expected to cause changes in Arctic marine ecosystem dynamics. Ringed seals (Phoca hispida) will likely experience changes in levels of predation, competition, and prey availability. The purpose of this thesis was to investigate seasonal, inter-annual, and spatial variation in Hudson Bay ringed seal feeding ecology. Fatty acid composition, δ15N, and δ13C varied significantly by season, suggesting seasonal changes in foraging habitat and diet. Spatial differences in ringed seal stable isotope ratios occurred between western and eastern Hudson Bay, and there was a strong relationship between spring air temperature and δ15N. Peak δ15N occurred within a range in spring air temperatures between approximately -5°C and -2°C. I propose that the high δ15N observed in ringed seals within this temperature range is indicative of relatively greater importance of capelin (Mallotus villosus) in the ringed seal diet.

No description available.

Thesis (Ph. D.)--University of Helsinki, 2000. / Includes bibliographical references (p. 35-43). Also available in electronic format via Internet.

This thesis presents an exploratory approach using detailed zooarchaeological analysis to evaluate the nature of ringed seal ( Phoca hispida) remains from three seasonally different Thule sites in the Hazard Inlet area of Somerset Island, Nunavut. Most Thule research focuses on winter occupation and presents Thule as a whaling society. Little attention has been given on the nature of sealing during Thule occupation and research on seasonal differences of seal remains from Thule sites remains scarce. This thesis is thus one of the first to focus on ringed seal remains from seasonally different Thule sites through an analysis of over 30,000 bone specimens. The goal of this thesis is to determine if the seal assemblages are a product of differential butchering and transport, taphonomic processes, or if external factors are also playing a role in shaping the faunal record. The analysis considers variability within each site as well as between the sites. Overall, a moderate to strong correlation was found between bone density and the seal bone elements identified while a negative correlation existed with the elements and FUI (food utility indices). This led to the conclusion that taphonomy was the leading agent shaping the seal remains at Hazard Inlet. However, enough variation existed within each site to consider the role of outside factors, such as the presence of dogs, food preferences, food storage and season of occupation in shaping the seal remains at Hazard Inlet.

Dental annuli analyses were performed on 170 ringed seal (Phoca hispida) canines recovered from five Thule semisubterranean houses located at site PaJs-13 at Hazard Inlet, Somerset Island in the central Canadian Arctic. Season of death results indicate greater seal hunting during the spring. Age at death results were used to produce mortality profiles which, when compared with idealized patterns, revealed a prime-dominated pattern indicating the presence of some selective factor in the subsistence strategy. Based on ethnographical studies of traditional seal hunting techniques, conscious selection was eliminated as a factor. Biological studies of ringed seal demonstrate that during the spring, older, sexually mature seals, occupy breeding areas in stable fast ice formations located close to the coast in complex coastal areas. Younger immature seals, on the other hand, occupy areas of unstable pack ice formations either further from the shore in complex coastal areas, or along simple coastlines. The archaeological mortality patterns do not clearly resemble either complex or simple coast modern populations, although a trend toward simple coasts was observed. This observation is consistent with the site location, which allows greater access to pack ice formations. The appearance of selective biological factors affecting random human subsistence strategies indicates that caution must be utilized when interpreting mortality patterns.

Persistent organic pollutants such as polychlorinated biphenyls (PCBs), DDT and polybrominated diphenyl ethers (PBDEs) tend to accumulate in biota and are transferred through the aquatic food web, which result in a high accumulation in marine mammals. In recent years various novel flame retardants (nBFRs), which have replaced the banned PBDEs, have also started to occur in the environment. These nBFRs have similar properties as PBDEs, such as long-range transport and accumulation in biota. The purpose with this study was to evaluate a method by using pre-packed silica columns for quantification of PCBs, DDT, PBDEs and nBFRs in seal blubber, in order to facilitate the pre-treatment and decrease the time. To elute the different POPs from the pre-packed silica column; hexane, toluene and dichloromethane were used in different stages. By using this method levels of PCB and DDT were determined. For DDT the concentration was 8.28 ng/g lipid and 8.94 ng/g lipid for the two samples that was analysed, and the analysis of the PCBs showed a higher trend for the higher chlorinated PCBs. As the pre-packed silica columns are a relative new method. Further studies are therefore needed on these columns to further improve the sample clean-up and fractionation of the different POPs in environmental samples.

No description available.

No description available.

The release of 260 kg of polychlorinated biphenyls (PCBs) by a military radar station into Saglek Bay (Labrador) in the eastern Canadian Arctic contaminated adjacent marine sediments, and some fish, seabirds, and ringed seals. However, attributing the PCBs found in high trophic level and highly mobile marine mammals to any point source is, in most cases, impossible. This thesis demonstrated the extent to which a local PCB source at Saglek Bay led to the contamination and health effects in ringed seals. The dominance of PCBs at this contaminated marine site afforded a unique opportunity to evaluate the effects of this single class of industrial chemical in a manner that has not been previously possible in marine mammals. We used a variety of tools to characterize the contribution of local PCB contamination in the Labrador ringed seal food web. These tools included: 1) univariate and multivariate statistical exploration of contaminant patterns; 2) stable isotope ratios and fatty acid signatures to describe feeding ecology; and 3) satellite telemetry to track the movements of seals on the coast. Divergent PCB congener profiles and contaminant ratios enabled an assignment of seals into either ‘local’ or ‘long-range’ categories, with up to 60% of ringed seals sampled exhibiting patterns consistent with the local source. PCB concentrations in locally-contaminated adult males were 2-fold higher than in those exposed only to long-range PCB sources. Seals with smaller home ranges had an increased likelihood of feeding on prey contaminated by the local PCB source. Similar fatty acid profiles between those seals with ‘local’ PCB profiles and those with ‘long-range’ or background profiles indicate little support for the possibility that differential feeding ecologies explained the divergent PCB profiles. Ringed seals fed predominantly on zooplankton (Mysis oculata and Themisto libellula), dusky snailfish (Liparis gibbus) and arctic cod (Boreogadus saida). Heavier PCB profiles in the Saglek food web, compared to the same species exposed to only background contaminants, provided additional insight into the mechanisms of localized PCB contamination of some Labrador ringed seals. In addition to ascertaining the importance of a point source to contamination in ringed seals, we assessed the effects of PCBs on their health through quantitative real-time polymerase chain reaction (qPCR) assay. Levels of mRNA transcripts for five gene targets, including aryl hydrocarbon receptor (Ahr), interleukin-1 beta (Il1b), estrogen receptor alpha (Esr1), insulin-like growth factor receptor 1 (Igf1) and glucocorticoid receptor alpha (Nr3c1), correlated with increasing levels of PCBs, indicating an effect of this persistent organic pollutant (POP) in these seals. Threshold values were calculated for these five genes, with the most conservative value being 1,380 ng/g lipid weight (lw). Approximately 14% of the seals sampled exceeded this threshold, suggesting a risk of adverse effects in a proportion of the local population attributed to PCBs. While the implications for these sublethal molecular changes at the individual or population level are unclear, contaminant-related changes in endocrine, immune, and molecular endpoints have been observed in ringed seals from the Baltic Sea exhibiting reproductive and developments abnormalities, and virus epizootics. Results of this study improve our understanding of the effects of PCBs in free-ranging marine mammals and provide new information needed to inform mitigation and monitoring efforts, both for ringed seals in the north and other seals around the world. / Graduate / 0306 / 0768 / 0383 / tanya@raincoast.org