68 research outputs found
Narwhal (Monodon monoceros) diet and dive behaviour as an assessment of foraging adaptability with changing climate
No full textNarwhals (Monodon monoceros) are sentinel species in the Arctic environment and are a vital component for Inuit culture and subsistence. The Arctic is undergoing rapid changes in temperature and sea ice cover and relatively little is known about how this has and will change narwhal foraging behaviour. There are three narwhal populations in the world, the Baffin Bay (BB), Northern Hudson Bay (NHB), and East Greenland (EG) populations; however, foraging behaviour, in terms of dive behaviour and primary dietary components, has really only been investigated in the BB population. Using a combination of stable isotopes, fatty acids, genetic techniques, and satellite tracking technologies I evaluated foraging behaviour in all three of the world’s narwhal populations. I also investigated social structure in the BB population to determine how adaptable narwhals are to a changing and dynamic Arctic environment. Stable isotopes (δ13C and δ15N) and fatty acids are chemical signatures in the tissues of an organism that can provide long-term information on their diet over varying temporal scales depending upon the tissue. Stable isotope analysis in the three narwhal populations found they forage on different primary prey, suggesting narwhal are adaptable in their preferred prey and that there is potential for them to adjust foraging behavior in the face of changing climate. Dietary changes were also assessed over three decades to determine how sea ice changes have affected narwhal foraging for the NHB and BB populations. Dietary changes were evident and can be attributed to changes in sea ice patterns and an altered migratory pathway for narwhals. An understanding of narwhal social structure is also needed to determine how behaviourally flexible narwhal are in diet and site fidelity. Genetic relatedness and dietary signatures from fatty acids were assessed for an entrapped group to determine if individuals that are closely related forage together, which would support a matrilineally driven social structure where females teach their young foraging strategies, and/or travel and forage together. I found no evidence that narwhals form a matrilineal social group, but they may display a fission-fusion structure, which may be an adaptation to patchy prey distribution in the Arctic. Finally, narwhal dive behaviour in all three populations was investigated to determine if dive behaviour could be used to predict diet. Dive differences among populations did correspond with differences in diet, suggesting that narwhals employ specialized foraging strategies. This has repercussions for their ability to adapt to ecosystem changes. Overall, narwhals may be more flexible in terms of their foraging behaviour than previously believed. However, an increased resilience to changing food webs will not be the only predictor of how narwhals will fare in the face of a changing climate; how they respond to increased industrial activities in their preferred habitats, increased predation from southern predators, and increased competition from southern cetaceans and humans alike, will play an equally large role in how they cope with the future.February 201
Trace element and stable isotope analysis elucidate stock structure in a narwhal (Monodon monoceros) population with no genetic substructure
No full textChemical composition of tissues acts a biological tag to discriminate among groups of animals that inhabit different areas. In Canada, subsistence hunting of the Baffin Bay narwhal (Monodon monoceros Linnaeus, 1758) population is managed as stocks represented by summer aggregations. However, narwhals are highly mobile and hunted during the migration while stocks mix. Thus, information that can help managers decipher the stock origin of hunted individuals to prevent overexploitation of animals adapted to particular summering grounds is needed. Stable isotope and trace element analyses were conducted on narwhal skin tissues from five stocks in the eastern Canadian Arctic from 1990-2015. Discriminant analysis showed there was a significant difference between Admiralty Inlet and Eclipse Sound stocks in the summer residency period and both differed from Jones Sound and Somerset Island. During the migration season, there was more overlap and less distinction among stocks, but 75% of animals were classified correctly to their defined stocks in both periods. Together stable isotope and trace element analyses are useful for delineating stocks, and could be used to complement other stock discrimination approaches.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
The Fine Art of Leaving
No full textA personal narrative is presented which explores the author\u27s experience of resigning and employing into a new job as a nurse
Evaluating the relationship between blubber lipids and fatty acids across blubber thickness in beluga whales (Delphinapterus leucas) harvested for subsistence in the Inuvialuit Settlement Region
No full textBlubber is an adapted fat layer common to marine mammals that is used for buoyancy, thermoregulation, and energy storage. Its thickness ranges widely between species, from 2.5 cm in harbour porpoises (Phocoena phocoena), up to 50 cm in bowhead whales (Balaena mysticetus). Blubber is composed of various lipids and fatty acids and is not homogenous in structure or function throughout its depth. Depletion of energy stores from environmental or nutritional stress affects blubber thickness and thus decreases its functionality and the fitness and survival of the animal. Recently, beluga whales (Delphinapterus leucas) from the Eastern Beaufort Sea (EBS) population have been observed with thinner blubber. Changes in blubber thickness and composition may reflect changes in prey availability and quality, or infection/injury of an individual, which may impact individual growth and reproduction rates, and overall population health. The composition and stratification of fatty acids and total lipid percent of EBS beluga blubber was examined and compared between individuals of differing blubber thicknesses. The influence of environmental temperature on fatty acid composition, as well as how biological covariates influence total lipid percent in the blubber and muscle tissue was also explored. Stratification of fatty acids was present, and the inner, middle, and outer blubber layers contained different proportions of fatty acid types as a function of blubber thickness. The innermost blubber layer contained more dietary fatty acids and fatty acids with higher melting points such as polyunsaturated fatty acids (PUFAs) and long-chain monounsaturated fatty acids (LCMUFAs), while the outermost blubber layer contained non-dietary fatty acids and fatty acids with lower melting points such as the short-chain monounsaturated fatty acids (SCMUFAs). The outer layers of blubber contained greater delta-9 desaturation values, demonstrating the impact that environmental temperature has on the fatty acid composition of the blubber. Whales with thinner blubber contained more SCMUFAs and fewer LCMUFAs than whales with thicker blubber, providing evidence of lower feeding rates in this subset of whales and demonstrating the altered distribution of fatty acids with lower melting points in thinner blubber in order to address environmental temperature effects. Total lipid percent was not influenced by body length, harvest location, standardized blubber thickness (body condition), or age, and was greatest in the middle layer of blubber. A significant, negative relationship was found between total lipid percent in the muscle tissue and outer blubber lipid percent, and a positive, significant relationship was found between total lipid percent in the muscle and total protein percent in the muscle. A shift in prey species distributions due to climate change is occurring in the Arctic, and thus a greater occurrence of thin beluga blubber and loss of the lipid-rich middle layer may occur. An overall reduction in thickness may render belugas vulnerable to increases in energy expenditure to maintain core body temperatures. Knowledge of beluga blubber, what factors affect its composition, and what compositional changes occur in thinner blubber is necessary to best inform conservation and management practices.February 202
Seasonal estuary use of beluga whales
No full textBeluga whales are year-round residents of the Arctic and top predators in the ecosystem. Many beluga whale populations are migratory and spend winters in polynyas and breaks in the ice to avoid entrapment. Once the ice in begins to break up and melt, beluga whale populations migrate to the same Arctic estuaries year after year. Possible uses of estuaries include feeding, aiding in skin sloughing, protection of calves from predators, and other warm water benefits. However, much is still unknown about the use of these habitats both spatially and ecologically. I investigated estuary use by Cumberland Sound beluga whales, through their distribution. Their summering area covers northern fiords of Cumberland Sound, including Clearwater Fiord where there is a large estuary. While the whales are known the frequent the fiords, the specific distribution and core areas were unknown. Using very high resolution satellite imagery, I established critical habitat within the summering region. I also provided an updated estuary abundance estimate for this small beluga whale population. Second, I explored estuary use of Hudson Bay beluga whales by investigating the primary feeding season. Migratory species often have one season where they eat the majority of their food for the year and build fat reserves, which provides energy and supports thermoregulation. This fat can be used to investigate feeding ecology of whales. Despite being the largest beluga population, fundamental ecological knowledge of Hudson Bay beluga whales, such as the primary feeding season is unknown. I used lipid content and adipocyte size throughout the blubber of Hudson Bay beluga whales to identify when they were consuming the majority of their food. I determined that there was no consistent primary feeding season, and therefore both summering and wintering areas were used for feeding. By exploring the beluga whales’ use of seasonal habitat through distribution and foraging ecology, my thesis illuminates fundamental ecological knowledge about two beluga whale populations.University of Manitoba
Province of ManitobaMay 202
Using underwater images to sample and determine trends in lateralization and group counts when beluga calves and juveniles are present
No full textIn this thesis, I used underwater images to determine patterns in lateralization and group size when beluga calves and juveniles are present. Usually, lateralization is defined by either a left or right preference, but using underwater images (an untested, non-invasive approach) provided an opportunity to analyze position bias from three distinct planes, the sagittal (left or right), coronal (dorsal or ventral), and transverse (anterior or posterior). My research found that the presence of the boat may have affected lateralization as juveniles were most frequently observed on the left. This position bias was possibly due to their mothers, who may have positioned themselves between their young and the less familiar boat. Additionally, while both calves and juveniles preferred to be positioned in ventral positions near their mother, juveniles were most frequently observed at the anterior of the head region, while calves were in the posterior or tail region or infant position. This difference is likely due to juveniles having increased swimming abilities, allowing them to compromise the hydrodynamic benefits of the infant position for the anterior position, as the head or anterior is preferred for social interactions in whales. In my second chapter, I determined if mother and calf/juvenile dyads selected larger groups. My results indicated that groups that contained calves and juveniles had more adults present than groups that contained adults only. In comparison with aerial surveys, I found that group sizes in underwater images were significantly larger across all age classes. This may be an effect of methods used, as boats used to collect camera images may have moved to locations where beluga were aggregating. However, further research is needed to determine the effect of boats on juveniles’ interactions.Assiniboine Park Zoo
Project Learning Tree CanadaOctober 202
Behavioral divergence in a changing Arctic: Novel insights into the movement ecology of Eastern Beaufort Sea belugas from historical tracking data
No full textThe Eastern Beaufort Sea (EBS) population undertakes an annual migration from their summering grounds in the western Canadian Arctic to their winter range in the Chukchi and Bering Seas. EBS belugas were instrumented with satellite-linked transmitters in the shallow waters of the Mackenzie Delta over the course of the 1990s, 2000s and 2010s in collaboration with Inuvialuit communities. This thesis aggregated these datasets to examine the range and diversity of EBS beluga movements at two different scales. First, dynamic Brownian Bridge Movement Models (dBBMMs) were used to re-establish seasonal ranges and high-use areas across the annual migration cycle. Evidence of individual stopovers on bathymetric features, together with a potential fall staging area in the Chukchi Sea, suggests that EBS belugas depend on a network of sites across their annual range to support long-distance movements. Second, variation in summer space use was quantified, individuals with similar summer movements were clustered, and the link between space use and migration timing was examined. Three main summering groups were identified, and targeted distinct high-use areas and were generally associated with different individual traits: A group of mature males departed from the Mackenzie Estuary by mid-July and travelled to Viscount Melville Sound, a mixed group remained in the Amundsen Gulf and travelled between nearshore and offshore sites throughout the season, while a smaller, mixed group targeted the Beaufort Sea slope and similarly returned to the Estuary before migrating. Fall migration timing varied between and within groups, suggesting that summer space use, individual variation and external drivers influence the date of departure. These findings highlight avenues for future research on EBS beluga space use, migration timing, population structure and abundance that may better account for the presence of spatially and temporally segregated groups.ArcticNet
Fisheries and Oceans CanadaFebruary 202
Monitoring beluga whales from space: estimating abundance and evaluating social structure using VHR satellite imagery
No full textImproving monitoring efforts of Arctic species is becoming increasingly important given the rate of change in Arctic marine ecosystems and the presumed impact on Arctic marine mammals, such as beluga whales (Delphinapterus leucas). Very High Resolution (VHR) satellite imagery is emerging as a promising tool for efficiently monitoring beluga whale populations, which can be logistically challenging with current methods. Here we use VHR satellite imagery to investigate two conservation relevant aspects of beluga whale populations: abundance and social dynamics. First we determined two missing pieces of information required to estimate beluga whale abundance in VHR satellite imagery: 1) depths that beluga whales are visible in VHR satellite images, which are used to define availability bias correction factors, and 2) a comparison of abundance estimates in VHR satellite imagery to current aerial methods. We determined that beluga whales can be detected only at the surface in turbid water and at depths of 0 – 2 m in clear water in 0.31 m resolution VHR imagery, and that beluga whale availability bias corrected abundance estimates made from synchronous VHR satellite imagery and drone surveys were comparable. We further used VHR imagery to describe beluga whale group size, composition, and cohesion in beluga whale populations from Cumberland Sound, Eastern High Arctic – Baffin Bay, and Western Hudson Bay in relation to anthropogenic disturbance, density, and social context. We found that group size decreased with harvest, which seemingly reflects population decline or removal of key social individuals, while recent increases in vessel traffic were associated with larger group sizes and greater spatial cohesion, possibly suggesting an adaptative response to increase vigilance to vessel disturbance. Beluga whale social cohesion was mainly influenced by the presence of juvenile whales, with adult-juvenile mixed groups having smaller inter-individual distances than groups with adults only. Future beluga whale management efforts may benefit from incorporating VHR imagery into research programs and continuing to assess beluga whale social group dynamics alongside traditional abundance estimates; particularly given the expansion of anthropogenic disturbance in the Arctic.October 202
A semi-automated method using object-based image analysis (OBIA) to detect and enumerate beluga whales in summer from very high-resolution (VHR) satellite imagery
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