Temporal variation in western Hudson Bay ringed seal Phoca hispida diet in relation to environment

Chambellant, Magaly; Stirling, Ian; Ferguson, Steven H.

doi:10.3354/meps10134

Cited by 56 publications

(72 citation statements)

References 76 publications

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“…However, the degree of ontogenetic diet and niche shift varied spatially. Our mixing model results revealed that pelagic forage fish, mainly Arctic cod, are the principal prey for both age classes, but that subadults consume more zooplankton than adults, in agreement with previous research (Lowry et al 1980;Bradstreet and Cross 1982;Weslawski et al 1994;Holst et al 2001;Dehn et al 2007;Chambellant et al 2013). In the Arctic, among ringed seal prey items, Arctic cod possesses a higher energy content than zooplankton and crustaceans (24.2 and 12.3-21.1 kJ/g dw −1 , respectively; Weslawski et al 1994) and other pelagic fish such as capelin (21.2 kJ/g dw −1 ; Hedeholm et al 2011) and sand lance (20.1 kJ/g dw −1 ; Anthony et al 2000).…”

Section: Discussionsupporting

confidence: 92%

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Spatial and temporal variation of an ice-adapted predator’s feeding ecology in a changing Arctic marine ecosystem

et al. 2015

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Spatial and temporal variation can confound interpretations of relationships within and between species in terms of diet composition, niche size, and trophic position (TP). The cause of dietary variation within species is commonly an ontogenetic niche shift, which is a key dynamic influencing community structure. We quantified spatial and temporal variations in ringed seal (Pusa hispida) diet, niche size, and TP during ontogeny across the Arctic-a rapidly changing ecosystem. Stable carbon and nitrogen isotope analysis was performed on 558 liver and 630 muscle samples from ringed seals and on likely prey species from five locations ranging from the High to the Low Arctic. A modest ontogenetic diet shift occurred, with adult ringed seals consuming more forage fish (approximately 80 versus 60 %) and having a higher TP than subadults, which generally decreased with latitude. However, the degree of shift varied spatially, with adults in the High Arctic presenting a more restricted niche size and consuming more Arctic cod (Boreogadus saida) than subadults (87 versus 44 %) and adults at the lowest latitude (29 %). The TPs of adult and subadult ringed seals generally decreased with latitude (4.7-3.3), which was mainly driven by greater complexity in trophic structure within the zooplankton communities. Adult isotopic niche size increased over time, likely due to the recent circumpolar increases in subarctic forage fish distribution and abundance. Given the spatial and temporal variability in ringed seal foraging ecology, ringed seals exhibit dietary plasticity as a species, suggesting adaptability in terms of their diet to climate change.

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Section: Discussionsupporting

confidence: 92%

“…), Themisto libellula, Arctic cod, capelin, sand lance, and sculpin (Bradstreet and Cross 1982;Dehn et al 2007;Chambellant et al 2013). Prey items were collected in 2009-2010 and 2012 via nets and trawls in the summer (June-September) in Resolute and Saglek Bay.…”

Section: Sample Collection and Preparationmentioning

confidence: 99%

Spatial and temporal variation of an ice-adapted predator’s feeding ecology in a changing Arctic marine ecosystem

et al. 2015

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“…(Gaston et al, 2012;Chambellant et al, 2013). Rainbow smelt (Osmerus mordax), a temperate species that is expected to thrive in Hudson Bay (Franzin et al, 1994), has also begun to appear in the diet of ringed seals harvested from Arviat (Chambellant et al, 2013). Although the effects that such changes could have on ringed seals are unclear, it has been suggested that climate-related shifts in marine mammal prey communities could lead to nutritional stress caused by limited access to high-quality prey (Bluhm and Gradinger, 2008).…”

Section: Discussionmentioning

confidence: 99%

“…Bottom-up processes also appear to be influencing ecosystem dynamics in the Hudson Bay marine environment and changing the feeding ecology of ringed seals and marine birds (Gaston et al, 2012;Chambellant et al, 2013;Young and Ferguson, 2014). Changes in pelagic fish species include a shift from an abundance of Arctic cod (Boreogadus saida) to an increase in sub-Arctic species such as capelin (Mallotus villosus) and sandlance (Ammodytes sp.)…”

Section: Discussionmentioning

confidence: 99%

“…Changes in pelagic fish species include a shift from an abundance of Arctic cod (Boreogadus saida) to an increase in sub-Arctic species such as capelin (Mallotus villosus) and sandlance (Ammodytes sp.) (Gaston et al, 2012;Chambellant et al, 2013). Rainbow smelt (Osmerus mordax), a temperate species that is expected to thrive in Hudson Bay (Franzin et al, 1994), has also begun to appear in the diet of ringed seals harvested from Arviat (Chambellant et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

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Variation in Ringed Seal Density and Abundance in Western Hudson Bay Estimated from Aerial Surveys, 1995 to 2013

Young¹,

Ferguson²,

Lunn³

2015

ARCTIC

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ABSTRACT. We conducted systematic aerial surveys of ringed seals along strip transects in western Hudson Bay (WHB), Canada, in late May to early June of 1995June of -97, 1999June of , 2000June of , 2007June of -10, and 2013. The density of ringed seals hauled out on ice over the entire study area ranged from 1.22 seals/km 2 in 1995, to 0.20 seals/km 2 in 2013. Density estimates varied significantly over the study period and, with the exception of 2013, appeared to follow a cyclical pattern. Although density estimates also appear to follow a downward trend over time, results of multiple linear regression, weighted by survey effort, indicated no significant trend in ringed seal density as a function of year, survey date, or proportion of open water. In addition, no significant correlation was observed among any of the environmental variables and density estimates. As the proportion of seals hauled out at the time of the survey is unknown, the density estimates of WHB ringed seals presented in this study should be considered indices that might be useful to explore trends in abundance. Although our results do not indicate that a significant decline has occurred, the low density estimate in 2013 may indicate that population changes unrelated to a natural cycle are taking place. We were unable to test for direct effects of changes in food supply or predation, but polar bears, Arctic foxes, and Inuit communities in the Hudson Bay region all would be negatively affected should ringed seal populations undergo significant declines. Further monitoring and directed research are necessary to understand what mechanism may be responsible for the observed changes in ringed seal density.

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Distance measures and optimization spaces in quantitative fatty acid signature analysis

Bromaghin

Rode

Budge

et al. 2015

Ecology and Evolution

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Quantitative fatty acid signature analysis has become an important method of diet estimation in ecology, especially marine ecology. Controlled feeding trials to validate the method and estimate the calibration coefficients necessary to account for differential metabolism of individual fatty acids have been conducted with several species from diverse taxa. However, research into potential refinements of the estimation method has been limited. We compared the performance of the original method of estimating diet composition with that of five variants based on different combinations of distance measures and calibration-coefficient transformations between prey and predator fatty acid signature spaces. Fatty acid signatures of pseudopredators were constructed using known diet mixtures of two prey data sets previously used to estimate the diets of polar bears Ursus maritimus and gray seals Halichoerus grypus, and their diets were then estimated using all six variants. In addition, previously published diets of Chukchi Sea polar bears were re-estimated using all six methods. Our findings reveal that the selection of an estimation method can meaningfully influence estimates of diet composition. Among the pseudopredator results, which allowed evaluation of bias and precision, differences in estimator performance were rarely large, and no one estimator was universally preferred, although estimators based on the Aitchison distance measure tended to have modestly superior properties compared to estimators based on the Kullback–Leibler distance measure. However, greater differences were observed among estimated polar bear diets, most likely due to differential estimator sensitivity to assumption violations. Our results, particularly the polar bear example, suggest that additional research into estimator performance and model diagnostics is warranted.

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Temporal variation in western Hudson Bay ringed seal Phoca hispida diet in relation to environment

Cited by 56 publications

References 76 publications

Spatial and temporal variation of an ice-adapted predator’s feeding ecology in a changing Arctic marine ecosystem

Spatial and temporal variation of an ice-adapted predator’s feeding ecology in a changing Arctic marine ecosystem

Variation in Ringed Seal Density and Abundance in Western Hudson Bay Estimated from Aerial Surveys, 1995 to 2013

Distance measures and optimization spaces in quantitative fatty acid signature analysis

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