Decreasing sea ice conditions in western Hudson Bay and an increase in abundance of harbour seals (Phoca vitulina) in the Churchill River

Florko, Katie R. N.; Bernhardt, Warren; Breiter, C-Jae C.; Ferguson, Steven H.; Hainstock, M.; Young, Brent G.; Petersen, Stephen D.

doi:10.1007/s00300-018-2277-6

Cited by 17 publications

(7 citation statements)

References 47 publications

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“…have been observed in lower trophic level predators such as thick-billed murres Uria lomvia (Gaston et al 2003) and ringed seals (Young & Ferguson 2014, Yurkowski et al 2016. Similarly, the lengthening of the open-water period due to sea ice decline in the Arctic supports an increase in sub-Arctic marine mammals such as harbour seals (Florko et al 2018).…”

Section: Temporal Patterns and Sea Icementioning

confidence: 93%

“…Changes in sea ice conditions may affect prey availability, as harbour seals increased and ringed seals decreased in WH polar bear diet from 1994 to 1998, which was correlated with earlier breakup (Iverson et al 2006). Furthermore, harbour seals increased in abundance as sea ice cover declined in western Hudson Bay from 1996 to 2016 (Florko et al 2018). Lastly, higher δ 15 N values have also been associated with fasting (Hobson et al 1993) and WH polar bears have been reported to be spending more time on land, without access to prey, be cause of earlier breakup and later freeze-up (Stirling et al 1999, Regehr et al 2007, Lunn et al 2016, potentially leading to an increase in δ 15 N values.…”

Section: Temporal Patterns and Sea Icementioning

confidence: 99%

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Temporal and intra-population patterns in polar bear foraging ecology in western Hudson Bay

Johnson¹,

Hobson²,

Lunn³

et al. 2019

Mar. Ecol. Prog. Ser.

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Climate-mediated sea ice declines have led to alterations in ecosystem composition, phenology, and primary productivity, potentially altering trophic dynamics in Arctic marine ecosystems. As one of the Arctic's top predators and a species dependent on sea ice habitat for survival, polar bears Ursus maritimus are at risk of habitat loss from sea ice declines, and therefore have been used to monitor the effects of climate change in the Arctic. We used stable isotope (δ 15 N, δ 13 C) values of 806 hair samples collected from Western Hudson Bay (WH) polar bears from 1993−1994 and 2004−2016 to examine variations in isotopic niche size and diet within the population, patterns in foraging ecology over time, and the relationship between hair isotopic values and sea ice dynamics. We found significant variation in isotopic values between age-and sex-classes. Adult males had the highest δ 15 N and δ 13 C values and the largest isotopic niches, reflecting broader diets. In contrast, adult females (with and without cubs) and subadults differed isotopically from adult males, and their relatively smaller isotopic niches potentially make them more vulnerable to habitat change. Population δ 15 N values significantly increased over time from 1993 (mean ± SD: 18.8 ± 0.5 ‰) to 2016 (19.5 ± 0.7 ‰), while δ 13 C values significantly decreased from 1993 (−16.2 ± 0.3 ‰) until 2011 (−17.7 ± 0.2 ‰) before increasing until 2016 (−17.0 ± 0.3 ‰). Values of δ 13 C were significantly correlated with length of the open-water period, suggesting that this apex predator's foraging ecology was affected by climate change. We suggest that WH polar bears may have undergone a significant dietary niche shift and/or that the baseline isotopic values in this ecosystem may have changed over the last 25 yr in response to climate change.

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Section: Temporal Patterns and Sea Icementioning

confidence: 93%

Section: Temporal Patterns and Sea Icementioning

confidence: 99%

Temporal and intra-population patterns in polar bear foraging ecology in western Hudson Bay

Johnson¹,

Hobson²,

Lunn³

et al. 2019

Mar. Ecol. Prog. Ser.

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“…Changes in environmental conditions may affect species directly by challenging their physiological tolerance levels or indirectly by disrupting vital interspecies interactions (Tylianakis et al 2008). Species may respond with changes in abundance or shifts in distribution (Florko et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Spatio-temporal patterns in fin whale Balaenoptera physalus habitat use in the northern Gulf of St. Lawrence

Schleimer¹,

Ramp²,

Plourde³

et al. 2019

Mar. Ecol. Prog. Ser.

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Significant ecosystem changes in the Gulf of St. Lawrence (GSL) have had farreaching effects at all trophic levels. The abundance of fin whales (Balaenoptera physalus) has declined significantly in the northern GSL over the past decade. This study aimed to test the hypothesis that the observed decline was correlated to changing environmental conditions. Cetacean sighting data from 292 surveys, resulting in 2986 fin whale encounters from 2007 to 2013, were used to fit two separate generalised additive models in terms of (1) bathymetric and oceanographic variables (the proxy model) and (2) modelled krill biomass (the prey model). The concept of "handling time" was introduced to correct for time off search effort, applicable to other studies relying on opportunistically sampled data. While a positive correlation between krill biomass and fin whale numbers was found, the performance of the proxy model (24.2 % deviance explained) was overall better than the prey model (11.8 %). Annual predictive maps derived from the final proxy model highlighted two key areas with recurrently high relative fin whale abundance and a significant overlap with shipping lanes. While both models provided evidence for an annual decline in relative fin whale abundance, static bathymetric features were the most important predictors of habitat use and no correlation between dynamic variables and the decline was found. High resolution prey data and a better understanding of the feeding ecology of fin whales are proposed to further investigate the predator-prey relationship and decline of fin whales in the GSL.

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“…They even tend to avoid areas with thick ice where they cannot maintain breathing holes and are at risk of predation by polar bears [10,150]. As such, decreasing sea ice may increase the available habitat for harbour seals in seasonally ice-covered areas such as Svalbard, the western Hudson Bay, the St Lawrence Estuary or Greenland [150][151][152], which in turn could result in a northwards range expansion. However, other features, such as bathymetry, may still limit their expansion, as harbour seals are generally considered relatively shallow divers [100,153,154].…”

Section: Changes In Physical Habitat Affect Distribution Patternsmentioning

confidence: 99%

Marine Mammals in a Changing World

2022

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Decreasing sea ice conditions in western Hudson Bay and an increase in abundance of harbour seals (Phoca vitulina) in the Churchill River

Cited by 17 publications

References 47 publications

Temporal and intra-population patterns in polar bear foraging ecology in western Hudson Bay

Temporal and intra-population patterns in polar bear foraging ecology in western Hudson Bay

Spatio-temporal patterns in fin whale Balaenoptera physalus habitat use in the northern Gulf of St. Lawrence

Marine Mammals in a Changing World

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