Demographic, ecological, and physiological responses of ringed seals to an abrupt decline in sea ice availability

Ferguson, Steven H.; Young, Brent G.; Yurkowski, David J.; Anderson, Randi; Willing, Cornelia; Nielsen, Ole

doi:10.7717/peerj.2957

Cited by 90 publications

(49 citation statements)

References 72 publications

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“…Changes in body condition have also been reported in several other marine predators in the Beaufort Sea ecosystem, which have been hypothesized to reflect an increase in secondary productivity and a decrease in the availability of Arctic cod (Boreogadus saida), an important forage fish and the main prey of the beluga population (Harwood et al, 2015;Loseto et al, 2009). Reductions in body condition of ringed seals, Pusa hispida (Ferguson et al, 2017), and polar bears, Ursus maritimus (Stirling and Derocher, 2012), and mortality events in walrus, Odobenus rosmarus (Fischbach et al, 2009), have similarly been associated with climate-induced loss of sea ice. Reductions in sea ice not only affect habitat use by Arctic whales but have also facilitated the northward migration of temperate species (Bouchard et al, 2017;Falardeau et al, 2014).…”

Section: Introductionmentioning

confidence: 89%

Body condition impacts blood and muscle oxygen storage capacity of free-living beluga whales (Delphinapterus leucas)

Choy

Campbell

Berenbrink

et al. 2019

Journal of Experimental Biology

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Arctic marine ecosystems are currently undergoing rapid environmental changes. Over the past 20 years, individual growth rates of beluga whales (Delphinapterus leucas) have declined, which may be a response to climate change; however, the scarcity of physiological data makes it difficult to gauge the adaptive capacity and resilience of the species. We explored relationships between body condition and physiological parameters pertaining to oxygen (O 2 ) storage capacity in 77 beluga whales in the eastern Beaufort Sea. Muscle myoglobin concentrations averaged 77.9 mg g −1 , one of the highest values reported among mammals. Importantly, blood haematocrit, haemoglobin and muscle myoglobin concentrations correlated positively to indices of body condition, including maximum half-girth to length ratios. Thus, a whale with the lowest body condition index would have ∼27% lower blood (26.0 versus 35.7 ml kg −1 ) and 12% lower muscle (15.6 versus 17.7 ml kg −1 ) O 2 stores than a whale of equivalent mass with the highest body condition index; with the conservative assumption that underwater O 2 consumption rates are unaffected by body condition, this equates to a >3 min difference in maximal aerobic dive time between the two extremes (14.3 versus 17.4 min). Consequently, environmental changes that negatively impact body condition may hinder the ability of whales to reach preferred prey sources, evade predators and escape ice entrapments. The relationship between body condition and O 2 storage capacity may represent a vicious cycle, in which environmental changes resulting in decreased body condition impair foraging, leading to further reductions in condition through diminished prey acquisition and/or increased foraging efforts.

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Section: Introductionmentioning

confidence: 89%

Body condition impacts blood and muscle oxygen storage capacity of free-living beluga whales (Delphinapterus leucas)

Choy

Campbell

Berenbrink

et al. 2019

Journal of Experimental Biology

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“…In contrast, southern seals invested more into offspring at an earlier age to take advantage of more productive environmental conditions (Stearns, 1992). In the south, seals cycled seasonally from high blubber storage (up to 60% of body mass) to very low body condition (30% blubber) that likely threatened their survival (Ferguson et al, 2017;Ferguson et al, 2018;Young & Ferguson, 2013). Progeny born into southern regions likely encountered good feeding conditions during the open-water season allowing for faster growth and earlier reproduction, with shorter longevity as a tradeoff.…”

Section: Discussionmentioning

confidence: 99%

“…We were unable to measure maximum lifespan and instead used median age of seals harvested in autumn (August-December) as an index to compare age distribution of seals in the north versus south. Previous research has indicated that the autumn hunt during the open-water season provides samples that are representative of the population age-sex distribution (Ferguson, Young, Yurkowski, Anderson, & Willing, 2017).…”

Section: Age Structurementioning

confidence: 99%

Do intraspecific life history patterns follow interspecific predictions? A test using latitudinal variation in ringed seals

et al. 2019

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Mammals adapted to unpredictable and low‐energy environments often evolve a “bet‐hedging” life history strategy characterized by less costly reproductive outputs over a longer and slower‐growing life. In contrast, species adapted to more predictable (i.e., low variation) and higher energy environments may evolve greater fecundity over a shorter and faster‐growing life. We tested whether this known interspecific pattern also occurs within a species. We compared life history traits of the ringed seal (Pusa hispida) in the Canadian High Arctic to those closer to the southern limit of the species' circumpolar distribution. We found that northern seals grew slower than southern seals (Brody growth coefficient), achieved a greater asymptotic body weight (82 and 69 kg vs. 74 and 54 kg female and male, respectively), reached sexual maturity later (6.1 years vs. 4.5 years), had lower fecundity (1.8 years vs. 1.3 years interbirth interval), longer average lifespan (5 years vs. 3 years median age), and greater movements (1,269 vs. 681 km). Mating systems also likely differed with northern seals showing morphological evidence of a promiscuous mating system with potential sperm competition as indicated by greater relative testes size. The northern region was also characterized by more unpredictable environmental timing of seasonal events, such as spring sea ice breakup. Life history variation between the intraspecific groups of seals appears to agree with interspecific patterns and provides a better understanding of how species' life history parameters shift in concert with environmental conditions.

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“…The probability of a seal giving birth to a pup is associated with individual body condition, which results from foraging success (Ferguson et al, 2017;Guinet, Roux, Bonnet, & Mison, 1998;Stenson, Buren, & Koen-Alonso, 2016). The mass of a mature female at the start of lactation is a proxy for body condition which can vary between years but also sets limits on maternal expenditure (the net change in maternal mass from birth to weaning of the pup) in phocid seals (Arnbom, Fedak, & Boyd, 1997).…”

Section: Introductionmentioning

confidence: 99%

Environment‐sensitive mass changes influence breeding frequency in a capital breeding marine top predator

Smout

King

Pomeroy

2019

Journal of Animal Ecology

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The trade‐off between survival and reproduction in resource‐limited iteroparous animals can result in some individuals missing some breeding opportunities. In practice, even with the best observation regimes, deciding whether ‘missed’ years represent real pauses in breeding or failures to detect breeding can be difficult, posing problems for the estimation of individual reproductive output and overall population fecundity. We corrected fecundity estimates by determining whether breeding had occurred in skipped years, using long‐term capture–recapture observation datasets with parallel longitudinal mass measurements, based on informative underlying relationships between individuals’ mass, breeding status and environmental drivers in a capital breeding phocid, the grey seal. Bayesian modelling considered interacting processes jointly: temporal changes in a phenotypic covariate (mass); relationship of mass to breeding probability; effects of maternal breeding state and mark type on resighting. Full reproductive histories were imputed, with the status of unobserved animals estimated as breeding or non‐breeding, accounting for local environmental variation. Overall fecundity was then derived for Scottish breeding colonies with contrasting pup production trends. Maternal mass affected breeding likelihood. Mothers with low body mass at the end of breeding were less likely to bear a pup the following year. Successive breeding episodes incurred a cost in reduced body mass which was more pronounced for North Rona, Outer Hebrides (NR) mothers. Skipping breeding increased subsequent pupping probability substantially for low mass females. Poor environmental conditions were associated with declines in breeding probability at both colonies. Seal mass gain between breeding seasons was (a) negatively associated with lagged North Atlantic Oscillation for seals at NR and (b) positively associated with an index of seal prey (Ammodytes spp) abundance at Isle of May, Firth of Forth (IM). Overall fecundity was marginally greater at IM (increasing/stable pup production) than at NR (decreasing). No effects of mass were detected on maternal survival. Skipping breeding in female grey seals appears to be an individual mass‐dependent constraint moderated by previous reproductive output and local environmental conditions. Different demographic trends at breeding colonies were consistent with the fecundities estimated using this method, which is general and adaptable to other situations.

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Demographic, ecological, and physiological responses of ringed seals to an abrupt decline in sea ice availability

Cited by 90 publications

References 72 publications

Body condition impacts blood and muscle oxygen storage capacity of free-living beluga whales (Delphinapterus leucas)

Body condition impacts blood and muscle oxygen storage capacity of free-living beluga whales (Delphinapterus leucas)

Do intraspecific life history patterns follow interspecific predictions? A test using latitudinal variation in ringed seals

Environment‐sensitive mass changes influence breeding frequency in a capital breeding marine top predator

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