Long-term variation in polar bear body condition and maternal investment relative to a changing environment

In the Arctic, warming air and ocean temperatures have resulted in substantial changes to sea ice, which is primary habitat for polar bears (Ursus maritimus). Reductions in extent, duration, and thickness have altered sea ice dynamics, which influences the ability of polar bears to reliably access m...

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Autores principales:	Todd C. Atwood, Karyn D. Rode, David C. Douglas, Kristin Simac, Anthony M. Pagano, Jeffrey F. Bromaghin
Formato:	article
Lenguaje:	EN
Publicado:	Elsevier 2021
Materias:	Arctic Body condition Climate change Marine mammal Maternal investment Polar bear Ecology QH540-549.5
Acceso en línea:	https://doaj.org/article/78c85dfa41f34aff9bfd427505752144
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spelling	oai:doaj.org-article:78c85dfa41f34aff9bfd4275057521442021-11-26T04:31:15ZLong-term variation in polar bear body condition and maternal investment relative to a changing environment2351-989410.1016/j.gecco.2021.e01925https://doaj.org/article/78c85dfa41f34aff9bfd4275057521442021-12-01T00:00:00Zhttp://www.sciencedirect.com/science/article/pii/S2351989421004753https://doaj.org/toc/2351-9894In the Arctic, warming air and ocean temperatures have resulted in substantial changes to sea ice, which is primary habitat for polar bears (Ursus maritimus). Reductions in extent, duration, and thickness have altered sea ice dynamics, which influences the ability of polar bears to reliably access marine mammal prey. Because nutritional condition is closely linked to population vital rates, a progressive decline in access to prey or an increase in the energetic cost of accessing prey has the potential to adversely affect polar bear population dynamics. We examined long-term (1983–2015) patterns of spring body condition (indexed using residual body mass) and maternal investment (i.e., litter mass of cubs-of-the-year and yearlings; COY and YRL) of polar bears from Alaska’s southern Beaufort Sea to evaluate potential relationships with regional- and circumpolar-scale sea ice conditions and atmospheric patterns. The length of the summer open-water (OW) season (i.e., the period of time the sea ice is mostly absent from the continental shelf) increased at a rate of 18 days decade-1 over the study period. However, the OW season duration was not a strong determinant of spring residual body mass or litter mass. Residual body mass of independent (i.e., subadults and adults) female bears varied relative to age class, reproductive status, and the strength of the prior winter’s Arctic Oscillation (i.e., a circumpolar-scale mode of climate variability driven by long-term atmospheric patterns). Spring residual mass of independent males varied with age class and variation in wind speed (i.e., regional-scale short-term atmospheric patterns) during the winter of the year preceding capture. Over the study period, mean annual body mass of adult females unaccompanied by COY declined by 4 kg/ decade-1, while no temporal trends were evident in the mean annual body mass of adult females with COY, adult males, and subadults. Litter mass of COY varied relative to capture date, maternal age class and mass, litter size, and year of capture. Litter mass of YRL varied with capture date, maternal age class and mass, litter size, variation in winter wind speed (the year of and year preceding capture), and the strength of the prior winter’s Arctic Oscillation. Mean annual litter mass of COY decreased at a rate of 2.6 kg decade-1 and declined 0.68 kg for every 10 kg reduction in maternal mass. No trend was evident in the mean annual litter mass of yearlings. These findings suggest a nuanced response of the southern Beaufort Sea polar bears to environmental change, where some demographic groups (e.g., adult males and subadults) are presently more resilient than others to changes in the Arctic marine ecosystem.Todd C. AtwoodKaryn D. RodeDavid C. DouglasKristin SimacAnthony M. PaganoJeffrey F. BromaghinElsevierarticleArcticBody conditionClimate changeMarine mammalMaternal investmentPolar bearEcologyQH540-549.5ENGlobal Ecology and Conservation, Vol 32, Iss , Pp e01925- (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Arctic Body condition Climate change Marine mammal Maternal investment Polar bear Ecology QH540-549.5
spellingShingle	Arctic Body condition Climate change Marine mammal Maternal investment Polar bear Ecology QH540-549.5 Todd C. Atwood Karyn D. Rode David C. Douglas Kristin Simac Anthony M. Pagano Jeffrey F. Bromaghin Long-term variation in polar bear body condition and maternal investment relative to a changing environment
description	In the Arctic, warming air and ocean temperatures have resulted in substantial changes to sea ice, which is primary habitat for polar bears (Ursus maritimus). Reductions in extent, duration, and thickness have altered sea ice dynamics, which influences the ability of polar bears to reliably access marine mammal prey. Because nutritional condition is closely linked to population vital rates, a progressive decline in access to prey or an increase in the energetic cost of accessing prey has the potential to adversely affect polar bear population dynamics. We examined long-term (1983–2015) patterns of spring body condition (indexed using residual body mass) and maternal investment (i.e., litter mass of cubs-of-the-year and yearlings; COY and YRL) of polar bears from Alaska’s southern Beaufort Sea to evaluate potential relationships with regional- and circumpolar-scale sea ice conditions and atmospheric patterns. The length of the summer open-water (OW) season (i.e., the period of time the sea ice is mostly absent from the continental shelf) increased at a rate of 18 days decade-1 over the study period. However, the OW season duration was not a strong determinant of spring residual body mass or litter mass. Residual body mass of independent (i.e., subadults and adults) female bears varied relative to age class, reproductive status, and the strength of the prior winter’s Arctic Oscillation (i.e., a circumpolar-scale mode of climate variability driven by long-term atmospheric patterns). Spring residual mass of independent males varied with age class and variation in wind speed (i.e., regional-scale short-term atmospheric patterns) during the winter of the year preceding capture. Over the study period, mean annual body mass of adult females unaccompanied by COY declined by 4 kg/ decade-1, while no temporal trends were evident in the mean annual body mass of adult females with COY, adult males, and subadults. Litter mass of COY varied relative to capture date, maternal age class and mass, litter size, and year of capture. Litter mass of YRL varied with capture date, maternal age class and mass, litter size, variation in winter wind speed (the year of and year preceding capture), and the strength of the prior winter’s Arctic Oscillation. Mean annual litter mass of COY decreased at a rate of 2.6 kg decade-1 and declined 0.68 kg for every 10 kg reduction in maternal mass. No trend was evident in the mean annual litter mass of yearlings. These findings suggest a nuanced response of the southern Beaufort Sea polar bears to environmental change, where some demographic groups (e.g., adult males and subadults) are presently more resilient than others to changes in the Arctic marine ecosystem.
format	article
author	Todd C. Atwood Karyn D. Rode David C. Douglas Kristin Simac Anthony M. Pagano Jeffrey F. Bromaghin
author_facet	Todd C. Atwood Karyn D. Rode David C. Douglas Kristin Simac Anthony M. Pagano Jeffrey F. Bromaghin
author_sort	Todd C. Atwood
title	Long-term variation in polar bear body condition and maternal investment relative to a changing environment
title_short	Long-term variation in polar bear body condition and maternal investment relative to a changing environment
title_full	Long-term variation in polar bear body condition and maternal investment relative to a changing environment
title_fullStr	Long-term variation in polar bear body condition and maternal investment relative to a changing environment
title_full_unstemmed	Long-term variation in polar bear body condition and maternal investment relative to a changing environment
title_sort	long-term variation in polar bear body condition and maternal investment relative to a changing environment
publisher	Elsevier
publishDate	2021
url	https://doaj.org/article/78c85dfa41f34aff9bfd427505752144
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Long-term variation in polar bear body condition and maternal investment relative to a changing environment

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