Spatiotemporal variation of ringed seal blubber cortisol levels in the Canadian Arctic

Abstract

Climate change in the Arctic has widespread and complex effects on the health of animals and their populations. We used radioimmunoassay to measure blubber cortisol in ringed seals (Pusa hispida) sampled in Ulukhaktok, Inuvialuit Settlement Region, Northwest Territories, Canada (spring, 2002, 2004–2005, 2007–2012) and Arviat, Nunavut, Canada (autumn, 2003–2012) to examine chronic stress relative to biology (age, sex, length), body condition (blubber depth), and diet (δ13C, δ15N, and isotopic niche size). Ulukhaktok ringed seals had higher cortisol concentrations overall (0.46 ± 0.04 ng/g) than Arviat ringed seals (0.36 ± 0.03 ng/g), and these higher concentrations were associated with higher muscle δ15N and lower blubber thickness. In contrast, blubber cortisol concentrations for Arviat ringed seals decreased with blubber depth and increased with age, though testing of age effects individually suggests that age-related patterns are weak. Annual mean cortisol concentration increased from 2003 to 2012 in Arviat ringed seals, but low sample sizes precluded analysis of annual patterns for Ulukhaktok ringed seals. The trend of increased cortisol over time in Arviat ringed seals suggests that they might be experiencing greater chronic stress over time, which could have implications for numerous population health metrics including reproduction and pup recruitment.

Large and in charge: cortisol levels vary with sex, diet, and body mass in an Antarctic predator, the leopard seal

“…Similarly, animals that consume less food, lower-quality food, and/or have a less nutritious diet can exhibit nutritional stress, an imbalance of the intake of essential nutrients, that can lead to higher cortisol concentrations (McEwen and Lasley, 2002;Bryan et al, 2013); this pattern is well documented in terrestrial mammals (Barboza et al, 2004;Bryan et al, 2013;George et al, 2014;Lafferty et al, 2015) and birds (Kitaysky et al, 1999;Cockrem, 2007). In harbor (Phoca vitulina), ringed (Pusa hispida), and spotted (Phoca largha) seals, for example, studies have shown an inverse relationship between cortisol and diet (d 15 N); as d 15 N values increase, cortisol decreases ( (Karpovich et al, 2019;Ogloff et al, 2022). Furthermore, in spotted seals, measurements of cortisol and d 15 N along whiskers (which represents a longitudinal time-series) showed that cortisol increased concurrently with a decrease in d 15 N; this shows that higher cortisol is associated with feeding at a lower Comparison of mean circulating cortisol concentrations in pinnipeds (blue), ursids (green), and mustelids (yellow) calculated from peer-reviewed studies and this study.…”

“…Cortisol is commonly measured in pinnipeds (seals, sea lions, and walrus) to evaluate the relationship between their physiology and other biological metrics (Constable et al, 2006;du Dot et al, 2009;Trumble et al, 2013;Keogh and Atkinson, 2015;Shero et al, 2015;Kershaw and Hall, 2016;Peck et al, 2016;Beaulieu-McCoy et al, 2017;Karpovich et al, 2019;Thompson and Romano, 2019;Keogh et al, 2020;Sperou, 2020;Ogloff et al, 2022). Among pinnipeds, Southern Ocean pinnipeds (six species: Ross seals, Ommatophoca rossii; Weddell seals, Leptonychotes weddellii; crabeater seals, Lobodon carcinophaga; leopard seals, Hydrurga leptonyx; Antarctic fur seals, Arctocephalus gazella; and southern elephant seals, Mirounga leonina) have some of the highest cortisol concentrations ever recorded (Liggins et al, 1979;Barrell and Montgomery, 1989;Bartsh et al, 1992;Liggins et al, 1993;Harcourt, 2001;Tryland et al, 2012).…”

A Review of Circumpolar Arctic Marine Mammal Health—A Call to Action in a Time of Rapid Environmental Change

“…Years with little sea ice have been correlated with low body condition indices in adult female ringed seals and low reproductive success [ 365 , 366 ]. Novel methods of assessing blubber such as proteomics and blubber metabolomics could improve our understanding of the relationship of blubber depth to nutritional status and overall health [ 367 , 368 , 369 ]. Malnutrition could increase host susceptibility to all of the pathogens reviewed above [ 19 ].…”

Variation of blubber thickness for three marine mammal species in the southern Baltic Sea

“…This may translate into misjudgments regarding the health of the population based on blubber thickness—even if sampling occurs following standardized age categories and sampling seasons, variations related to unknown factors can bias the interpretation of the blubber thickness data. Studies in several seal species demonstrate that a qualitative and quantitative analysis of various parameters in and of the blubber have the potential to reveal further information about health and physiology like fatty acid composition and stratification ( Walton and Pomeroy 2003 ; Guerrero et al, 2017 ), hormone levels and profiles and pollutants ( Kershaw and Hall 2016 ; Troisi et al, 2020 ; Ogloff et al, 2022 ). Thus, further investigations including various analyses of some additional blubber parameters are strongly desired for a better evaluation of the overall health condition of individuals.…”