Thometz Nicole M, Hermann-Sorensen Holly, Russell Brandon, Rosen David A S, Reichmuth Colleen
Department of Biology, University of San Francisco, 2130 Fulton St, San Francisco, 94117 CA, USA.
Institute of Marine Sciences, University of California Santa Cruz, Long Marine Laboratory, 115 McAllister Way, Santa Cruz, 95060 CA, USA.
Conserv Physiol. 2021 Jan 5;9(1):coaa112. doi: 10.1093/conphys/coaa112. eCollection 2021.
Arctic seals, including spotted (), ringed () and bearded () seals, are directly affected by sea ice loss. These species use sea ice as a haul-out substrate for various critical functions, including their annual molt. Continued environmental warming will inevitably alter the routine behavior and overall energy budgets of Arctic seals, but it is difficult to quantify these impacts as their metabolic requirements are not well known-due in part to the difficulty of studying wild individuals. Thus, data pertaining to species-specific energy demands are urgently needed to better understand the physiological consequences of rapid environmental change. We used open-flow respirometry over a four-year period to track fine-scale, longitudinal changes in the resting metabolic rate (RMR) of four spotted seals, three ringed seals and one bearded seal trained to participate in research. Simultaneously, we collected complementary physiological and environmental data. Species-specific metabolic demands followed expected patterns based on body size, with the largest species, the bearded seal, exhibiting the highest absolute RMR (0.48 ± 0.04 L O min) and the lowest mass-specific RMR (4.10 ± 0.47 ml O min kg), followed by spotted (absolute: 0.33 ± 0.07 L O min; mass-specific: 6.13 ± 0.73 ml O min kg) and ringed (absolute: 0.20 ± 0.04 L O min; mass-specific: 7.01 ± 1.38 ml O min kg) seals. Further, we observed clear and consistent annual patterns in RMR that related to the distinct molting strategies of each species. For species that molted over relatively short intervals-spotted (33 ± 4 days) and ringed (28 ± 6 days) seals-metabolic demands increased markedly in association with molt. In contrast, the bearded seal exhibited a prolonged molting strategy (119 ± 2 days), which appeared to limit the overall cost of molting as indicated by a relatively stable annual RMR. These findings highlight energetic trade-offs associated with different molting strategies and provide quantitative data that can be used to assess species-specific vulnerabilities to changing conditions.
北极海豹，包括斑海豹（）、环斑海豹（）和髯海豹（），受到海冰流失的直接影响。这些物种将海冰用作各种关键活动的上岸平台，包括它们一年一度的换毛。持续的环境变暖将不可避免地改变北极海豹的日常行为和整体能量预算，但由于它们的代谢需求尚不清楚（部分原因是研究野生个体存在困难），因此难以量化这些影响。因此，迫切需要有关特定物种能量需求的数据，以便更好地了解快速环境变化的生理后果。我们在四年时间里使用开放式流动呼吸测量法，追踪了四只斑海豹、三只环斑海豹和一只参与研究的髯海豹在静息代谢率（RMR）方面的精细纵向变化。同时，我们收集了补充的生理和环境数据。特定物种的代谢需求遵循基于体型的预期模式，最大的物种髯海豹表现出最高的绝对静息代谢率（0.48±0.04升氧气/分钟）和最低的质量特异性静息代谢率（4.10±0.47毫升氧气/分钟·千克），其次是斑海豹（绝对：0.33±0.07升氧气/分钟；质量特异性：6.13±0.73毫升氧气/分钟·千克）和环斑海豹（绝对：0.20±0.04升氧气/分钟；质量特异性：7.01±1.38毫升氧气/分钟·千克）。此外，我们观察到静息代谢率呈现出清晰且一致的年度模式，这与每个物种独特的换毛策略有关。对于换毛间隔相对较短的物种——斑海豹（33±4天）和环斑海豹（28±6天）——代谢需求随着换毛而显著增加。相比之下，髯海豹表现出延长的换毛策略（119±2天），这似乎限制了换毛的总体成本，年度静息代谢率相对稳定就表明了这一点。这些发现突出了与不同换毛策略相关的能量权衡，并提供了可用于评估特定物种对变化条件脆弱性的定量数据。
