野生动物健康的个人水平评估,生命率,觅食生态对于理解暴露于压力源的全人群影响至关重要。大型鲸鱼面临多重压力,包括,但不限于,海洋噪音,污染,船罢工。因为baleen是一种不断增长的角化结构,串行提取,沿baleen长度的激素和稳定同位素的定量提供了鲸鱼生理和觅食生态的历史记录。此外,baleen分析可以对死亡标本进行调查,甚至几十年后,允许历史和现代人口之间的比较。这里,我们检查了五种亚成年灰鲸的baleen,并观察到沿baleen板长度的δ15N值振荡的不同模式,从而可以估算baleen的生长速率和在越冬和夏季觅食期间鲸鱼同位素生态位宽度的差异。相比之下,δ13C值没有明显的规则模式。死亡前四个人皮质醇的长期升高表明慢性压力可能影响了他们的健康和生存。三碘甲状腺原氨酸(T3)在死亡原因不明的鲸鱼中增加了数月,同时皮质醇升高,但是在一例由于虎鲸捕食而导致的急性死亡病例中,两种激素都保持稳定。皮质醇和T3的这种平行升高挑战了对它们相互作用的经典理解,并且可能与暴露于压力源时能量需求的增加有关。亚成年人的生殖激素谱没有显示出周期性趋势,表明他们还没有达到性成熟。这项研究强调了baleen分析回顾性评估灰鲸生理状态的潜力,暴露于压力源,生殖状态,在他们死亡前的几个月或几年里觅食生态,这可能是保护诊断的有用工具,以减轻异常死亡事件。
Individual-level assessments of wild animal health, vital rates, and foraging ecology are critical for understanding population-wide impacts of exposure to stressors. Large whales face multiple stressors, including, but not limited to, ocean noise, pollution, and ship strikes. Because
baleen is a continuously growing keratinized structure, serial extraction, and quantification of hormones and stable isotopes along the length of
baleen provide a historical record of whale physiology and foraging ecology. Furthermore,
baleen analysis enables the investigation of dead specimens, even decades later, allowing comparisons between historic and modern populations. Here, we examined
baleen of five sub-adult gray whales and observed distinct patterns of oscillations in δ15N values along the length of their
baleen plates which enabled estimation of
baleen growth rates and differentiation of isotopic niche widths of the whales during wintering and summer foraging. In contrast, no regular patterns were apparent in δ13C values. Prolonged elevation of cortisol in four individuals before death indicates that chronic stress may have impacted their health and survival. Triiodothyronine (T3) increased over months in the whales with unknown causes of death, simultaneous with elevations in cortisol, but both hormones remained stable in the one case of acute death attributed to killer whale predation. This parallel elevation of cortisol and T3 challenges the classic understanding of their interaction and might relate to increased energetic demands during exposure to stressors. Reproductive hormone profiles in subadults did not show cyclical trends, suggesting they had not yet reached sexual maturity. This study highlights the potential of baleen analysis to retrospectively assess gray whales\' physiological status, exposure to stressors, reproductive status, and foraging ecology in the months or years leading up to their death, which can be a useful tool for conservation diagnostics to mitigate unusual mortality events.