Southern Ocean Persistent Organic Pollutants Program, Environmental Futures Research Institute, Griffith University, 170 Kessels Road, Nathan, QLD, 4111, Australia.
Institute for Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Hobart, TAS, 7004, Australia.
Sci Rep. 2020 Oct 26;10(1):18274. doi: 10.1038/s41598-020-75370-5.
Southern hemisphere humpback whales are classified as high-fidelity Antarctic krill consumers and as such are vulnerable to variability and long-term changes in krill biomass. Evidence of heterogeneous feeding patterns of east coast of Australia migrating humpback whales has been observed, warranting a comprehensive assessment of interannual variability in their diet. We examined the lipid and fatty acid profiles of individuals of the east coast of Australia migrating stock sampled between 2008 and 2018. The use of live-sampled blubber biopsies showed that fatty acid profiles varied significantly among all years. The two trophic indicator fatty acids for Antarctic krill, 20:5ω3 and 22:6ω3 remained largely unchanged across the 10-year period, suggesting that Antarctic krill is the principal prey item. A distance-based linear model showed that 33% of the total variation in fatty acid profiles was explained by environmental variables and climate indices. Most of the variation was explained by the Southern Annular Mode (23.7%). The high degree of variability observed in this study was unexpected for a species that is thought to feed primarily on one prey item. We propose that the observed variability likely arises from changes in the diet of Antarctic krill rather than changes in the whale's diet.
南半球的座头鲸被归类为高保真南极磷虾消费者，因此容易受到磷虾生物量的可变性和长期变化的影响。已经观察到澳大利亚东海岸洄游座头鲸存在异质的摄食模式，这需要对其饮食的年际变化进行全面评估。我们检查了 2008 年至 2018 年间采样的澳大利亚东海岸洄游种群个体的脂质和脂肪酸图谱。使用活体取样的鲸脂活检显示，所有年份的脂肪酸图谱差异显著。南极磷虾的两种营养指标脂肪酸 20:5ω3 和 22:6ω3 在 10 年期间基本保持不变，这表明南极磷虾是主要的猎物。基于距离的线性模型表明，脂肪酸图谱总变异的 33%由环境变量和气候指数解释。大部分变异由南方环状模式（23.7%）解释。对于一种被认为主要以一种猎物为食的物种，本研究中观察到的高度可变性是出乎意料的。我们提出，观察到的可变性可能源于南极磷虾的饮食变化，而不是鲸鱼的饮食变化。
