Environmental conditions and marine heatwaves influence blue whale foraging and reproductive effort

Environmental conditions and heat waves influence blue whale foraging and reproductive effort

Authors: Dawn R. Barlow1*, Holger Klinck2,3, Dimitri Ponirakis2, Trevor A. Branch4, Leigh G. Torres1

1Geospatial Ecology of Marine Megafauna Lab, Marine Mammal Institute, Department of Fisheries, Wildlife, and Conservation Sciences, Oregon State University, Newport, Oregon, USA

2K. Lisa Yang Center for Conservation Bioacoustics, Cornell University, Ithaca, New York, USA

3Marine Mammal Institute, Department of Fisheries, Wildlife, and Conservation Sciences, Oregon State University, Newport, Oregon, USA

4School of Aquatic and Fisheries Sciences, University of Washington, Seattle, Washington, USA 

*[e-mail] 

Abstract 

Animal behavior is motivated by the fundamental need to feed and reproduce, and these behaviors can be inferred from spatiotemporal variations in biological signals such as vocalizations. Yet, linking foraging and reproductive effort to environmental drivers can be challenging for wide-ranging predator species. Blue whales are acoustically active marine predators that produce two distinct vocalizations: song and D calls. We examined environmental correlates of these vocalizations using continuous recordings from five hydrophones in the South Taranaki Bight region of New Zealand to investigate call behavior relative to ocean conditions and infer life history patterns. D calls were strongly correlated with oceanographic drivers of upwelling in spring and summer, indicating associations with foraging effort. In contrast, song displayed a highly seasonal pattern with peak intensity in fall, which aligned with the timing of conception inferred from whaling records. Finally, during a marine heatwave, reduced foraging (inferred from D calls) was followed by lower reproductive effort (inferred from song intensity).

环境条件与热浪影响蓝鲸的觅食与繁殖投入

作者：Dawn R. Barlow1*, Holger Klinck2,3, Dimitri Ponirakis2, Trevor A. Branch4, Leigh G. Torres1

1 美国俄勒冈州立大学渔业、野生动物与保护科学系海洋哺乳动物研究所海洋巨型动物地理生态实验室
2 美国康奈尔大学K. Lisa Yang保护生物声学中心
3 美国俄勒冈州立大学渔业、野生动物与保护科学系海洋哺乳动物研究所
4 美国华盛顿大学水产与渔业科学学院

* 通讯作者邮箱：[e-mail]

摘要
动物行为的核心驱动力为觅食与繁殖，而诸如发声这类生物信号的时空变化可用于推断其行为模式。然而，对于活动范围广泛的捕食者物种而言，将其觅食与繁殖投入与环境驱动因素建立关联颇具挑战。蓝鲸为声学活跃的海洋捕食者，可发出两种截然不同的发声类型：鸣唱（song）与D叫声（D calls）。本研究借助新西兰塔拉纳基湾南部5台水听器（hydrophones）的连续录音数据，分析了这两类发声的环境关联因子，以探究蓝鲸发声行为与海洋环境的相关性，并推断其生活史模式。D叫声与春夏季上升流的海洋学驱动因子呈显著相关，表明其与蓝鲸的觅食投入存在关联。与之相反，鸣唱则呈现出极强的季节性规律，秋季达到发声强度峰值，这与基于捕鲸记录推断的蓝鲸受孕时间相吻合。最后，在海洋热浪（marine heatwave）期间，基于D叫声推断的觅食活动减少，随后出现了基于鸣唱强度推断的繁殖投入降低。