Collaborative Research: Geomagnetic Navigation by Weddell Seals Beneath Antarctic Ice

尽管对信鸽等物种进行了数十年的研究，但许多动物在长距离准确导航的非凡能力仍然无法得到科学解释。海洋哺乳动物利用地球磁场导航的证据不太清楚，但许多报告推断，各种海洋哺乳动物具有这种感觉能力。这一机制中的错误可能与鲸鱼和海豚的大规模搁浅有关，更好地了解海洋哺乳动物的航行最终可能有助于预防或预测这些事件。韦德尔海豹在黑暗中航行数百米后，精确定位南极海冰上的呼吸孔，导航失误可能会导致死亡。在这个项目中，研究人员将通过使用定制设计的视频和数据记录器来测试利用地磁场进行海洋哺乳动物冰下导航和定位的新想法，该记录器能够在潜水时监控精细的动物行为和运动。该项目还将推动NSF向公众提供科学发现和培训新一代科学家的目标。公众将通过网站、针对代表人数不足的群体的系列讲座以及编写在全国传播的K-12教材来参与。在整个项目过程中，许多研究生和本科生将接受科学发现技术的培训。由于冰下潜水时氧气储备有限，韦德尔海豹面临着强大的选择压力，必须准确有效地导航以定位呼吸孔。研究人员假设，地磁导航是韦德尔海豹返回呼吸孔附近的必要条件和充分条件。该项目将是第一个在海洋哺乳动物身上进行严格的地磁导航现场测试的项目，也是第一个测量地磁导航行为的能量成本并评估身体储氧量和屏气时间如何影响潜水哺乳动物的空间定向和导航策略的项目。研究人员将测量单个海豹对不同地磁场特性的行为和能量反应的变化，并对照准确的预测对这些反应进行测试。通过在高光强/长日长和低光强/短日长期间进行测试，同时记录声源和水流，该实验设计提供了一种强大的技术，用于在操纵其他感官模式时识别地磁响应。这些成本将与其他脊椎动物的成本进行比较，以评估地磁导航的进化驱动因素。海豹地磁导航的演示还将为其他潜水动物的精细活动和实现长距离迁徙的机制提供新的见解。因此，这些结果有可能改变我们对所有潜水动物导航的理解。

The remarkable ability of many animals to navigate accurately over long distances has defied scientific explanation despite decades of research on species such as homing pigeons. Evidence that marine mammals use the Earth's magnetic field for navigation is less clear but numerous reports infer this sensory capability in a variety of marine mammals. Mistakes in this mechanism may be involved in mass strandings of whales and dolphins and a better understanding of marine mammal navigation ultimately may be useful in preventing or forecasting these events. Weddell seals precisely locate breathing holes in Antarctic sea ice after traveling hundreds of meters in darkness and a navigation mistake can result in death. In this project, the investigators will test a novel idea about marine mammal sub-ice navigation and orientation using geomagnetic fields by employing a custom-designed video and data recorder capable of monitoring fine-scale animal behaviors and movements when diving. The project will also further the NSF goals of making scientific discoveries available to the general public and of training new generations of scientists. The general public will be involved via web sites, a lecture series targeting underrepresented groups, and development of nationally disseminated K-12 teaching materials. A number of graduate and undergraduate students will be trained in the techniques of scientific discovery over the course of the project.With limited oxygen stores during under-ice diving, Weddell seals are under strong selective pressure to navigate accurately and efficiently to locate breathing holes. The investigators hypothesize that geomagnetic navigation is both necessary and sufficient for Weddell seals to return to the vicinity of breathing holes. This project will be the first to rigorously field test geomagnetic navigation in a marine mammal as well as the first to measure the energetic cost of geomagnetic navigational behavior and evaluate how body oxygen stores and breath-hold duration influence spatial orientation and navigational strategies in a diving mammal. The investigators will measure changes in the behavioral and energetic responses of individual seals to different geomagnetic field properties and test those responses against precise predictions. By conducting tests during periods of high light intensity/long day length and low light intensity/reduced day length while simultaneously documenting sound sources and water currents, the experimental design provides a powerful technique for identifying a geomagnetic response as other sensory modalities are manipulated. These costs will be compared to those of other vertebrates to assess the evolutionary drivers for geomagnetic navigation. Demonstration of geomagnetic navigation in seals would also provide new insights into fine scale activities of other diving animals and the mechanisms that enable long distance migrations. Thus, the results have the potential to transform our understanding of navigation in all diving animals.