Resolving Migratory Connectivity of Basking Sharks (Cetorhinus maximus) in the Western Atlantic Ocean: Integrating Novel Geochemical Tracers with Satellite Archival Tags

动物迁徙是自然界最壮观而又神秘的现象之一。迁移模式也具有相当大的生物学意义，决定了地理上分离的种群在生态时间尺度上的基因流动和种群在生态时间上的迁移连通性。不幸的是，海洋生态系统的迁移研究落后于陆地环境，这是由于跟踪水生动物的逻辑限制，这些动物可能在不透明的三维环境中长途旅行。然而，最近使用电子标签的研究揭示了大型远洋鱼类在盆地尺度上的显著迁移。然而，由于尺寸和电池寿命的限制，人工标签还不能提供长寿物种的终生迁移历史。因此，研究人员将结合电子档案标签和椎骨中的天然同位素标记来研究北大西洋西部姥鲨（Cetorhinus maximus）的扩散和迁徙连通性。该项目将建立在初步档案标签数据的基础上，这些数据显示姥鲨从科德角湾转移到巴西海岸附近的水域。研究结果将为保护世界第二大鱼类提供相关见解，这种鱼类分布在全球各地，但由于其范围内的过度捕捞而被列入世界自然保护联盟濒危物种红色名录。稳定同位素已成功地用于追踪鸟类的迁徙连通性，并检查硬骨鱼的出生归巢。研究人员希望通过分析从椎体样本中分离出的特定有机化合物中的碳和氮同位素来研究姥鲨一生的运动模式，从而改变这一领域。通过分析C和N同位素营养分异程度不同的必需氨基酸和非必需氨基酸，他们将避免混淆运动和饮食变化。弹出式档案标签的结果将与北大西洋浮游生物碳和氮同位素的荟萃分析相结合，并用于生成预测的稳定同位素剖面，然后将与在姥鲨椎骨中观察到的模式进行测试。渔业和保护生物学家已经认识到，构成海洋捕捞鱼类种群动态基础的许多生物和物理过程具有重要的空间方面。研究人员将开发和应用工具，为大型远洋鲨鱼的扩散和迁徙连通性提供独特的估计。这些工具将很容易适用于其他进行盆地规模迁移的大型上层生物，特别是那些在夏季利用高纬度地区高初级和次级生产力的大型上层生物。这项研究将支持马萨诸塞大学达特茅斯分校渔业海洋学系一名博士生的博士研究。研究人员将积极招募申请WHOI暑期学生奖学金计划的代表性不足的学生参与该项目。最后，他们将通过WHOI和Numedeon Inc.之间的独特合作解决K-12教育问题，Numedeon Inc.为8-15岁的学生开发了一个充满活力的在线学习社区（Whyville）。pi将与Whyville的教育专家合作开发一项在线活动，该活动将引导学生更好地了解科学研究的过程，并探索与鱼类洄游和本研究相关的具体概念。最后，在研究期间进行的实地工作将被记录下来，由世界领先的水下电影制作人之一通过网络、电视和其他媒体向公众传播。

Animal migrations represent one of nature's most spectacular and yet mysterious phenomena. Movement patterns also have considerable biological significance, determining gene flow among geographically separated populations over ecological time scales and migratory connectivity among populations over ecological time. Unfortunately studies of migration in ocean ecosystems have lagged behind those in terrestrial environments due to the logistic constraints associated with tracking aquatic animals that may travel vast distances in an opaque 3-dimensional environment. Recent research using electronic tags have, however, revealed remarkable basin scale migrations in large pelagic fishes. Nonetheless, limited by size and battery life, artificial tags cannot yet provide lifetime migration histories of long-lived species. The investigators therefore will combine electronic archival tags and natural isotope markers in vertebrae to examine dispersal and migratory connectivity of basking sharks (Cetorhinus maximus) in the western North Atlantic Ocean. The project will build on preliminary archival tag data that has shown basking sharks moving from Cape Cod Bay to waters off the coast of Brazil. The results will provide insights relevant to conservation efforts directed at the world's second largest fish species that is globally distributed but listed on the IUCN Red List of Threatened Species as vulnerable due to overfishing throughout its range.Stable isotopes have been used successfully to trace migratory connectivity in birds and to examine natal homing in teleost fishes. The investigators hope to transform the field by analyzing carbon and nitrogen isotopes in specific organic compounds isolated from vertebral samples to examine lifetime movement patterns of basking sharks. They will avoid confounding movement and a change in diet by analyzing essential and non-essential amino acids that differ in the degree of trophic fractionation for C and N isotopes. Results from pop-up archival tags will be combined with a meta-analysis of plankton carbon and nitrogen isotopes in the North Atlantic Ocean and used to generate predicted stable isotope profiles that will then be tested against observed patterns in the basking shark vertebrae. Fisheries and conservation biologists have come to the realization that many of the biological and physical processes that underlie population dynamics of marine-capture fish species have important spatial aspects. The investigators will develop and apply tools that will provide unique estimates of dispersal and migratory connectivity in a large pelagic shark. The tools will be readily applicable to other large pelagics that make basin-scale migrations and particularly those that take advantage of high primary and secondary productivity in high latitudes during summer months.The research will support the PhD studies of a PhD student in the Department of Fisheries Oceanography at UMASS Dartmouth. The investigators will actively recruit under-represented students applying to WHOI's summer student fellowship program to work on the project. Finally, they will address K-12 education by way of a unique collaboration between WHOI and Numedeon Inc. who have developed a dynamic online learning community (Whyville) for students ages 8-15. The PIs will work with the education experts at Whyville to develop an online activity that will lead students to better understand the process of scientific research as well as explore specific concepts related to fish migration and this research. Finally, fieldwork conducted during the study will be documented for dissemination to the public through the web, television, and other media by one of the world's leading underwater filmmakers.