A Magnetic Map Leads Juvenile European Eels to the Gulf Stream

The “Orientation” worksheet provides information on the magnetic displacement experiments performed with European glass eels. Experiments were performed using a coil system that could precisely control the magnetic field experienced by eels, recreating conditions that exist in specific regions along the oceanic migration route of the eels. 16 orientation arenas were placed on a platform at the center of the coil system. Upon removal of a plastic settling cylinder, eels could escape in 1 of 12 directions, spacing of 30°. Column A indicates the arena number (1-16), Column B indicates the region of the magnetic field (NW Atlantic, Mid Atlantic, Sargasso Sea, and Ambient (Test Site)), Column C indicates the escape direction of the eel (0°-330°, 0°=north, 90°=east, 180°=south, 270°=west), Column D and E indicate the date (ddmmyy) and time (h:m) that the trials begun. The “Simulation’ worksheet provides information on the virtual particle tracking simulations performed within the Global Hybrid Coordinate Ocean Model. Particles were released within the region of the model that corresponded to the location of the test fields. Particles were released in different years and at different depths and were programmed to either drift passively with the modelled ocean currents or to swim in the median escape direction that the eels adopted in corresponding test field. If eel orientation could not be distinguished from random, swimming was not simulated. 15000 particles were released during the month of May for each year, region, depth and behaviour and were allowed to drift for 180 days. From each region, we assessed the percentage of particles entering the Gulf Stream within this time period. For the Sargasso Sea simulations, particles were counted as entering the Gulf Stream if they crossed north of 25°N and west of 77°W. For the NW Atlantic region, particles were counted as entering the Gulf Stream if they crossed north of 40°N and east of 53°W. For the Mid Atlantic simulations, particles were already released within the Gulf Stream. Thus, values presented indicate the percentage of particles that had net eastward movement after 180 days. Column A indicates the region of particle release (Sargasso Sea, NW Atlantic, Mid Atlantic), Column B indicates the year of release (2000, 2005, 2010), Column C indicates the depth of release (30, 150, 300 m), Column D indicates the percentage of passively drifting particles that entered the Gulf Stream within 180 days, and Column E indicates the percentage of swimming particles that entered the Gulf Stream within 180 days (if applicable).

"Orientation"工作表提供了针对欧洲玻璃鳗开展的磁位移实验相关信息。本实验采用可精准调控鳗鱼所受磁场的线圈系统，复刻了鳗鱼远洋洄游路线中特定区域的环境条件。线圈系统中心的平台上放置了16个定向测试池，移除塑料沉降筒后，鳗鱼可朝12个间隔为30°的方向（取值范围0°至330°）逃逸，其中0°对应北、90°对应东、180°对应南、270°对应西。表格A列代表测试池编号（1-16），B列代表磁场区域（西北大西洋、大西洋中部、马尾藻海以及环境对照（测试位点）），C列代表鳗鱼的逃逸方向，D列与E列分别代表实验开始的日期（格式为ddmmyy）与时间（格式为h:m）。

"Simulation"工作表提供了基于全球混合坐标海洋模式（Global Hybrid Coordinate Ocean Model）开展的虚拟粒子追踪模拟实验相关信息。粒子被投放于与实验磁场区域对应的模式模拟区域中，按不同年份与深度释放，并被设定为两种运动模式：随模式模拟的海流被动漂移，或沿对应实验场中鳗鱼采用的中位逃逸方向游动。若无法区分鳗鱼的定向行为与随机运动，则不设置游动模拟。针对每一年份、区域、深度与运动模式，于5月期间投放15000个粒子，并允许其漂移180天。本研究统计了各区域内该时间段内进入墨西哥湾流（Gulf Stream）的粒子占比：马尾藻海模拟中，粒子跨越北纬25°以北、西经77°以西即被视为进入墨西哥湾流；西北大西洋区域模拟中，粒子跨越北纬40°以北、西经53°以东即被视为进入墨西哥湾流；大西洋中部区域模拟中，粒子初始即被投放于墨西哥湾流内，因此统计结果为180天后粒子的净东向运动占比。表格A列代表粒子投放区域（马尾藻海、西北大西洋、大西洋中部），B列代表投放年份（2000、2005、2010），C列代表投放深度（30、150、300 m），D列代表180天内被动漂移粒子进入墨西哥湾流的占比，E列代表180天内游动粒子进入墨西哥湾流的占比（如适用）。