Swimming is a fundamental trait of many protists and optimizes growth and survival. We present an easy to use set-up for filming algal cells using Apocalathium aciculiferum and Borghiella dodgei as case studies; both dinoflagellates are model organisms of psychrophilic dinoflagellates. We filmed at low temperature (4.5°C) using a digital camera directly connected to a microscope and used open-source software to track their movement. We encountered several technical issues that were solved by using specific software settings (scaling, grey scale of images, restrictive particle recognition), and thus we obtained unbiased speed estimates. Borghiella dodgei showed a faster (minimum = 80, maximum = 255, median = 141 µm s −1 ) swimming speed than A. aciculiferum (minimum = 29, maximum = 134, median = 85 µm s −1 ). We linked differences in swimming speed to the dinoflagellates’ environmental niche, and suggested that B. dodgei is more adapted to turbulent spring conditions than A. aciculiferum , occurring under ice. The use of a generic digital camera and open-source software makes filming and tracking of plankton movement very affordable. We provided code and detailed instructions to disseminate this type of movement analysis of plankton.

中文翻译：

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藻类细胞的追踪：以适应冷环境的甲藻游泳速度为例

游泳是许多原生生物的基本特征，可以优化生长和生存。我们提供了一种易于使用的设置，用于使用 Apocalathium aciculiferum 和 Borghiella dodgei 作为案例研究来拍摄藻类细胞；两种甲藻都是嗜冷甲藻的模式生物。我们使用直接连接到显微镜的数码相机在低温（4.5°C）下拍摄，并使用开源软件来跟踪它们的运动。我们遇到了几个通过使用特定软件设置（缩放、图像灰度、限制性粒子识别）解决的技术问题，因此我们获得了无偏的速度估计。Borghiella dodgei 表现出比 A. aciculiferum 更快（最小值 = 80，最大值 = 255，中值 = 141 µm s -1 ）的游泳速度（最小值 = 29，最大值 = 134，中值 = 85 μm s -1 ）。我们将游泳速度的差异与甲藻的环境生态位联系起来，并表明 B. dodgei 比发生在冰下的 A. aciculiferum 更适应湍流的春季条件。通用数码相机和开源软件的使用使得浮游生物运动的拍摄和跟踪变得非常实惠。我们提供了代码和详细说明来传播这种类型的浮游生物运动分析。