Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany.
Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, 8093 Zurich, Switzerland.
Proc Natl Acad Sci U S A. 2022 Aug 9;119(32):e2203191119. doi: 10.1073/pnas.2203191119. Epub 2022 Aug 2.
Phytoplankton come in a stunning variety of shapes but elongated morphologies dominate-typically 50% of species have aspect ratio above 5, and bloom-forming species often form chains whose aspect ratios can exceed 100. How elongation affects encounter rates between phytoplankton in turbulence has remained unknown, yet encounters control the formation of marine snow in the ocean. Here, we present simulations of encounters among elongated phytoplankton in turbulence, showing that encounter rates between neutrally buoyant elongated cells are up to 10-fold higher than for spherical cells and even higher when cells sink. Consequently, we predict that elongation can significantly speed up the formation of marine snow compared to spherical cells. This unexpectedly large effect of morphology in driving encounter rates among plankton provides a potential mechanistic explanation for the rapid clearance of many phytoplankton blooms.
浮游植物的形状种类繁多，但长形形态占主导地位——通常有 50%的物种的长宽比大于 5，而形成浮游植物水华的物种通常形成链状，其长宽比可以超过 100。然而，浮游植物在湍流中的伸长如何影响遭遇率仍不得而知，因为遭遇控制着海洋中海洋雪的形成。在这里，我们展示了在湍流中长形浮游植物之间的遭遇模拟，结果表明，在中性浮力条件下，长形细胞之间的遭遇率比球形细胞高 10 倍，而当细胞下沉时，甚至更高。因此，我们预测与球形细胞相比，伸长可以显著加快海洋雪的形成。这种形态在驱动浮游生物遭遇率方面的意外大影响，为许多浮游植物水华的快速清除提供了一种潜在的机制解释。
