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DY: Fachverband Dynamik und Statistische Physik

DY 2: Active Matter I (joint session BP/CPP/DY)

DY 2.7: Talk

Monday, March 18, 2024, 11:15–11:30, H 1028

Gravitactic bioconvection drives emergent transport and mixing in harmful algal blooms — •Soumitree Mishra¹ and Anupam Sengupta^1,2 — ¹Physics of Living Matter Group, Department of Physics and Materials Science, University of Luxembourg — ²Institute for Advanced Studies, University of Luxembourg

Bioconvection, the active self-sustaining transport phenomenon triggered by the accumulation of motile microbes, has been long studied. Yet, if and how this collective behavior, driven by competing physico-chemical cues, impacts ecological processes including Harmful Algal Blooms (HABs) remains unexplored. Here, using a bloom-forming model phytoplankton, we present a comprehensive mechanistic study on the biophysical factors governing the emergent collective patterns and capture the eco-physiological implications of bioconvective flows. Leveraging our Ocean-On-Chip platform, together with particle tracking velocimetry (PTV) and particle image velocimetry (PIV), we uncover flow fields around isolated self-organized microbial plumes, using which we extract the spatial range of active transport. Using data-backed fluid dynamic simulations, we extract the Lyapunov exponents, revealing the mixing capacity of such plumes in confined environments. Our findings significantly advance our understanding of bioconvection's functional role in ecological contexts[1], providing a novel playground where ecology meets active matter. [Reference 1] Bioconvection mediates transport and mixing dynamics within harmful algal blooms: S. Mishra & A. Sengupta (manuscript in preparation).

Keywords: Bioconvection; Gravitaxis; collective behavior; Harmful algal blooms