Phytoplankton, one of the most diverse groups of single-celled eukaryotic microorganisms, are key drivers of global biogeochemical cycles. Owing to their aquatic habitat, phytoplankton are perpetually exposed to a range of environmental cues, in particular, nutrient and light gradient, and physical forces triggered by hydrodynamic shear and turbulent flows. In oceans, turbulence along with light and nutrient availability, have long been known to determine the growth, selection and succession of phytoplankton species. Contrary to the traditional wisdom that they drift passively in oceans, recent studies show that phytoplankton species have exquisite mechanisms to swim and respond to changes in their environment, and thereby rapidly adapt to turbulence. This discovery opens up the possibility of sophisticated sensors in action, at fast timescales, that could allow phytoplankton to actively perceive and respond to ecologically pertinent biophysical stimuli. However, due partly to the recentness of this discovery, we lack a mechanistic understanding of how fluctuating mechanical signals get transduced into biochemical pathways in phytoplankton. In this project, I will perform quantitative measurements of the fluctuation-induced signal transduction, focusing specifically on two ubiquitous cues: (a) shear forces due to laminar flows; and (b) gravity forces, due to turbulence-induced upturning events that change cells’ swimming direction relative to the gravity vector. The shear fields will be generated using microfluidic chips, while gravity changes will be studied within millifluidic chambers in lab and under micro- and hyper-gravity conditions aboard parabolic flights. Using a combination of high resolution microscopy and custom-built imaging, automation, and biomolecular analyses, I will identify the key signalling players and characterize their pathways under different doses (duration and intensity) of hydrodynamic stimulation. These novel biophysical and molecular data will significantly propel our understanding of emergent transduction pathways, with potentially far-reaching insights on microbial ramifications under rapidly changing conditions of our oceans.