Mathematical Biology seminar Anthony Jajeh University of Utah "Modeling biological drivers of sea ice permeability" Tuesday, March 17 1-2pm in LCB 215 Abstract: Algae living in the brine inclusions of polar sea ice produce a protective gelatinous coating of extracellular polymeric substances (EPS), which helps them survive in their harsh sea-ice habitat. One consequence of EPS production may be a reduction in nutrient availability, as EPS alters the ice microstructure, reducing permeability and the flux of nutrient-rich seawater into the ice. Here, we identify and analyze a novel biophysical feedback loop in which algae modify their environment through EPS production, thereby affecting nutrient availability and subsequent algal growth. To quantify the physical component of this feedback, we develop a microstructure fluid-transport model that represents sea ice as a connected network of brine inclusions, idealized as a heterogeneous pipe lattice with EPS-dependent permeability. We extend network models of interconnected brine channels by incorporating EPS transport, deposition, and clogging that dynamically reduce local cross-sectional area and hydraulic connectivity. Using pressure-driven flow solved on the network, we characterize how EPS accumulation restricts fluid exchange and nutrient delivery into the ice, providing a mechanistic basis for the EPS-permeability-nutrient feedback underlying algal bloom dynamics.