78th Annual Meeting of the APS Division of Fluid Dynamics (Nov 23 — 25, 2025)

V030: The coral 'heartbeat' - using cilia beating frequencies for real-time tracking of host failure and oxygen dynamics

A coral colony's resilience hinges on a complex symbiosis between the coral host, its algal endosymbionts, and an associated suite of bacteria and viruses. This holobiont masks real-time tracking of the coral host's physiological collapse and its 'time of death', as other commonly used metrics reflect the entire colony's slower decline. Sessile reef corals actively generate local fluid motion via surface cilia, critical for vital mass transfer. Our approach uses high-speed imaging to measure cilia beating frequencies as a novel, real-time indicator of the coral host's physiological collapse-a 'heartbeat'-allowing us to infer individual host mortality at a much higher temporal resolution. This work underscores biologically driven hydrodynamics' vital importance, highlighting how thermal perturbations compromise these systems, offering a new lens to pinpoint critical mortality events at the host level.