Hydrodynamic Feedbacks in Coral Reefs: from Organisms to Geomorphic Development

Greta Sartori , Daniel Harris, Peter J Mumby

Coral reefs are shaped by tightly coupled interactions among geomorphology, hydrodynamic forcing, and ecological processes. In this review, we synthesize current knowledge on how hydrodynamic processes regulate coral reef functioning across scales, from exchanges at organismal surfaces to reef-scale morphodynamics.
Hydrodynamic forcing governs mass and momentum transfer across scales through nested boundary layers, linking organismal performance, growth and ecological interactions to carbonate production, redistribution, and reef morphodynamics. Reef geomorphology modifies these flow regimes by generating spatially heterogeneous patterns of turbulence, wave dissipation, and current acceleration that regulate disturbance, substrate stability, productivity, and benthic community structure. Through carbonate accretion, bioerosion, and sediment reworking, ecological processes in turn reshape reef geomorphology.
Many reef processes respond non-linearly to hydrodynamic forcing, such that carbonate production and reef growth are maintained only within ranges of flow conditions where these processes remain mutually compatible. Rather than forming a single optimal state, these context-dependent hydrodynamic “Goldilocks” envelopes are spatially fragmented by reef geomorphology, generating mosaics of benthic states, disturbance regimes, and recovery trajectories across reefscapes. Within these dynamic environments, disturbance is not solely destructive but also contributes to reef development through the generation, transport, and stabilization of carbonate sediments and rubble. Building on these concepts, we propose hydrodynamic resilience as the capacity of reef systems to maintain or reorganize constructive flow-form feedbacks following disturbance.
By integrating hydrodynamic, ecological, and geomorphic perspectives, this review provides a framework for understanding reef spatial organization, resilience and geomorphic evolution as emergent properties of interactions across spatial and temporal scales.