A Synthesis of Plant Mass Mortality Events in Coastal Ecosystems

BioScience, 2026

By Camille L Stagg, Emily C Fromenthal, Judith Z Drexler, Eric E Grossman, Michael J Osland & Karen M Thorne

Abstract

Around the world, mass mortality events are disrupting the ecological and economic stability of shorelines. To better understand mechanisms of mass mortality in coastal ecosystems, we provide a global synthesis of over 250 reports of plant mass mortality events in six coastal ecosystems: coastal freshwater forests, tidal freshwater marshes, salt marshes, mangrove forests, seagrass meadows, and kelp forests, highlighting commonalities. Mass mortality events were associated with both climate and land-use change drivers in all six coastal ecosystems. Furthermore, increases in disturbance intensity and frequency, including climate extremes, and compound disturbances were key aspects of mass mortality events. Land-use change disturbances that altered hydrology, nutrient availability, and trophic structure often interacted with climate stressors, leading to mass mortality events. Therefore, beyond global climate mitigation, remediating local land-use disturbances represents a tractable opportunity for intervention. Insights from this synthesis may help managers to anticipate mass mortality events and prevent future habitat loss.