LETTER Mechanical vulnerability explains size-dependent mortality of reef corals

Understanding life history and demographic variation among species within communities is a cen-tral ecological goal. Mortality schedules are especially important in ecosystems where disturbance plays a major role in structuring communities, such as coral reefs. Here, we test whether a trait-based, mechanistic model of mechanical vulnerability in corals can explain mortality schedules. Specifically, we ask whether species that become increasingly vulnerable to hydrodynamic dislodg-ment as they grow have bathtub-shaped mortality curves, whereas species that remain mechani-cally stable have decreasing mortality rates with size, as predicted by classical life history theory for reef corals. We find that size-dependent mortality is highly consistent between species with the same growth form and that the shape of size-dependent mortality for each growth form can be explained by mechanical vulnerability. Our findings highlight the feasibility of predicting assem-blage-scale mortality patterns on coral reefs with trait-based approaches