Disturbance-induced changes in population size structure promote coral biodiversity

Mariana Álvarez-Noriega*, Joshua S. Madin, Andrew H. Baird, Maria Dornelas, Sean R. Connolly

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Reef-building coral assemblages are typically species rich, yet the processes maintaining high biodiversity remain poorly understood. Disturbance has long been thought to promote coral species coexistence by reducing the strength of competition (i.e., the intermediate disturbance hypothesis [IDH]). However, such disturbance-induced effects are insufficient to inhibit competitive exclusion. Nevertheless, there are other mechanisms by which disturbance and, more generally, environmental variation can favor coexistence. Here, we develop a size-structured, stochastic coral competition model calibrated with field data from two common colony morphologies to investigate the effects of hydrodynamic disturbance on community dynamics. We show that fluctuations in wave action can promote coral species coexistence but that this occurs via interspecific differences in size-dependent mortality rather than solely via stochastic fluctuations in competition (i.e., free space availability). While this mechanism differs from that originally envisioned in the IDH, it is nonetheless a mechanism by which intermediate levels of disturbance do promote coexistence. Given the sensitivity of coexistence to disturbance frequency and intensity, anthropogenic changes in disturbance regimes are likely to affect coral assemblages in ways that are not predictable from single-population models.
Original languageEnglish
Number of pages12
JournalAmerican Naturalist
Issue number5
Early online date29 Sept 2023
Publication statusPublished - Nov 2023


  • Coexistence
  • Wave disturbance
  • Evironmental variability


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