Persistent Geographic Patterns of Coral Recruitment in Hawaiʻi

Abstract

Coral life cycle dynamics are poorly understood in most reefs, especially at the large geographic scales commensurate with ocean transport, genetic flow, and other synoptic scale processes. We present a spatially explicit, large-scale, and multi-temporal study of coral settlement along a 30 km long reef system in the Southwest portion of Hawaiʻi Island. Here, we focused on interannual variability in coral recruitment from 2021 to 2024, a period without a major marine heatwave. We used stratified random site selection to place 320 coral settlement tiles at 32 sites (10 tiles per site) at 10 ± 3 m water depth annually to monitor recruitment of the three most common coral genera found in the region (Montipora, Pocillopora, Porites). Site-level interannual variability in coral recruitment was high yet the overall geographic distribution of recruits was consistent through time. This occurred despite a decrease in benthic temperature and recruitment rates during the study period. Persistent geographic patterns in coral recruitment strengthen our understanding of mechanisms and conditions that drive reef resilience. They also strongly suggest a need to protect areas of high recruitment while studying drivers of low recruitment in contrasting habitats. This approach will further increase support of coral production in an era of climate- and coastal pollution-driven declines in coral reefs.

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