Oceanic productivity and high-frequency temperature variability—not human habitation—supports calcifier abundance on central Pacific coral reefs

Past research has demonstrated how local-scale human impacts—including reduced water quality, overfishing, and eutrophication—adversely affect coral reefs. More recently, global-scale shifts in ocean conditions arising from climate change have been shown to impact Here, we surveyed benthic reef communities at 34 U.S.-affiliated Pacific islands spanning a gradient of oceanic productivity, temperature, habitation. We re-evaluated patterns reported for these the early 2000s which uninhabited reefs were dominated by calcifiers (coral crustose coralline algae) thought be more resilient global change. Using contemporary data collected nearly two decades later, our analyses indicate this projection was not realized. Calcifiers are no longer dominant group islands. Calcifier coverage now averages 26.9% ± 3.9 SE on (compared 45.18% 2000s). then asked whether past sea surface temperatures (SST), or acute heat stress supersede impacts habitation cover. Indeed, found variation cover best explained population densities, but remotely sensed metrics chlorophyll- , SST, island-scale estimates herbivorous fish biomass. Specifically, higher CCA observed productive waters with greater biomass herbivores, while turf increased daily SST variability herbivore Interestingly, positively correlated negatively monthly variation. Surprisingly, Our results reveal that is primary correlate calcifier central island reefs, highlight addition productivity high-frequency list factors supporting builder abundance.