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Over recent decades, many Caribbean reefs have transitioned to states where stony corals are no longer spatially dominant. The community dynamics culminating in this outcome are well known, but its functional implications remain incompletely understood. Here we used annual surveys from 1992 to 2019 to describe coral communities at 6 sites off St. John, US Virgin Islands, and explored how their ecological dynamics interact with their capacity to sustain estimated coral community calcification (G, kg CaCO 3 m -2 yr -1 ). These communities had low coral cover (≤4.4%), but they changed through small and incremental events that summed to a slight decline in coral cover and changes in species assemblages favoring biotic homogenization and weedy species. Estimated coral G remained low, between 0.3 and 1.3 kg CaCO 3 m -2 yr -1 (8.2-35.6 mmol CaCO 3 m -2 d -1 ), but it differed among sites and years. The dominant contributors to G were Siderastrea siderea (1 site), Porites astreoides (1 site), and Orbicella spp. (4 sites), but higher G only occurred where Orbicella spp. remained relatively common; G dramatically declined at 1 site when the abundance of this genus decreased. These results suggest that some coral-depleted reefs may maintain low G that could be sufficient to avoid transitions into net negative budget states, provided that biological and physical erosion and dissolution of CaCO 3 (not recorded here) are minimal. Further mortalities of the few coral species remaining on these reefs through disturbances like stony coral tissue loss disease would compromise this delicate production-erosion balance, and likely see transitions of such reefs into negative carbonate budget states. 

This paper is a short note describing the detection of an unusually large number of diseased sponges in January 2021 

Coral reefs have long attracted attention because of their biological and economic importance, but this interest now has turned to examining the possibility of functional extirpation. Widespread declines in coral abundances have fueled the shift in motivation for studying reefs and catalyzed the proliferation of monitoring to record the changes underway. Despite appreciation of monitoring as a scientific endeavor, its primary use has continued to be the quantification of cover of coral, macroalgae, and a few other space holders. The limitations of coral cover in evaluating the consequences of changing coral abundance were highlighted decades ago. Yet neglect of the tools most appropriate for this task (demographic approaches) and continuing emphasis on a tool (coral cover) that is not ideal, indicates that these limitations are not widely appreciated. Reef monitoring therefore continues to underperform with respect to its potential, thus depriving scientists of the approaches necessary to project the fate of coral reefs and test hypotheses focused on the proximal causes of declining coral cover. We make the case that the coral reef crisis creates a need for coral demography that is more acute now than 4 decades ago. Modern demographic approaches are well suited to meet this need, but to realize their potential, consideration will need to be given to the possibility of expanding ecological monitoring of coral reefs to provide the data necessary for demographic analyses of their foundation taxon, the Scleractinia.