Three‐dimensional photogrammetry‐based monitoring to enhance site‐level carbonate budget assessments of coral reefs

Census‐based carbonate budget assessments synthesize metrics on biologically derived carbonate production and erosion rates to generate estimates of net carbonate production (NCP). ReefBudget is a widely used in‐water carbonate budget approach, but this methodology can be field‐intensive and logistically challenging, limiting spatial data coverage. Large‐area imagery (LAI) is increasingly used to evaluate benthic communities and offers applications to leverage existing monitoring programs for use in carbonate budget assessments. Here, we introduce a Photogrammetry‐Based Carbonate Budget (PBCB) tool that uses site‐level LAI datasets to expand the spatial coverage of data obtainable for carbonate budget assessments. To validate the PBCB approach, long‐term monitoring data from Cheeca Rocks (Florida, USA) were used to compare PBCB carbonate budgets to in‐water ReefBudget surveys and a transect‐based LAI technique (six 100 m 2 plots sampled in 2018, 2019, and 2022). The PBCB method provided estimates of NCP similar to those of prior methodologies, enabling a means to expand transect‐based approaches to larger three‐dimensional datasets. While methodological variations were observed for the PBCB approach, such as lower estimates of CCA carbonate production and higher microbioerosion, these did not meaningfully impact NCP due to their relatively low contributions to reef budgets at the site. Coral species richness was > 2× higher using the PBCB method, suggesting that this site‐level technique better captures the heterogeneous nature of coral reefs. This new tool represents an advancement to carbonate budget assessments by enabling larger spatial estimates of benthic carbonate production/erosion from LAI, thereby providing a more comprehensive and scalable evaluation of reef growth and persistence.