Carbonate budget methods comparison at Cheeca Rocks (Florida, USA) (NCEI Accession 0305035)

Carbonate budget assessments quantify changes to reef habitat structure by measuring the cover of habitat altering taxa (calcifies and eroders) and assimilating literature-reported carbonate production/erosion rates, ultimately yielding estimates of net carbonate production. This dataset was used to test the efficacy of our novel site-level Photogrammetry-Based Carbonate Budgets (PBCB) technique by performing a methods comparison at Cheeca Rocks (Florida, USA). The PBCB-derived carbonate budget results were compared to two established transect-based methods: in-water ReefBudget surveys and a modified large-area imagery technique. The ‘carbonateBudget’ csv file includes percent cover of prominent benthic taxa, carbonate production/erosion of habitat altering taxa (coral, CCA, microborers, macroborers, parrotfish, and urchins), the three primary components of a carbonate budget (net carbonate production, gross carbonate production, gross carbonate erosion), and site/transect rugosity. The ‘coralGenus_Data’ csv file includes percent cover and carbonate production by each coral genus observed at the study site. The ‘coralData_PBCB’ csv file includes all coral data extracted from segmented coral colonies (i.e. boundary of distinct areas of coral tissue) using the PBCB workflow. These data reveal that all three methods produce similar estimates of net carbonate production, validating the efficacy of the PBCB method to be used for future carbonate budget assessments.

The Photogrammetry-Based Carbonate Budgets (PBCB) methodology is a site-level carbonate budget approach that combines large-area imagery (LAI) datasets with in-field grazer surveys to calculate reef habitat growth and erosion. The LAI data sources employed in this technique include: (1) two-dimensional orthoprojections, (2) three-dimensional digital elevation models, (3) segmented polygons of coral colonies annotated at the species/genus level, and (4) benthic points (25 points m-2) overlaid on the orthoprojections annotated at the functional group level.

Benthic carbonate production is quantified as the sum of coral carbonate production (derived from segmented polygons) and carbonate production by non-coral calcifiers (derived from benthic points). Benthic carbonate erosion by microborers and macroboring sponges is calculated using percent cover (derived from benthic points) and literature-reported bioerosion rates. Surface values from digital elevation models are used to translate the planar area of each benthic component into surface area, providing a more accurate representation of three-dimensional structure within the calculated carbonate production and erosion rates. Since LAI techniques are unable to robustly capture grazer populations, field-survey data of parrotfish and urchins (recorded to the species and size-class level) are used to quantify grazer erosion. Site-level carbonate budgets are then estimated by summing benthic carbonate production, benthic carbonate erosion, and grazer erosion.