The USGS Rotating X-Ray Computed Tomography (RXCT) Coral-Core Archive: Scope, Access, and Standardization

We announce the U.S. Geological Survey (USGS) Rotating X-ray Computed Tomography (RXCT) Coral-Core Archive, a digital resource derived from ~360 coral reef cores curated at the USGS Pacific and St. Petersburg Coastal and Marine Science Centers. The archive delivers calibrated 3-dimensional image volumes that enable reproducible values of skeletal density, linear extension, and calcification from decadal- to centennial-scale records of coral growth and bioerosion. Cross-study comparability within the archive is supported by a unified RXCT workflow that minimizes imaging artifacts. This includes rejecting image-intensity–density calibrations with r2 < 0.95, back-calculating standard densities to verify a ±10% target precision, and confirming that band-averaged density values fall within published species- and site-specific ranges. Our release of data under FAIR (Findable, Accessible, Interoperable, Reusable) principles is important given global coral reef decline and the rarity of physical coral archives. Calibrated imagery and scan metadata are distributed through CoralCache/CoralCT for analysis (DOI: 10.5194/essd-2025-598), while core locations and collection metadata are published through the USGS Geologic Core and Sample Database (DOI: 10.5066/F7319TR3) with links to CT imagery in a USGS ScienceBase repository (DOI: 10.5066/P139Y9H4). This archive provides a powerful dataset for evaluating environmental controls on coral growth, establishing restoration baselines, and improving coastal hazard assessments in the face of global coral reef declines.