Puerto Rico Coral Reef Monitoring Program Water Quality Data from 2023–2025

Coral reefs are declining due to a combination of global and local anthropogenic stressors. While water quality is an important driver of coral reef condition, the lack of systematic water quality monitoring efforts has prevented a more thorough analysis of the role of water quality parameters in modulating coral reef declines. Here we present 8,032 measurements representing seawater temperature, salinity, dissolved oxygen, pH_NBS, Secchi depth, CO₂ chemistry (dissolved inorganic carbon and total alkalinity), biological oxygen demand (BOD), total suspended solids, settleable solids, turbidity, chlorophyll-a, ortho-phosphate, nitrite + nitrate (NOx), total Kjeldahl nitrogen (TKN), and Enterococcus spp. from 42 Puerto Rico coral reef sites from 2023 to 2025. These data provide a critical baseline for coral reef water quality that can be used to develop and assess water quality thresholds, explore spatiotemporal variability in seawater chemistry, ground truth remote sensing observations, and downscale earth system models to improve global monitoring efforts and projections for coral reefs under ongoing anthropogenic impacts.