Dissolved inorganic carbon, total alkalinity, pH, water temperature and salinity measured from discrete surface samples, taken at the site of GraysRf_81W_31N mooring in Gray’s Reef National Marine Sanctuary, East Coast of the United States on 2025-06-29 (NCEI Accession 0306562)

This NCEI accession consists of dissolved inorganic carbon, total alkalinity, pH, water temperature and salinity measured from discrete surface samples, taken at the site of GraysRf_81W_31N mooring in Gray’s Reef National Marine Sanctuary, East Coast of the United States on 2025-06-29. Operation of the Grays Reef time-series mooring has been a multi-organization effort which has successfully collected high-resolution data since 2006. The mooring is located in the South Atlantic Bight offshore Georgia, USA and within the boundaries of Gray’s Reef National Marine Sanctuary. It sits along the divide between the inner and middle shelf with water depths of 20 m. Water chemistry is primarily controlled by the middle shelf oceanic dynamics, but during heavy rain events, it can be affected by freshwater plumes coming from the numerous rivers along the Georgia and South Carolina coast. Temperature also plays a major role in the partial pressure of carbon dioxide (pCO2) variability with seasonal changes being apparent. During summer months, GRNMS acts as a CO2 source to the atmosphere while during winter months it is a CO2 sink. The benthic community at GRNMS has proven to be hardy enduring large seasonal swings of seawater CO2 and pH.