Diel variability in discrete samples of reef seawater temperature, salinity, dissolved inorganic carbon, pH, and stable carbon isotopes from Willemstad, Curaçao from February 2023 to May 2025

These data capture bihourly variability in the carbonate chemistry parameters of dissolved inorganic carbon (DIC), pH, and seawater stable carbon isotopes (δ13CDIC) measured from discrete bottle samples of seawater collected from Piscadera (Willemstad), Curaçao during 36-hour field campaigns in February 2023, March 2024, November 2024, and May 2025. In-situ water temperature of each sample was captured via Onset HOBO deployable sensors deployed at the sampling location. DIC concentrations, pH (total scale), and sample salinity were measured via coupled coulometric titration, spectrophotometry, and salinometry, respectively in controlled laboratory conditions at 20 degrees Celsius. δ13CDIC was measured via isotope ratio mass spectrometry (IRMS). Monitoring carbon cycling in shallow water coral reef ecosystems on diel-to-seasonal timescales directly informs our understanding of natural and externally-forced changes to reef metabolism, structure, function, and ultimately stability. These data help establish gradients in modern Southern Caribbean coral reef metabolism and were collected by a team of researchers associated with an NSF P4Climate-supported award on Southern Caribbean climate change studies.