Dataset: Photo-irradiance curve of Pocillopora corals from an outdoor mesocosm experiment in Pacific Panama, February 2023

This study was conducted at the Smithsonian Tropical Research Institute in Panama City, Panama. Samples were collected from the Gulf of Panama (GoP) and the Gulf of Chiriquí (GoC) along the Pacific coast of Panama, where shallow reefs are dominated by Pocillopora corals. Sampling took place at three sites within each gulf near protected islands or archipelagos: Canales de Afuera (7.69594, -81.63292), Granito de Oro (7.59378, -81.71281), and Machete (7.63956, -81.74150) in the GoC; and Contadora (8.63245, -79.02834), Mogo Mogo (8.57442, -79.01646), and Saboga (8.62807, -79.05462) in the GoP.

Pocillopora coral fragments (~5 cm long) were collected by SCUBA from tagged colonies at six sites across the Gulf of Chiriqui (GoC) and Gulf of Panama (GoP) (three sites per gulf). At each site, we collected fragments from Pocillopora capitata (n=21) and Pocillopora lacera (n=24) colonies . Coral fragments were transported to the aquarium facilities at the Naos Laboratories of the Smithsonian Tropical Research Institute (STRI) in Panama City, Panama, and acclimated in aquaria supplied with a continuous flow of filtered seawater from the nearby Bay of Panama for 2–5 days prior to experimentation. We then conducted light-gradient exposure trials over seven consecutive days beginning on 8 February 2023. One fragment from each colony was exposed to an increasing light gradient (0–900 µmol photons m⁻² s⁻¹ photosynthetically active radiation, PAR) over approximately 8 h. Oxygen measurements were conducted for approximately 20 minutes at each of nine light levels, ranging from 0 to ~900 PAR. Between each irradiance step, we performed a light on-off-on transition and allowed coral fragments to acclimate to the new irradiance level for 15 minutes before taking oxygen measurements. Rates of oxygen evolution (respiration and net photosynthesis) were corrected from background oxygen concentration and standardized to coral surface area.