Dataset: Photoacclimation 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 two fragments from four Pocillopora capitata and four Pocillopora lacera colonies, except at one site where only two P. capitata colonies were available. 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, and rapid light curves (RLCs) were measured immediately before and after the treatment. The second fragment from each colony was maintained under constant low irradiance (~150 µmol photons m⁻² s⁻¹ PAR) for the same duration and served as the control. Following each treatment, both experimental and control fragments were frozen at −80°C until tissue processing for chlorophyll a concentration and symbiont density measurements.