ALBERT

Description: A 2-year monthly survey has been carried out in Port Island (Hon Kong, SAR China) from April 2018 to March 2020 to monitor the water quality conditions and assess the physiological status of coral colonies Platygyra carnosa. Seawater parameters were measured every month along the water column using a YSI EXO2 multiparameter sonde to record values of chlorophyll, conductivity, depth, oxygen concentration, salinity, total dissolved solids, blue-green algae, turbidity, pH and temperature. Light intensity at coral depth (3-4 m) was measured using a Hobo light-meter during each survey. These data were used to identify the seasonal influence of water conditions on metabolism, productivity, and calcification of the coral Platygyra carnosa.

Description: A 2-year monthly survey has been carried out in Port Island (Hon Kong, SAR China) from April 2018 to March 2020 to monitor the water quality conditions and assess the physiological status of coral colonies Platygyra carnosa. Physiological parameters of P. carnosa were measured using the same protocols at each deployment survey to make repeated observations of health status under natural conditions. Respiration (R) and net photosynthesis (Pn) rates were measured at the coral surfaces using an underwater respirometer (CISME Instruments LLC) following measurement and calibration protocols as previously described by Dellisanti et al. (2020; doi:10.1016/j.marpolbul.2020.111005). Daily coral energetics, as holobiont productivity, were quantified as the ratio of oxygen production through gross photosynthesis (Pg) to consumption through respiration (R) and indicated as Pg/R ratio. At the end of each light incubation, a sample of the recirculated chamber water was collected for measurement of total alkalinity (At). Rates of coral calcification (CA) were determined using the alkalinity anomaly technique (Schoepf et al., 2017; doi:10.1007/s00338-016-1507-z) normalized to the coral surface area (24.5 cm2). The photosynthetic capacity of the symbiont was measured as maximum quantum yield (Fv/Fm) using a pulse amplitude modulated (PAM) fluorometer (diving-PAM, Heinz Walz, Effeltrich, Germany) equipped with a standard glass-fiber optic probe (Ralph et al., 1999; doi:10.3354/meps180139). PAM measurements were taken on randomly selected polyps of the same coral spot where CISME was deployed after 15 min dark acclimation. Digital photographs were taken on the same coral spot for colorimetric analysis to quantify the levels of whiteness as a measure of discoloration or quantification of bleaching (Chow et al., 2016; doi:10.1016/j.jembe.2016.03.003). The whiteness value was measured as the dissimilarity percentage in colour composition between treated and control corals using the SIMPER tool of Primer 6.0 software (Primer-E Ltd). The data were used to identify the seasonal influence of water conditions on metabolism, productivity, and calcification of the coral Platygyra carnosa.