One coral colony per tank was used for oxygen flux measurements, with incubations conducted every 7 days (n = 3 per treatment). On measurement days, oxygen fluxes were assessed 1 hour after organic C treatment using a beaker incubation technique. Corals were placed in 160 ml glass beakers filled with tank water, sealed underwater, and incubated in a thermostat-controlled (~25°C) water bath with stirring (190 rpm). Incubations lasted 1.5 h in light (~100 µmol photons m⁻² s⁻¹ PAR) and 1.5 h in dark, with oxygen concentrations recorded before and after using an optode sensor. Xenia umbellata originates from the Red Sea.

Study location: Aquarium experiment at the University of Bremen, GermanyTreatments: 3 carbon enrichment treatments of 20 mg C/L. DOM (glucose), 2. POM (phytoplankton), 3. POM (zooplankton)Date of study: May 2022Duration of study: 28 daysSpecies information: Xenia umbellata native to the Indo-Pacific and Red Sea