Bleached Sorites orbiculus specimens were re-inoculated with Symbiodiniaceae strains in a laboratory experiment for 19 days, and the percentage of host area covered with symbionts was monitored with Confocal Laser Scanning Microscopy. Specimens were placed in 6-well plates, with 2 samples containing 2 replicates per treatment / control. Treatments were exposed to Symbiodinium microadriaticum (strains KB8 and CCMP2467) and Fugacium kawagutii (strain F2) individually and collectively at a concentration of 1e5 cells ml-1. The medium was supplemented with a Nannochloropsis food mixture and exchanged twice weekly. Control groups included non-bleached specimens and bleached specimens maintained with or without 5 µmol L-1 DCMU in artificial seawater (ASW). Environmental conditions were maintained at 22 - 24°C temperature, 37.5 - 40.5‰ salinity, and 46 - 63 µmol photons cm-2 s-1 illumination under a 12:12 h light-dark cycle.

Symbiodinium microadriaticum, strain CCMP2467: collected in the Gulf of Aquaba on 2004-07-30, symbiont isolated from Stylophora pistillataSymbiodinium microadriaticum, strain KB8: collected in Hawaii, symbiont isolated from Cassiopaia xamanchaFugacium kawagutii, strain F2: collected in Jamaica, Caribbean, symbiont isolated from Meandrina meandrites