PAM fluorometry monitoring re-inoculation of Symbiodiniaceae in the foraminifera Sorites orbiculus@en

Bleached Sorites orbiculus specimens were re-inoculated with Symbiodiniaceae strains in a laboratory experiment for 19 days, and the photosystem II efficiency of the symbiotic algae was monitored using PAM fluorometry. Specimens were placed in 6-well plates, with 12 samples containing 4 replicates and 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.