PAM fluorometry monitoring bleaching in the foraminifera Sorites orbiculus

Sorites orbiculus specimens were subjected to a bleaching treatment in a laboratory experiment. The photosystem II efficiency of the symbiotic algae was monitored using PAM fluorometry with 14 samples containing 8 replicates and 5 samples containing 2 replicates per control / treatment. The treatment involved exposure to 5 µmol L-1 DCMU continuously and 0.19 mmol L-1 menthol during 6-hour incubation periods per day for 5 days per week over 27 days. Specimens were maintained in 120 ml of artificial seawater, with full water exchanges conducted twice daily, five days per week. In the final three days, specimens were incubated in the dark with only DCMU present. During the 18 h incubation periods, the weekends and the last three days, a Nannochloropsis food mixture was added. Control groups underwent identical conditions without the addition of bleaching agents. Environmental parameters were maintained at 26°C temperature, 37.5‰ salinity, and an illumination of 48 µmol photons cm-2 s-1 under a 12:12 h light-dark cycle.