Fig. 9a, b: During the isolation process the ionic conditions for zooxanthellae change fundamentally compared to the in hospite situation (Fig. 9a). The higher energy demand to readjust and maintain compatible ion conditions in vitro influence carbon assimilation negtatively (Fig. 9b, left hand). The carbon assimilation rate increases under ionic conditions simulating the in hospite situation (Fig. 9b, right hand). The numbers in the figures indicate sodium concentrations in the different compartments. Numbers in the columns indicate numbers of replicates. ASWM = artificial sea water medium; HICM = a medium isoionic with the host.
