Figure 6.

(a) Growth of cultures of strain 371 after different treatments and transfer from SWM to DSWM. ‘Medium strain 371', ‘Medium strain 32' and ‘Sterile med. strain 371' refer to the inoculation of the antibiotic-treated culture of strain 371 with 0.1% (v/v) of medium from non-treated cultures of strains 371 and strain 32, respectively, where strain 32 is a purely marine strain of Ectocarpus and ‘sterile' medium was autoclaved prior to inoculation. All experiments were carried out in triplicates and yielded highly similar results, but only one replicate is shown here. Differences in morphology between algae cultivated in DSWM and SWM have been previously described (Dittami et al., 2012), and may be related to the described differences in the bacterial phycosphere. (b) Quantum yield (Fv/Fm) of cultures kept under identical conditions as in panel a, 1 week after the transfer to fresh medium. Means with different letters are significantly different (Tukey's HSD, P<0.05). Fv/Fm is a measure of photosystem II efficiency and rapidly decreases in response to stress.