Fig. 10.

Relative electron transport rate (rETR/μmol electrons m⁻² s⁻¹) under increasing light intensity up to 2973 μmol photons m⁻² s⁻¹ in Zygnema B sp. (a, n = 3), Zygnema sp. G (b, BBM, 800 mM, n = 3; 400 mM, n = 2), Zygnema sp. D (c, n = 3) and Zygnema sp. E (d, n = 3). Measurements were carried out in BBM (solid line) and after incubation in 400 mM (dashed line) and 800 mM (smooth dashed line) sorbitol for 3 h. P–E curves were fitted according to Eilers and Peeters (1988).