Age and site-specific pattern on encrustation of charophytes

Botanical Studies

Table 4 Difference in O₂ evolution of C. tomentosa with the addition of CaCl₂, KCl, MgCl₂ and NaCl referred to control (without addition)

Addition	1.2	2.4	3.6	4.8	6.0	7.2	8.4
CaCl₂	2.1 ± 2.8 a	0.1 ± 3.6 a	− 1.2 ± 3.7 a	− 1.2 ± 3.6 a	− 1.3 ± 3.5 a	− 1.0 ± 3.9 a	− 0.2 ± 3.6 a
KCl	− 1.0 ± 3.3 b	0.0 ± 4.0 a	1.4 ± 4.9 b	1.4 ± 5.2 a	1.1 ± 5.5 a	0.9 ± 5.7 ab	1.2 ± 5.9 a
MgCl₂	− 0.6 ± 2.3 b	− 3.8 ± 2.3 b	− 4.6 ± 2.9 c	− 4.0 ± 3.6 b	− 3.4 ± 4.2 b	− 2.7 ± 4.3 bc	− 1.7 ± 4.5 a
NaCl	− 0.9 ± 3.7 b	− 5.1 ± 5.5 b	− 6.8 ± 5.4 c	− 6.2 ± 5.8 b	− 5.9 ± 5.6 b	− 5.3 ± 5.9 c	− 4.1 ± 5.6 b

1.2 mmol L⁻¹ of CaCl₂, KCl, MgCl₂ and NaCl was added stepwise. O₂ evolution (mmol O₂ h⁻¹ g chl a⁻¹) is presented as accumulated concentrations (1.2, 2.4, 3.6, 4.8, 6.0, 7.2 and 8.4 mmol L⁻¹). Sample size was n = 8 for the 20 min measurement of photosynthesis. Different letters indicate significant differences within a concentration level (Fischer LSD post hoc test, p < 0.05)