Table 2.

Chlorophyll a, carotenoids, phycocyanin, and phycoerythrin pigment concentrations (mg/gFW) of Phymatolithon lusitanicum under 400, 550 and 750 μatm conditions after 20 months of high CO₂ under low light ambient irradiance (8 μmol photons m⁻² s⁻¹). Values expressed as mean ± standard error (n = 5). p Values show the significance of the effects of CO₂ levels on pigment concentration

pCO2 (μatm)	Chlorophyll a (mg/gFW)	Carotenoids (mg/gFW)	Phycocyanin (mg/gFW)	Phycoerythrin (mg/gFW)
400	0.040 ± 0.006	0.016 ± 0.004	0.004 ± 0.000	0.122 ± 0.019
550	0.048 ± 0.004	0.014 ± 0.002	0.004 ± 0.000	0.153 ± 0.015
750	0.039 ± 0.002	0.016 ± 0.001	0.003 ± 0.000	0.097 ± 0.016
p Values	.901	.887	.446	.105