Table 1.

Surface area, internal gas volume and O₂ pools at atmospheric saturation at 20 °C in dense populations of 90 g m⁻² d. wt in L. dortmanna and 400 g m⁻² d. wt in Z. marina

	Surface area (m2 m−2 of sediment)
Species	Leaves	Roots	Gas volume (cm3 m−2)	O2 pool (mg O2 m−2)
Lobelia dortmanna	2·2	3·6	945	265
Zostera marina	4·7	2·0	284	80

Background values from Fig. 1.