Figure S1. Cross-section of Fucus vesiculosus thallus showing the cryptostomata cavity and hyaline hairs. Scale bar, 500 μm.

Figure S2. O2 microprofiles in the diffusive boundary layer (A) and the net O2 production versus irradiance (B) of Fucus vesiculosus. The net production was calculated using eq. S1 (see methods in Appendix  S1 for equations). The solid line in (B) represents the nonlinear curve fit of eq. S2 to the net production, and Ek was calculated according to equation S3. Ec is the compensation point in μmol photons·m−2 · s−1.

Figure S3. Oxygen concentration (○) and pH (▽) measured at the surface of the Fucus vesiculosus thallus in darkness (black symbols), at the onset of illumination (gray symbols), and after onset of illumination (open symbols). Irradiance was ~500 μmol photons·m−2 · s−1 (= 2, error bars indicate standard deviation).

Figure S4. Oxygen microprofiles measured through thallus and cryptostomata in darkness and at saturating irradiance (~500 μmol photons·m−2 · s−1). The two points were measured ~10 mm apart. Calculations of Pm and respiration are presented in Table  1.

Appendix S1. Methods.

JPY_894_sm_FigS1-4.pdf145KSupporting info item
JPY_894_sm_AppS1.pdf19KSupporting info item

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