Table 1.
Terminology.
Fig 1.
(A) Growth rate of C. neogracilis cultures versus growth irradiance at 0°C (circles) and 5°C (triangles). A Poisson function was fitted to the data and gives an estimate of μmax of 0.63 d-1 and a KE of 19 μmol photon m-2 s-1 at 0°C and a μmax of 1.1 d-1 and a KE of 35 μmol photon m-2 s-1 at 5°C. (B) Chl a: C ratio of C. neogracilis cells versus growth irradiance at 0°C (circles) and 5°C (triangles). In (A) each data point is the mean growth rate of 3 cultures measured each day over 10 consecutive days. In (B), each data point is the mean of 3 cultures measured each day over 3 consecutive days (23, 50, 80, 150, 400 μmol photon m-2 s-1) or 2 days (10 μmol photon m-2 s-1). Error bars represent standard deviations.
Fig 2.
Photoacclimation of carbon fixation.
EKC (A), and α* (B) versus growth irradiance at 0°C (circles) and 5°C (triangles). PCm (squares), PCe (diamonds) and μ (hexagons) versus growth irradiance at 0°C (C) and 5°C (D). PCe versus μ (E) and PCm versus μ at 0°C (circles) and 5°C (triangle). Each data point is the mean of 3 cultures measured each day during 3 consecutive days (50, 80, 400 μmol photon m-2 s-1) or 2 days (10 μmol photon m-2 s-1). In A, E, F, the dotted lines represent the 1:1 line Error bars represent standard deviations.
Fig 3.
Photoacclimation of the Rubisco content.
Rubisco content versus growth irradiance at 0°C (circles) and 5°C (triangles). The grey line represents the mean rubisco content measured in various mesophilic diatoms (Thalassiosira weissflogii, Thalassiosira oceanica, Skeletonema costatum, Chaetoceros muelleri, Phaeodactylum tricornutum from Losh et al. (2013)). Dashed lines represent standard deviations. Each data point is the mean of 3 cultures measured each day during 3 consecutive days (23, 50, 80, 150, 400 μmol photon m-2 s-1) or 2 days (10 μmol photon m-2 s-1). Error bars represent standard deviations.
Fig 4.
Effect of the acclimation irradiance on the xanthophyll cycle of C. neogracilis.
(Dt +Dd)/Chl a (A) and Dt / Chl a (C) versus growth irradiance at 0°C (circles) and 5°C (triangles). (Dt +Dd) / Chl a (B) and Dt / Chl a (D) versus E/KE at 0°C (circles) and 5°C (triangles). In C an insert shows an enlargement of low irradiances. Each data point is the mean of 3 cultures measured each day during 3 consecutive days (23, 50, 80, 150, 400 μmol photon m-2 s-1) or 2 days (10 μmol photon m-2 s-1). Error bars represent standard deviations.
Fig 5.
EKC versus EKETR (A), EKO2 versus EKETR (B) and EKC versus EKO2 (C) at 0°C (circles) and 5°C (triangles). In A, B, C, the dotted lines represent the 1:1 line. The growth irradiance at which growth rate (μ), carbon fixation (14C), O2 net production, ETR and NPQ saturate (E = EKi) is presented in D at 0°C (white bars) and 5°C (grey bars). In D, horizontal lines indicate growth irradiances (10, 23, 50, 80, 150, 400 μmol photon m-2 s-1).