Primary production models and pigment algorithms for remote optical systems including satellites, moorings, or drifters depend on an improved understanding of the relationship between spectral light absorption, pigments, and photosynthesis for species of phytoplankton that are widespread and numerically abundant. Cultures of colonial Phaeocystis antarctica, a prymnesiophyte that can dominate the phytoplankton community in the Southern Ocean, were grown under blue light at seven different levels ranging from 14 to 542 mol quanta m Ϫ2 s Ϫ1 at 4ЊC under nutrient-replete conditions. Chlorophyll-specific absorption ( ) at 436 nm increased linearly from 0.03 to 0.11 m 2 a* ph mg chlorophyll a Ϫ1 with increasing light intensities. This variability is attributed to pigment packaging effects and pigmentation. The 2.5-fold range in the values of (676 nm) demonstrates significant pigment packaging effects a* ph due to the intracellular pigment content, single cell diameter within the colony, and thylakoid stacking. Quantum yield for growth ( ) varied 30-fold, ranging from 0.003 to 0.09 mol carbon fixed (mol quanta absorbed)Ϫ1 . Under low light conditions, the relatively high and high () may enable Phaeocystis to accumulate a seed population a* ph to initiate blooms at the beginning of spring when light levels are low, mixed layers are deep, and sea ice is still significant. These aspects of its photophysiology may contribute to the ecological success of Phaeocystis in polar regions.

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Abstract.A compiled set of in situ data is important to evaluate the quality of ocean-colour satellite-data records. Here we describe the data compiled for the validation of the ocean-colour products from the ESA Ocean Colour Climate Change Initiative (OC-CCI). The data were acquired from several sources (MOBY, BOUSSOLE, AERONET-OC, SeaBASS, NOMAD, MERMAID, AMT, ICES, HOT, GeP&CO), span between 1997 and 2012, and have a global distribution. Observations of the following variables were compiled: spectral remote-sensing reflectances, concentrations of chlorophyll a, spectral inherent optical properties and spectral diffuse attenuation coefficients. The data were from multi-project archives acquired via the open internet services or from individual projects, acquired directly from data providers. Methodologies were implemented for homogenisation, quality control and merging of all data. No changes were made to the original data, other than averaging of observations that were close in time and space, elimination of some points after quality control and conversion to a standard format. The final result is a merged table designed for validation of satellite-derived ocean-colour products and available in text format. Metadata of each in situ measurement (original source, cruise or experiment, principal investigator) were preserved throughout the work and made available in the final table. Using all the data in a validation exercise increases the number of matchups and enhances the representativeness of different marine regimes. By making available the metadata, it is also possible to analyse each set of data separately. The compiled data are available at doi:10.1594/PANGAEA.854832 (Valente et al., 2015).