Relationships between pigment ratios and growth irradiance in 11 marine phytoplankton species

Light-dependent variation in pigment content was examined in 11 marine phytoplankton species representing 8 algal classes. Batch cultures of each species were acclimated to 7 irradiances between 10 and 700 mu mol photons m(-2) s(-1). High-performance liquid chromatography analysis on exponentially growing cultures revealed that pigment ratios normalised to chlorophyll a (chl a) generally fell within the ranges previously reported for species of the same taxa. Unambiguous light-harvesting pigments (e.g. chlorophylls, fucoxanthin) showed limited amplitude of variation between low and high light conditions, while those involved in photoprotection (e.g. zeaxanthin, lutein, alloxanthin, diatoxanthin) dramatically increased under high light. Most of the relationships between pigment: chl a ratios and growth irradiance were quite well described using simple linear models. Among pigments shared by several species, chl b and c(3), fucoxanthin, zeaxanthin, lutein, diadinoxanthin and diatoxanthin exhibited similar trends regardless of the species studied, allowing general equations to be determined for each of these pigments. Determination of light: pigment relationships is a prerequisite for the development of more advanced modeling techniques such as artificial neural networks in chemotaxonomic studies.