Growth rates and pigment patterns of haptophytes isolated from estuarine waters

Abstract

Eleven haptophyte species were isolated over a two year period (2001–2002) from the Nervion River estuary (Biscay Bay) and batch cultured under non-axenic, isothermal (18 °C), isohaline (30 psu) conditions at three different light levels (60, 110 and 350 µmol photons m − 2 s − 1 ). The variation pattern of growth rate with light intensity was different among species. In all cases growth rates were maxima at 350 µmol photons m − 2 s − 1 and ranged from 0.93 divisions d − 1 in Chrysochromulina throndsenii, the slower growing species at the highest light studied, to 2.23 divisions d − 1 in Pleurochrysis roscoffensis, the faster one at the three light intensities tested. Differences in growth rate were less acute between cultures growing at 60 and 110 µmol photons m − 2 s − 1 but large species-specific differences were observed between 110 and 350 µmol photons m − 2 s − 1 . Based on the occurrence of chl c-type pigments and fucoxanthin and its derivatives, the isolated species belonged to six of the eight pigment types known in Haptophyta. Most haptophytes isolated could be unequivocally distinguished from other algal groups based on pigment composition. Chlorophyll c- and fucoxanthin-type pigment ratios normalized to chl a showed a decrease with the increase in light intensity and growth rate. The observed decrease in pigment ratios were more marked for the fucoxanthin pool than for the chlorophyll c-pool. The intensity of the changes were highly species-specific reflecting both differences in the pigment composition of the different components of the light harvesting protein complexes as well as the balance between them and the reaction centre complexes.