Responses of pigment composition of the marine diatom Thalassiosira weissflogii to silicate availability during dark survival and recovery

Abstract

Responses of light-harvesting and photoprotective pigments to the length of dark storage and silicate avail- ability were determined for the marine diatom Thalassiosira weissflogii during dark survival and recovery. During 14- day's darkness, no significant changes in the concentration of silicate were observed, whereas the cell density increased by 34% for 8 days and decreased afterward. All cellular pigment contents decreased sharply between days 3 and 5 and stayed at relatively constant levels on days 11 and 14. Once the cells were exposed to a light:dark cycle on days 3, 8, and 14 of the dark storage experiments, there was a significant loss of all cellular pigment contents during the first 24 h of the light:dark cycle, which corresponded to the log-phase of growth. Cellular photoprotective pigment levels then started to recover to levels similar to those observed on days 11 and 14 in the dark storage experiments. When the dark- acclimated cells were exposed to light:dark cycle conditions, cell growth was immediately restored. The growth rate de- creased significantly with increasing length of dark storage but not with silicate availability. This observation may sug- gest that T. weissflogii trapped in ballast water are able to survive in total darkness and to restore cell division once they are released into ambient coastal waters within two weeks.