Microphytobenthic diatoms isolated from sediments of the Adventfjorden (Svalbard): growth as function of temperature

Benthic diatoms (Bacillariophyceae) represent the major phototrophic group in microphytobenthic communities worldwide. They are the main component of shallow water coastal habitats with important ecological functions such as sediment stabilisation or high primary production. Little is known on the species composition and ecophysiology particularly in the polar regions, which are characterised by relatively low water temperatures and strong differences in the light regime during polar summer and winter. Therefore, the growth behaviour at different temperatures was evaluated in eight benthic diatom species isolated from the Adventfjorden (Svalbard, Norway). As a first comprehensive pilot study, their temperature requirements for growth were studied under controlled conditions between 1 and 20 A degrees C. Five out of eight of the investigated species grew between 1 and 20 A degrees C, but with different rates, while growth of two strains was inhibited at 1 A degrees C and of one strain at 20 A degrees C. The general response patterns clearly showed a preference for 6-15 A degrees C, pointing to rather eurythermal and psychrotolerant growth behaviour of Arctic benthic diatoms.