The adaptation of Arctic phytoplankton to low light and salinity in Kongsfjorden (Spitsbergen)

The basic environmental variables and adaptability of phytoplankton communities to low light and salinity were studied using incubation experiments in Kongsfjorden, a high Arctic fjord of Spitsbergen, in late summer 2006. Chlorophyll a concentrations were steady or decreased slightly in darkness after one day or one week incubation. Chlorophyll a concentrations showed an initial decline when exposed to natural light after one week incubation in darkness, and then increased significantly. In a salinity experiment, the maximal growth rate was observed at a dilution ratio of 10%, however, higher dilution ratios (≥40%) had an obvious negative effect on phytoplankton growth. We suggest that the phytoplankton communities in fjords in late summer are darkness adapted, and the inflow of glacial melt water is favorable for phytoplankton growth in the outer fjords where the influence of freshwater is limited.