The basic environmental variables and adaptability ofphytoplankton communities to low light and salinity were stud- ied 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 （≥0%） had an obvious negative effect on phytoplankton growth. We suggest that the phytoplankton communities in fjords in late summer are dark- ness adapted, and the inflow of glacial melt water is favorable for phytoplankton growth in the outer fiords where the influence of freshwater is limited.
CUI ShikaiHE JianfengHE PeiminZHANG FangLIN LingMA Yuxin
The 16S and 18S ribosomal ribonucleic acid genes of microbial organisms collected from the contrasting environments （temperature, salinity, silicate, phosphate and nitrate, p 〈0.05） of the inner and outer basins of Kongsfjorden （Spitsbergen, Arctic） were studied using polymerase chain reaction-denaturing gradient gel electrophoresis（DGGE） fingerprinting. Comparison of the microbial fingerprints and the physicochemical parameters revealed that molecular methodology exhibited a greater sensitivity. Sequences obtained from bacterial DGGE were affiliated with four main phylogenetic groups of bacteria：Proteobacteria（Alpha, Beta and Gamma）, Bacteroidetes, Verrucomicrobia and Cyanobacteria. The relationships between the genotype distribution of these microbes and associated biotic/abiotic factors, revealed by canonical correspondence analysis, showed that Station 1 at 30 m （outer fjord） was grouped separately from the other sites. This difference could be a consequence of the thermocline and base of the euphotic layer at this depth where the Atlantic and Arctic-type waters overlapped.
