Algae. 1999; 14(3): 169-179.

Cryophilic Diatoms Navicula glaciei and N. perminuta in Antarctic Coastal Environment. I. Morphology and Ecology

Jae-Shin Kang, Sung-Ho Kang, Jin Hwan Lee

Polar Research Center, Korea
Ocean Research & Development Institute. Department of Biology, Sangmyung University

We investigated seasonal variation of microalgal assemblages in Marian Cove, King George Island and compared with environmental factors from January to December 1996. Annual mean air temperature (avg. -0.7℃) was 1.3℃ higher than mean of last years. Annual mean water temperature was -0.28℃ and 0.4℃ higher than air temperature. The lowest salinity (31.97 psu) was formed in February, which was about 2.5 psu lower than the highest salinity (avg. 34.4 psu) in July, by melt water input. Annual mean Chl a concentration was 1.38 μg·l super(-1). Pico- and nano-sized algae (20 μm) was 0.75 μg·l super(-1) and 0.63 μg·l super(-1), accounting for 54% and 46% of total Chl. a, respectively. More than 80% (avg. 2.28 μg·l super(-1)) of total Chl. a was concentrated between October and March. Ecology of perdominant diatoms, Navicula glaciei Van Heurk and Navicula perminuta Grunow was studied. The higher cell abundance of the species was found during austral autumn (March to May, avg. 1.01 × 10 super(5) cell·l super(-1) and during austral spring(September to November, avg. 1.97 × 10 super(5) cell·l super(-1)). The cell numbers were lower during austral winter (June to August, avg. 3.99 × 10 super(3) cell·l super(-1)) and austral summer (December, January and February, avg. 7.04 × 10 super(4) cell·l super(-1)). We found five abrupt increase of Navicula glaciei and N. perminuta cells (>1.0 × 10 super(6) cell·l super(-1)) during the study period (2 peaks in austral autumn and 3 peaks in austral spring). Mechanisms causing the peaks were different between seasons. The highest abundance (2.10 × 10 super(6) cell·l super(-1)) was measured on 11 May when frazil ice was formed. Frazil ice formation and inflow of colder water formed near glacier cliff seem to ge main factors during austral autumn, whereas melting of sea ice due to the change of physicochemical environment and resuspension by tidal mixing seem to be amjor factors during austral spring. Ourresults suggest that the diatoms N. glaciei and N. perminuta could be indicator species to indicate inflow of colder water formed near glacier cliff during austral autumn and resuspension and melt water input during austral spring.

Keywords : cryophilic diatom, fraxil ice, glacier cliff, Navicula glaciei, N. perminuta