Title: Experimental Study on the Initial Formation of Ice Algal Community
Principal Investigator:

Satoru TAGUCHI, Professor
Faculty of Engineering, Soka University

Co-Principal Investigator:

Kunio SHIRASAWA, Associate Professor
Low Temperature Science InstituteHokkaido University
Hiroshi HATTORI, Professor
Faculty of Engineering, Hokkaido Tokai University
Kazutaka TAKAHASHI, Researcher
Tohoku National Fisheries Research Institute
Akira SHIBATA, Assistant Professor
Faculty of Engineering, Soka University

Duration: 2001 fiscal year (one year)
Introduction
Ice algal community is well known to develop densely under surface layer of sea ice in the highlatitudes. Ice algal community is consisted of various groups of marine organisms which areincorporated into the sea ice. Ice algal community can live in brine channels as long as sea ice cangrow. Ice algal community forms unique ecosystem in brine channels as isolated but relatively
complete microbial loops. But those microbial loops are slightly different from so-called microbial
loops in the sea. The microbial loops in ice algal community are dominated often by large celldiatoms. Based on our previous study, small cells in picoplankton size were abundant at thebeginning of ice formation. This comparison strongly suggests the occurrence of species succession
as sea ice grows. Our novel method to study the ice formation and incorporation of organisms intofragile ice was applied to study on the species succession of ice algal community.
Materials and Methods
Experimental site was located near the coast of Sakaeura in Saroma-ko lagoon. Thickness of sea
ice was about 45 cm with 1-2 cm overlying snow. A square pool was made and sea ice was completely
removed from the surface. Surface water was collected and placed into ten light and dark
incubation containers. The ice formation experiment was initiated with inoculation of NaH13CO3 onFebruary 21, 2001 and lasted until March 1, 2001. Ice temperature at ice and sea water boundarywas monitored with Nchiyu Giken Kogyo underwater thermometer Model NWT-SN. Salinity wasdetermined on ATAGO salinity reflectometer Model S/Mill-E. Subsamples were filtered onto
Whatman glass fiber filters for analysis of chlorophyll pigments, and precombusted Whatman glass
fiber filters for analysis of particulate organic carbon and nitrogen, and 13C. Second subsamples
were filtered onto membrane filters for analysis of biogenic silica. Third subsamples were filteredthrough Millipore Milex HV filter for analysis of macronutrients. Chlorophyll pigments weremeasured on Turner Design fluorometer Model 10-AU. Nitrate, nitrite, phosphate, and silicate wereanalyzed on Bran and Lubbe Autoanalyzer Model AACS-II. Biogenic silica was determined
spectrophotometrically. Particulate organic carbon and nitrogen were analyzed on FISON
elemental analyzer Model NA1500 NCS standardized by acetanilide. 13C was analyzed on FISON
elemental analyzer Model NA1500 NCS connected to Finnigan Tracer Matt. Ta xonomical
identification and numeration of algal species were carried out on the light microscopy.
Results and Discussion
Temperature at ice and water boundary was fluctuated daily according to daily solar radiation.
Salinity in sea ice decreased as sea ice grew and salinity in the seawater under the sea ice increased.
Macronutrient concentrations did not change in sea water during the incubation whilemacronutrients appeared in the newly formed sea ice on the third day of incubation. Chlorophyll aconcentration also increased in the sea ice on the third day of incubation. A 2-0.2 µm size fraction ofchlorophyll a concentration was dominant during the ice formation. Relative contribution of lightabsorption by chlorophyll a particles to total particles in the sea ice increased from 9.6 % on thethird day to 13 % on the eighth day. 13C uptake was not observed for the first four days and higher
than 4.8 mgCm-3h -1 was observed from the sixth day. Their photosynthetic activity ranged from 0.42
to 1.7 mgC[mgChl.a]-1d-1. The present observation may suggest that phytoplankton cells
incorporated into newly formed sea ice require 5-6 days to acclimate to new ice habitats to produce
the organic matter.
Publications
Taguchi, S., F. Satoh, S. Hamanaka, M. Ikeda, M. Ishikawa, and K. Shirasawa 2000. Effect of sea
ice on the natural assemblages of phytoplankton in the coastal water of Okhotsk Sea. Polar
Bioscience 13: 1-14.