Chlorophyll a Distribution in Water Column and Sea Ice during the
Laptev Sea Freeze-Up Study in Autumn 1995
K. v. Juterzenka and K. Knickmeier
Institut jur Po/ardk%gie, Universitiit Kie/, Wischhofstrasse 1-3, D 24148 Kie/, Germanv
Received 20 February 1997 and accepted in revised form 19 January 1998
Abstract - During the Transdrift III expedition to the Laptev Sea in October 1995, samples
were taken from the water column as well as various types of newly formed sea ice and
analysed for Chlorophyll a ( ChI a) as indicator of algal biomass, Ice samples included
grease ice, nilas and cores from young ice (::; 25 em), The phytoplankton biomass in the
water column (water depth 14 m to 40 m) as expressed by integrated ChI a values ranged
between 2.3 mg m- 2 north of the Lena Delta and 15.9 mg m- 2 in a polynya at Buor Khaya
Bay southeast of Tiksi. Pigment concentrations in the ice samples varied considerably (0.3
to 2.36 mg m- 3 in grease ice and 0.2 to 14.6 mg m- 3 in nilas, respectively). However, the
ChI a content increased as soon as ice floes were formed from grease ice or pancake ice.
Greenish slush ice and overlying water flooding the ice near cracks showed low pigment
concentrations, indicating that the colouring was not caused by algae.
The ChI a distribution in water column and sea ice during autumnal freeze-up was compared
with data from August/September 1993 (Transdrift I). The observed patterns are discussed
with respect to the highly variable sediment load of sea ice ("clean" and "dirty" ice).
Introduction
Freezing in the Laptev Sea starts in October and results in the development of a coastal belt of
fast ice and a zone of pack ice, separated from each other by a polynya (an overview of Laptev
Sea characteristics was given by Timokhov (1994)). As soon as ice crystals form, suspended
particles and organisms such as microalgae from the water column are incorporated into the ice
sheet by various mechanisms, e.g. scavenging by frazil ice crystals or wave pumping (Ackley
et a!., 1987; Reimnitz et a!., 1993; Ackley and Sullivan, 1994; Gradinger and lkavalko, 1998).
Several studies reported on temporal and spatial variability with regard to the distribution and
primary production of sea-ice microalgae (e.g. Gosselin et a!., 1986; Hsiao, 1988; Legendre et
aI., 1992a, b). Ackley and Sullivan (1994) presented the variation of Chi a concentrations in
the Antarctic Weddell Sea ice as a function of pack ice texture. In the Canadian Arctic, the Chi a
- content of first year ice parallels an inshore-offshore salinity gradient on a large scale whereas
the variation of snow-ice cover and therefore irradiance at the bottom of the ice seemed to be
responsible for patchiness on a small-scale (Gosselin et a!., 1986; Smith et a!., 1988).
However, information on algal biomass in newly formed sea ice in Arctic shelf seas is still
limited and mechanisms causing distribution patterns on different scales are not well understood
as yet.
The Laptev Sea is one of the most important sea-ice producing areas in the Arctic, and it is
known that sediment can be entrained into the ice in large amounts and transported via the
Transpolar Drift (e.g., Eicken et aI., 1997). Consequently, the shallow Laptev Sea may be
considered as "starting point" for the development of the sea ice communities found in other
regions of the Arctic Ocean. The ice-algal biomass provides not only food for the microbial
community within the ice, but can be consumed at the ice underside as well. The interface
between sea ice and underlying seawater provides a habitat for a distinctive flora and fauna as it
was reported especially from multi-year ice (Melnikov and Bondarchuk, 1987; Gulliksen and
L0nne, 1989; L0nne and Gulliksen, 1991; Werner, 1997).
In: Kassens, H., H.A. Bauch, I. Dmitrenko, H. Eicken, H.-W. Hubberten, M. Melles, J. Thiede and L. Timokhov (eds.)
Land-Ocean Systems in the Siberian Arctic: Dynamics and History. Springer-Verlag, Berlin, 1999. 153-160.
Laptev Sea Freeze-Up Study in Autumn 1995
K. v. Juterzenka and K. Knickmeier
Institut jur Po/ardk%gie, Universitiit Kie/, Wischhofstrasse 1-3, D 24148 Kie/, Germanv
Received 20 February 1997 and accepted in revised form 19 January 1998
Abstract - During the Transdrift III expedition to the Laptev Sea in October 1995, samples
were taken from the water column as well as various types of newly formed sea ice and
analysed for Chlorophyll a ( ChI a) as indicator of algal biomass, Ice samples included
grease ice, nilas and cores from young ice (::; 25 em), The phytoplankton biomass in the
water column (water depth 14 m to 40 m) as expressed by integrated ChI a values ranged
between 2.3 mg m- 2 north of the Lena Delta and 15.9 mg m- 2 in a polynya at Buor Khaya
Bay southeast of Tiksi. Pigment concentrations in the ice samples varied considerably (0.3
to 2.36 mg m- 3 in grease ice and 0.2 to 14.6 mg m- 3 in nilas, respectively). However, the
ChI a content increased as soon as ice floes were formed from grease ice or pancake ice.
Greenish slush ice and overlying water flooding the ice near cracks showed low pigment
concentrations, indicating that the colouring was not caused by algae.
The ChI a distribution in water column and sea ice during autumnal freeze-up was compared
with data from August/September 1993 (Transdrift I). The observed patterns are discussed
with respect to the highly variable sediment load of sea ice ("clean" and "dirty" ice).
Introduction
Freezing in the Laptev Sea starts in October and results in the development of a coastal belt of
fast ice and a zone of pack ice, separated from each other by a polynya (an overview of Laptev
Sea characteristics was given by Timokhov (1994)). As soon as ice crystals form, suspended
particles and organisms such as microalgae from the water column are incorporated into the ice
sheet by various mechanisms, e.g. scavenging by frazil ice crystals or wave pumping (Ackley
et a!., 1987; Reimnitz et a!., 1993; Ackley and Sullivan, 1994; Gradinger and lkavalko, 1998).
Several studies reported on temporal and spatial variability with regard to the distribution and
primary production of sea-ice microalgae (e.g. Gosselin et a!., 1986; Hsiao, 1988; Legendre et
aI., 1992a, b). Ackley and Sullivan (1994) presented the variation of Chi a concentrations in
the Antarctic Weddell Sea ice as a function of pack ice texture. In the Canadian Arctic, the Chi a
- content of first year ice parallels an inshore-offshore salinity gradient on a large scale whereas
the variation of snow-ice cover and therefore irradiance at the bottom of the ice seemed to be
responsible for patchiness on a small-scale (Gosselin et a!., 1986; Smith et a!., 1988).
However, information on algal biomass in newly formed sea ice in Arctic shelf seas is still
limited and mechanisms causing distribution patterns on different scales are not well understood
as yet.
The Laptev Sea is one of the most important sea-ice producing areas in the Arctic, and it is
known that sediment can be entrained into the ice in large amounts and transported via the
Transpolar Drift (e.g., Eicken et aI., 1997). Consequently, the shallow Laptev Sea may be
considered as "starting point" for the development of the sea ice communities found in other
regions of the Arctic Ocean. The ice-algal biomass provides not only food for the microbial
community within the ice, but can be consumed at the ice underside as well. The interface
between sea ice and underlying seawater provides a habitat for a distinctive flora and fauna as it
was reported especially from multi-year ice (Melnikov and Bondarchuk, 1987; Gulliksen and
L0nne, 1989; L0nne and Gulliksen, 1991; Werner, 1997).
In: Kassens, H., H.A. Bauch, I. Dmitrenko, H. Eicken, H.-W. Hubberten, M. Melles, J. Thiede and L. Timokhov (eds.)
Land-Ocean Systems in the Siberian Arctic: Dynamics and History. Springer-Verlag, Berlin, 1999. 153-160.