Diatoms from Surface Sediments of the Saint Anna Trough
(Kara Sea)
R.N. Djinoridze 1 , G. I. Ivanov 2 , E. N. Djinoridze 2 , and R. F. Spielhagen 3
(1) St. Petersburg State University, 199004 St. Petersburg, Russia
(2) VNII Okeangeologia, 190121 St. Petersburg, Russia
(3) GEOMAR Forschungszentrumfiir marine Geowissenschaften, Wischhofstrasse 1-3, D 24148 Kiel,
Germany
Received 7 April 1997 and accepted in revised form 3 March 1998
Abstract - 15 samples from surface sediments of the St. Anna Trough served as the basis
of this study. 91 recent species (29 genera) were identified, of which 30 belong to the class
Centrophyceae and 61 belong to the class Pennatophyceae. Besides that II reworked
Paleogene species were found. True marine planktic diatom species constitute 92-98% of all
specimens in the surface sediments. The biogeographical composition of the
thanatocoenoses corresponds to biocoenoses inhabiting the water masses of the Arctic seas.
In the surface sediments, arctoboreal and bipolar planktic and kryopelagic species are
prevailing, which reflect the low temperatures and the seasonally ice-covered environment:
Melosira arctica, Fragilariopsis oceanica, Poroira glacialis, Thalassiosira gravida, T.
antarctica (spores), T. kryophila, T. hyalina, and T. nordenskioldii. Warm-water species
are absent in the sediments, probably because Atlantic waters have cooled significantly
before entering the St. Anna Trough.
Introduction
The St. Anna Trough is a subbathyal depression with depths down to 620 m, separating the
northern Kara Sea and Barents Sea shelves (Figure 1). The hydrological regime (Rudels et aI.,
1994) of the northern Kara Sea is controlled by the inflow of several water masses into the St.
Anna Trough area. Atlantic waters derived from the North Atlantic Drift flow across the Barents
Sea, further along the St. Anna Trough, and finally enter the intermediate waters of the Arctic
Ocean. Another branch of Atlantic water, turning east around northern Svalbard and sinking
below the low-salinity surface layer while flowing along the Barents Sea continental margin,
reaches the St. Anna Trough from the North at depths of 100-4S0 m. Another important water
mass is constituted from freshwater transported mainly by the large Siberian rivers Ob and
Yenisei. According to data obtained during cruise 9 of RV "Professor Logachev" in 1994, the
upper water layer in the central and southern St. Anna Trough has temperature between 1-2.4
°c, while in the North and Northeast they vary from -0.1 to -1.2 ° C (Ivanov et aI., 1995).
The field of salinity on ocean surface tests significant freshening due to summer melting of
floating ice. Salinity of surface waters in the trough changed in summer 1994 in the limits from
30.00 up to 33.75%0.
Materials and methods
Diatoms were studied in 15 samples of surface sediments collected during cruise 9 (J 994) of
RV "Professor Logachev" in the St. Anna Trough from stations with water depths of 100-60S
m (Figure I). The treatment of diatom valves was carried out only slightly changed according to
the method described by Schrader and Gersonde (1978). Dried and weighed sediment (1S-20
g) was boiled first with H20 2 (30%), then with HCI (30%) and then was washed out by
distilled water. The sediment was cleaned of clay by washing out S-6 times with Na3P04 *
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, 1999,553-560.
(Kara Sea)
R.N. Djinoridze 1 , G. I. Ivanov 2 , E. N. Djinoridze 2 , and R. F. Spielhagen 3
(1) St. Petersburg State University, 199004 St. Petersburg, Russia
(2) VNII Okeangeologia, 190121 St. Petersburg, Russia
(3) GEOMAR Forschungszentrumfiir marine Geowissenschaften, Wischhofstrasse 1-3, D 24148 Kiel,
Germany
Received 7 April 1997 and accepted in revised form 3 March 1998
Abstract - 15 samples from surface sediments of the St. Anna Trough served as the basis
of this study. 91 recent species (29 genera) were identified, of which 30 belong to the class
Centrophyceae and 61 belong to the class Pennatophyceae. Besides that II reworked
Paleogene species were found. True marine planktic diatom species constitute 92-98% of all
specimens in the surface sediments. The biogeographical composition of the
thanatocoenoses corresponds to biocoenoses inhabiting the water masses of the Arctic seas.
In the surface sediments, arctoboreal and bipolar planktic and kryopelagic species are
prevailing, which reflect the low temperatures and the seasonally ice-covered environment:
Melosira arctica, Fragilariopsis oceanica, Poroira glacialis, Thalassiosira gravida, T.
antarctica (spores), T. kryophila, T. hyalina, and T. nordenskioldii. Warm-water species
are absent in the sediments, probably because Atlantic waters have cooled significantly
before entering the St. Anna Trough.
Introduction
The St. Anna Trough is a subbathyal depression with depths down to 620 m, separating the
northern Kara Sea and Barents Sea shelves (Figure 1). The hydrological regime (Rudels et aI.,
1994) of the northern Kara Sea is controlled by the inflow of several water masses into the St.
Anna Trough area. Atlantic waters derived from the North Atlantic Drift flow across the Barents
Sea, further along the St. Anna Trough, and finally enter the intermediate waters of the Arctic
Ocean. Another branch of Atlantic water, turning east around northern Svalbard and sinking
below the low-salinity surface layer while flowing along the Barents Sea continental margin,
reaches the St. Anna Trough from the North at depths of 100-4S0 m. Another important water
mass is constituted from freshwater transported mainly by the large Siberian rivers Ob and
Yenisei. According to data obtained during cruise 9 of RV "Professor Logachev" in 1994, the
upper water layer in the central and southern St. Anna Trough has temperature between 1-2.4
°c, while in the North and Northeast they vary from -0.1 to -1.2 ° C (Ivanov et aI., 1995).
The field of salinity on ocean surface tests significant freshening due to summer melting of
floating ice. Salinity of surface waters in the trough changed in summer 1994 in the limits from
30.00 up to 33.75%0.
Materials and methods
Diatoms were studied in 15 samples of surface sediments collected during cruise 9 (J 994) of
RV "Professor Logachev" in the St. Anna Trough from stations with water depths of 100-60S
m (Figure I). The treatment of diatom valves was carried out only slightly changed according to
the method described by Schrader and Gersonde (1978). Dried and weighed sediment (1S-20
g) was boiled first with H20 2 (30%), then with HCI (30%) and then was washed out by
distilled water. The sediment was cleaned of clay by washing out S-6 times with Na3P04 *
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, 1999,553-560.