Cremer: Spatial Distribution otDiatom Swiace Sediment Assemblages
537
Permanent slides were prepared according to the method of Battarbee (1973) with the high
resolution diatom resin MOUNTEX®. Counting of slides was carried out after Schrader and
Gersonde (1978) using a Zeiss-Axiophot microscope (Plan-Neofluar 1 OOxllJO oil objective) at
a magnification of xl 000. Generally 300 valves were counted without resting spores of the
genus Chaetoceros. The total abundance of diatoms was determined and the relative
abundances of the most important taxa and taxa groups were expressed in percentages of the
total diatom assemblage in each sediment sample.
For description and definition of diatom surface sediment assemblages the data set was treated
with a factor analysis realized with the program StatView (Abacus Concepts, Inc., Berkeley,
1992). The steps, results and interpretation of a factor analysis can be checked in Imbrie and
Kipp (1971) and Maynard (1976).
Table 1: Number of genera and taxa identified in surface sediment samples of the Laptev Sea shelf.
No. of
Genus identified
Achnanthes
Actinocyclus
Amphora
Asterionella
Aulacoseira
Bacteriosira
Biremis
Caloneis
Chaetoceros
Cocconeis
Coscinodiscus
Craspedopleura
Cyclotella
Cymatop/eura
Cymhella
Denticula
Diatoma
Diatomella
Didymosphaenia
Diplolleis
Entomolleis
Epithemia
EUllotia
Fallacia
Fossula
Fragi/aria
Fragi/ariopsis
Frustulia
Observations and discussion
Taxonomy
taxa
16
1
2
I
3
I
1
7
10
6
1
1
4
1
20
I
5
1
2
12
4
2
20
2
I
20
No. of
polar
taxa
0
0
0
0
0
I
0
0
1
0
0
1
0
0
2
0
0
1
I
4
3
0
I
0
I
0
1
0
No. of
No. of
Genus identified
polar
taxa
taxa
Gomphonema
II
0
Grammatophora
2
0
Gyrosigma
5
2
Hantzschia
I
0
Hasleil
I
I
Melosira
4
I
Meridioll
I
0
Minidiscus
I
0
Navicu/a
72
25
Neidium
5
0
Nitzschia
21
9
Opephora
0
Paralia
()
Pinnu/aria
27
10
Placolleis
2
0
Pleurosigma
I
I
Porosira
I
0
Pseudogomphonema
4
4
Pseudo-Nitzs('hia
2
2
Rhopa/odiil
I
0
Staurolleis
7
I
Stenolleis
2
2
Stephanodiscus
3
0
Surirel/a
5
0
Tabellaria
I
0
TetraC\'c/us
2
0
Thalass ios i ra
II
4
Thaiassiothrix
I
()
56 Genera
345
78
A total of 345 taxa from 56 genera were identified from surface sediment samples of the Laptev
Sea shelf with the genera Navicula, Pinnularia, Nitzschia, Fragilaria, Cymbella, and Eunotia
being the most diverse ones (Table 1). A complete taxa list with remarks to synonymy,
references, ecology and biogeographic distribution is given in Cremer (1998). Most of the taxa
identified (214 taxa) are freshwater diatoms all of which usually inhabit Siberian lakes and
537
Permanent slides were prepared according to the method of Battarbee (1973) with the high
resolution diatom resin MOUNTEX®. Counting of slides was carried out after Schrader and
Gersonde (1978) using a Zeiss-Axiophot microscope (Plan-Neofluar 1 OOxllJO oil objective) at
a magnification of xl 000. Generally 300 valves were counted without resting spores of the
genus Chaetoceros. The total abundance of diatoms was determined and the relative
abundances of the most important taxa and taxa groups were expressed in percentages of the
total diatom assemblage in each sediment sample.
For description and definition of diatom surface sediment assemblages the data set was treated
with a factor analysis realized with the program StatView (Abacus Concepts, Inc., Berkeley,
1992). The steps, results and interpretation of a factor analysis can be checked in Imbrie and
Kipp (1971) and Maynard (1976).
Table 1: Number of genera and taxa identified in surface sediment samples of the Laptev Sea shelf.
No. of
Genus identified
Achnanthes
Actinocyclus
Amphora
Asterionella
Aulacoseira
Bacteriosira
Biremis
Caloneis
Chaetoceros
Cocconeis
Coscinodiscus
Craspedopleura
Cyclotella
Cymatop/eura
Cymhella
Denticula
Diatoma
Diatomella
Didymosphaenia
Diplolleis
Entomolleis
Epithemia
EUllotia
Fallacia
Fossula
Fragi/aria
Fragi/ariopsis
Frustulia
Observations and discussion
Taxonomy
taxa
16
1
2
I
3
I
1
7
10
6
1
1
4
1
20
I
5
1
2
12
4
2
20
2
I
20
No. of
polar
taxa
0
0
0
0
0
I
0
0
1
0
0
1
0
0
2
0
0
1
I
4
3
0
I
0
I
0
1
0
No. of
No. of
Genus identified
polar
taxa
taxa
Gomphonema
II
0
Grammatophora
2
0
Gyrosigma
5
2
Hantzschia
I
0
Hasleil
I
I
Melosira
4
I
Meridioll
I
0
Minidiscus
I
0
Navicu/a
72
25
Neidium
5
0
Nitzschia
21
9
Opephora
0
Paralia
()
Pinnu/aria
27
10
Placolleis
2
0
Pleurosigma
I
I
Porosira
I
0
Pseudogomphonema
4
4
Pseudo-Nitzs('hia
2
2
Rhopa/odiil
I
0
Staurolleis
7
I
Stenolleis
2
2
Stephanodiscus
3
0
Surirel/a
5
0
Tabellaria
I
0
TetraC\'c/us
2
0
Thalass ios i ra
II
4
Thaiassiothrix
I
()
56 Genera
345
78
A total of 345 taxa from 56 genera were identified from surface sediment samples of the Laptev
Sea shelf with the genera Navicula, Pinnularia, Nitzschia, Fragilaria, Cymbella, and Eunotia
being the most diverse ones (Table 1). A complete taxa list with remarks to synonymy,
references, ecology and biogeographic distribution is given in Cremer (1998). Most of the taxa
identified (214 taxa) are freshwater diatoms all of which usually inhabit Siberian lakes and