Coccolithophores as Indicators of Ocean Water Masses, Surface-Water
Temperature, and Paleoproductivity - Examples from the South Atlantic
K.-H. Baumann*, M. Cepek and H. Kinkel
Universitiit Bremen, Fachbereich Geowissenschaften, Postfach 33 0440,
D-28334 Bremen, Germany
*corresponding author (email} .. khb@mail.sedpal.uni-bremen.de
Abstract: The present study was designed to ascertain the significance of coccolithophores as a
proxy for paleoceanographic and paleoproductivity studies in the South Atlantic. Literature data is
briefly reviewed and new results on the regional distribution of living coccolithophores, their
distribution in surface sediments, and their development in the late Quaternary from both the equatorial
Atlantic and the eastern South Atlantic are introduced. The spatial dynamics of living
coccolithophores in the surface and subsurface-waters shows considerable variation in cell numbers
and distribution patterns. In general, cell densities reached maximal up to 300xl 0' coccospheres/l in
the equatorial Atlantic whereas up to about 400xl0 3 coccospheres/l were observed in the eastern
South Atlantic. Generally, Emiliania huxleyi is the dominant species in the plankton. In addition,
Calcidiscus leptoporus, Gephyrocapsa ericsonii, Syracosphaera spp., Umbell05phaera irregularis,
U. tenuis, and holococcolithophores also considerably contribute to the communities. Coccolith
assemblages in bottom sediments of the eastern South Atlantic generally reflect the distribution and
composition of the living coccolithophore communities within the surface-waters. Implications from
down-core data both for paleoproductivity estimates in the equatorial Atlantic and for variations in
sea-surface temperatures in the eastern South Atlantic are discussed. Highest numbers of coccoliths
are observed during relatively cold periods and most probably are indicative of relatively nutrientrich waters. Thus, variations in the coccolithophore assemblages give relative temperature changes.
Absolute sea-surface temperatures are determined by alkenone data (Uk'J7- index). Nevertheless, the
relationship between alkenone-derived SST data and coccolithophore assemblages still is an open
question. Abundances of G. oceanica fit best to alkenone concentrations, whereas the calibration
made by E. huxleyi yield the more reasonable SSTs.
Introduction
Coccolithophores are a major group of marine,
unicellular phytoplankton. Their cell surfaces are
covered with minute external calcite scales
(=coccoliths) bearing a complex ornamentation.
These coccoliths form an important part of finegrained deep-sea sediments and, therefore, are
extensively used in biostratigraphic, paleoecologic,
and paleoceanographic studies (e.g. McIntyre
1967; Geitzenauer et al. 1977; Roth and Coulbourn
1982; Crux and van Heck 1989; Winter and Siesser
1994). Coccoliths constitute the single most important component of deep-sea sediments and provide
key floral, and biomarker signals for interpreting
global change in the geological record. In addition,
their exceptional fossil record makes them an outstanding biostratigraphic group and gives them unusual potential for testing evolutionary hypotheses
(Young et al. 1994). Recently, coccolithophores
have gained increased attention as they make an important contribution to the oceanic primary productivity. Hence, they may provide a good index of open
ocean primary productivity (Brummer and van
Eijden 1992). They playa significant role in the CO/
02 exchange between the ocean and atmosphere
and are peculiar because of their combined effects
on both, the biological and the carbonate pump.
Because of their optical (albedo - masses of detached coccoliths substantially reflect incoming light)
From FISCHER G, WEFER G (eds), 1999, Use of Proxies in Paleoceanography: Examples from the South Atlantic. Springer-Verlag
Berlin Heidelberg, pp 117-144
Temperature, and Paleoproductivity - Examples from the South Atlantic
K.-H. Baumann*, M. Cepek and H. Kinkel
Universitiit Bremen, Fachbereich Geowissenschaften, Postfach 33 0440,
D-28334 Bremen, Germany
*corresponding author (email} .. khb@mail.sedpal.uni-bremen.de
Abstract: The present study was designed to ascertain the significance of coccolithophores as a
proxy for paleoceanographic and paleoproductivity studies in the South Atlantic. Literature data is
briefly reviewed and new results on the regional distribution of living coccolithophores, their
distribution in surface sediments, and their development in the late Quaternary from both the equatorial
Atlantic and the eastern South Atlantic are introduced. The spatial dynamics of living
coccolithophores in the surface and subsurface-waters shows considerable variation in cell numbers
and distribution patterns. In general, cell densities reached maximal up to 300xl 0' coccospheres/l in
the equatorial Atlantic whereas up to about 400xl0 3 coccospheres/l were observed in the eastern
South Atlantic. Generally, Emiliania huxleyi is the dominant species in the plankton. In addition,
Calcidiscus leptoporus, Gephyrocapsa ericsonii, Syracosphaera spp., Umbell05phaera irregularis,
U. tenuis, and holococcolithophores also considerably contribute to the communities. Coccolith
assemblages in bottom sediments of the eastern South Atlantic generally reflect the distribution and
composition of the living coccolithophore communities within the surface-waters. Implications from
down-core data both for paleoproductivity estimates in the equatorial Atlantic and for variations in
sea-surface temperatures in the eastern South Atlantic are discussed. Highest numbers of coccoliths
are observed during relatively cold periods and most probably are indicative of relatively nutrientrich waters. Thus, variations in the coccolithophore assemblages give relative temperature changes.
Absolute sea-surface temperatures are determined by alkenone data (Uk'J7- index). Nevertheless, the
relationship between alkenone-derived SST data and coccolithophore assemblages still is an open
question. Abundances of G. oceanica fit best to alkenone concentrations, whereas the calibration
made by E. huxleyi yield the more reasonable SSTs.
Introduction
Coccolithophores are a major group of marine,
unicellular phytoplankton. Their cell surfaces are
covered with minute external calcite scales
(=coccoliths) bearing a complex ornamentation.
These coccoliths form an important part of finegrained deep-sea sediments and, therefore, are
extensively used in biostratigraphic, paleoecologic,
and paleoceanographic studies (e.g. McIntyre
1967; Geitzenauer et al. 1977; Roth and Coulbourn
1982; Crux and van Heck 1989; Winter and Siesser
1994). Coccoliths constitute the single most important component of deep-sea sediments and provide
key floral, and biomarker signals for interpreting
global change in the geological record. In addition,
their exceptional fossil record makes them an outstanding biostratigraphic group and gives them unusual potential for testing evolutionary hypotheses
(Young et al. 1994). Recently, coccolithophores
have gained increased attention as they make an important contribution to the oceanic primary productivity. Hence, they may provide a good index of open
ocean primary productivity (Brummer and van
Eijden 1992). They playa significant role in the CO/
02 exchange between the ocean and atmosphere
and are peculiar because of their combined effects
on both, the biological and the carbonate pump.
Because of their optical (albedo - masses of detached coccoliths substantially reflect incoming light)
From FISCHER G, WEFER G (eds), 1999, Use of Proxies in Paleoceanography: Examples from the South Atlantic. Springer-Verlag
Berlin Heidelberg, pp 117-144