Spatial distribution of the calcareous dinoflagellate Thoracosphaera heimii in the upper water column of the tropical and equatorial Atlantic |
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| Authors: | B Karwath D Janofske H Willems |
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| Institution: | Fachbereich-5 Geowissenschaften, Universit?t Bremen, Postfach 330 440, D-28334 Bremen, Germany Fax: +0421-2184451 e-mail: karwath@micropal.uni-bremen.de, DE
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| Abstract: | The horizontal and vertical distribution of the phototrophic, calcareous dinoflagellate Thoracosphaera heimii in the upper part of the water column (10–200 m) of the equatorial and tropical Atlantic Ocean has been studied. This first
survey has been made to determine which part of the water column is inhabited by T. heimii and is subsequently represented as a signal in the sediment record by this species. The study concentrates on the fossilisable
vegetative coccoid life stage of the species and differentiates between T. heimii shells with cell content and empty ones. The highest quantities of T. heimii shells with cell content have been observed in water depths between 50 and 100 m and coincide with relatively lower temperatures
and relatively higher salinities than respective surface conditions. We propose that in the tropical equatorial Atlantic the
major part of the environmental signal given by T. heimii can be assumed to represent the deeper levels of the upper water column.
Received: 9 November 1998 / Accepted: 19 April 1999 |
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| Keywords: | Key words Calcite Dinoflagellates Phytoplankton Atlantic Actuopalaeontology |
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