Antarctic Science

Earth Sciences

Calcareous dinoflagellate cysts from the Pleistocene (Marine Isotope Stage 31) of the Ross Sea, Antarctica

Michael Strenga1 c1, Oliver Espera2 and Jutta Wollenburga2

a1 Palaeobiology Programme, Department of Earth Sciences, Uppsala University, Villavägen 16, 75236 Uppsala, Sweden

a2 Alfred Wegener Institute of Polar and Marine Research, Columbusstraße, 27568 Bremerhaven, Germany

Abstract

Following a report of supposed fragments of calcareous dinoflagellate cysts from a Pleistocene drill core (CRP-1) recovered in the Ross Sea, Antarctica, sediments of the same core were re-investigated for their microfossil content. Besides common foraminifera and other microfossils, rare complete cysts of calcareous dinoflagellates were found. All cysts belong to the species Caracomia arctica (Gilbert & Clark, 1983) Streng, Hildebrand-Habel & Willems, 2002, a taxon characteristic of late Neogene high latitude, coldwater environments. Two morphotypes can be distinguished, C. arctica f. arctica and C. arctica f. rossensis, of which the latter is described as a new form. The presence of C. arctica strengthens diatom-based palaeoenvironmental reconstructions of periodical sea ice-free conditions at the time of deposition. Accordingly, cysts of C. arctica are interpreted as resting cysts that allow survival during harsh intervals of the high latitude environment. Previously reported calcareous dinoflagellates cyst fragments from these sediments are re-interpreted as test fragments of bilamellar foraminifera, which represent the most common group of foraminifers in the sediments.

(Received May 04 2010)

(Accepted June 30 2011)

(Online publication September 01 2011)

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