T66 From the Caspian to Mediterranean: Environmental Change and Human Response during the Quaternary (IGCP 610)

Sunday, 1 November 2015
1:30 PM - 5:30 PM
Room 325/326

HOLOCENE SEA SURFACE SALINITY CHANGES IN THE NORTHERN AEGEAN SEA: EVIDENCE FROM SIZE VARIATIONS OF EMILIANIA HUXLEYI-COCCOLITHS

Paper number: T66-13
Program: Technical Sessions
Time: 4:25 PM – 4:40 PM

Authors

Abstract

The Aegean Sea is a key area for our understanding of the impact of changes in the hydrological cycle on ocean circulation in the Mediterranean Sea. The Aegean Sea appears to be very sensitive to climate changes in Europe because of its small volume and its position between high- and low-latitude climate regimes. Therefore, it is assumed to record environmental change, especially changes in sea surface water salinity (SSS) without a significant time lag with respect to the forcing process. However, up to date, SSS cannot be easily reconstructed from geological archives because several assumptions need to be made that lead to a significant error of the salinity estimates. Here, we present the first high resolution SSS reconstruction from a Holocene (between 3 - 11 kyr BP) sediment core (SL152) based on a recently developed transfer function using the morphological variation of E. huxleyi coccoliths (Bollmann & Herrle 2007, Bollmann et al., 2009).

Three major SSS events can be identified at about 8.2, 8.7 kyr, and between 9.6 to 7.0 kyr which correspond to the 8.2 kyr Event, the Black Sea outflow into the AS and the sapropel S1 formation respectively. The most rapid salinity increase of >1 occurred during the short-lived 8.2 kyr cold event, which was most likely triggered by a melt-water related perturbation of the Atlantic Meridional Overturning and associated decrease of ocean heat transport to the North Atlantic. The onset of the Black Sea outflow can be identified at 8.7 kyr which is marked by decreasing SSS of >1. In contrast, the onset and end of the sapropel formation is characterized by a gradual change in SSS.

Bollmann, J., Herrle, J.O., 2007. Morphological variation of Emiliania huxleyi and sea surface salinity. EPSL 255, 273–288.

Bollmann, J., Herrle, J.O., Cortez, M., Fielding, S.R., 2009. The effect of sea water salinity on the morphology of Emiliania huxleyi in plankton and sediment samples. EPSL 284, 320-328.