DATE2018-05-21 07:48:30
IDABSTRACT20180521074830-0175
CONTACTskampaelisavet@gmail.com
PRESENTATIONPOSTER
INVITED0
IDSESSION2
TITLECOUPLING PLANKTON-SEDIMENT TRAP-SURFACE SEDIMENT AND THE FOSSIL RECORD FOR THE DETECTION OF EMT-LIKE EVENTS: A CASE STUDY FROM THE NORTH AEGEAN SEA (NE MEDITERRANEAN)
AUTHORSE Skampa (1) , MV Triantaphyllou (1) , MD Dimiza (1) , A Gogou (2) , E Xoplaki (3) , J Luterbacher (3) , E Malinverno (4) , M Fatourou (1) , C Parinos (2) , S Stavrakakis (2) , K-H Baumann (5)
AFFILIATIONS
  1. National and Kapodistrian University of Athens, Athens, Greece
  2. Hellenic Centre for Marine Research, Anavyssos, Greece
  3. Justus-Liebig-University Giessen, Giessen, Germany
  4. University of Milano-Bicocca, Milano, Italy
  5. University of Bremen, Bremen, Germany
ABSTRACTQuantitative coccolithophore analyses were performed on data from plankton samples (0–100 m water depth), the sinking particulate matter collected by a sediment trap time series (2011–2015) and the surface sediment of the North Aegean Sea (Athos basin, NE Mediterranean) M2 sampling site, in order to achieve a better understanding of potential modifications between the plankton vs. the exported through the water column coccolithophore assemblage and the one accumulated in the underlying sediment. Sediment trap coccolithophore multiannual mean fluxes (20 x108 coccoliths m2 day-1) documented similar values to the accumulation rates recorded in the surface sediment (23.6 x108 coccoliths m-2day-1). The dominant species in all three sampling types was Emiliania huxleyi reaching in some cases striking abundances (85–90%). Notably, F. profunda was not included in the plankton assemblage but in those of the sediment traps and the surface sediments, yet is presumed to flourish in nutrient-enriched layers below the sampled 100 m water column depth. Several fragile Syracosphaeraceae and holococcolithophore species and the delicate Algirosphaera robusta were found to have been gone while sinking through the water column down to the sea floor; however the main features of the living assemblages were generally preserved. Morphometric analyses on E. huxleyi coccoliths document the presence of a lightly calcified morphotype in plankton (increased frequency of low relative tube width values) and sediment trap samples (bimodal relative tube width pattern), indicating enhanced Black Sea Water inflows during May 2011, February 2015 and October 2015. However, such signal is not preserved in the surface sediment assemblage, presumable due to processes of secondary calcite overgrowth. The recorded high abundances of E. huxleyi were in accordance with positive North Atlantic Oscillation (NAO) shifts during recent production of dense waters in the North Aegean. The recent past (last 500 years) coccolithophore assemblage revealed a periodic change in the dominance of E. huxleyi (>60%), indicating strong water column convection at 1980–present, 1900–1950, 1760–1840 and 1620–1680 years AD, coupled with NAO positive shifts, Dalton solar minimum and volcanic activity. Stratified water column was detected when flourishing of F. profunda, possibly related to enhanced BSW influx. Climatic model data provided from the Coupled Model Intercomparison Project (CMIP5) simulations on annual and seasonal resolution were coupled with the E. huxleyi abundance changes in relation to the δ 18OG.ruber isotopic signal and the alkenone Sea Surface Temperature record in order to sufficiently evaluate past EMT-like events in the North Aegean Sea.
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