Decadal scale Variability of the Mediterranean Ecosystem
MedEcos
The project aims to lead to an improved understanding of the evolution of the
Mediterranean Marine Ecosystem in decadal time scales, in order to proceed to more
reliable predictions in the context of currently evolving anthropogenic climatic change.
The Mediterranean is ideal for testing ecosystem models based on long-term
instrumental (Maillard et al., 2001; Painter and Tsimplis, 2003; Manca et al., 2004) as
well as sedimentary records (e.g. Frigola et al.,2008), due to the fact that it exhibits
large amplitude variability in decadal time-scales. While the succession between
different states of the ecosystem has clearly been recorded in the sedimentary record of
the Mediterranean at time-scales of hundred to thousands of years, there is still much
uncertainty about the decadal scale variability leading to the long-term changes
(Rossignol-Strick, 1995; Casford et al., 2002). However, as the length of instrumental
records has grown comparable to time-scales characteristic of the evolution of water
properties of several deep-basins (Zervakis et al., 2003), it is possible to use them in
testing analytical and numerical models that would shed light in the processes dominant
on decadal time-scales. Especially the regions in the vicinity of the connecting Straits
are most important, as their sedimentary and hydrographic record reflects the intensity
of the exchange between adjacent basins (Zervakis et al., 2000) at such short timescales. This project aims to fill the spectral gap between modern instrumental and
biogeochemical and paleoceanographic information in an effort to develop well-tested
circulation and ecosystem models to be used in climatic predictions for the 21st century.
In order to do so, the proposed project will:
• Collect all related information on astronomical and meteorological, as well as regional
forcing (local buoyancy forcing, including freshwater and heat exchanges through
connecting Straits). Identify correlations and teleconnections. Build regional and global
forcing time-series for the instrumental period.
• Fill the existing oceanographic and biogeochemical time-series at the selected
locations with the necessary additional measurements. Estimate trends and identify
extreme events.
• Obtain very high-temporal resolution sediment cores from isolated basins in the
vicinity of the connecting Straits of the Mediterranean, as well as reference positions.
We will concentrate on natural Holocene climate shifts using multi-technique proxyrecords. Criterion for location selection should be the highest possible pelagic
sedimentation rate, to allow decadal scale resolution of the sediment corresponding to
the instrumental period (20th-21st century). Such locations have been identified even in
the extremely oligotrophic Aegean Sea (Roussakis et al., 2004; Gogou et al., 2007)
• Develop site-specific circulation and ecosystem models for the modern as well as past
states. Special attention should be given to the models’ capacity to follow the transition
between equilibrium states of the system (i.e. the instrumentally recorded trends of deep
water properties in isolated basins, or the succession of well-oxygenated and sapropel
periods). Alternative diapycnal mixing algorithms should be tested.
• Having tested the models based on the pelagic and sedimentary information for the
instrumental period, proceed to
o An attempt to reproduce instances of the longer past of the Mediterranean
(extending back to the last deglaciation), as recorded by the sedimentary record, and
o Produce predictions for the evolution of the marine ecosystem, based on the
projected climatic impacts of the various scenarios on the regional climate.
Project coordinator:
Vassilis Zervakis, Department of Marine Sciences, University of the Aegean, Mytilene,
Greece. zervakis@marine.aegean.gr
Project partners:
Alexandra Gogou, Hellenic Centre for Marine Research (HCMR)
Institute of Oceanography, Anavyssos, Greece. agogou@ath.hcmr.gr
Maria Triantaphyllou, University of Athens, Faculty of Geology and Geoenvironment,
Athens, Greece. mtriant@geol.uoa.gr
Joan Grimalt, Consejo Superior de Investigaciones Scientificas (CSIC), Barcelona,
Spain. jgoqam@cid.csic.es
Patrizia Ziveri, ICTA (Institute of Environmental Science and Technology), Bellaterra,
Spain. patrizia.ziveri@uab.cat