Axinja Stark

Name:             Axinja Stark
Institute:          Alfred Wegener Institute
Department:     Integrative Ecophysiology
Phone:            +49-(0)471-4831-1331
Web link:

PhD-project title: CO2 impact on calcification in marine bivalves - a key to understand past, present and future climate records of polar ecosystems

The increase in atmospheric carbondioxide (CO2) levels and the associated temperature rise are a result of excessive burning of fossil fuels during the industrial period. Earth`s ocean take up high concentrations of CO2 from the atmosphere, the CO2 leads to a reduction of pH. If the global CO2 emissions continue to rise, the pH of the oceans will be reduced from 8.1 to 7.3 within the next 300 years.
The current project will combine CO2 effects on the arctic Greenland cockle Serripes groenlandicus with associated temperature rise that is predicted to occur during global warming. Beside the physiological impact of CO2 and temperature rise, the focus also includes relating changes in biomineralization/calcification of the shell to new scientific findings on present and past climate data.
In general shells reflect changing environmental conditions experienced during their lifetime. It is expected that if the relation between skeleton parameters and underlying environmental parameters is known, the skeleton parameter will serve as proxy of the environmental parameter and hence as indicator on past and present time scales. Bivalve shells are already used to reconstruct past climate data. Hence, they can serve as multi-proxy, high resolution and highly sensitive monitors of climate change.
The overall objective of the project is to link sclerochronological methods and physiological techniques to present and past climate change and their effects on the sensitive ecosystems of high latitudes.
Start of doctoral thesis: 15.09.2008

Thesis Committee:

Supervisor: Prof. Dr. Hans-Otto Pörtner (AWI)
Co-supervisor: Prof. Dr. Thomas Brey (AWI), Dr. Franz-Josef Sartoris (AWI)
Further members: PhD Magdalena Gutowska (AWI/IfM-Geomar)


Axinja Stark, O. Heilmayer, T. Brey and H.-O. Pörtner, CO2 and temperature sensitivity of the Greenland smoothcockle, Serripes groenlandicus. Koordinationsworkshop des DFG-SPP 1158 2010, Hamburg, 8th -9th October 2010.(Poster)
Axinja Stark, S. Treydte, O. Heilmayer, T. Brey and H.-O. Pörtner, Is the Greenland smoothcockle (Serripes groenlandicus) sensitive to elevated CO2 and temperature levels? Society of Experimental Biology Annual Meeting 2010, Prague, 30th June – 3rd July 2010.


Svalbard: 27th April – 31st July 2009,
White Sea: 03rd August – 26th September 2010 


BioAcid Training Workshop "Physiological approaches to body-fluid physiochemistry and acid-base regulation", Franz Josef Sartoris, Christian Bock, Ulf Bickmeyer, Timo Hirse, Axinja Stark und Hans Otto Pörtner, 15.03-19.03.2010,