Carbon cycling in Antarctic benthic communities subject to glacier retreat

Master Thesis subject (30 ECTS)
The Western Antarctic Peninsula (WAP) is one of the most rapidly warming areas on Earth, having experienced a 2°C increase in the annual mean temperature and a 6°C rise in the mean winter temperature since 1950. In the Northern region of the WAP, substantial sea ice loss has induced a decline in phytoplankton stocks over 80%, with regime shifts in zooplankton community composition and dramatic changes in the distribution of higher trophic levels that rely on krill (fish, seals, whales, penguins and other seabirds) as a result. At the tip of the WAP, on King George Island, lies Potter Cove, a fjord-like small embayment (3 km2), influenced by the Fourcade Glacier that has been actively retreating since the 1950s. Several contrasting benthic habitat types are present within the bay. Although bathymetric and granulometric characteristics are similar, the sediment-inhabiting fauna community composition is very different, ranging from colonist to medium developed benthic communities in a gradient from the melting glacier that once covered Potter Cove. Efficient carbon cycling is especially crucial in this very productive bay. The large biomass produced yearly by primary producers (mainly benthic microalgae and large macroalgae) needs to be recycled to the basic nutrients. Since benthic communities are - through their feeding and burrowing activities - strongly involved in the degradation of organic matter, it can be expected that the gradient in development of benthic communities in Potter Cove is somehow reflected in the local patterns in carbon cycling. In 2015, we had the unique opportunity to measure carbon cycling in situ over a seasonal cycle (summer, winter - under ice measurements!- and spring). To this aim, skilled divers deployed a set of benthic chambers in the sediment and measured fluxes of oxygen, inorganic carbon and nutrients at the sediment-water interface. At the same time, the sediment was sampled to assess environmental variables and benthic community structure. This seasonal set of carbon cycling measurements along a gradient of benthic communities in Potter Cove will provide an example dataset of direct and indirect effects of glacier retreat on benthic ecosystem functioning. These data are unique in the Western Antarctic Peninsula region. For this topic, we are looking for a motivated student that is enthusiastic to explore the many facets of the ecological richness of this very productive ecosystem. The selected student can choose to analyze either benthic community structure or environmental samples (pigment and organic matter content, etc.). The final aim is to link the carbon cycling measurements with benthic community structure and environmental variables.
Number of students: 
academic year: 
Contact person email: 
contact person first name: 
Ulrike Braeckman
Other people involved: 
dr. Francesca Pasotti
Reference Number: RP-39771