WP-4: Biological response to climate change

Polar biota are highly adapted to the extreme environment and appear vulnerable to climate shifts. One of the main consequences of climate change in polar coastal zones are high sedimentation rates due to coastal run-off as a consequence of glacier melting. The major primary producers, the phytoplankton, from the coastal areas are strongly affected by ice cover, glacier melt and sedimentation, since these factors all determine the underwater light climate as well as irradiance dynamics due to vertical mixing. The presence of particles additionally affects zooplankton and could indeed alter the equilibrium between the different groups. Futhermore, benthic meiofauna (animals between 0.032 and 1mm in body size), which lacks a pelagic life stage and shows in general a high turn-over, will respond quickly to changes in the sedimentary environment and food supply.

Effects of glacial erosion on coastal meiobenthic communities from the Western Antarctic Peninsula (IP-6)

Ann Vanreusel, Francesca Pasotti (Ghent University, Belgium)

One of the main consequences of climate change in polar coastal zones are high sedimentation rates due to coastal run-off as a consequence of glacier melting. The meiofaunal response will be investigated in two ways. A field study will be carried out in order to compare the structure and the function of meiofauna sampled in and outside the reach of glacier sediment plumes. Areas with increased sedimentation rates will differ in sediment composition and food supply, which could be reflected in the associated meiofauna. We will investigate differences in standing stock, biodiversity, community composition and trophic interactions between areas influenced by high and low run-off.

In addition, laboratory experiments will be performed using in situ collected fauna, in order to determine the impact of the changing food supply and sedimentation in relation to temperature rise on community biodiversity, structure and trophic interactions. Both field and experimental studies will be performed at King George Island. The overall aim of this study is to investigate the resilience of polar benthic meiofauna to climate change, and to investigate the reliability of the use of meiofauna as a proxy for climate change related effects on the benthic ecosystem.

Consequences of enhanced glacial melting on coastal phytoplankton communities of King George Island, Antarctic Peninsula region (IP-7)

Anita Buma, Anouk Piquet (Groningen University, The Netherlands)

The effects of climate change on marine microbial communities in the Potter Cove area will be investigated. We will pursue two major lines of research. The first research line is meant to provide detailed information on phytoplankton species composition and diversity, related to relevant environmental conditions, in particular the impacts of melt water input on turbidity and water column stabilization. The second research line is meant to provide information on changes in growth, species composition and diversity as a function of relevant environmental conditions under change. More specifically, we will test the following working hypotheses:

• Nanophytoflagellates dominate throughout the season in Potter Cove and adjacent waters:tThis hypothesis is based on field and experimental observations where nanophytoflagellates dominate low biomass, low irradiance, deeply mixed waters.
• Input of turbid meltwater significantly reduces phytoplankton growth and will affect species composition in favour of nanophytoplankton. Ad II: This hypothesis is based on earlier similar work performed in a high Arctic fjord, (Kongsfjord, Spitsbergen, Norway).

Climatic constraints of productivity and trophic structure in an Antarctic fjord ecosystem (Admiralty Bay, King George Island) (IP-8)

Andrzej Tatur, Agnieszka Wasilowska (Department of Antarctic Biology, Polish Academy of Sciences, Warsaw, Poland)

Our preliminary studies suggest that stratification of chemical and primary production in the water column in Admiralty Bay (King George Island) are strongly affected by the following processes:

• Input of freshwater and mineral suspension from melting glaciers
• Water mixing and exchange of bay water masses with the open ocean, strongly related to wind speed and direction as well as to the tidal current system. Surface water movements are mostly determined by strength and direction of strong catabatic winds, which cause the outflow of surface layers towards the open ocean. When winds are slow movements of both surface and deeper layers are dependent on tides
• Occurrence of fast ice in the bay during the winter and early summer

The aim of our project is to deliver a first comprehensive, high resolution picture of the Admiralty Bay ecosystem and the climatic impact on its functioning. The following data are collected: meteorological parameters, physical and chemical properties of the water column, current directions, phytoplankton biomass (chlorophyll a), taxonomic composition of phytoplankton assemblages (calculated from concentration of diagnostic pigments and complemented by detail analysis of nano-, pico- and bacterioplankton).