Molecular Assessment of Salp Gut Content - an improved method to determine phytoplankton biodiversity in the Southern Ocean?

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Changes in plankton community structures in response to climate change and the climatic sensitivity of species are currently driving topics in marine ecology. It is expected that climate related environmental change could result in changes in the abundance, spatial distribution, biogeography or dominance of plankton species. This would strongly influence biogeochemical cycling, and also marine food-webs up to top predators like fish or birds. Phytoplankton is the base of marine food webs, it consist of cells from the pico-, nano-, and microplankton. In order to evaluate consequences of climate change for marine ecosystems in the Antarctic, it is necessary to possess comprehensive information on the abundance, biodiversity or community structure of marine phytoplankton. By applying Automated ribosomal RNA intergenic spacer analysis (ARISA), PHYLOCHHIP – analysis and sequencing of 18S rDNA clone librarieson on the gut content of two Southern Ocean salps, Salpa thompsoni and Ihlea racovitzai from various season of the Lazarev sea, we will investigate the seasonality and spatial variablility of phytoplankton. The co-occurrence of Salpa thompsoni and Ihlea racovitzai on the same stations will be used to test the hypothesis, that salp guts truly give an integrated signal of phytoplankton diversity over the entire water column. Detailed studies of the plankton diversity will give further insights in the diet of salps in the Southern Ocean, particular during winter time, when phytoplankton is scare.