Structuring of marine pelagic microbial communities by glacial meltwater in Ryder Bay, Antarctica

Summary

The Western Antarctic Peninsula (WAP) is warming more rapidly than any other region in the Southern Hemisphere and significant glacial retreat is already reported. The associated changes in meltwater input to the ocean may impact coastal marine biota, of which the microbial communities (phytoplankton, bacteria) form the basis. Ryder Bay (Southern WAP) is highly influenced by glacial meltwater, especially during summer. Meltwater may enhance microalgal activity by increasing water column stabilization as well as through nutrient (notably Fe) input. In contrast, increased meltwater input will further reduce surface salinity, thereby challenging the survival of marine organisms, or may reduce irradiance levels for algal growth when meltwater turbidity is high.

At present, it is unknown how meltwater shapes microbial performance in the WAP area and thus, the consequences of enhanced meltwater input cannot reliably be predicted. In this project we address the main question how glacial meltwater structures growth, diversity and species composition of marine microbial pro- and eukaryotes. The project includes two large campaigns, of which the first one was completed successfully in the 2012-2013 season. Both field campaigns focus on meltwater properties, and how these affect microbial performance. Second, we will participate in the RaTS monitoring program, by analysing three annual cycles of microbial diversity as a function of environmental factors.

We will mostly use molecular tools, including 16S/18S rDNA markers, DGGE, cloning and next generation sequencing. The proposed research will reveal implications for possible alterations in marine food webs related to changing freshwater discharge in the Southern WAP and is a multidisciplinary cooperation between Dutch, British and American research groups.

NWO-NPP, Rothera cluster programme, major research partner British Antarctic Survey, Cambridge, UK