Mild climate, harsh times for polar marine microbes

Promotie: mw. A.M. Piquet, 13.15 uur, Academiegebouw, Broerstraat 5, Groningen
Proefschrift: Mild climate, harsh times for polar marine microbes
Promotor(s): prof.dr. A.G.J. Buma, prof.dr. H.J.W. de Baar
Faculteit: Wiskunde en Natuurwetenschappen
Contact: Anouk Piquet, tel. 050-363 2286, e-mail: a.m.t.piquet@rug.nl

Mild climate, harsh times for polar marine microbes

Local temperature rise in polar regions has direct and indirect effects on polar coastal regions. The increased glacial and sea ice meltwater input induces alterations to the surface water salinities and the underwater light regime. The goal of this PhD-research was to provide insight in polar marine microbial community shifts in relation to relevant environmental factors.

Effects of salinity, UV-radiation and water turbidity on microbial communities were studied in both polar regions by application of molecular techniques. This enabled simultaneous analysis of prokaryotic (Bacteria) and eukaryotic (phytoplankton) microorganisms from water samples collected from the Arctic and Antarctic. Our sequence analysis provided the first sequence dataset for microbial communities from these polar research sites.

The study conducted in Ryder Bay (Antarctica) revealed a direct shift in phytoplankton community composition following an alteration to the stability and salinity of the water column. Bacteria unveiled a slower and probably a secondary response. UV-irradiation experiments conducted on the Eastern Antarctic coast (Prydz Bay) and exposing natural Antarctic marine microbial communities to different UVR treatments revealed that the bacterial fraction of the community was being shaped by UV-radiation. Effects on the phytoplankton remained unclear. Every summer, the Arctic Kongsfjorden-Krossfjorden system (Spitsbergen) is strongly influenced by glacial sediment-rich meltwater. The increase in sediment-rich meltwater appeared to affect the composition of marine bacterial communities the most and it enriched the system with non-marine bacteria.

This research has demonstrated that various environmental factors altered by climate change significantly affect polar marine micro-organisms.