A comparative study of cryo-pelagic coupling of protist communities in the Arctic and Southern Ocean

• Main Author: Wietkamp, Stephan
• Format: Thesis
• Language: unknown
• Published: University of Hamburg 2016
• Subjects: Antarc*; Antarctic; Arctic; Arctic Ocean; Sea ice; Southern Ocean
• Online Access: https://epic.awi.de/id/eprint/52406/; https://epic.awi.de/id/eprint/52406/1/Masterarbeit_SWietkamp.pdf; https://hdl.handle.net/10013/epic.5d979c93-3318-4f2a-b22f-2a55c30b3ec8

Protists are single-celled organisms, which are very sensitive to changes in environmental parameters. They show a high diversity and occur under a huge variety of environmental conditions – also in polar regions. They live in and on the ice flows, as well as in the water column beneath. The knowledge about the interchange of marine protists between sea ice and the water surface is still insufficient, whereas more and more studies pay attention to the cryopelagic coupling of these microorganisms. Recently in the context of global change, where sea ice minima are observed more frequently - especially in the Arctic Ocean. The central hypothesis of this thesis refers to the coupling of the protist communities in the sea ice and the water column. During the freezing process, the salt leaves the ice through a channel system (“brine channels”), which contains high salinities and offers many habitats for different organisms to coexist on small scales. Therefore, we assume a higher diversity in the sea ice than in the under-ice water. Although the distance between both habitats is relatively small, results of other studies in the Arctic Ocean showed already differences in the community composition. To address this hypothesis, a molecular approach has been chosen. The protist community in the ice and the water shows a similarity of ~ 60-70%. This result indicates, that the exchange between ice and water is relatively high, which confirms former studies about cryo-pelagic coupling. The second part of this thesis is about the comparison of the cryo-pelagic coupling between the Arctic and the Southern Ocean, to get insides into potentially different mechanisms in both polar regions. Data for the Southern Ocean are still scarce in this context. Therefore, we include Antarctic samples from the equivalent season. A taxonomic overlap of ~ 60-70% between the sea ice and the under-ice water is remarkable. Therefore, we conclude similar mechanisms like in the Arctic Ocean. In total, ~ 60% of the taxa are found in both, the Arctic ...