Identification of key environmental drivers influencing macroalgal communities in high Arctic fjords

In the inner part of Billefjord, Svalbard, UNIS has three littoral sampling stations, included one close to the glacier front, one with freshwater input without glacier, and one with little input from glacier and freshwater, more affected by Atlantic water. The three stations were measures throughout the summer 2021, mainly for spatial differences, using an autonomous surface vehicle (USV), enabling safe remote control and sampling. The sampling regime included e.g. CTD, turbidity, PAR measurements and split beam echosounder. The observational data were validated with remote drop cameras and baited video rigs.  Billefjord had large spatial differences in physical-chemical traits due to the inputs from glaciers and freshwater, including the effects on the formation of seasonal sea ice, making the site suitable as a model system for abiotic drivers during climate changes. The establishment of macroalgae will be one of the drivers for changes in benthic and fish communities. The study showed that the macroalgae established relatively early after retreat of the glaciers, and that increased turbidity close to glaciers had relatively little effect on the establishment.The study showed large spatial differences in plant coverage of kelp, with the lowest distribution of macroalgae in the habitat affected by freshwater input. The kelp communities had a depth distribution down to 30 m, and while the Atlantic water station showed a decreased with depth, the freshwater and glacier station increased with depth. Master thesis at The University Centre in Svalbard (supervisor Børge Damsgård), and University of Bremen (supervisor Kai Bischof)