Identifying drivers controlling the distribution of a keystone species in a changing Arctic

• Main Author: Thyrring, Jakob
• Format: Thesis
• Language: English
• Published: 2016
• Subjects: Arctic; Greenland; Climate change; Sea ice; Subarctic
• Online Access: https://oceanrep.geomar.de/id/eprint/59623/; https://oceanrep.geomar.de/id/eprint/59623/1/PhD_Thyrring_J_2016.pdf

Current climate change as a consequence of large-scale global emissions of greenhouse gases results in an unsurpassed warming of the Arctic, leading to melting of sea ice and glaciers. This results in an increased freshening of the ocean that, in combination with warming, affects the unique features of the Arctic environment and biodiversity. While the impact of changes in ice and temperatures on physical and chemical processes is well documented, the effects on the marine biology in the Arctic remain largely understudied. Greenland is the world's largest island stretching from 59°N to 83 °N, en-compassing 12% of the world's coastline. The largely north-south orientated coastlines of Greenland constitute a unique climate gradient from the subarctic to the High Arctic, along which multiple species meet their distribution limits. However, the biology of Greenland's coastal and intertidal systems has received limited attention and remains poorly understood. Therefore, by linking ecology, physiology and genetics of a keystone species, the blue mussel, this thesis aims at increasing knowledge of the Greenland intertidal zone by specifically studying what climatic and physiological factors determine the distribution and polarward limits of intertidal species. Hitherto, it has been commonly accepted that only one blue mussel species (Mytilus edulis) inhabited the Arctic. However, by utilizing genetic tools, we revealed that three blue mussel species inhabit the Arctic, and that the blue mussel M. edulis dominates in Southwest Greenland, while the congener M. trossulus dominates in the North (Paper I). Historically, work on the distribution of blue mussels in West Greenland has only been descriptive, but I quantified the abundance and population dynamics of the genus as far north as 77°N (Paper II). In doing so, I found that sub-zero air temperatures and air exposure time are of central importance for the distribution, and that abundances are controlled at the earliest life stage, not during adulthood. In addition, I ...