Sensitivity of Antarctic fish to ocean warming - an energy budget approach

• Main Author: Sandersfeld, Tina
• Other Authors: Richter, Claudio, Knust, Rainer, Peck, Myron
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universität Bremen 2015
• Subjects: Notothenioids; Southern Ocean; Climate Change; Energy allocation; Temperature tolerance; Growth; 570; 570 Life sciences; biology; ddc:570; Arctic; Antarctic; The Antarctic; Antarctic Peninsula; Antarc*; Antarktis*; Climate change; Sea ice
• Online Access: https://media.suub.uni-bremen.de/handle/elib/934; https://nbn-resolving.org/urn:nbn:de:gbv:46-00104771-12

Like the Arctic, the Antarctic region hosts some of the hot spots of climatic change. At the western Antarctic Peninsula, alterations of air and water temperature, pH, salinity and sea-ice regime were reported and associated shifts in species abundance and changes in food web structure have already become evident. In contrast, for most high-Antarctic regions, no climate related changes have yet been found. However, future temperature increases are also projected for these areas. Ocean warming affects marine ectotherms by directly impacting their body temperature and thus physiology. Antarctic marine ectotherms, such as fish, are highly adjusted to the very cold and stable conditions of the Southern Ocean and are suggested to be highly temperature sensitive. Fish constitute an important link in Antarctic food webs by being prey and predator alike. While various studies focused on the impact of elevated temperature on lower organisational levels in Antarctic fish, trade-offs of increased temperature for the whole organism remain unclear, but are highly relevant from an ecological perspective. Thus, this thesis aimed to assess the impact of increasing temperature on Antarctic fish at the whole-organism level from an energy budget perspective. The energy taken up by an organism can be allocated to different vital functions, such as routine metabolism, growth, reproduction and excretion. When routine metabolic costs are covered, energy can be allocated to growth and reproduction, the factors influencing a species abundance and population structure. In the first study of this thesis, energy allocation to routine metabolism as well as response patterns to an acute increase of temperature in the fish species Lepidonotothen squamifrons, Trematomus hansoni and Lepidonotothen nudifrons were analysed using oxygen consumption measurements. While metabolic responses to changing temperature were comparable in all species, metabolic costs of high-Antarctic fish were higher at habitat temperatures. Starting from higher metabolic ...