FishBase 2017: Michael Axelsson
Channel: Fishbase Sweden
Date: 30/10/2017

Michael Axelsson, University of Gothenburg, gave a lecture titled "WITH THE HEART ON THE FREEZING POINT: CARDIOVASCULAR PHYSIOLOGY IN POLAR LIVING FISH"

Abstract: Temperature affects both physical properties and chemical reaction rates. Chemical reactions are affected by a factor of 2-3 for every 10 C temperature change and the physical properties such as the viscosity of fluids and the solubility of gases, most importantly oxygen is affected. Ectotherms such as fish are thus directly affected by temperature in their environment. 
The polar regions share some features such as the extreme light conditions with long polar nights and days, the extremely low and stable water temperatures and the, at present, rapid changes in temperature in the Arctic and west Antarctic region. The polar regions also differ in many aspect, The opening of Drake sound and the establishment of the polar front 15-20 million years ago geographically, hydrologically isolated the Antarctic fish fauna genetically while there are not geographical and hydrological barriers for fish to move in and out of Arctic waters. Due to the isolation and low and in many regions stable water temperatures the polar living ectotherms are thought to be stenothermal and a very interesting research question is if this will limit their survival chances when the temperature increase in these regions?
One of the first adaptations to the frigid water temperature that was studied and described was the anti-freeze production that allows fish to live in water with a temperature down to the freezing point of water around -1.9C. Another area that have fascinated and intrigued scientists for over 40 years is the function and regulation of the cardiorespiratory system. Its primary function is to transport respiratory gases and nutrients and it has been claimed that the cardiovascular system might be the limiting factor, especially at elevated temperatures. The effects of temperature on the physiology and survival of polar living fish (and other ectotherms) is an intense research area with both good and not so good studies pointing to various future scenarios.  
This presentation will focus on the cardiorespiratory system and its function in polar fishes, how is it adapted to the extreme temperature condition and will it cope with the unprecedented fast changes in temperature that we see and predict for the future.