Antarctic fish may aid cardiac research

The Antarctic cod maintains a very low heart rate of less than 10 beats per minute and has 'antifreeze' in its blood.  For the first time researchers will attempt to determine the how the fish evolved to live in Antarctica.

Discovering how the species may cope with predicted environmental change could help stock management or conservation of biodiversity within the Southern Ocean.  It is possible that this work may lead to advances in medicine, especially relating to the problems experienced by human hearts.  Findings of this study could be applied when hearts are made to beat slowly during surgery involving heart-lung bypass or fail to beat fast enough, for instance as a result of hypothermia in water or exposure on a mountain. 
   
Physiologist Dr Stuart Egginton, from the University of Birmingham's Medical School is leading the study: he says, "This pioneering work will shed light on what animals get up to during the impending 24 hour darkness of a polar winter, how sensitive they are likely to be to global warming, and perhaps pave the way to prevent a cold heart from fluttering. We know enough to realise this cod is different from those species living in the chilly North Sea, but not enough to be sure whether its strange characteristics are a response to the extreme cold, or because it is a descendant of unusual ancestors that has developed this way during its extended isolation from other fishes".

At the BAS Rothera Research Station on the Antarctic Peninsula small acoustic tags (called 'pingers' due to the sound they make) are painlessly attached to the fish and the signals picked up by underwater microphones, while data loggers measure heart rate.   Back in the laboratory, monitoring the fish in a similar manner to patients in a chest pain clinic shows how the heart rate is controlled, and its response to changing demand placed on the heart due to feeding or a rise in environmental temperature. Information is sent back to colleagues at the University of Birmingham and at BAS Cambridge.

Dr Keiron Fraser from British Antarctic Survey says: "This is the first time that we've been able to find out how these fish live.  Many Antarctic marine animals can live only within narrow temperature ranges and some die at around +5 degrees centigrade.  Climate models predict a 2 degree rise on global sea temperatures over the next 100 years.  One of the areas that we are trying to understand is how this fish species will respond or adapt to major environmental stresses, and how well it may survive the predicted environmental warming".