Antarctic fish study may aid cardiac research

A species of fish that lives in Antarctic waters may hold clues to climate change and lead to advances in heart medicine. Researchers from the University of Birmingham and the British Antarctic Survey (BAS) are investigating the behaviour and physiology of the ’Antarctic Cod’ (Notothenia coriiceps) which became isolated from its warmer water cousins around 30 million years ago when the Antarctic circumpolar current was formed.

The olive-coloured fish has broad head and a narrow body. Whilst scientists know that it has ‘antifreeze’ in its blood and maintains a very low heart rate of less than 10 beats per minute, almost nothing is known about its behaviour or how it evolved to live in Antarctica’s extreme environment.

Discovering how the species may cope with predicted environmental change could help stock management or conservation of biodiversity within the Southern Ocean. In addition, it is possible that this research could lead to advances in medicine, especially relating to the problems experienced by human hearts when made to beat slowly (e.g. during surgery involving heart-lung bypass) or fail to beat fast enough (e.g. as a result of hypothermia in water or exposure on a mountain).

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 to monitor position, while data loggers measure heart rate. In the laboratory, Dr Hamish Campbell, monitors heart performance of the fish in a similar manner to that used with patients in a chest pain clinic. The unique combination of tracking and recording technology shows how the heart rate is controlled, and its response to changing demands due to feeding or a rise in temperature.

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 24h darkness of a polar winter, how sensitive they are likely to be to climate change, and perhaps pave the way to understanding how we may 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”.

Dr Keiron Fraser from BAS 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°C. Climate models predict a 2ºC 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.’