The Impact of Hypoxia on Cardiorespiratory Function, Carbohydrate Metabolism, and Adenosine Levels in Fish.
Declining fish stocks have had a profound affect on marine ecosystems and on the lifestyles of Canadians who have traditionally exploited fishing as their primary source of income. Areas of water with low concentrations of oxygen (hypoxia), are becoming common in the worlds oceans. Like other animals, fish require oxygen to survive and reproduce, however, some species of fish are better able to deal with hypoxia than others. Uncovering the mechanisms that allow some species of fish to survive hypoxia may allow managers to better predict the impact of hypoxia on economically important fish stocks.
We used blood flow probes, similar to those used in clinical settings, to study cardiovascular characteristics in fish exposed to hypoxia. We also used biochemical techniques, such as high performance liquid chromatography, to identify compounds that are involved in hypoxia-survival in fish.
Adenosine is a naturally produced compound that helps tissues survive oxygen limitation. The characteristics of adenosine metabolism are well described for mammals but not for fish. As fish are able to survive hypoxia better than mammals, we are studying whether differences in adenosine metabolism may lead to increased low oxygen tolerance.
The metabolism of adenosine in fish appears to be different than the established model described for mammals. Unlike mammals, the species of fish that weve studied do not accumulate adenosine during hypoxia, suggesting important differences between fish and mammals in their responses to low oxygen stress.
As hypoxic areas become more widespread in commercial fishing areas around the world, information on the physiological hypoxia-tolerance of fish will be incorporated into stock assessment models. This information could allow a more accurate prediction of whether a particular species of fish would be found in an area with low oxygen levels.