Fish respiration may help detect environmental contamination

Washington, August 14 : Purdue University researchers say that the presence of minute levels of toxic substances in the water can be detected before they cause substantial harm by measuring rates of oxygen use in developing fish, which are sensitive to contaminants and stressful conditions.

Marshall Porterfield, an associate professor of agricultural and biological engineering, says that this process may be used as an early warning system against environmental contamination or even biological weapons.

He highlights the fact that respiration-the process wherein animals and other organisms burn oxygen to produce energy-is often the first of a fish's bodily functions affected by contaminants.

His team has shown that using fibre optics to quickly monitor this activity can produce results within minutes.

"Say you are exposed to the common cold virus. Before symptoms develop and you become aware of the bug's presence, it has already begun to attack your cells. Similarly, fish and other organisms are affected by contaminants before behavioural changes appear. Our technology detects heretofore undetectable changes to act as an early warning system," he said.

A research article in the online edition of the journal Environmental Science and Technology says that the novel system detected the presence of several common pollutants, such as the widely-used herbicide atrazine, even at levels near or below those that the U.S. Environmental Protection Agency deems acceptable for drinking water.

"This means the technology could not only help monitor environmental quality but may be used to enforce important water quality standards," said Marisol Sepulveda, lead author and assistant professor of forestry and natural resources at Purdue.

She revealed that testing also registered noticeable changes in the respiratory activity of fish embryos when the heavy metal cadmium was present at levels 60 times lower than the EPA limit.

Given that contaminants did not destroy the eggs of laboratory-raised fathead minnows-a commonly studied fish species-throughout the study, the researchers say that this further demonstrates the tool's ability to discern subtle changes before they become fatal.

Porterfield said the technology could be used on other organisms.

A team of Purdue researchers has already begun adjusting it to work with a type of crustacean.

Porterfield reckons that a prototype should be ready to test in the field in four years if improvements continue.

While the technology currently tests immobilized eggs in a laboratory setting, there are plans to make the tool more versatile.

The researchers also believe that the technology may have some medical uses too-it could be conjugated with tumour cells to screen potential cancer drugs or help find new therapeutic targets.

ANI