Copper prevents fish from avoiding danger

Fish fail to detect a danger odour signal emitted by other fish in waters contaminated with copper, a new study has claimed.
Research conducted by Dr Bill Dew at the University of Lethbridge in Canada looked for the first time at the effect of the metal contaminants nickel and copper on specific fish olfactory sensory neurons.
He also analysed how these affect the fish's ability to detect and swim away from an odour released by other fish of the same species (conspecifics) when a predator attack takes place.
"Our research shows that copper affects the function of a specific type of olfactory neurons in fish, preventing them from detecting important olfactory signals used to detect fish injured by predation," Dew said.

Using a technique that measures the response of the olfactory system to odours, the researchers showed that copper and nickel affect the ability of different cells to detect odours.
Furthermore, using a series of anti-predator trials, which measured avoidance of fish to a conspecific skin extract, the researchers found that fathead minnows exposed to copper do not avoid the skin extract, while unexposed and nickel-exposed fish do.
"This means that fish in an environment contaminated with copper would not be able to detect compounds released during a predation event and potentially not avoid predators, while fish in a nickel contaminated environment would be able to detect these compounds and undertake predator-avoidance behaviours," Dew said.

The study was be presented at the Society for Experimental Biology meeting in Valencia, Spain.