Copper can block a fish's ability to smell the odor released by other fish when in danger, a new study presented at the meeting for the Society for Experimental Biology found.
Led by Bill Dew at the University of Lethbridge in Canada, the report is the first to look at the effect of nickel and copper on specific fish olfactory sensory neurons and how these, in turn, affect the fish's ability to detect and swim away from an odor released by other fish of the same species (conspecies) when a predator attacks.
"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 in a press release.
In order to carry out the study, Dew and his team used a technique that measures the response of the olfactory system to odors. As they did this, the researchers showed that both copper and nickel affect the ability of different cells to detect odors.
Additionally, the scientists used a series of anti-predator trials that measured fish's avoidance to a conspecific skin extract. In doing so, they discovered that fathead minnows exposed to copper did not react when exposed to the extract while unexposed and nickel-exposed fish did.
"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," Dew summarized, "while fish in a nickel contaminated environment would be able to detect these compounds and undertake predator-avoidance behaviors."
In addition to the seemingly benign act of tossing pennies into natural fountains and other pools of water - a problem for places such as Bermuda's anchialine caves - an ever-increasing collection of human trash on the ocean floor means more and more fish are likely to be exposed to copper-contaminated waters and, ultimately, increased predation.