A study conducted by Jennifer MacIntyre of Washington State University, reveals that even the most minute amount of copper in water can impair a salmon’s ability to sense schreckstoff. Schreckstoff is a German term literally meaning “scary stuff”. This is a chemical released in the water by injured salmon that alerts other fish there is a predator nearby, allowing them the opportunity to protect themselves. Anywhere as little as 5 parts per billion of copper in water will affect the ability of salmon to detect schreckstoff, and decrease their chances of survival.
“A copper-exposed fish is not getting the information it needs to make good decisions,” McIntyre said in a statement on Tuesday. Her research was just published in the latest issue of the journal Ecological Applications.
Salmon have a flower-shaped bit of tissue in their nose called a rosette, which is studded with sensory receptors. Previous work has found that copper interferes with a fish’s sense of smell by damaging or even killing the sensory neurons on the rosette, McIntyre explained in a phone interview.
The effect isn’t necessarily permanent, as the neurons can regrow, but that takes time. And if the copper is still in the water, the salmon’s sense of smell will continue to be impaired.