While the study showed storm water runoff is more damaging to fish than previously thought, researchers found bioretention systems improved aquatic conditions
Researchers at Washington State University Vancouver found that storm water is more harmful to fish than previously thought. The study, which appeared in the academic journal Scientific Reports, found that storm water damages the hairlike sensory nerve cells on the heads of coho salmon. These nerve cells are essential for the fish to find food, sense predators and navigate, therefore, with the nerves blunted by storm water runoff the fish are less likely to survive.
“We’re showing that even if the fish are surviving the storm water exposure, they still might not be able to detect the world around them as well, which can make it harder for them to find food or more likely for them to get eaten,” said Allison Coffin, an assistant professor of neuroscience at WSU Vancouver.
The researchers collected storm water runoff from state Highway 520 in Seattle and then exposed zebra fish and coho salmon embryos to the runoff. They found that while some of the fish were still able to survive, the functionality was seriously impaired as they grew less sensory nerve cells. Additionally, the researchers found that less fish survived in samples taken from 2015 than 2014, suggesting that the storm water became more toxic.
The silver lining was that water filtered through a bioretention system improved the condition of the zebra fish, though it did not improve the condition of the coho salmon.