According to a new research, toxic runoff from highways and the other man-made structures is killing coho salmon in the urban streams.
The research found that the inexpensive filtration of urban runoff though sand and soil could help in protecting the fish from the effects of the contaminants.
Julann Spromberg, research scientist at NOAA Fisheries’ Northwest Fisheries Science Center in Seattle said, “Untreated urban runoff is very bad for salmon health. Our goal with this research is to find practical and inexpensive ways to improve water quality. The salmon are telling us if they work.”
California, southwestern Washington and Oregon coho salmon are listed under the Endangered Species Act. And the stormwater runoff is making the conservation of the salmon very difficult. Researchers are urging to install filtration columns that are similar to rain gardens that are being utilized in the Northwest, to save the species from extinction.
Nat Scholz, Ecotoxixology program manager at the NWSFC in Seattle and coauthor of the study said, “If we can incorporate clean water design strategies into future growth, as some transportation projects are already doing, wild salmon might have a chance, they can’t take the kinds of losses we’ve documented in urban streams.”
For the study, researchers have exposed adult coho from the Suquamish tribal hatchery to different levels of water pollution and clean water. They observed that all of the fished exposed to runoff from a busy urban highway in Seattle dies within 24 hours. When the researchers filtered this toxic water through a three-foot high column composed of natural materials such as sand and soil, they observed that coho thrives as well as they did in unpolluted water. Test revealed that the simple filtration system reduced toxic heavy metals by 58 percent and byproducts of gasoline combustion by as much as 94 percent.
Jen McIntyre, a researcher at the stromwater program at WSU’s Puyallup Research and Extension Center and the co-author of the study said, “What impressed me most was the effectiveness of the treatment, it’s remarkable that we could take runoff that killed all of the adult coho in less than 24 hours – sometimes less than four hours – and render it non-toxic, even after putting several storms worth of water through the same soil mixture.”
The findings of the study are published in the recent edition of the Journal of Applied Ecology.