Something as simple as stormwater is causing chaos for the fish, as coho salmon is dying off due to toxic runoff from urban areas carried over into their environment by storms.
- The rate of coho salmon death is currently at a high 50%
- The toxic runoff from highways and roads can kill the fish in a matter of hours (4 hours in some cases)
- This results in the death of many adult coho salmon before they are able to spawn
- Researchers designed a simple and cheap filtering system that seems to keep the fish safe from pollution
Coho salmom (Oncorhynchus kisutch) is a species commonly found within the northwestern parts of the United States. It holds exceptional economical and cultural value, but their death rate has increased to a disturbing 50%. The fish perish due to the toxic chemicals that are brought into the waters after storms, long before they can spawn. This has pushed their species to near extinction.
In a matter of hours, the toxic spill made of an unidentified number of substances effectively kill the fish. Researchers in Seattle have long suspected and finally proven that urban runoff is the blame of such a drastic increase in premature death rates. Fortunately, they quickly began testing and searching for filtering systems to improve their chances at life.
Their first experiments indicated that there are numerous substances that may be hazardous to the coho salmon. Researchers began with a mix of a variety of metals, crude oil and other chemicals, but found that brake oils, dust and vehicle exhaust were also part of the problem. This has led them to the creation of a green stormwater infrastructure technology.
They filtered the toxic runoff through a simple and inexpensive system of gravel, sand, bark, and compost before conducting their test. Specimens of coho salmon were exposed to both the filtered stormwater and the actual mixture that drips unhindered into lakes from highways. It took mere hours for the fish in the toxic tank to perish, while the other survived due to the very simple filtering system.
According to Julann Spromberg, who took part in the research, their ambition aimed for something inexpensive and effective to help save the species from extinction. And they managed to achieve their goals. The green stormwater infrastructure technology was able to decrease toxicity from heavy metals by 58%, and of polyaromatic hydrocarbons by a near flawless 98%. This underlines very simple way to prevent a potentially unfortunate consequence of lakes near urban areas.
Researchers are now attempting to incorporate this simple filtering system in future clean water design strategies, and then perhaps this particular species might have a chance. It would reportedly take years to understand precisely what chemical is causing the coho salmon to die in a matter of hours after exposure. However, in the meantime, they developed a proper way to stop it, no matter what it is.
Image source: dehlitimes.com