WHERE THE BIOSWALES ARE: PROTECTING OUR FISH USING HEAVY METAL PLANTS
Reed canyon today is home to a large variety of fish species, ranging from the charismatic Coho Salmon Oncorhynchus kisutch to the tiny Threespine Stickleback Gasterosteus aculeatus aculeatus (1). However, prior to 2001, the fish of Reed Canyon, especially salmon young, were getting stuck in the Crystal Springs stream, a prime spawning point for mothering fish due to its pristine variety of gravels. The fish needed to be able to move to the safety of Reed Lake where they had a better chance of reaching maturity, but were forced to move towards the ocean where they would be gobbled up by large predators. However, the restoration team at Reed Canyon had a plan: build a ladder for the baby fish to climb!
While the project was a success, Zac Perry, the head of the restoration effort, and his team noticed that the fish were still not doing as well as they should have been. Quickly, they came up for a reason why: heavy metal toxicity, which was causing a slew of issues in the fish of Reed Lake, such as nerve damage. The source of this toxicity may sound familiar to many of us: a byproduct of the cars we drive. However, the largest problem was not the car’s exhaust, rather, it was the result of slamming the brakes a little too hard.
Brake dust is made every time a car uses its brakes, and therefore accumulates quickly in natural resources near roads. Many brake pads include heavy metals, such as nickel, zinc, and even mercury! One common material, copper has been shown to have a very negative effect on fish, including impairing their sense of smell (2), preventing them from escaping from danger. Imagine trying to dodge a predator with a stuffy nose!
So, what did the canyon restoration team use to combat this issue? Plants!
Using a mixture of native plants approved by the city of Portland, such as Meadow Barley Hordeum brachyantherum, Large Leaf Lupine Lupinus polyphyllus, and Cascara Frangula purshiana trees (1), the team built up a system of bioswales next to roads adjacent to the canyon. Bioswales act as a filter for heavy metals, trapping and storing them in their roots and leaves instead of allowing them to wash into nearby rivers and streams (3). Of course, heavy metals aren’t any better for plants than they are for animals, so the plants used are specifically selected for their hardiness and lack of agricultural use!
So, through the power of bioswales and some heavy metal plants, the day was saved for baby fish everywhere (well, maybe not everywhere, but certainly for those calling the Reed Canyon home.) But you may be wondering, what about in places where there are no bioswales? Where heavy metals are free to wash from the roadside and into the homes of fish and other aquatic critters?
On the west coast, Washington and California have implemented landmark regulations regarding the use of copper and other toxic materials in brake pads. The Better Brakes Law in Washington aims to eliminate the use of copper in brake pads by 2025 by gradually phasing them out of production (4). However, many states in the US have yet to follow suit, including Oregon, which has no significant regulations on brake pad composition yet.
What can you do to help protect Oregon’s fish and wildlife?
References
- Reed College | Canyon | Natural History of the Canyon, Reed College, www.reed.edu/canyon/natu/index.html.
- Baldwin, D.H., Sandahl, J.F., Labenia, J.S. and Scholz, N.L. (2003), Sublethal effects of copper on coho salmon: Impacts on nonoverlapping receptor pathways in the peripheral olfactory nervous system. Environmental Toxicology and Chemistry, 22: 2266-2274. https://doi.org/10.1897/02-428
- Biofilters (Bioswales, Vegetative Buffers, & Constructed ... State of Oregon Department of Environmental Quality, www.oregon.gov/deq/FilterPermitsDocs/biofiltersV2.pdf.
- “Better Brakes Law, Washington State Department of Ecology, ecology.wa.gov/Waste-Toxics/Reducing-toxic-chemicals/Better-Brakes-law.
