Wild About Wetlands- Part 2: Floating Wetlands

It’s me again-the girl who loves wetlands! My last blog, Wild About Wetlands, introduced readers to the importance and beauty of wetland ecosystems. Now I am here to inform you about another type of wetland that I have been experimenting with this summer- Floating Wetlands.

As explained in my previous blog, we all know that wetlands are important for a variety of reasons such as, the crucial habitat they provide for many aquatic, avian, and terrestrial species. Another important benefit that wetland ecosystems provide is the ability to act as “nature’s kidneys” to help purify the water by removing excess nutrients and contaminants that have entered our waterways via stormwater runoff. How do wetlands act as “nature’s kidneys” you ask? Great question! Wetlands rely on natural processes to biologically filter water as it passes through shallow areas of dense aquatic vegetation and permeable bottom soils. The primary mechanisms for nutrient removal are transformation and uptake by microbes and plants, assimilation and absorption into organic and inorganic sediments, and converted into gas through volatilization. Aquatic plants take up and remove these elements from the sediment and water column into their plant material or biomass. In other words, aquatic plants have microbial friends living on their roots and other plant parts that enjoy eating phosphorus, nitrogen, and other contaminants in the water, and then they use that food energy to help the plants grow. Nature is so cool!

However, I also pointed out in my previous blog that since the arrival of European settlers in the 1800’s, approximately 80% of Ohio’s wetlands have been lost to development such as urbanization and agriculture. Cuyahoga County is heavily urbanized and has very little acreage dedicated to wetlands. Coupled with high levels of stormwater runoff due to vast amounts of impervious surfaces, our waterways, which drain directly into Lake Erie, could use our man-made help and this brings me to floating wetlands.

Floating wetlands are small artificial platforms that allow aquatic emergent plants to grow in water that is typically too deep for them. Their roots grow down into the water creating dense columns with lots of surface area. Not only do the plants take up nutrients and contaminants themselves, the plant roots and floating mat material provide extensive surface area for microbes to grow, forming a slimy layer of biofilm. The biofilm is where the majority of nutrient uptake and degradation occurs in a floating wetland system. The shelter provided by the floating mat also allows sediment and elements to settle by reducing turbulence and mixing by wind and wave action. The unique ecosystem that develops creates the potential to capture nutrients and transform common pollutants that would otherwise plague and harm our lakes into harmless byproducts. Not only do floating wetlands treat and purify our fresh water supply, but they also create important habitat for fish and aquatic invertebrates by giving them cover, shade, and cooler water temperatures in an aquatic environment that would typically be comparable to a desert lacking vegetation and canopy cover. Floating wetlands work in various freshwater systems such as stormwater ponds, wastewater lagoons, and landfill leachate ponds.

So I reached out to the City of Westlake, found a stormwater pond that would be a great location for a first run at growing our own floating wetland, and voila, the City of Westlake now has a floating wetland stationed at the Westlake City Recreation Center on Hilliard Boulevard. We planted the eight foot squared mat in the beginning of May with aquatic sedges, rushes, and flowering plants. At first, I had to battle with geese munching on my beautiful buffet of wetland plants, but after anchoring loose netting to the mat, the plants have been happily growing ever since. I paddle out to the mat every ten days or so to check on the growth and health of the plants, and to tend to the mat if there are any issues- I have collected quite the array of fishing lures and hooks that have gotten snagged on the netting. We will continue to allow the plants to grow through the season, removing them before they start to senesce in September and planting them in their forever home at a stream restoration site in need of new aquatic plants in North Royalton. There, the plants will overwinter and restart their growing period again in the spring.

Overall, our vison for this pilot season was to grow the wetland plants large enough to be able to withstand wave action once they are planted in their forever home, all while removing harmful pollutants from our waterways prior to reaching Lake Erie, as well as creating great habitat for fish and aquatic invertebrates. This project has been a great learning experience for me, as well as the residents who frequent the Westlake Rec Center pond or who visit our social media accounts. If this pilot season turns out well and we can secure funding, it would be amazing to turn this into a large-scale project and to anchor floating wetlands in stormwater retention basins throughout the county. If man-made development has gotten us into this mess, then maybe man-made development is what can help us clean up our waterways and our precious drinking source of Lake Erie.

View the photos above to see the progress of the floating wetland from May until now!

Blog Author: Jaimie Johnson, Watershed Coordinator

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