Locally, our Biscayne Bay estuary has been struggling with water quality issues for the last few decades, largely driven by nutrient inputs. Between hydrological changes, water management for flood control, and non-point source pollution, the historically oligotrophic Bay has shifted toward a more nutrient-laden system. Waste and stormwater infrastructure challenges, septic systems, and other nutrients have cumulatively resulted in algal blooms, seagrass loss, and fish kills. The 2021 Miami-Dade County fertilizer ordinance is showing early signs of nutrient reduction on nearshore coral reefs (Walker et al. 2025) and is a good start for slowing the rate of nutrients into local waterways.
In addition to ordinances like this one, an emerging tool in the toolbox comes in the form of Productive Floating Wetlands (PFW), a moniker introduced to me by Dr. Jazmin Locke-Rodriguez of Florida International University (FIU).
PFW is more or less synonymous with “constructed floating wetlands” or “floating treatment wetlands,” referring to artificial structures that mimic natural ecosystems. These structures have the potential to attract wildlife, and more importantly, assist with water quality improvement. Often found in urban areas that used to naturally host these systems, floating wetlands are becoming more common as an aesthetic, educational, and functional nature-based solution.
Dr. Locke-Rodriguez has been working with PFWs here in Miami for the last several years, examining the feasibility of growing various species in fresh versus brackish water environments. Dr. Locke-Rodriguez has been learning a lot about these systems and believes that their ability to uptake nutrients may prove valuable as a watershed management technique.
As PFWs take advantage of existing bodies of water, their construction relies upon the use of an artificial, buoyant structure (such as a Beemat), which rises and falls on the surface when water levels fluctuate (such as during the wet season). The structures allow for the plant roots to grow down into the water, with the biomass growing vertically. Dr. Locke-Rodriguez and her colleagues found nutrient retention is most successful when the plants are continuously harvested (Locke-Rodriguez et al. 2023). In addition to the potential for water quality improvement, PFWs can create habitats for birds, fish and other aquatic creatures, create shade to help regulate water temperature, even sequester carbon. These structures are not permanent, offering flexibility when it comes to regulatory considerations.
Dr. Locke-Rodriguez piloted PFW structures in Miami-Dade County, one on a canal in Pinecrest, and two on the FIU Biscayne Bay campus. The species being cultivated include ornamental flowers like marigolds, and native plants for restoration like black and red mangroves, and sea oats. I’ve had the opportunity to visit the sites and even help with the installation of one of the FIU structures. It’s exciting to see the science and innovation being pursued here in Miami, and I look forward to the results from these pilot installations.
Other notable floating wetlands include installations at Baltimore’s Inner Harbor, the Wild Mile in Chicago and the Charles River Floating Wetland in Boston.
Literature Cited:
Locke-Rodriguez, J., Troxler, T., Sukop, M., Scinto, L., Jayachandran, K. 2023. Floating flowers: Screening cut-flower species for production and phytoremediation on floating treatment wetlands in South Florida. Environmental Advances, Volume 13. 11pp.
Walker, B., Williams, G., Hanert, E., Dobbelaere, T., Whitall, D., Maynard, J., Aeby, G. 2025. Defining water quality seascapes in the KJCAP, their relationship to hydrographic modeling connectivity, the 2023 coral bleaching, and SCTLD. Final report. FDEP. Miami, FL. 69pp.
0
