An assessment performed by the University of Florida indicated that the non-native broadleaf seagrass, Halophila stipulacea showed potential for the plant to become invasive. Dr. Justin Campbell of Florida International University (FIU) published a paper in 2024, confirming the presence of this species at Crandon Marina in Key Biscayne, FL.
Since Halophila has been well-established in other parts of the Caribbean in areas containing high numbers of boats, it stands to reason that boating served as the inadvertent transport mechanism from its native range (The Red Sea, Persian Gulf, and Indian Ocean (Campbell et al. 2024)).
Aren’t all seagrasses alike?
This theory seems as though it could make sense, however, not all seagrasses perform the same ecosystem functions. As with terrestrial non-native plants, Halophila is a prime potential invasive species here in Florida: it can withstand a wide range of salinities, temperatures, grows very quickly and can easily out-compete our native seagrasses for space. Its shallow root system will not hold sediment in place as effectively as our native seagrasses, and scarier yet, Halophila can reproduce by fragmentation-meaning, that if any pieces are broken off, they can move around and re-establish themselves, continuing to grow.
What’s being done about this?
Last week, Dr. Campbell along with the Florida Fish and Wildlife Conservation Commission (FWC) held a Halophila removal event. Multiple partners gathered to perform three different treatments of the invasive seagrass:
1) hand removal
2) trimming of the canopy
3) tarping the seagrass
Working under multiple permits, about 30 people from the Florida Department of Environmental Protection Biscayne Bay Aquatic Preserves, Florida State Parks, FWC, FIU, Miami-Dade County DERM, and UF/IFAS Extension collaboratively performed the aforementioned tasks.
Ultimately, we removed a minimum of 500 pounds of Halophila from the area as well as completed the other treatment methods. Dr. Campbell and his team will continue their research to determine the best future methods for management. We anticipate future removal events as Halophila has become well-established, and preliminary surveys document that it has spread beyond where it was first spotted.
How can you help?
If you are on the water and spot what you suspect may be Halophila or a non-native plant, it’s critical *not* to attempt removal. The best thing to do is take a photo if you can, and take a GPS coordinate, either on your phone or on your boat, and report it to InvasivePlants@myFWC.com. Since Halophila reproduces very easily from just small pieces, we want to make sure that the area remains undisturbed.
Literature Cited:
Campbell, J., Allen, A., Sattelberger, D., White, M., Fourqurean, J. 2024. First record of the seagrass Halophila stipulacea (Forskkal) Ascherson in the waters of the continental United States (Key Biscayne, Florida). bioRxiv, 12pp.
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