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Invasive aquatic plant can threaten waterways
T
he Mobile Area Water and Sewer System closed Big Creek ing all five Gulf Coast states. In Alabama, people first discovered Lake when it discovered giant salvinia growing in the 3,600giant salvinia growing in two ponds in Auburn in 1999. Soon after acre reservoir near Semmes. that, people identified it in the Tallapoosa and Chattahoochee watersheds as well as ponds in Lee, Montgomery, Greene, Pickens, MAWSS officials sprayed the lake with herbicide to kill the noxious plant and built a boat washing facility near the only landing Russell and Sumter counties. on the water-supply reservoir. The impoundment on the EscatawMore recently, researchers detected it in Gainesville Reservoir pa River watershed partially reopened to fishing and boating in and backwater sections of the Tombigbee River. A pond in Autauga County contained a bad infestation. Giant salvinia in the June 2022 after remaining closed for 10 months. People must wash Elk River, which flows into the Tennessee River, probably died out their boats and trailers before launching into Big Creek Lake to from cold. As a tropical plant, giant salvinia thrives in warm water, curtail the spread of the invasive plant. but a hard freeze could kill it. “We sprayed the giant salvinia with an EPA-approved product,” “The occurrence of giant salvinia is sporadic in Alabama,” says Bud McCrory, MAWSS director. “We’ll never get giant salvinia out of the lake completely, but we’re going to try to mitigate Armstrong says. “We eliminated it in certain areas and weather how it spreads. The boat washing will help reduce our risk at some took care of it in other places. We’ve had reports of it in the Mobile-Tensaw Delta in expercentage.” treme southern Alabama. Native to southeastern I would not be surprised if Brazil, this aquatic fern it’s in some backwater argrows extremely rapidly. eas with limited flow in the In ideal conditions, it can delta. It’s a freshwater plant double in size in less than a so it probably can’t handle week and quickly dominate too much salt like in Moportions of any freshwater bile Bay.” system. Once established, The plant probably came giant salvinia chokes out to the U.S. for aquariums native plants and reduces or water gardens. When dissolved oxygen levels in people no longer wanted the water. to maintain an aquarium, “Giant salvinia grows they probably dumped it at such a high rate that it into the nearest stream, shades out the bottom,” pond or lake. In addition, says Dave Armstrong, the flood conditions can overAquatic Nuisance Species flow ponds and water garCoordinator for the Alabama Division of Wildlife Giant salvinia is an aggressive, fast-growing exotic that chokes out native plants and dens, washing the plants and Freshwater Fisheries. can kill everything beneath it that depends on sunlight to survive. into nearby rivers. “It’s amazing how deep this Giant salvinia can surPHOTO COURTESY ALABAMA DIVISION OF WILDLIFE AND FRESHWATER FISHERIES vive out of water for up to a stuff will grow. It grows to year. In addition, the plant clings to boat hulls and trailers. When where there’s very little sunlight. It grows in layers upon itself until someone launches a boat carrying the plant into another system, it completely fills in a small pond from top to bottom.” the invader multiples prolifically in its new home. People also theOne of the most aggressive aquatic plants, this fast-growing exotic can grow so thick that boats cannot pass. It blocks the sunorize that particles can attach to the legs and feet of wading birds light, killing everything beneath it that depends upon sunlight to like herons and egrets. Once established, the plant rapidly takes survive. over portions of that waterbody. “When giant salvinia covers the surface, it kills the plankton,” “The main way this plant spreads is by sticking to boat hulls Armstrong says. “All fish require plankton, at least when they’re and trailers,” Armstrong says. “It’s so clingy it’s almost like Velcro. young. Small fish, prey for larger fish, eat plankton. If the plant Little eggbeater-like hairs on the leaves grab onto anything. Birds reduces phytoplankton and zooplankton in a system, fish won’t ingest it and spread it that way. Once it gets into a system, spraying get enough food to it.” masses of it is the only way to control it.” To help curb the spread of giant salvinia and other noxious exThis noxious invader currently exists in at least 11 states includotic plants, always wash boats and trailers or anything else before launching into another waterbody. To report giant salvinia infesJohn N. Felsher is a professional freelance writer who lives in Semmes, Ala. He also hosts an outdoors tips show for WAVH FM tations, contact Dave Armstrong at 251-331-7050 or email Dave. Talk 106.5 radio station in Mobile, Ala. Contact him at j.felsher@ Armstrong@dcnr.alabama.gov. See giant salvinia on outdooralhotmail.com or through Facebook. abama.com and other internet sources.
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7/14/22 12:03 PM
