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Wildlife agency turning invasive water hyacinth into organic fertilizer

LakeOCleaningHydra.jpg
Florida Fish and Wildlife Conservation Commission
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A mechanical harvester scoops out water hyacinth from Lake Okeechobee in a pilot project by the Florida Fish and Wildlife Conservation Commission

Right now there is a box-shaped, metal thing sliding along the surface of Lake Okeechobee. It’s called a boat, but it resembles an aluminum scooper that doesn’t look like it should float. It moves with paddlewheels and sports a pitchfork.

The machine’s purpose is to rid the surface of the lake of water hyacinth, an invasive species from South and grows crazy fast.

The vessel’s bow folds down and as it moves forward, the waterweed slides into a cavernous hold with its bulbs, its spongy and bulbous stalks, and it roots colored black and purple. Along the way it may scoop up a frog or two, and sometimes a lot of sediment gets into the pile.

The mix does not smell good.

After being shredded it turns to a nitrogen-rich slurry, which is pumped onto land owned by willing nearby farmers where it turns into an organic alternative to store-bought fertilizer.

The smelly, messy endeavor is the Florida Fish & Wildlife Conservation Commission’s latest stab at ways to rid Lake Okeechobee of water hyacinth, groups of which can double in size in one week. The individual numbers of hyacinth can multiply by more than a hundredfold in less than a month.

The hope of the 35-acre pilot program is to find a way to successfully clear a body of water, or parts of it, of hyacinth without using chemicals or other extreme measures.

“This project highlights the FWC’s commitment to seeking innovative and effective solutions to manage invasive aquatic plants in Florida,” Melissa Tucker, director of the FWC’s Division of Habitat and Species Conservation, said in a statement. “While it is too soon to tell if we will be able to use this technique on a larger scale, we are excited about the possibility of having a new tool in the toolbox.”

Worst weed in the world

Other than its pretty pink or lavender flowers, it would be difficult to design a more unpleasant plant.

The water hyacinth blocks out the sun, which kills native plants growing below. As those decay, the oxygen in the water is used up, and a fish kill results. The hyacinth also harbors a freshwater snail that hosts a parasitic worm that can cause schistosomes in humans. Schistosomiasis can infect the intestines and urinary tract resulting in some unpleasant trips to the bathroom. Untreated, it can cause kidneys to fail, liver damage, infertility, or bladder cancer.

Fresh plants have a prickly sort of crystal formation that can cause a serious bout of itching. Then there are the mosquitos, who love to breed in the nooks and crannies of the plants which collect stagnant water.

A 2018 article in The Times of India covered an event where about 15,000 people living in Mundhwa were stung with mosquitoes. Soon after, villagers staged a protest to get the local government to remove the hyacinth. They covered themselves in mosquito-type netting and lined a river filled with the plants – and the mosquitos. The paper called the plants “highly invasive and commonly considered as the worst weed in the world” that created the “mosquito menace.”

The water hyacinth has also invaded Europe, Asia, Africa, New Zealand, Australia, the Independent State of Papua New Guinea, and Ghana, among other countries.

Army Corps vs. water hyacinths

Water hyacinths made their way from South America to the United States in the 1880’s. Nobody is sure exactly how the plants got here, but theories abound. The leading theory is that the plant was a gift from a delegation from Japan at the 1884 World's Fair in New Orleans. Another has the plant being spread throughout the country by a New Jersey-based exotic seed purveyor.

The plant spread so rapidly that by 1890 it blocked rivers in Florida and Louisiana, impeding trade and recreational boats. The states asked the federal government to do something and the Army Corps of Engineers was given the task.

Today, the Army Corps uses a combination of biological, mechanical, and chemical ways to try and control water hyacinths.

First problem: The water hyacinth love slow-flowing water with high concentrations of nutrient concentrations like, for example, Lake Okeechobee, which has been polluted by run-off from large agricultural operations and development for decades.

Second problem: The plant’s ability to grow is faster than anybody’s ability to haul it out by mechanical means.

The agency abandoned mechanical removal for mass clearing of hyacinths in the 1980s. The Army Corps found the methods too expensive, too limited, and too damaging to other vegetation and animals.

That was after the agency tried to employ harvesters to replace chemicals on Lake Okeechobee. The plants simply grew faster than the machines could corral them.

Now the Army Corps is doing what the FWC is testing out, which is to use harvesters to cut trails in the water, clear navigation channels, and remove the plant from around water intake systems, dams and locks. The FWC, however, is taking things a step further by processing the plants into a nutrient-rich slurry and the donating it to farmers.

FWC spokeswomen Carli Segelson said the harvester test is the latest of many ways the agency is trying to rid the big lake of small but rapidly growing invasive species, including water lettuce. The harvesters are working at the Indian Prairie Canal on the northwest edge of the lake.

The agency has tried several different ways to manage aquatic plants, including herbicides, other types of mechanical harvesting, biological controls like non-reproducing grass carp to eat it, and manual removal.

“What is unique about this situation is not because the mechanical harvester is being used on the lake,” Segelson said. “But the way we are disposing of the material.”

Environmental reporting for WGCU is funded in part by VoLo Foundation, a non-profit with a mission to accelerate change and global impact by supporting science-based climate solutions, enhancing education, and improving health. 

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