Salvinia Smackdown: Kauai tackles invasive plant

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Dan Lager, with the state Department of Land and Natural Resources Division of Aquatic Resources, helps clean salvinia out of the Kilauea River.

KILAUEA, HI — This plant can take over a river from just one leaf.

It starts along the banks and forms a thick mat across the top of the water, blocking sunlight and changing the ecosystem underneath as it grows.

And with Kauai’s connected waterways, it is currently spreading without remorse.

“Salvinia starves the river of sunlight and oxygen, but also when it decomposes, it falls to the bottom and changes the system; turns it into more marshy,” said Justin Goggins, biologist with the state Department of Land and Natural Resources Division of Aquatic Resources.

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Salvinia creeps in from the edges of the Kilauea River in October 2017.

The aquatic plant hails from Brazil and is the most invasive species in Hawaii. It spreads through seeds and through fragments and is in many of Kauai’s waterways, said DAR’s education specialist Katie Nalesere.

The two are part of a team that was on Kauai for five days in October 2017, cleaning salvinia out of the Kilauea River with a boat-mounted suction system that filters the plant out of the water using a hose.

About 12 people from DAR, state Department of Agriculture and Kauai Invasive Species Committee took on the project Tuesday, with one volunteer, Kilauea resident Beryl Blaich.

“I live in the area and I missed the Kilauea Neighborhood Association cleanup last year,” Blaich said. “I wasn’t about to miss it again.”

KNA partnered with KISC in August 2016 in a one-day cleaning blitz that helped curb the water plant, for a while, but the fast-growing plant is quickly repopulating.

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Bob Warren drives his flat-bottom boat across the Kilauea River for the salvinia removal project. 

Bob Warren, who lives along the Kilauea River and offers his property as a staging area for cleanup efforts, said they need something bigger to take on the problem.

“When we were out here last time we, realized it’s too much to try and manually take all of this out,” Warren said. “That’s why we’re using the super sucker.”

The super sucker is basically a  floating river vacuum, and the contraption’s maiden voyage on the Kilauea River was during the project.

Though they had some problems with the system clogging, within the first hour the team pulled 31 bags of the invasive plant from the river using both the suction system and manual labor. Each bag weighed about 40 pounds.

While KISC and DAR staff members worked the suction system, others tackled salvinia with nets, rakes and other tools.

It was piled along the riverbank and after it dries out, County of Kauai is helping to transport the salvinia to the Kilauea Ag Park, where it will be composted.

While there are a few hands helping with the project, state workers and

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Salvinia spreads through seed pods, or through leaves like this clump floating in the Kilauea River.

conservationists are asking for help with the problem from visitors and residents of Hawaii.

“We need all the help we can get, especially people who are willing to get wet,” Nalesere said.

And getting wet could mean submersing yourself to your neck in the river, scooping armfuls of leaves and roots into mesh bags.

Other jobs include steering a kayak, netting salvinia, and helping transport bags to the drying pile.

But, cleaning out the invasive weed is just the beginning of the project.

“We’re building a database of where the salvinia is on the island, so we know the extent and how to best approach it,” Nelesare said. “We’re asking people to report salvinia to KISC, and then we’ll go out and verify and put it into our database.”

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Salvinia is one of the most invasive species in all of Hawaii, according to the state. 

The team is also using environmental DNA testing to narrow down the location of the plant. The next round of EDNA testing is set for November or December, with an analysis that DAR staff is hoping will be complete by spring 2018.

“This project will hopefully provide a model moving forward (in salvinia eradication),” Nelesare said.

After this week’s project is finished, Goggins said community members could also help by doing periodic, organized sweeps of the river

“If community groups could get together and monitor the river, come behind us and help out, that’s what’s going to be really helpful over here,” Goggins said.


Written for The Garden Island Newspaper, photos taken by Jessica Else. Published Oct. 25, 2017.

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