Commitment must be made now to control alien plant

By SHANNON TOMPKINS, Staff

David Mitchell shook his white-haired head as he looked out over the little reservoir in eastern Chambers County. Half, perhaps more, of the lake's 50 acres were covered with a solid mat of green/brown vegetation, the carpet looking thick enough to walk on.

"You've got a bloody problem," he said, his words and accent betraying his Australian homeland.

His somber tone said he was serious - bloody serious.

When one of the world's most respected and experienced experts on limnology, water weeds and wetlands looks at a piece of water and immediately pronounces it in dire straits, you believe him.

It didn't take Mitchell's assessment for me to know the lake and its adjacent twin were in sad shape. He just verified it.

If anyone doubts the destructive ability of giant salvinia, an alien water fern officially discovered in the Houston area a little more than a year ago, a visit to the two lakes would solve that.

Mitchell didn't take any convincing. Currently a professorial associate at Charles Sturt University in New South Wales, Mitchell has for more than 25 years seen with his own eyes the ecological, economic and social impact of salvinia molesta.

He has seen what it has done to Africa's Lake Kiraba where solid mats of salvinia cover more than 250,000 acres of the giant reservoir's surface. There, it caused whole shoreline communities to relocate, wrecking the fishery and social order.

He has seen what salvinia did to the aboriginal cultures along the Sepik River in Papua New Guinea when it covered so much of the lagoons and sloughs and river channels that it made movement by boat, the only mode of transportation, impossible.

The impact was incredible, Mitchell said. It almost destroyed the culture of the disparate tribes along the river.

"It was a bloody nightmare," he said.

Mitchell has seen it in Australia, New Zealand and the other places salvinia has reared its green head since humans transported it from its native home in southern Brazil and loosed it on waters where it has become one of the most damaging alien plants in the world.

Now, Mitchell has seen salvinia molesta in Texas.

He doesn't like what he sees.

"If you don't do something to control it, you're going to see some serious consequences," said Mitchell, probably the foremost expert on salvinia and its control, as he looked over the lake this past Monday afternoon.

Mitchell and Bill Haller, professor at the University of Florida's Center for Aquatic Plants and a top U.S. expert on alien plants, along with their Texas "tour guides," Rhandy Helton and Larry Hartmann of the Texas Parks and Wildlife Department's aquatic vegetation control program, had agreed to meet me Monday afternoon to look at the two lakes on my fishing lease.

I knew what they'd find.

A year ago, I, like most people, had never heard of giant salvinia. I've since learned I'd already seen it. I just didn't know the devil when I met it.

The lakes, full of bass and crappie and sunfish and situated in an isolated setting along a bayou and adjacent to bottomland forest of palmettos, oaks and rattan, had for decades been tremendous fisheries.

Then something happened. This strange floating plant showed up.

At first, the plant with the velvet-like leaves was limited to fringes of the lake, creating a kind of skirt on the water.

But within a couple of months, it had covered nearly every inch of the surface. It was impossible to fish the lakes.

The mat of vegetation, in addition to sucking all the suspended nutrients from the water, had shut out all sunlight. Also, it prevented oxygen from mixing with the water. Nothing could live under that.

The lakes were basically dead, smothered.

I wrote the lakes off, but kept paying the annual lease fee, hoping the vegetation would somehow disappear and fishing would return to its former glory.

That was three years ago.

A month or so ago, I saw that strange fern again.

It was covering a six-acre pond in Liberty County. Helton and Hartmann along with staff from the U.S. Department of Agriculture were there to release Brazilian Cyrtobagous beetles in an experiment which, experts hope, will help control the spread of salvinia molesta.

At that time, the six-acre pond was the largest continuous mat of salvinia documented in Texas, Hartmann and Helton said.

That changed Monday when we topped the levee in Chambers County and the scientists saw "my" lakes and the salvinia-clogged canals adjacent to them.

"It seals off the surface quite efficiently," Mitchell said. "That prevents the air/water interface, and prevents oxygen from mixing with the water."

While preventing sunlight from entering the water, blunting photosynthesis and killing beneficial aquatic plants, salvinia also ties up the nutrients in the water.

So what's the answer? How do Texans attack this new and growing problem?

We will never get shed of salvinia now that it's here, Mitchell said.

The plant can be controlled, though. It'll just take education, commitment and money - three things not easy to come by.

First, it'll take education of anglers and boaters and others likely to encounter salvinia. They need to know how to identify it, prevent its spread and where to report suspected infestations.

But what about getting rid of it where it's established?

Forget mechanical harvesting, Mitchell said. There's no way harvesters can pick up all the plants, and salvinia can reproduce from pieces of itself.

"You have to use an integrated control regime," he said.

While Mitchell says he is "no fan at all" of herbicides, he believes the plant poisons are a necessary part of controlling salvinia . Combined with biological controls such as the Cyrtobagous beetles, herbicides can keep salvinia under control.

Those who oppose all use of aquatic herbicides are fooling themselves if they think the "cure" is worse than the "disease."

"The effects of salvinia on fisheries are a lot worse than any approved herbicide used to control it," Mitchell said.

The challenge will be most daunting on private waters infested with salvinia. The current political climate isn't conducive to taking action. This is particularly a problem in Texas, where any government "intrusion" on private property is met with stiff resistance. Add to that the vocal and politically connected opposition to using any chemical controls on aquatic vegetation, and you've got a problem.

With little government help in controlling salvinia, landowners will be left to address the problem themselves. Most will not or cannot spend the money necessary to attack salvinia.

But unless something is done - unless there's some commitment of resources to stemming the spread of what has been called "the world's worst weed" - Texas and the rest of the South face serious consequences.

"You either deal with it now, or you're facing a bloody disaster," Mitchell said.

He'd know.