Invasive plants threaten state’s lakes



Outdoors


TPWD's Aquatic Habitat Enhancement Team applies herbicide to a giant salvina infestation on a Texas lake.


John Findeisen/

TPWD’s Aquatic Habitat Enhancement Team applies herbicide to a giant salvina infestation on a Texas lake.



By

Matt Williams , Special Contributor


Summer is in full swing across Texas, and John Findeisen and his crew have got their pedals to the metal.

Findeisen leads the Texas Parks and Wildlife Department’s Aquatic Habitat Enhancement Team. The small staff is charged with the huge responsibility of helping to keep an army of aquatic monsters at bay on inland waters across 254 Texas counties.

The monsters are invasive plants with peculiar names: giant salvinia, common water hyacinth, common salvinia, yellow floating heart and crested floating heart, to name just a few.

Some are considered noxious weeds. Any of them can gobble up acres of surface area on a body of water in short order. The plants can form thick canopies that can crowd out native species, hamper boating traffic, clog water intakes and upset ecosystems.

“It keeps us busy,” Findeisen said. “There are only six of us. Between our three trucks we average around 11,000 miles on the road per month. We get spread pretty thin at times.”

Invasive plants, particularly giant salvinia, pose a vexing problem on Texas lakes that is very costly to deal with.

Findeisen said the Texas Legislature has approved $6.3 million in funding to TPWD to fight aquatic invasive plants and animals twice in the last four years. His team has an annual budget of $1.73 million for spending on herbicides, fuel, spraying equipment and other necessities for carrying on the unending battle.

Additionally, the biologist allocates funds for rearing giant salvinia weevils. The tiny insects eat the plant and reproduce on the leaves. When the eggs hatch the larvae burrow into the plant’s stem. This causes it to die.

Most worrisome

Left unchecked, giant salvinia can consume big surface areas in short order. The noxious plant is currently causing problems on 18 Texas lakes.


Texas Parks & Wildlife Department/

Left unchecked, giant salvinia can consume big surface areas in short order. The noxious plant is currently causing problems on 18 Texas lakes.

While any of the aforementioned plants can spell trouble for a reservoir, giant salvinia is the most worrisome of all. The aquatic fern is native to the Amazon River Basin in Brazil. Researchers believe it was transported to the United States years ago in a tainted shipment of tropical plants or fish.

It was first discovered in Texas in 1998 in a small pond near Houston. It was found in Toledo Bend later that same year, marking the beginning of a widespread battle that has since spread to at least two dozen Texas lakes.

According to Findeisen, 18 Texas lakes are infested with giant salvinia. Among them are Brandy Branch, Caddo, Conroe, B.A. Steinhagen, Livingston, Martin Creek, Murvaul, Nacogdoches, Naconiche, Lake O’ the Pines, Palestine, Raven, Sam Rayburn, Sheldon, Striker, Texana, Timpson and Toledo Bend.

The plant has been discovered and subsequently eradicated in a handful of lakes over the years, including Wright Patman, Welsh, Gilmer, Falcon and, most recently, at Lake Athens and Lake Fork.

Findeisen says the chances of eradication are always best when a new infestation is discovered early enough to be contained with booms and sprayed with herbicide before the plant has the opportunity to spread.

Sadly, however, a successful eradication effort doesn’t guarantee giant salvinia won’t regain a foothold on the same water body later. That’s because the plant is very mobile, extremely hardy and can be easily transported from one lake to the next.

Fast to Spread

Experts say one of the primary ways giant salvinia and other invasive plants are transported from lake to lake is on boat trailers.


Texas Parks & Wildlife Department/

Experts say one of the primary ways giant salvinia and other invasive plants are transported from lake to lake is on boat trailers.

Giant salvinia can spread so rapidly under good growing conditions that coverage areas can double size within seven to 10 days. Findeisen said the plant does not root to bottom and floats where the wind takes it. It flourishes in still backwaters that are often inaccessible to boat traffic, often becoming well established before discovery.

Giant salvinia is sneaky, too. The plant is prone to cling to whatever it touches, including duck decoys, boat anchors and trolling motors.

Experts believe the most common way new infestations occur is by boat trailer transport. The plants can live on moist trailer bunks for days and will float free the next time the trailer enters the water. All it takes is a single sprig to lead to a giant salvinia infestation on a lake where previously there was none.

Mother Nature can help

Left unchecked, giant salvinia can consume big surface areas in short order. The noxious plant is currently causing problems on 18 Texas lakes.


Larry D. Hodge/

Left unchecked, giant salvinia can consume big surface areas in short order. The noxious plant is currently causing problems on 18 Texas lakes.

Texas scientists have learned that Mother Nature may be the plant’s worst enemy.

Findeisen says flooding events combined with high wind will often flush the vegetation out of remote backwaters and into the main lake.

“It doesn’t do well when exposed to wave action,” he said. “The wave action will destroy the mats, beat the plant up, and eventually deposit it on shore where it dies.” Big flood events combined with cold winters the last two years were a blessing for Caddo Lake, a 26,800-acre lake near Karnack that ranks among the state’s top natural wonders.

According to Findeisen, giant salvinia covered nearly 6,000 acres at Caddo in fall 2017. The coverage area had been slashed to 362 acres by March 2019.

Caddo’s ongoing battle with the plant is highlighted in an animated documentary, There’s Something in the Water. Co-produced by Dallas-area restaurateur Shannon Wynne the informative video is circulating in area film festivals. You can view the trailer at www.theressomethinginthewater.com.

Zebra mussels threat

Zebra mussels are small in size but the invasive species can cause big problems on lakes and rivers. TPWD says 15 reservoirs have established reproducing populations.


Texas Parks & Wildlife Department/

Zebra mussels are small in size but the invasive species can cause big problems on lakes and rivers. TPWD says 15 reservoirs have established reproducing populations.

Zebra mussels are another invasive species threatening Texas lakes. Native to Eurasia, the mussels surfaced in the Great Lakes region in the 1980s and were first discovered in Texas in 2009 at Lake Texoma. They have since been found in five Texas river basins and 14 other reservoirs, including Austin, Belton, Bridgeport, Canyon, Dean Gilbert, Eagle Mountain, Georgetown, Lady Bird, Lewisville, Livingston, Randell, Ray Roberts, Stillhouse Hollow and Travis.

TPWD says the mussels can cause harm to aquatic species, create algal blooms and leave beaches and rocks riddled with sharp shells. They also can clog water intakes and damage water treatment facilities, boats and motors.

Boaters are required by law to drain all water from all vessels and onboard receptacles before leaving or approaching a body of fresh water to prevent the transfer of invasive species.

Transporting any invasive species is a violation of the law and punishable by a fine of up to $500 per violation. Anyone who spots an invasive species outside affected areas is urged to report it by calling (409) 698-9121 or (512) 389-4848 or emailing aquaticinvasives@tpwd.texas.gov.

Matt Williams is a freelance writer based in Nacogdoches.

Original Source: https://sportsday.dallasnews.com/other-sports/outdoors/2019/06/22/invasive-plants-threaten-states-lakes

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