Texas Parks and Wildlife Department officials report that cold weather and flooding have decreased the amount of giant salvinia in East Texas lakes.

Lake Athens and Lake Palestine were among 22 lakes showing salvinia last year. Others included Caddo Lake, Toledo Bend Reservoir, Sam Rayburn Reservoir, Lake Texana, B.A. Steinhagen Lake, Lake Murvaul, Timpson Reservoir, Lake Naconiche, Lake Fork, Lake Nacogdoches, and Martin Creek Reservoir.

Giant salvinia is a floating fern from southern Brazil that has become one of the most problematic aquatic plants in Texas. Infestations can double in about a week under the right circumstances. It blocks out sunlight and decreases oxygen concentrations to the detriment of fish and other aquatic animals. When plant masses die, decomposition lowers dissolved oxygen further.

“We can thank Mother Nature for the cold snap and subsequent flooding that caused a massive decrease in giant salvinia on Caddo Lake and at our other infested East Texas lakes,” said John Findeisen, Brookeland Aquatic Habitat Enhancement Team lead, in a press release. “A hard freeze in January 2018 made a huge dent in the giant salvinia, freezing much of the plant material and loosening the dense mats. This was followed by high water inflows a month later, pushing the remaining giant salvinia to the open lake where it was destroyed by wind and waves and washed up on shore.”

Findeisen said the outlook for the 2019 treatment season looks good with much of the giant salvinia flushed out from the recent flooding. For the remaining giant salvinia in East Texas reservoirs, Findeisen said herbicide applications will do the majority of the heavy lifting to keep it under control.

Lake Athens was declared essentially free of giant Salvinia last September after it had been discovered there in February. TPWD officials are continuing to spray and monitor the lake to prevent its return.

Last February, giant salvinia was found in less than one acre at Lake Athens. The TPWD Brookeland team surveyed the impacted area and deployed a containment boom from just west of the boat ramp across the cove to the AMWA office to prevent the salvinia from leaving the containment areas.

Since September 2017, TPWD and its contractors have treated 18,390 acres of giant salvinia statewide.

“Natural events that help reduce the amount of giant salvinia in lakes and flush it out are great, but there is still a need for herbicide treatments to maintain control of the remaining giant salvinia,” Findeisen said. “Additionally, we are (using) giant salvinia weevils in areas where flooded timber is too thick to navigate a spray boat or areas where the giant salvinia is mixed with beneficial vegetation that we want to preserve.”

Boaters recreating on one of the lakes infested with giant salvinia should be particularly vigilant about taking these actions.

“We need boaters to take the necessary steps to keep it from moving into new lakes,” Findeisen said. “I am hopeful we are going to see less of it spreading this year because we are seeing an increase in piles of giant salvinia around boat ramps, which suggests people are doing their part to help protect our lakes by cleaning their boats and equipment.”

In Texas, moving prohibited invasive species is punishable by a fine of up to $500 per violation. Boaters are required to drain all water from their boats and onboard receptacles before leaving or approaching a body of fresh water to prevent the transfer of aquatic invasive species like giant salvinia. Other species of concern in Texas include zebra mussels, crested floating heart, water hyacinth, yellow floating heart, hydrilla and American lotus.

Because early detection is an important part of reducing or eliminating the presence of giant salvinia, TPWD encourages boaters to report new sightings to 409-384-9965, aquaticinvasives@tpwd.texas.gov, or via the online report form.

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