# New Article on Texas Invasives



## Tex Guy (Nov 23, 2008)

*Unwanted guests*
In an effort to catalog alien and invasive species whose presence may be causing costly damage, scientists working primarily in the Galveston Bay area are conducting surveys and collecting samples
By SHANNON TOMPKINS
Copyright 2011 Houston Chronicle
June 22, 2011, 9:24PM

Shannon Tompkins Chronicle
A team of scientists retrieves a gill net set in Brays Bayou as part of a coordinated effort to catalog locations and abundance of alien and invasive species in the Galveston Bay area.

To most people, the pretty minnow with the blue fringe coloration on its fins would have been just another little fish among the dozens recently collected from a stream in northwest Houston.
But to someone intimately familiar with the native species of topminnow killifish, gambusia, darters and other small fish inhabiting local waterways, the fish was an enigma.
"It wasn't a species I'd ever seen," Dr. George Guillen, professor of biology at the University of Houston-Clear Lake and executive director of the Environmental Institute of Houston, said of the fish collected by students.

There was a good reason for that. The jewel-like minnow, known as a bluefin killifish, isn't native to Texas; it's endemic only to parts of Florida.

Its discovery in that little stream marked only the second time a bluefin killifish had been documented in Texas. The only other occurrence, in 2008, was in the lower Guadalupe River system, where its introduction was traced to having hitched a hidden ride in a shipment of plants used in a wetland rehabilitation project near Victoria.

With those discoveries, Texas added another species to its long and growing list of alien species and improved the knowledge of its distribution in the state.

*Knowing is half the battle*
It's too early to know if the bluefin killifish will turn from alien to invasive species - a non-native organism that causes ecological or economic damage. It's also too early to know if it will spread or even survive in Texas.

But simply knowing bluefin killifish are out there and where they can be found is hugely important information for scientists trying to understand and monitor the spread and impact of the growing number of alien/invasive species in Texas.

Gathering and compiling such basic knowledge of alien/invasive species is the goal of an intense, weeklong effort wrapping up today and involving approximately 50 scientists scattered across the terrestrial and aquatic landscape around Galveston Bay.

Termed the Texas Rapid Assessment Team - Galveston, the group includes scientists from across the spectrum of disciplines and expertise conducting surveys and collecting samples to document all the alien/invasive species they can find. Their focus is strictly the Galveston Bay area, particularly the watersheds feeding the bay.

"We have cooperators looking at everything from phytoplankton and algae to fish, vegetation, mammals - the whole spectrum," said Leslie Hartman, a Texas Parks and Wildlife Department coastal fisheries scientist and coordinator of the TxRAT project.

More than 30 state and federal agencies, universities and private organizations are helping support the effort with personnel, equipment and funding. The aim is to catalog as many alien/invasive species as possible and include information on their locations and distribution. This information will serve as a "baseline" for future monitoring of alien species and their impacts, Hartman said.
Such information is crucial to effectively managing terrestrial and aquatic resources. Invasive exotic species can and have had severe environmental and economic impacts in Texas. The list of major offenders is depressingly long: feral hogs, nutria, Asian grass carp, tilapia, fire ants, salvinia, water hyacinth, hydrilla, channeled apple snails, saltcedar, Chinese tallow, Macartney rose, buffelgrass and dozens more.

*Expensive report*
Feral hogs alone cause more than $50 million a year in agricultural losses in Texas. Estimates from 2005 placed the United States' annual economic loss tied to invasive species at a staggering $138 billion.

And those numbers don't include the environmental damage - destruction of native terrestrial and aquatic habitat, predation on native species, invasives with no natural enemies out-competing and replacing native species, etc.

The TxRAT effort focused much of its effort on areas that see little or no regular surveying or monitoring - secondary streams, urban areas where alien/invasives are usually introduced, and other environmental nooks and crannies.

"If we can find new invasives early, when they are just getting established, it gives us a chance to address them before they spread," Guillen said Tuesday morning as he and other TxRAT scientists traveled by boat up Brays Bayou in the middle of Houston.

The team included staffers from TPWD's inland and coastal fisheries division, the U.S. Fish and Wildlife Service, the Nature Conservancy and the U.S. Coast Guard.

Using gill nets and fish traps set by coastal fisheries staff and an electrofishing boat operated by inland fisheries scientists, they collected samples of fish in the bayou.

While many of the fish collected were native species - largemouth bass, sunfish, blue catfish, menhaden, spotted gar, striped mullet - the nets and "shock boat" revealed an abundance of non-native species living in the shadow of downtown Houston.

The quick-hit survey on Brays collected four alien species - common carp, Asian grass carp, Rio Grande perch and armored catfish. Previous surveys of the bayou also turned up tilapia.
Two of the aliens collected Tuesday - common carp and Rio Grande perch - are not considered invasive. (Rio Grande perch are native to Texas, although only to the Rio Grande watershed; they have been introduced in central Texas waters and several streams around Houston.)
But the other two - grass carp and armored catfish - are problem species.

Grass carp, vegetarians introduced in an effort to control invasive aquatic plants such as hydrilla, flourished and reproduced in Texas waters. Voracious eaters that can grow to weigh 30 pounds or more, grass carp will strip a waterway of beneficial native plants while leaving harmful invasives such as salvinia and hyacinth.

The armored catfish are South American natives. Commonly called plecostomus, "plecos," "sucker catfish" or "algae eaters" in the aquarium trade, juvenile armored catfish are sold to hobbyists. The small catfish eat the algae growing on aquarium glass.

But little plecos grow into big armored catfish. And when owners tire of the fish or the fish get too large for the tanks, they end up in streams and bayous.

Houston's bayou system swarms with armored catfish, which thrive in the near-tropical water. They face no natural enemies or other population controls and get big, with some growing to more than 2 feet long.

While their impacts on native species remain unclear, armored catfish do have a definite environmental and economic impact.

Like most catfish, they are "cavity nesters." The well-named armored catfish, their heads and bodies encased in a bone-hard exterior, carve "nest" holes in the clay sides of the bayou. When water levels are low, the holes can be seen along the banks of the bayou. In some places, dozens of these cavities pock the bayou.

Those holes weaken the bayou bank, causing sections to slough into the water and otherwise accelerating erosion, costing the public money to maintain the banks for flood control.

*Catching the culprits*
The Brays Bayou collection effort didn't turn up any new alien or exotic species, but the TxRAT project appears to be finding some.

"We've had a couple of plants and two crawfish (species) we haven't been able to identify," Hartman said.

Results of the TxRAT project will be compiled over the coming month, giving scientists a "snap shot" of the alien/invasive species in the Galveston Bay area and their distribution.

That information will prove crucial in attempting to maintain the environmental and economic health of the largest and most economically important bay system on the Texas coast.
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## kimcadmus (Nov 23, 2008)

Thanks for posting bill!


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## BobAlston (Jan 23, 2004)

Interesting article.

Bob


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