Big and small, invasive pests spread trouble along coastal Louisiana

Big and small, invasive pests spread trouble along coastal Louisiana
Updated: Aug. 15, 2017 at 3:54 PM CDT
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(WVUE) - In the Honey Island Swamp, feral hogs gobble up vegetation and prey on tiny critters.

"They eat any kind of little animal that moves in the soil," said Bob Thomas, Ph.D., head of Environmental Communication at Loyola University. "They eat bigger animals that they can run down and grab."

Thomas points out that the hogs bring devastating, long-term impacts to the marsh, swamps and even levees.

"When I go into an area that has been rooted up, you find nothing, no living things at the surface or under the surface," he said.

The hogs are hardly the only invasive species spreading trouble along coastal Louisiana. In the state's bayous and canals, water hyacinth and salvinia plants choke the waterways.

At the Audubon Louisiana Nature Center, Chinese tallow trees have crowded out native species despite aggressive efforts by managers and volunteers to rid the site of the trees.

The state runs an annual bounty program to keep in check the population of nutria, a rodent native to South America.

Big and small, South Louisiana copes with an invasion of species that nature never meant to be here, often something that hitchhiked on a ship or that man intentionally released.

"These things breed like crazy, and all of the sudden they've pushed other things out," Thomas said.

Thomas points out that state law is silent on the question of releasing hogs into the wild. Some refuge managers, he noted, have spent taxpayer dollars ridding public lands of hogs, only to have a neighbor release young hogs on adjacent properties for the purpose of hunting them later.

Hyacinth pose a particularly stubborn problem. Land managers have cleared a canal or bayou of hyacinth only to see them pop back up in the following months or even years, Thomas noted.

"Water clears up and you say, 'Gee, we won that game.'  All of the sudden, they start springing up from seeds," Thomas said.

At the moment, nothing alarms biologists more than the scale insect munching on roseau cane in the marsh. The roseau cane mealy bug has damaged thousands of acres of cane in southern Plaquemines Parish over the last year and has spread to several other parishes, according the Louisiana Department of Wildlife and Fisheries.

The scale, native to China and Japan, has been identified as nipponaclerda biwakoenis. Cattle rancher Earl Armstrong was among the first to spot the insect, which is smaller than a human fingernail.

"Roseau cane is the backbone of this lower delta," said Armstrong, who worries that as tall cane dies, there will be nothing left to hold soil in place.

Scientists now are finding dead cane in some places without evidence of the bug, raising the possibility a combination of factors could be at play.

"We know there's devastation going on," Thomas said, "but we don't quite have a handle on it yet.  We don't know how far this is going to go."

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