Low Water and Drought - Caddo Lake Article

http://twri.tamu.edu/publications/drought/2011/october/on-caddo-lake-giant-salvinia-infestations-decline

Sen. Hutchison Praises Caddo Lake Giant Salvinia Work

Last week we had the privilege of U.S. Sen. Kay Bailey Hutchison visiting Caddo Lake and touring the Center for Invasive Species Eradication’s salvinia weevil-rearing facility located at the wildlife refuge.

Following the tour, Hutchison spoke to a group gathered at the Caddo Lake National Wildlife Refuge about the threat that invasive species such as the giant salvinia pose to the refuge and to Texas lakes.

“While Caddo Lake is home to hundreds of animal, fish and plant species, invasive species threaten this magnificent resource,” said Hutchison. “We are proud to work with the Caddo Lake Institute and Texas A&M University on creating a center of excellence focused on eradicating invasive species.”

You can read the full AgriLife TODAY story for more information. Visit our Facebook page for more photos of the day's events.

Sen. Hutchison also applauded the Caddo Lake Giant Salvinia Eradication Project in her weekly column in the Mineola Monitor, noting that "this promising research will help restore Caddo's habitats and protect this unique natural treasure." Read the full Mineola Monitor article for more information.

Recap of Congressional Hearing on Giant Salvinia

Back in June, we attended a Congressional hearing in Shreveport on giant salvinia.

Experts at the hearing testified that there is no silver bullet for giant salvinia. They also stressed that research collaboration in combination with various management methods and education is essential to fighting the plant.

Testimony by federal agencies, Texas and Louisiana state agencies, universities and non-governmental organizations on efforts to control and eradicate giant salvinia were heard during the field hearing of the U.S. House of Representatives Subcommittee on Fisheries, Wildlife, Oceans, and Insular Affairs on June 27 at Louisiana State University–Shreveport.

Subcommittee Chairman Rep. John Fleming from Louisiana and Rep. Louie Gohmert from Texas attended the hearing. Staff from the Texas AgriLife Extension Service and the Texas Water Resources Institute (TWRI) attended the hearing.

“We are losing ground on something we don’t have an answer for,” said Robert Barham, secretary of the Louisiana Department of Wildlife and Fisheries. Louisiana has seen its state-wide infestation of giant salvinia grow from approximately 13,000 acres to more than 25,000 acres in two years.

Richard Lowerre, Caddo Lake Institute president, highlighted our work on rearing the salvinia weevils for release into the lake and educating the public, with collaborators Texas AgriLife Research, Texas AgriLife Extension, and the Texas Parks and Wildlife Department.

Dr. Michael J. Grodowitz, U.S. Army Corps of Engineers research entomologist, said the biological control of giant salvinia with salvinia weevils is “highly promising” but said managing the plant through biological control is a long-term process. Grodowitz said besides looking at ways to control the plant, research needs to be done on what underlying factors in a particular waterbody allow the plants to grow and out-compete native plant species.

Other witnesses were Louisiana State Rep. Henry Burns; Ross Melinchuck, Texas Parks and Wildlife Department deputy director; Michael Massimi, Barataria-Terrebonne National Estuary Program invasive species coordinator; Ken Ward, Caddo Parish Department of Public Works project manager; Dr. Randy Westbrooks, U.S. Geological Survey National Wetlands Research Center invasive species prevention specialist; Dr. Dearl Sanders, Louisiana State University Idlewild Research Station resident coordinator; Jeffrey Trandahl, National Fish and Wildlife Foundation executive director; and Dr. Damon Waitt, University of Texas Lady Bird Johnson Wildflower Center senior director.

Read the Natural Resources Committee news release. Listen to the hearing.

Giant Salvinia Article - Houston Chronicle

Interesting article from the Houston Chronicle regarding the issue of the invasive plant, Giant Salvinia.

http://www.chron.com/disp/story.mpl/outdoors/tompkins/7602063.html

Large-Scale Weevil Releases Begin

Over the past month, we've begun releasing the weevil infested material from our tanks onto the largest giant salvinia patches we can find on the lake. We have released large numbers of weevils at three locations and will be monitoring it consistently as summer progresses. We will be releasing at a fourth site in the near future which will complete the number of initial release sites required for the research protocol. Additional large-scale releases will be made as the weevils re-expand their numbers in the tanks and the giant salvinia begins to rapidly expand with the progressing summer heat.

To date, we've released a little over 70,000 weevils in the three locations (and an additional estimated 217,000 weevil larvae that would be within the released plant material). These weevils came from only two tanks in which we removed approximately 80% of the material of each tank. The two tanks had a spring weevil population "explosion" in which the adult weevil population density increased from 8 adults per pound to an estimated 85 weevils per pound! Consequently (and not surprisingly), the salvinia in the weevil tanks quickly began to crash due to this high number of weevils. As a result, every time we're on the water, we bring in fresh giant salvinia off the lake to keep our remaining weevils happy, well-fed, and reproducing. Hopefully, we'll be seeing some progress from the released weevils and will be able to report all findings.

Thanks to Bryan Higdon and Adam Fisher who volunteered their time to help with the weevil releases. Our next large-scale release will likely require more volunteers so we'll be putting the call out at some point later this summer.

Recent Media Regarding Invasives and Caddo Lake Efforts

LINKS TO THREE MEDIA STORIES:

http://www.thecherokeean.com/news/2011-04-20/Outdoors/Texas_Giant_Salvinia_Effort_Reaches_Boaters_Raises.html

http://outdoornews.com/state_news/article_97ed963e-6b6c-11e0-bfe4-001cc4c002e0.html

http://lubbockonline.com/texas/2011-05-01/henleys-work-paying-caddo-lake

Hurry Up...and Wait. Salvinia Still Recovering

In late March of 2011, we released approximately 1,500-2,000 weevils into a small area (less than an acre) of semi-green giant salvinia that persisted through the cold winter. We are closely monitoring this release site in hopes of collecting valuable data regarding early season weevil reproduction, weevil feeding activity, as well as environmental variables that may affect overall weevil success.

As of early May, there appears to be few, if any mats of giant salvinia that appear large and green enough for a large scale weevil release (however, the water hyacinth seems to be recovering rapidly). We know this situation will change quickly as we progress into May and early-June; as summer approaches, it's quite possible we'll have many covered areas that will be ideal for weevil releases.






Based upon the preliminary results of our ongoing "weevil egg-laying and larvae cage study", it's clear that lake temperatures are within range for weevil reproduction. This is critical because the larvae (pictured on the right), not the adults, are the most effective in controlling giant salvinia. These 1-2 mm larvae tunnel through the plant rhizome (rhizome is basically the stem connecting the leaves of the plant) causing massive damage to the plant. By dissecting the plants in our cage study, we are finding lots of these larvae doing their work. In fact, the giant salvinia in our weevil tanks are starting to show this larvae-induced damage (shown in the yellow/brown coloration in the bottom picture). Thus, the sooner we can get these bugs out and reproducing, the better.

We are hoping to do our first large scale release in the next 2-3 weeks. Of course, this is anticipating that we have some spots with adequate giant salvinia on the lake. If you are interested in assisting with this and other weevil releases, please email paireland@ag.tamu.edu to receive more information. As giant salvinia growth increases and CISE efforts ramp up, look for more updates on the blog and facebook page.