Since September, Buford Lessley, a UTRGV multidisciplinary sciences graduate student, has monitored the restoration of
three resacas in Brownsville and developed an index that will show the health of the ecosystem.
“We’re looking at the restored and unrestored resacas in Brownsville,” Lessley said. “We’re working in conjunction
with [the Brownsville Public Utilities Board]. … We’re looking at various structural and functional indicators that will be used to create a multimetric index for the resaca ecosystem health.”
Lessley’s research received Best Graduate Student Presentation honors at a conference of the Society for Ecological Restoration-Texas Chapter, held Nov. 13-15 at Trinity University in San Antonio.
In his Powerpoint presentation, Lessley discussed what resacas were and how it was a localized term as well as
what he was monitoring and the index he created. A resaca is a combination of former distributaries of the Rio Grande
and oxbow lakes.
“The index will include all of the data we’re gathering, such as the decomposition rates,” Lessley said. “Our fish community index, our riparian index and several other indexes.
… We’re going to merge those together, add weights to them
… to show what’s important for resaca health. That way,[BPUB], private citizens,interest groups that are interested in the restoration of the resacas can use those indexes. They can go out and gather baseline data and they can take that data, look at what we’ve created, plug their numbers into it and it gives them an overall health of the resaca.”
He has been collecting data on fish and water quality since August 2014, before the start of the monitoring process.
“Our data is limited,” Lessley said about the difference between the restored and unrestored resacas. “December will be the fourth month that we pull data. Right now, we do see somewhat of a difference in depth, obviously, because [BPUB]
is doing a dredging project. We see a difference in the relationship between depth and water clarity.”
The [BPUB] Resaca Restoration Project began March 22, 2013, at Cemetery Resaca, located along the Old City Cemetery in Brownsville.
“The Resaca Restoration Project is a very big undertaking,” said Ryan Greenfeld, BPUB senior communications and public relations coordinator. He said specialized boats called dredgers act “like a vacuum to suction out debris, sediment,
trash, things of that nature.”
The dredger has cutters used to help break up the debris and sediment. The dredger then pumps material, sending it
through floating pipes until it winds up at the dewatering system.
After material has been sent through the pipes, the dewatering system separates large trash and debris as well as sand from the water. Specially designed sediment removal equipment is being used to separate the dredged sediment particles from the slurry in order to produce dry sediment material and a clear, clean effluent that can be discharged back into the resacas,Greenfeld said.
In his research, Lessley monitors decomposition rates, chlorophyll concentrations, basic water quality and fish sampling from two pools of each resaca. The resacas in Lessley’s research are the Fort Brown, De La Palma and Town systems.
Lessley said he expects to graduate in December 2016 and plans to get a job for a state agency, such as Texas Parks and
Alejandro Fierro, UTRGV multidisciplinary sciences assistant professor, also attended the conference in San Antonio and is the adviser for students in the program.
He said the important part of Lessley’s research was presenting a monitoring and assessment project, not a restoration
“In the large majority in the restoration efforts worldwide … not just aquatic systems and resacas but also terrestrial systems like grasslands, deserts, tropical forests, any kind of ecosystems … lack completely the monitoring and assessment part,” Fierro said. “There’s a lot of money invested worldwide to restore this or that but there is little information in terms of data to say, ‘OK, this is going well, it’s progressing as expected or it’s a waste of money and a waste of time and waste of energy.’ … It’s important to be able to assess if the system is actually recovering or not.”