Texas A&M University at Galveston professors warn that droughts like the record-breaking 2011 drought continue to affect the ecosystem and economy of the Texas coast. They are looking at weather impacts on marine life and marshlands related to severe weather events.
World-renowned biologist and Texas A&M marine biology Professor Sammy Ray is monitoring drought and flooding impacts on oysters and other marine life.
Anna Armitage, an associate professor of marine biology and habitat restoration expert, is evaluating extreme drought effects on Texas coastal systems.
Pearls of wisdom
Ray, who is a shellfish pathologist, has studied oysters for more than 60 years. A pioneer in preserving and protecting oysters and their habitat, he says healthy oysters are beneficial to the environment and the economy. Oysters serve as natural filtration systems cleaning the water and ensuring the health and productivity of estuaries. They are a $30 million industry in Texas.
That industry was diminished during Hurricane Ike in 2008, and is now being challenged by an ongoing statewide drought that started in 2011. Oyster lease closings due to weather not only impact the oyster industry, but also trickle down to restaurants, grocery stores and related businesses.
“Healthy oysters need a balance of saltwater and freshwater to survive and reproduce,” Ray said. “Too much freshwater kills off oysters by the bushel and too much saltwater spawns diseases. A healthy salt balance in water is about two percent.
Rain in Central and North Texas fills streams and rivers in normal years, causing fresh water to flow down to the Gulf. There it mixes with saltwater in bays and estuaries and it sets up an environment allowing oysters to thrive and reproduce.
“In 2011, the drought caused Texas coastal water to be so salty that predators and diseases thrived,” Ray said. “At that time, oysters were vulnerable to the deadly “dermo” parasite and toxic “red tide” algae that was spawned by the warm, salty water.
“The recovery of oyster reefs in Texas, which began in the latter part of 2010, could require a significant flooding in oyster-producing bays,” he said.
But, Ray also adds that floods would cause a tradeoff. He cites an example. “Two, 10-inch rainfall events in the San Antonio area, at the end of May 2013, caused flooding in the San Antonio River that dispersed into coastal marshes,” he said. “It had the potential to kill oyster predators and diseases, but it could also cause oyster mortality. We are still testing and monitoring the flood outcome.”
Ray says beyond some benefits to oysters, reduced salinity from the San Antonio flood may be beneficial in developing blue crabs and wolf berries, the primary food for endangered whooping cranes in their wintering grounds at the Aransas National Wildlife Refuge near Austwell, Texas.
Noting that the exchange of fresh and saltwater along the coast is a natural cycle, Ray said beyond the effects of weather, the natural cycle has likely been disrupted by human activities as well.
“Increased salinity was likely exacerbated by building of dams and reservoirs on all major rivers to provide high levels of freshwater for residential, industrial, and agricultural purposes,” he said. For future generations, we should be wise in helping maintain the balance of nature.”
While Ray monitors the effects of floods and droughts on oysters, Armitage studies the impacts of droughts on brackish marshes that include both fresh and saltwater.
What she finds in a marsh restoration project in the Lower Neches Wildlife Management Area near Port Arthur, Texas may provide solutions for similar drought-ravaged marshes all along the thirsty Texas coast.
Armitage along with marine biologist Antonietta Quigg and marine biology post-doctoral research associate Erin Kinney are in the fifth year of a seven-year, $1.3 million study. The project is primarily funded by the Texas General Land Office: Oil Spill Prevention and Response Program and the Coastal Management Program.
Armitage, who is the project’s principal investigator, says the team developed a timeline describing pre- and post-drought recovery in the Neches marsh.
“Data shows salinity levels in the Neches during the 2011 drought were three times higher than normal,” Armitage said.
“This high salinity level dramatically shifted plants and animals throughout the entire marsh. Fish, shrimp, and submerged aquatic vegetation declined during the drought likely due to increased salinity.”
Armitage says this decline directly impacts coastal economies by affecting recreational fishing, hunting and bird watching.
“These findings illustrate the ecological and economic importance of freshwater in coastal marshes, and highlights the need for active resource management,” she said.
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