By book-ending hurricane and tropical storm landfalls with research trips to the Louisiana coast, entomology associate professor Linda Hooper-Bui and her research team have made groundbreaking discoveries in the world of ants.
Because the status of ant populations can serve as an environmental health indicator for the area as a whole, Bui has been able to see just how devastating both natural disasters and the Deepwater Horizon oil spill have been to Louisiana’s ecosystem.
Before and after Hurricane Isaac, Bui and her team traveled to the wetlands of Breton Sound, just south of St. Bernard Parish and east of what’s left of the Mississippi River that far south.
What they found meant two things: Isaac was more devastating than most people originally thought, and it could take several months before the ecosystem can fully recover from the destruction wrought by the slow-moving system and its massive storm surge.
The ants are missing, Bui said, which doesn’t bode well for other wetland inhabitants.
“The plants are really unhappy after Isaac,” she said.
The storm surge, which grew as high as 11 feet in some areas, dragged in oil from the BP oil spill in April 2010.
“It looked like someone had poured barrels of motor oil all over the place,” said Bui, who discovered the free oil, which differs from tarballs previously found in areas supposedly clean of the ecosystem-strangling substance in Barataria Bay, west of the Mississippi River.
If oil left behind any surviving ants, storm surge flooding killed off most of the remaining ant populations in areas where flooding lingered because of Isaac’s lethargic pace. The Category 1 hurricane dumped rain over the wetlands for nearly 60 hours, submerging the insects for two-and-a-half days, Bui said.
Although Isaac devastated the ants, research done before and after Tropical Storm Lee’s landfall in September 2011 found more optimistic results for the usually pesky pests.
“We’re looking at the tipping point,” Bui said, referring to the level of storm surge needed to accomplish devastating damage to the ecosystems and the ants in particular.
Following Hurricane Katrina, Bui’s team, including current entomology master’s student Max Adams, dispelled a long-lived myth about ants during flooding.
When throngs of patients turned up at the PMAC covered with rashes, which turned out to be layers upon layers of fire ant stings, Bui’s team set out for New Orleans in search of the predators.
But three to four days after the storm, all the ants were gone.
It was long understood that ants would raft upon one another, floating atop floodwaters until they could reach dry land.
How they accomplished this feat, and for how long, was completely misunderstood for more than a century.
After extensive lab research, Bui, Adams and others found that submerged ants would collect bubbles underwater and ride them to the surface. More importantly, it was atop the larvae on which the rafts floated, essentially sacrificing the baby ants for the good of the colony.
Previously, entomologists thought the worker ants themselves floated on the water’s surface, while they kept the larvae safely protected inside the ball of ants.
“The difference between people and ants is we send our young guys for war — they send their old ladies,” Adams said, referring to the practice of floating on the bubbled-up larvae and either tossing the men overboard or eating them when food gets scarce on the bubble-boat.
In the lab, rafts could survive in fresh water up to two weeks at the most, Adams said, although that could increase a week or so in a natural environment under ideal circumstances.
Bui said oil will be around for years to come, and with every tropical system that blows through, it will likely rise to the surface, reminding Louisianians of the tragedy that continues to punish their beloved marshes.
Senior Contributing Writer