The devastating toll Hurricane Helene inflicted on Georgia this fall will be felt for years in hard hit parts of the state. The storm caused an estimated $5.5 billion in damage to the state’s agriculture and forestry sectors, plus billions more in property losses — and claimed at least 33 lives.
But death and destruction may not be all Helene left behind: New federal projections show the storm might have helped spread invasive species, too.
An analysis released this week by the U.S. Geological Survey shows Hurricane Helene may have allowed as many as 222 nonnative and invasive species to infiltrate farther into parts of Florida, Georgia, the Carolinas and even deep into the Appalachian Mountains. Of those, 90 are considered invasive, meaning their potential introduction to new territory could threaten human health, the environment and the economy.
Hurricane Milton, which slammed Florida as a Category 3 storm about two weeks after Helene, may have dispersed unwanted critters of its own. The USGS’ early projections show the storm could have spread roughly 114 species, including 56 invasives. Most of Milton’s spread likely occurred on the Florida Peninsula, but rain from the storm that stretched into southeast Georgia could have allowed unwanted plants and creatures to expand their range there, too.
Credit: Paul Shafland, Florida Fish and Wildlife Conservation
Credit: Paul Shafland, Florida Fish and Wildlife Conservation
The agency did not analyze the effects of Hurricane Debby, which brought heavy flooding to Georgia and the Carolinas in August, though over a much smaller area.
USGS started conducting these surveys after major storms following Hurricane Harvey, which triggered historic flooding in the Houston area in 2017. The researchers rely on a mix of stream and river gauge readings, topographical data and information on the known presence of species to make their projections.
Hurricane Helene made landfall in late September in Florida’s Big Bend Region as a Category 4 hurricane with sustained winds of 140 miles per hour, ranking as one of the strongest storms on record to hit the U.S. Helene’s powerful winds mangled structures, crops and timber stocks across Georgia, but the inland flooding it unleashed — especially in the Carolinas and Tennessee — was to blame for the most severe damage.
Those same floodwaters may have provided avenues for invasives to spread, particularly aquatic species, said Ian Pfingsten, a USGS botanist who contributed to the analyses for Helene and Milton. An estimated 100 species had the potential to spread in Georgia via flooding or swollen waterways caused by the storms, Pfingsten said.
“We’re dealing with species that can not only float and disperse, like plants and mollusks, but also a lot of fish that will actively swim through the floodwaters,” he said.
Among the most concerning species that may have capitalized on the temporary travel corridors in Georgia are the Asian swamp eel, the giant applesnail and the cane toad.
Asian swamp eels, Monopterus albus, are native to India, Myanmar, China and other pockets of Asia but were introduced into ponds around the Chattahoochee Nature Center in Roswell in the mid-1990s, likely after being dumped from a home aquarium. The species has since proliferated in the Chattahoochee River Basin, particularly around Atlanta.
Atlanta saw record rainfall and major flooding during Helene, especially along tributaries of the Chattahoochee, and USGS experts said the high water could have given the eels an opportunity to venture downstream. Asian swamp eels are known to harbor dangerous parasites that can harm humans and other animals.
Credit: C.R. Morningstar, USGS
Credit: C.R. Morningstar, USGS
Giant applesnails, Pomacea maculata, might have also benefited from the storms. Native to the Amazon River basin and other parts of South America, the giant snails are already found in many Georgia waterways, including the Upper Chattahoochee River, the Lower Flint River and many more across South Georgia.
The snails are typically tan-brown or yellow and black with striped patterns, but are best distinguished by the wide opening to their shell. Applesnails are a known agricultural pest and, like eels, carry dangerous nematodes capable of causing serious illness in humans.
Then there’s the cane toad, Rhinella marina, an enormous, wart-covered amphibian native to South America.
The toads, which can weigh as much as 3 pounds, are already established in Florida and pockets of the Gulf Coast. Cane toads pack glands containing a toxic secretion that can poison dogs, cats and even people who come into contact with it.
Credit: Ian Hitchcock
Credit: Ian Hitchcock
Georgia wildlife officials say there have been sporadic cane toad sightings in the state before, but no breeding populations have been confirmed. USGS experts said there are no indications for now the hurricanes brought more of the pests to Georgia, but it could have been possible for tadpoles to hitch a ride in floodwaters.
Georgia already has its share of destructive invasive species.
Just weeks ago, state agriculture officials confirmed the spotted lanternfly, an invasive fly known for its stinky and destructive secretions, has been found in the state, but its arrival is likely unrelated to the hurricanes.
Still, Georgia officials said they are keeping their eyes open — and have asked the public to do the same.
A spokesperson for the Georgia Department of Agriculture said the agency has not seen an uptick in invasives after past storms but encouraged Georgians to remain vigilant if they see unusual plants, insects or animals. The public can report potential sightings by emailing pestid@agr.georgia.gov, but the agency said it’s “vital” that photos or specimens themselves are captured, if it’s safe to do so.
The Georgia Department of Natural Resources said it is aware that storms can help spread invasive species, but so far, staff contacted had not confirmed any new cases linked to hurricane season.
