Fish Animal

Intensifying hurricanes species spread across the U.S.

When Hurricane Isaias slammed into the Caribbean and eastern U.S. this summer, rising water levels allowed at least 114 non-native aquatic species to ride from one watershed to the next, according to the United States Geological Survey’s Nonindigenous Aquatic Species team.

Since apple snails were already established in many coastal freshwater ecosystems throughout the southeastern U.S., it’s likely that the recent active hurricane season has pushed them farther inland. Not only have hurricanes and tropical storms formed far earlier this year than usual, 10 have made landfall on the mainland U.S., smashing a record set in 1916.

Storm superspreaders

Because most non-native species first arrive via the aquarium and pet trades, “there’s always the possibility, with a major flooding event, that you’re going to release things in captivity that we never anticipated,” says Daniel. For instance, some scientists have speculated that 1992’s Hurricane Andrew damaged a breeding facility in South Florida, releasing dozens of the 10-foot-long reptiles into the wild. Whether the story is true or not, the USGS noted that the invasive species proliferated in the area after that natural disaster.

Invasion of the water bodies

Such accidental introductions can have far-reaching effects, says director of the Minnesota Aquatic Invasive Species Research Center at the University of Minnesota. They’ll restructure food webs once they get in there,” Phelps says, “or they’ll create new types of habitat when they start growing and outcompete native species. A prime example is the zebra mussel, a tiny mollusk originally from the Caspian Sea. Believed to have entered the U.S. via ballast water from ships in the 1980s, it has since infested U.S. lakes and waterways, causing every year.

The zebra mussels not only edge out native mussels, they attach masse to any human-made structure, disrupting municipal systems for drinking water and irrigation. Zebra mussels have traveled down the Mississippi and are now creeping into the mid-Atlantic region as well; they’ve been reported in Maryland, Virginia, and North Carolina. Sightings in these areas after recent hurricanes, including Isaias, suggest that the storms are abetting the species’ expansions, says Daniel. It takes only a few individuals to start a whole new population, he adds.