Get Ready for a Superstorm of Creepy Critters: Invasive Species Are Hitching Rides on Extreme Weather
As climate change increases the intensity and frequency of hurricanes, there’s a new danger lurking below the waves. Not only do superstorms wreak havoc on land and destroy coral reefs—scientists now say they could be spreading invasive species such as lionfish far and wide.
In a study published in the journal Global Change Biology, scientists at Fort Lauderdale, Florida–based Nova Southern University found that hurricanes can change the direction of ocean currents, which can carry invasive species to new territory.
Lionfish are a spiny, venomous, and voracious fish now entrenched along the southern Atlantic Coast of the United States. Their native waters are thousands of miles away, in the tropical South Pacific. Many believe the species was introduced to South Florida in 1992 when Hurricane Andrew slammed the coast, smashing a large aquarium that housed lionfish adjacent to Biscayne Bay. It’s more likely, though, that the species was already colonizing Florida as far back as 1985, when the first report of a lionfish being caught was documented just north of Miami.
The real catalyst for the invasion was people. Aquarium owners wanting to get rid of their tropical fish—but not wanting to flush them down the toilet—most likely released them into the ocean. In their new and unnatural surroundings, the lionfish have flourished, taking over reefs along the southern Atlantic Coast and eating everything in sight.
Since their arrival in Florida, ocean currents have pushed the species’ eggs up the Eastern Seaboard, with juvenile lionfish showing up as far north as Rhode Island. But by winter, the cooler water temperatures usually kill off the warm water-loving lionfish that get caught too far up the coast.
By nature, lionfish are not a migratory species. They hunker down on whatever reef they’re near and herd smaller fish into coral crevices for easy meals. So the natural ocean currents and the lionfish’s tendency to stay put should have kept the species contained. But ask any diver from Bermuda to Belize, and they’ll tell you all about lionfish.
That’s where hurricanes come in—specifically Category 3 or stronger storms, researchers noted. By sheer force, those storms shift the North Atlantic Current from its normal Gulf Stream–to-the-Northeast route to a strong eastern flow. When that happens, the eggs of lionfish that typically spread north head out toward the Caribbean.
The National Oceanic and Atmospheric Administration has deemed lionfish an “established” exotic species in the southeast U.S., the Caribbean, and the Gulf of Mexico. Its impacts on native species, coral reefs, and more are just beginning to be studied, but it looks like whatever they are, we’re stuck with the lionfish. Researchers believe their numbers will only grow, and trying to eliminate the species using “conventional methods” such as lionfish fishing derbies won’t work.
“Marine invaders are nearly impossible to eradicate once established,” said Matthew Johnston, a research scientist at Nova Southern University and coauthor of the study.
There’s more bad news.
“There are at least 30 exotic marine species documented from South Florida marine waters, most probably sourced from the aquarium industry,” Johnston said. “If any one of these exotic species begins breeding in our waters, hurricanes may be a common transport mechanism for them from South Florida to the Bahamas.”
One species in particular has caught scientists’ eye: the Asian tiger shrimp. Native to Indo-Pacific, Asian, and Australian waters, the species started showing up in the Gulf of Mexico in 2011. Researchers are studying what impacts Asian tiger shrimp are having on the native animals—including whether they carry disease, prey on other shrimp, or compete for similar food sources.
So far, they’ve been reported along the coast from North Carolina to Texas, but they haven’t infiltrated the Caribbean.
“These large, carnivorous shrimp are being found in increasing numbers, and they may benefit from hurricane-altered water flow,” Johnston said.
And climate change is increasing the intensity and frequency of hurricanes. And as ocean temperatures rise, lionfish will find more areas to colonize.
“Lionfish are currently limited to waters off of Cape Hatteras, North Carolina, as winter water temperatures drop below their thermal tolerance,” Johnston said. “Should ocean temperatures rise a few degrees, this could extend the range of lionfish farther north.”
What can we do? Develop a taste for lionfish, for starters. If we start eating the fish the same way we gobble down tuna or salmon, that could at least put a dent in an unwanted species that could be here to stay.