Since reaching the northern Atlantic less than 30 years ago, lionfish have quickly become one of the most widespread and voracious invasive species, negatively impacting marine ecosystems — particularly coral reefs — from the northeastern coast of the United States to the Caribbean archipelago, according to foreign media reports. In a new study, an international team of researchers, including the California Academy of Sciences, presented four new records of lionfish off the coast of Brazil, confirming for the first time the invasion of the South Atlantic by this predatory fish.
Their findings, published June 3 in the journal Biological Invasion, discuss how lionfish may have arrived in the region and hold important insights into how diving and fishing communities in Brazil can help manage that invasion before they can damage local ecosystems.
"For a while it was uncertain whether the lionfish would extend into the South Atlantic," said Luiz Rocha, director of the College of Ichthyology and co-author of the study. "Now that we know they're here, it's imperative that we discover how they arrived and work with the local community to control their numbers." If left unchecked, lionfish could have a huge impact on native species, especially those that are only present in coral reefs around islands in The Brazilian Ocean."
With its maroon stripes and more than a dozen stingers, the lionfish has long been a staple of the aquarium trade for enthusiasts. However, like other popular aquarium fish, they are sometimes irresponsibly released into the wild. In fact, this is likely how the invasion of lionfish in the Atlantic Ocean began.
Once the lionfish enter new waters, they quickly destroy the local ecosystem and spread to other places. Due to the lionfish's wide range of feeding habits, lack of natural predators, unique hunting methods, and the fact that buoyancy eggs that reproduce throughout the year can travel long distances with ocean currents, lionfish are expanding faster than any other invasive marine species.
Despite these features, lionfish have been conspicuously absent in the South Atlantic — a phenomenon that researchers attribute to northward-moving currents at the ocean boundary between Brazil and Caribbean waters. But in 2015, a local diver photographed a lionfish swimming off the southern coast of Brazil and alerted researchers that 11 months later, the researchers discovered and collected the specimen, confirming that the species had expanded to Brazil.
After the initial discovery, the researchers — with the help of local fishermen and divers — were able to track three other lionfish in Brazilian waters: two from deep-sea reefs known as mesomorphic reefs and one from around the island of Fernando di Noronha, about 200 miles off the country's northeast coast.
While all the events are troubling, the researchers say the record of Fernando-di-Noronha is particularly worrying. "The arrival of lionfish to The marine islands of Brazil is particularly worrisome," said Clara Buck, a marine biologist and study co-author. "These unique ecosystems are home to a large number of endemic species that are not found elsewhere on Earth, making them more sensitive to adverse effects."
In order to contain an invasion before it accelerates, it is crucial to know how the lionfish arrived in the area in the first place. In their study, the researchers suggested that lionfish found in Mesozoic reefs may have arrived as stepping stones, using deeper reefs beneath the Amazon plumes to slowly advance southward from the Caribbean Sea.
In contrast, they believe that the individuals found on the island of Fernando de Noronha arrived in a more conventional way, traveling as juveniles along the current between the archipelago and the Caribbean Sea. Because the archipelago is far from the mainland, lionfish larvae can subvert ocean boundaries close to the coastline.
Finally, while the lionfish off the southern coast is too far from the Caribbean sea to get there by dispersal or Mesozoic reef jumping, the researchers were able to confirm through DNA analysis that it came from a Caribbean population, suggesting that it may have moved out of the Caribbean and introduced into Brazilian waters through aquarium trade.
Regardless of how they arrived, now that the lionfish are already there, the researchers urge the Brazilian government and local communities to stop the invasion. While efforts elsewhere in the Atlantic suggest that the complete elimination of lionfish is unlikely, the researchers say keeping populations low could buy local species valuable time to adapt to this voracious fish and ultimately avoid predation.
From stabbing lionfish they encounter with harpoons to alerting researchers to emerging populations, local fishermen and divers will play a key role in managing the local species that invade and protect coral reefs and sustain their livelihoods.
Despite the challenges they face, Rocha is optimistic that they will be able to succeed. "Brazil, and especially Fernando de Noronha, has a strong local diving and fishing community," he said. If we put the right tools in their hands, it is absolutely possible to control the intrusion. ”