DNA links specimen to fish population that has spread through Caribbean.
Lionfish have overwhelmed ecosystems in the Gulf of Mexico and the Caribbean over the past three decades, eating or out-competing native species in what has been called the worst marine invasion ever. Now the fish seem to have extended their range to South America.
Researchers reported the first confirmed lionfish in Brazilian waters on 22 April in PLoS ONE1. The piscine pioneer was spotted by a group of recreational divers on 10 May 2014 in a reef off Cabo Frio, a municipality of Rio de Janeiro in southeastern Brazil. The divers returned to the site the next day with hand spears, and captured the fish so that scientists could study it.
When the researchers analysed the fish’s DNA, they found that it matched the genetic signature of the Caribbean lionfish population, and not that of specimens from their native Indo-Pacific region. This suggests that the fish may have reached Brazil through natural larval dispersal from the Caribbean, the study’s authors say.
But Mark Hixon, a marine ecologist at the University of Hawaii at Manoa, says that ocean currents typically flow in the wrong direction for larval dispersal from the Caribbean to the southeastern Brazilian coast. He says that it is just as likely that the lionfish was brought to Brazil by humans. “Lionfish are easy to capture and make beautiful pets,” says Hixon. “It’s easy to imagine boaters carrying lionfish as short-term pets in bait tanks or other containers on their vessels.”
However the lionfish got to Brazil, its arrival isn’t surprising, says James Morris, a marine ecologist with the US National Oceanic and Atmospheric Administration in Beaufort, North Carolina. He has been predicting since 2009 that the fish would eventually spread as far south as northern Argentina. But Morris says that it is not clear whether the first reported lionfish in Brazil is a “lone ranger” that might not be joined by other fish for years, or whether it heralds an imminent rapid increase in lionfish numbers. “It's going to have to be one of those wait-and-see sort of situations,” he says.
Once lionfish establish a population in a new area, predictable changes to local reef communities follow, Morris says. Lionfish are voracious predators, indiscriminately eating anything small enough to fit in their mouths — such as native fish and crustaceans — in large quantities. The lionfish’s gluttony affects the reef structure, causing changes ranging from the types of species found to their distribution.
Scientists are concerned that Brazilian waters are especially vulnerable to lionfish, given the low number of native species and the fact that many have very small ranges — in some cases, living only in a particular island cluster. (By contrast, many of the Caribbean’s native species have relatively large ranges, spanning Florida to Venezuela.)
“The oceanic islands [in Brazil] are probably going to be the more vulnerable places,” says Luiz Rocha, a marine biologist at the California Academy of Sciences in San Francisco, and one of the study’s authors. “If the lionfish does get there, the danger of driving [native species] to extinction is real.”
But Rocha says that Brazil has an opportunity to get ahead of the fearsome fish. “The best way to try to control an invasion is right at the beginning,” he says. “If everybody’s aware of it and everybody starts to try to reduce the population now, that’s the best chance we have.”
Ferreira, C. E. L. et al. PLoS ONE http://dx.doi.org/10.1371/journal.pone.0123002 (2015).
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Wilkinson, A. Invasive lionfish discovered in Brazil. Nature (2015). https://doi.org/10.1038/nature.2015.17414