Beauty as the Beast: lionfish invasion in the Caribbean

It is an unfortunate situation when something of beauty is at risk of being destroyed through no fault of it's own. But off the coast of Florida and throughout the Caribbean, that is the fate that awaits the lionfish (genus: Pterois). For all its graceful movement, striking color, and ornamentation, it is, regrettably, an invader that threatens the ecological balance of reef communities throughout the region.

I just returned from two weeks at sea along the shallow banks northwest of Grand Bahama, and with every reef dive I undertook I was guaranteed at least a half dozen sightings of these small Indo-Pacific predators. Known for having a voracious appetite to match its venomous spines, it was reported in one study that a lionfish can consume three-quarters of a reef's fish population in as little as five weeks. Left unchecked, the lionfish threatens the Bahamas' annual $5 billion tourism industry (that's billion with a "B") and nearly half of the island's employment. Bathers can get stung by the lionfish's dorsal spines or divers can find reefs denuded of colorful tropical fish and this can spell economic ruin for many Caribbean nations.

So, how did this all come about? How did a fish found in the South Pacific make its way halfway across the planet? Well, it certainly would need some help, an accomplice or two.

And that would be us.

The lionfish invasion in the Caribbean is a textbook example of invasive species distribution. Because of its beauty, juvenile lionfish are a popular addition to home saltwater aquariums. That is, popular until your other aquarium fish begin to disappear one by one as the lionfish grows and its appetite blossoms.

So, could it have found itself in the Atlantic when a frazzled home aquarist released it into the wild? Possibly, although it has been reported that the pivotal moment may have occurred in 1992 when Hurricane Andrew battered the southeast coast of the U.S., smashing an aquarium tank in Florida, and releasing six lionfish into open sea. Through the 90's, lionfish expansion was slow, but the first one showed up in the Bahamas in 2005. Two years later, the population exploded (some studies have indicated that a possible reason for the lionfish's successful growth is due to its resistance to many of the parasites commonly found in the Caribbean). The invasion was in full force and the war was on.

Over thousands of years, the lionfish found its proper place in the Indo-Pacific as both predator and prey. Groupers and other large fish fed on them, helping to control their numbers. But in the Bahamas, groupers have been overfished, so there aren't enough of these controlling predators to do the job (and even juvenile groupers are at risk of becoming a lionfish's next meal).

NOAA, the National Oceanic and Atmospheric Administration does not mince words when describing the lionfish invasion. "With few known natural predators, the lionfish poses a major threat to coral reef ecosystems in the Caribbean region by decreasing survival of a wide range of native reef animals via both predation and competition," says NOAA's Office of Research. "It was not unusual to observe lionfish consuming prey up to 2/3 of its own length. Results of the experiment show that lionfish significantly reduce the net recruitment of coral reef fishes by an estimated 80%. The huge reduction in recruitment is due to predation and may eventually result in substantial, negative ecosystem-wide consequences. It is also important to note that lionfish have the potential to act synergistically with other existing stressors, such as climate change, overfishing, and pollution, making this invasion of particular concern for the future of Atlantic coral reefs."



While in the Bahamas, I saw signs and posters proclaiming that the only good lionfish in Caribbean waters was basically a dead one. Crew members would regularly dive with short tri-tip spears in hand, looking under reef ledges - a favorite lionfish hangout - and stabbing any lionfish they came upon, leaving it there perhaps to eaten by a scavenging shark.

In fact, several of the crew reported trying to entice Caribbean reef or lemon sharks to feed on a speared lionfish in the hopes that the sharks would develop a taste for the enemy invader. The sharks would have to learn the best approach to avoid a discomforting sting and, in fact, I saw one shark make repeated bites - spitting out the lionfish until it found the right angle by which it could comfortably consume the free meal.

While the lionfish is one of the tropical ocean's most beautiful inhabitants (and one of my personal favorites), as an invasive species it unintentionally poses considerable risk to the Caribbean marine ecosystem. Could a natural balancing mechanism take hold through predation by fish who discover a new potential prey item in their midst? Or will mankind, having been responsible for the lionfish's introduction in the Caribbean in the first place, now have to take extraordinary steps to eradicate this species? To date, the success of the lionfish shows that there are no easy answers, as is often the case with other invasive plant and animals species around the globe.

Read about the lionfish invasion in NPR.org.
Read about NOAA studies of the lionfish invasion.

Lionfish and Pythons: invasive species paying the ultimate price

Well, I'm back from a very successful trip to Chattanooga, Tennessee. Hopefully I will have impressed a few listeners before they watch shark television programming that seems to be obsessed with one thing this year: shark attacks.

I caught two interesting news bits on invasive species. The introduction of foreign animal and plant life into an ecosystem can have disastrous effects either on the ecosystem itself - as in the case of invasive seaweeds or predators like the lionfish - or on our man-made infrastructures - like the damage caused to water pipes from freshwater mussels.

1. Speaking of lionfish: their population has been exploding in the warm waters off Florida and the Caribbean, ever since their introduction by aquarists who could no longer care for them at home and released them into the wild. Voracious by nature, the beautiful lionfish was thought to possibly be held in check through predation by larger animals like groupers. While that still may be the case someday, at the moment it's a losing battle. One that has prompted the development of "lionfish tournaments" which have netted as many as 1200+ lionfish in a single event.

2. TIME magazine just reported on a government-sanctioned program to rid the Florida Everglades of exotic Asian pythons - again, introduced into the wild by owners who could no longer manage them at home. These reptiles, like the Burmese python, can reach a length of up to 18 feet and can disrupt the Everglade's predator-prey hierarchy by feeding on everything from small rodents all the way up to the typical apex predator of the Everglades, the alligator. Officials from the Florida Fish and Wildlife Conservation are working with snake experts to round up some of the estimated 150,000 pythons and are considering even issuing bounty hunter permits.

It's a sad price that has to be paid by all invasive species, whether plant or animal, when the result is their wholesale destruction. But the real villain lies with man either through his thoughtlessness, negligence, or perverse need to own exotic animals as pets. And because of it, we must then cover our tracks at the end of a spear or the barrel of a gun.

Invaders from inner space: dealing with alien species

There has been some attention paid to the discovery of Lionfish in Caribbean/Southeastern US waters. Most likely the result of discarded aquarium fish, these beautiful but voracious reef predators have drawn concern because of the potential impact they can have on the reef community. Research is ongoing to monitor their impact and while it's known that they can prey heavily on smaller reef fish, there has been some initial evidence that the lionfish themselves have fallen prey to large groupers. Whether this will ultimately balance out the situation remains to be seen.

Invasive alien species (IAS) can take the form of plant or animal - from seaweeds and exotic forms of algae to invertebrates to fish, and more. Over 200 fish species have been introduced into the US alone, often through the home aquarium trade where unwanted fish or plants are discarded into lakes, rivers, streams, or directly to sea. Our increasing globalization and increased shipping has also been a major contributor, with ships having the ability to inadvertently transport a variety of species of seaweeds or invertebrates like zebra mussels that can push out endemic species or clog pipes and other man-made waterways.

Scientific theory used to adhere to the idea that a rich biodiversity was the best defense against IAS. Now, there are differing theories based on an ecosystem's species' maximum utilization of resources which allows for little variability. Splitting hairs? Might seem that way, but the bottom line is: the best defense is a good offense - healthy marine ecosystems and vigilance on our parts regarding international regulations and inspections. And if you are a home aquarium enthusiast - a little common sense.