Lionfish characteristics make them more ‘terminator’ than predator
From Science Daily
New research on the predatory nature of red lionfish, the invasive species that is decimating native fish populations in parts of the Caribbean Sea and Atlantic Ocean, seems to indicate that lionfish are not just a predator, but more like the ‘terminator’ of movie fame. In behavior that is called ‘alarming,’ it appears that in some cases lionfish will continue to hunt until the last fish of a local population is dead.
New research on the predatory nature of red lionfish, the invasive Pacific Ocean species that is decimating native fish populations in parts of the Caribbean Sea and Atlantic Ocean, seems to indicate that lionfish are not just a predator, but more like the “terminator” of movie fame.
The finding of behavior that was called “alarming” was presented today by Kurt Ingeman, a researcher from Oregon State University, at the annual meeting of the Ecological Society of America.
Most native predatory fish are attracted to prey when their numbers are high, when successful attacks are easy and when a minimum of energy is needed to catch and eat other fish, according to previous research done by Michael Webster, a fish ecologist who received his doctorate from OSU. As the population of prey diminishes, the native predators often move on to other areas where, literally, the fishing is better.
The new research concludes that lionfish, by comparison, appear to stay in one area even as the numbers of prey diminish, and in some cases can eat the population to local extinction. They have unique characteristics that make this possible, and like the terminator, they simply will not stop until the last of their prey is dead.
“Lionfish seem to be the ultimate invader,” said Ingeman, a doctoral candidate in the Department of Integrative Biology within the OSU College of Science. “Almost every new thing we learn about them is some characteristic that makes them a more formidable predator. And it’s now clear they will hunt successfully even when only a few fish are present. This behavior is unusual and alarming.”
This research was conducted on replicated natural reefs in the Bahamas, measuring prey mortality of the fairy basslet — a popular aquarium fish and a common prey of lionfish.
Predation rates were compared between reefs with the invasive lionfish and reefs with native predators alone, and across a range of population levels of the fairy basslet. Ingeman found that when prey fish were present at a low population density, the rate of mortality with lionfish present was four times higher than that caused by native predators alone, such as medium-sized groupers or trumpet fish.
The findings are of some importance, researchers said, because fairy basslet live in small local populations, which are most vulnerable to local extinction. It also shows that the mechanisms that ordinarily regulate population size can be altered.
“Reef fish usually hide in rocks and crevices for protection, and with high populations, there is a scramble for shelter,” Ingeman said. “Native predators take advantage of this situation by mostly eating when and where prey are abundant. As prey population levels decline, it takes a lot more energy to catch fish, so the predators often move on to other areas.”
Because of this process that scientists call “density-dependent” predation, populations of native prey fish tend to shrink when they get too large, grow when they get too small, and are rarely ever wiped out completely.
Lionfish, however, have such advantages as an invasive species that they apparently feel no need to move on for better or easier hunting. They may not be recognized as a predator by other fish, leading to high mortality even when shelter is abundant. Lionfish are also very efficient hunters, are well defended themselves by poisonous spines, and can thrive at deep levels in the ocean. They tolerate a wide range of habitats and water conditions, reproduce rapidly most of the year, eat many different species of native fish and may overeat rare species.
Still unclear, Ingeman said, is whether evolutionary pressures may allow native fish in the Atlantic Ocean to adapt new behaviors that provide better defense against lionfish.
“There’s a strong pressure here for natural selection to come into play eventually,” Ingeman said. “We know that fish can learn and change their behavior, sometimes over just a few generations. But we don’t have any studies yet to demonstrate this is taking place with native fish populations in the Atlantic.”
The lionfish invasion in the Atlantic Ocean is believed to have begun in the 1980s and now covers an area larger than the entirety of the United States. Ingeman’s advisor, Mark Hixon, and fellow graduate students have shown that lionfish can wipe out over 90 percent of more of the native fish in some hard-hit areas.
IMAGE: Research done with the fairy basslet, a common prey of lionfish in the Atlantic Ocean, demonstrates that lionfish are more voracious predators than other native fish, and will still hunt until almost the last of their prey is gone.
Credit: Image courtesy of Oregon State University
Related story:
Lionfish’s terminator-style killing alarms scientists
By Megan Gannon, From Live Science
Lionfish, an invasive Pacific Ocean species, have been wiping out native fish populations in the Caribbean Sea and Atlantic Ocean for the past couple of decades. Now, research reveals the “terminator”-style approach to hunting that has likely made them so successful: When other predatory fish quit stalking their prey to look for easier targets, lionfish just keep on killing.
“Lionfish seem to be the ultimate invader,” study researcher Kurt Ingeman, a doctoral student at Oregon State University, said in a statement. “Almost every new thing we learn about them is some characteristic that makes them a more formidable predator. And it’s now clear they will hunt successfully even when only a few fish are present. This behavior is unusual and alarming.”
Ingeman, who presented his research at the annual meeting of the Ecological Society of America in Sacramento, California, studied populations of the fairy basslet, a common lionfish prey, at reefs in the Bahamas. [Alien Invaders: Photos of Destructive Invasive Species]
Under normal conditions, the population of a small reef fish like the fairy basslet tends to fluctuate. These fish hide in rocks and crevices for shelter, Ingeman explained, meaning they become more difficult for predators to hunt when their population sinks to low numbers. But when predatory fish move on to other areas where prey are more abundant and thus easier to catch, the population of fairy basslets gets a chance to bounce back, and the cycle continues.
However, fairy basslets get no such relief when lionfish are present. Ingeman found that low-density populations of the prey fish that were living in reefs invaded by lionfish experienced a mortality rate four times higher than their counterparts living in reefs exposed to native predators like groupers and trumpet fish.
Lionfish, which are covered in venomous spines, are such successful invaders because they can tolerate a variety of habitats and they reproduce at alarming rates. They also have a voracious appetite and aren’t too picky about what they eat. In some spots in the Atlantic, scientists estimate lionfish have wiped out 90 percent of native fish.
In Atlantic and Caribbean waters, lionfish have no natural predators. Not even sharks could help curb the spread of the species, a study released last year found. Another recent investigation revealed that lionfish, thought to be confined to shallow environments, are thriving in surprisingly deep waters off the coast of Florida.
It’s still unclear whether native prey fish are adapting to their new tormentors.
“There’s a strong pressure here for natural selection to come into play eventually,” Ingeman said in the statement. “We know that fish can learn and change their behavior, sometimes over just a few generations. But we don’t have any studies yet to demonstrate this is taking place with native fish populations in the Atlantic.”
IMAGES:
In some places in the Atlantic Ocean, lionfish may be wiping out up to 90 percent of native fish, scientists estimate. Credit: Abel Valdivia
The fairy bassletPin It The fairy basslet is a common prey of lionfish in the Atlantic Ocean and a popular aquarium fish.
Credit: Oregon State UniversityView full size image
For more on this story go to: http://www.livescience.com/47361-lionfish-hunt-like-terminator.html
See iNews Cayman related story published August 3 2014 “Lionfish University wants more culling of lionfish and people to eat them” at: http://www.ieyenews.com/wordpress/lionfish-university-wants-more-culling-of-lionfish-and-people-to-eat-them/
Note: iNews Cayman have published multiple stories on lionfish. To read more please place word “lionfish” in our search engine top right.
