ANGFA Queensland

Media release from Oregon State University

The study this story is based on is available online: http://bit.ly/1f9fqbg

A scuba diver with a speared lionfish.

It may take a legion of scuba divers armed with nets and spears, but a new study confirms for the first time that controlling lionfish populations in the western Atlantic Ocean can pave the way for a recovery of native fish.

Even if it’s one speared fish at a time, it finally appears that there’s a way to fight back.

Scientists at Oregon State University, Simon Fraser University and other institutions have shown in both computer models and 18 months of field tests on reefs that reducing lionfish numbers by specified amounts – at the sites they studied, between 75-95 percent – will allow a rapid recovery of native fish biomass in the treatment area, and to some extent may aid larger ecosystem recovery as well.

It’s some of the first good news in a struggle that has at times appeared almost hopeless, as this voracious, invasive species has wiped out 95 percent of native fish in some Atlantic locations.

“This is excellent news,” said Stephanie Green, a marine ecologist in the College of Science at Oregon State University, and lead author on the report just published in Ecological Applications. “It shows that by creating safe havens, small pockets of reef where lionfish numbers are kept low, we can help native species recover.

“And we don’t have to catch every lionfish to do it.”

That’s good, researchers say, because the rapid spread of lionfish in the Atlantic makes eradication virtually impossible. They’ve also been found thriving in deep water locations which are difficult to access.

The latest research used ecological modeling to determine what percentage of lionfish would have to be removed at a given location to allow for native fish recovery. At 24 coral reefs near Eleuthera Island in the Bahamas, researchers then removed the necessary amount of lionfish to reach this threshold, and monitored recovery of the ecosystem.

On reefs where lionfish were kept below threshold densities, native prey fish increased by 50-70 percent. It’s one of the first studies of its type to demonstrate that reduction of an invasive species below an environmentally damaging threshold, rather than outright eradication, can have comparable benefits.

Some of the fish that recovered, such as Nassau grouper and yellowtail snapper, are critically important to local economies. And larger adults can then spread throughout the reef system – although the amount of system recovery that would take place outside of treated areas is a subject that needs additional research, they said.

Where no intervention was made, native species continued to decline and disappear.

The lionfish invasion in the Atlantic, believed to have begun in the 1980s, now covers an area larger than the entirety of the United States. With venomous spines, no natural predators in the Atlantic Ocean, and aggressive behavior, the lionfish have been shown to eat almost anything smaller than they are – fish, shrimp, crabs and octopus. Lionfish can also withstand starvation for protracted periods – many of their prey species will disappear before they do.

Governments, industry and conservation groups across this region are already trying to cull lionfish from their waters, and encourage their use as a food fish. Some removal efforts have concentrated on popular dive sites.

The scientists said in their report that the model used in this research should work equally well in various types of marine habitat, including mangroves, temperate hard-bottom systems, estuaries and seagrass beds.

A major issue to be considered, however, is where to allocate future removal efforts. Marine reserves, which often allow “no take” of any marine life in an effort to recover fish populations, may need to be the focus of lionfish removal. The traditional, hands-off concept in such areas may succeed only in wiping out native species while allowing the invasive species to grow unchecked.

Keeping lionfish numbers low in areas that are hot spots for juvenile fish, like mangroves and shallow reefs, is also crucial, the report said.

This research was done in collaboration with scientists at Simon Fraser University, the Reef Environmental Education Foundation, and the Cape Eleuthera Institute. It has been supported by the Natural Science and Engineering Research Council of Canada, the Boston Foundation and a David H. Smith Conservation Research Fellowship.

“Many invasions such as lionfish are occurring at a speed and magnitude that outstrips the resources available to contain and eliminate them,” the researchers wrote in their conclusion. “Our study is the first to demonstrate that for such invasions, complete extirpation is not necessary to minimize negative ecological changes within priority habitats.”

Media release from  James Cook University

Pterois volitans – the Lionfish with venomous spines

A spiny, toxic and beautiful member of the world’s coral reef communities, the Red Lionfish is invisible to the small fish it likes to eat.

A new study by James Cook University scientists Oona Lönnstedt and Professor Mark McCormick suggests this is one reason for the lionfishes’ incredible success in the Caribbean, where it is eating its way through the reef ecosystem.

“Lionfish are native to the Pacific, but have been taking over the Caribbean Basin ever since they were accidentally introduced almost 30 years ago,” Professor McCormick said.

“Their extreme success as an invasive predator has long been a mystery to ecologists worldwide.”

The new research, published in the latest issue of PLoS ONE suggests that the solution in part lies in the power of camouflage, as these voracious carnivores are virtually undetectable by small prey fish.

Red lionfish (Pterois volitans) are a rare and beautiful sighting for divers in their native waters around the Great Barrier Reef, but in the reefs around the Florida coast and Caribbean they are viewed as a huge nuisance.

“For over a decade, scientists have tried their best to understand how these gorgeous but deadly predators can wreak such havoc on their invaded ecosystem,” Professor McCormick said.

“Almost all of the work to date has focussed on the consequences of the interaction between these predators and their prey in areas where lionfish are invasive species.”

Now, as a world first, graduate student Ms Lönnstedt and Professor McCormick have found that lionfish are undetectable by prey, acting as ghosts able to feed on anything and everything without being discovered until it’s too late.

“We tested the response of small prey fish to three different predators, one of them the lionfish,” Ms Lönnstedt said.

“Surprisingly, the common prey fish were unable to learn that the lionfish represented a threat, which was very different to their response to two other fish predators.

“Lionfish were able to sneak up on their prey and capture every single one, while the other predators had much lower feeding success.”

This ability to bypass a very well-studied learning mechanism commonly used by prey to learn new risks is a world first, and has in part lead to the astounding success of lionfish in the Caribbean.

With release from any natural enemies in their new system and no problem catching food, the lionfish are practically unstoppable.

The paper ‘Ultimate Predators: lionfish have evolved to circumvent prey risk assessment abilities’ is published in the latest issue of PLOS ONE.

http://dx.plos.org/10.1371/journal.pone.0075781

More information:

Oona Lönnstedt, School of Marine & Tropical Biology, James Cook University, ph +46 700 21 83 46

Professor Mark McCormick, School of Marine & Tropical Biology, James Cook University, +61 7 4781 4048 or 0409 371 015

JCU Media: Jim O’Brien +61 (0)7 4781 4822 or 0418 892449

Media release by  Celeste Arbogast Bragorgos, College of Engineering, University of  Illinois

A project to map the microbes present in the digestive systems of fish species holds promise for monitoring the presence of Asian carp in Chicago area waterways and ultimately preventing their spread, according to a study published in Nature’s ISME Journal. The work, funded through the U.S. Environmental Protection Agency Great Lakes Restoration Initiative, is being conducted by researchers from the University of Illinois at Urbana-Champaign and the U.S. Geological Survey (USGS).

Dorosoma cepedianum – Gizzard Shad. Image: Duane Raver

Asian carp is a term used to refer to several invasive fish species including silver, bighead and black carp. Bighead carp and silver carp have already invaded much of the Mississippi River basin, where they compete for food with native species and dominate aquatic communities. Bighead carp and silver carp are considered one of the most severe aquatic invasive species threats facing the Great Lakes today, according to the Asian Carp Regional Coordinating Committee (ACRCC). The ACRCC is coordinating the efforts of federal, state, local and private resource management agencies to develop an Asian carp control program. Efforts to control the fish include research to understand their physiology and behavior and how they differ from that of native species, with an eye toward developing effective monitoring and management systems.

Gut microbiota—the microbial communities present in the digestive tracts of living things—are unique, according to Wen-Tso Liu, co-author of the study and a professor of civil and environmental engineering at Illinois. For that reason, careful analysis of fish gut microbiota can reveal host-specific biomarkers shed in fish feces that indicate the presence of a specific species, promising the development of precise monitoring systems. Since fish feces are plentiful in waterways, monitoring could be easier than with techniques that have focused on detecting the DNA of the targeted species in sloughed-off skin tissue, Liu says.

Hypophthalmichthys molitrix – Silver Carp. Image: Duane Raver

The researchers used a next-generation gene sequencing technology called 16S pyrosequencing, which focuses on the 16S rRNA gene sequences, to analyze the gut microbiota of the invasive silver carp and the native gizzard shad. They successfully discovered potential biomarkers for silver carp and are working to refine them, Liu says.

In addition, the research illuminated some important similarities and differences in the species. For example, he says, gizzard shad harbor microbial communities that are 10 times more diverse than that of silver carp, showing that their digestive processes are significantly more complicated. The researchers also discovered a common food-source microbe, which proves that the fish compete for the same food.

“This is why invasive species can be dangerous,” he says. “They can eat the same food, and if the invasive species consumes more food, then the native species can be out-competed and their population will start to decline, leading to ecological disaster.”

On the strength of these findings, the researchers are beginning an extensive project to confirm their findings in the fish species in the Chicago River—approximately 50 different ones—in order to map their gut microbiota and develop biomarkers for each species. The results will lead to a precise monitoring methodology, but the benefits will likely extend further, Liu says.

“There is a lot more beyond just monitoring,” Liu says. “We will also learn more about the diversity of fish, their diets, how their diets are related to their gut microbiota and how they metabolize inside the gut.”

The scientific article, “Fish gut microbiota analysis differentiates physiology and behavior of invasive Asian carp and indigenous American fish,” by Lin Ye, Jon Amberg, Duane Chapman, Mark Gaikowski, and Wen-Tso Liu, is available on the ISME Journal website.