Cannibalism helps invading invertebrates survive severe conditions

Date:May 7, 2020

Source:University of Southern Denmark

In a world where movements of non-native animal species are drastically disrupting whole ecosystems and causing economic harm and environmental change, it is becoming increasingly important to understand the features that allow them to colonize new habitats.

A new study, published in Communications Biology, shows that the prolific comb jelly, a marine invertebrate invader from North America that now frequently washes up on Baltic shores, is able to expand their geographical range thanks to the use of its own young as nutrient stores through long and nutrient deprived winters.

As jellies trace their lineage back to the beginning of all animal life, this work furthers the view of cannibalism as a pervasive trait amongst the animal kingdom.

Mysterious success

With their translucent gelatinous bodies, they may not look like much, but the expansion of the comb jelly, Mnemiopsis leidyi, from the east coasts of North and South America to Eurasian coastal waters has wreaked havoc on local environments.

Their success has remained something of a mystery especially as, instead of storing resources before wintering, they seemed to counterproductively invest in massive 'blooms' of offspring unable to survive long and nutrient deprived winters.

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Asian carp roundup in Kentucky opens new front in battle

FEBRUARY 12, 2020

by Travis Loller and John Flesher

Like a slow-motion, underwater cattle drive, wildlife officials in a half-dozen aluminum boats used pulses of electricity and sound on a recent gray morning to herd schools of Asian carp toward 1,000-foot-long (305 meters) nets.

The ongoing roundup on wind-rippled Kentucky Lake opens a new front in a 15-year battle to halt the advance of the invasive carp, which threaten to upend aquatic ecosystems, starve out native fish and wipe out endangered mussel and snail populations along the Mississippi River and dozens of tributaries.

State and federal agencies together have spent roughly $607 million to stop them since 2004, according to data compiled by The Associated Press. Projects in the works are expected to push the price tag to about $1.5 billion over the next decade.

That's more than five times the amount predicted in 2007 when a national carp management plan was crafted, and no end is in sight. Programs aim to reduce established populations and prevent further spreading, but wildlife officials concede they may never be able to eradicate the prolific fish.

Much of the focus has been on limiting their northerly migration and keeping them out of the Great Lakes, where experts say they could devastate a $7 billion fishing industry. That effort features an underwater electric barrier near Chicago, water sampling for carp DNA, subsidies for commercial fishers and experiments with a mass roundup-type harvest.

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Invasive bullfrog tadpoles devour native ones in the Andamans – via Herp Digest

by Neha Jain, Mongaby India, December 13, 2019

Experiments showed that tadpoles of the Indian bullfrog, an invasive frog species that has spread to six of eight human-inhabited islands in the Andamans, rapidly predated upon tadpoles of native frog species that are found only in the Andaman archipelago.

The results highlight the need to manage invasive Indian bullfrog populations. Researchers suggest screening at entry points and removal of small populations in South Andaman and Little Andaman may be effective strategies.

Multiple factors such as the presence of other predators, alternative food sources, anti-predator defense strategies and the presence of vegetation as refuges can influence the survival of native tadpoles in natural settings.

The invasive Indian bullfrog, native to the Indian subcontinent, is currently an invasive species in the Andaman archipelago in the Bay of Bengal. Yet, little is known about the impact it could have on native species. Now, a study has revealed that tadpoles of the Indian bullfrog quickly devoured native tadpoles when they were housed together.

Part of the Indo-Burma biodiversity hotspot, the Andaman archipelago consists of 300 tropical islands with 40 percent of its reptiles and amphibians endemic to the area — residing only in the islands. As a result, these species are vulnerable when faced with invasions by exotic species.

Since 2009, the range of the Indian bullfrog, Hoplobatrachus tigerinus, has expanded exponentially in the Andaman archipelago. It has now gained a foothold in six out of eight of the human-inhabited islands.

“Unless managed effectively, invasive populations of the Indian bullfrog are likely to spread to the Nicobar Islands, which are currently uncolonized by the bullfrog, and expand in new locations of the Andaman Islands,” said Nitya Mohanty, lead author of the study and post-doctoral fellow at Stellenbosch University, South Africa.

The large-bodied frog, measuring about 160 mm from snout to vent, commonly inhabits plantations and agricultural fields, preying on small native vertebrates. Its diet is similar to that of large native frogs. Tadpoles are carnivorous, consuming other larvae and occasionally engaging in cannibalism.

Mohanty conducted an experiment in the Andaman Nicobar Environment Team field station located in Wandoor, South Andaman Island to find out the chances of survival of native or endemic frog tadpoles when they encounter bullfrog tadpoles. He collected clutches of bullfrog eggs and those from two other native species that are also found in its breeding pools: Chakrapani’s narrow-mouthed frog, Microhyla chakrapanii and the Andaman tree frog, Kaloula ghoshi.

When tadpoles emerged, he randomly mixed Indian bullfrog tadpoles with those of the two native species in circular treatment pools filled with pond water in three different combinations: single-species, two-species, and all three species together. In each pool, density was kept at 30 tadpoles per treatment. The tadpoles were provided with food (leaf litter and algae) regularly and the pools were monitored to detect the time it took for the tadpoles to develop forelimbs, their body lengths upon completing metamorphosis (turning in to adult frogs), and survival of each species.

Rapid extermination of native tadpoles

When housed with the two native species, the voracious bullfrogs went on a killing rampage: they gobbled up all of the native tadpoles within the first week in 83 percent of the pools. And by the third week, the tadpoles in the remaining pools were also consumed by the bullfrogs. But Indian bullfrog tadpoles did not appear to benefit from preying on the native frog species in terms of their growth rate, time to metamorphosis and metamorph body size.

Although Mohanty’s team had expected high levels of predation by the bullfrog tadpoles, they were surprised at how fast they exterminated native tadpoles. They also expected to observe competitive interactions between the native and bullfrog tadpoles. “But, since the bullfrog tadpoles ate all the native tadpoles, there was no competition left to observe,” Mohanty remarked.

The survival of bullfrog tadpoles was low even in pools containing only members of their own species. In fact, on average only three bullfrog tadpoles survived—the rest were cannibalized, said Mohanty.

Native tadpoles fared better without bullfrogs present: on average three in every four made it to metamorphosis. According to Mohanty, this could be because “native tadpoles have not evolved anti-predatory strategies against invasive bullfrog tadpoles, as the bullfrog was only introduced to the Andamans very recently (in 2000).”

Controlling bullfrogs, complex predator-prey interactions

Mohanty acknowledges that inferences from these experiments have several limitations. “In natural settings, these interactions between bullfrog tadpoles and native tadpoles are likely to be influenced by the presence of other predators like dragonflies; and the availability of alternative food sources like mosquito larvae.”

Nevertheless, the findings highlight the need to manage to bullfrog population in the Andaman Islands. For his thesis, Mohanty modelled the invasive spread of bullfrogs under several management scenarios. The results suggested that the “most effective way to start management is to immediately deploy screening mechanisms between islands on the Andaman archipelago and at the Nicobar Island.”

This, he said, “should be followed by removal of the small populations present on South Andaman and Little Andaman, stressing that “ultimately, the Andaman and Nicobar Islands need a biosecurity agency to screen and prevent the entry of more non-native species.”

This is an important study with “huge implications in managing the native biodiversity of the islands,” said Karthikeyan Vasudevan, senior principal scientist at the Centre for Cellular and Molecular Biology, Hyderabad, who was not involved in the study. He agrees that the population of the Indian bullfrog in the Andaman and Nicobar Islands needs to be managed.

 “If a control mechanism is implemented to remove the bullfrog,” explained Vasudevan, “the success can be measured from the variables that are influenced by bullfrogs, such as the increase in abundance of other frogs, insects, and other vertebrates.”

Srinivas K. Saidapur, a reproductive biologist and professor at Karnatak University, Dharwad district, who was also not connected to the study, said that the results are interesting and that his team has also conducted similar unpublished experiments with bullfrog tadpoles as predators and Microhyla ornata tadpoles as prey. The latter is a frog species found in South Asia and the Andaman and Nicobar Islands

.

“We found that the Microhyla tadpoles being transparent are suited to escape predation,” he said, explaining that M. ornata are found in the surface waters or mid-water column whereas bullfrog tadpoles mostly dwell at the bottom of ponds but come up to occasionally gulp air.

Saidapur added that the presence of aquatic flora and other structural refuges could minimize the larval predation rate. Further, some prey tadpoles possess certain anti-predator defense strategies like remaining still for long periods and increased burst speed when attacked.

Consequently, Saidapur believes that it is unlikely that Indian bullfrog tadpoles will completely eradicate M. ornata tadpoles.

Like Mohanty, Saidapur points out that during the breeding periods, frog eggs and tadpoles are also predated upon by other predators such as aquatic predators such as crabs or visiting birds and snakes, for example. In ephemeral ponds where frogs breed, desiccation is another threat which can cause the death of eggs and tadpoles, he noted.

CITATION

Mohanty, N. P., & Measey, J. (2019). No survival of native larval frogs in the presence of invasive Indian bullfrog Hoplobatrachus tigerinus tadpoles. Biological Invasions, 21(7), 2281-2286.

An invasive flatworm from Argentina, Obama nungara, found across France and Europe

FEBRUARY 6, 2020

by PeerJ

One of the consequences of globalization is the inadvertent human-mediated spread of invasive species. The presence of a new invader, named Obama nungara, is reported in France by an international team led by Jean-Lou Justine of ISYEB (Muséum National d'Histoire Naturelle, Paris, France). This is the first study of this invasion, reported in an article published in the open-access journal PeerJ.

As is the case for other land planarians including the New Guinea flatworm, Platydemus manokwari, and giant hammerhead flatworms from Asia, already reported in France, the origin of the invasion by O. nungara is likely to be via the international trade of plants, since adult planarians and cocoons can easily travel in potted plants. However, in contrast to the previously recorded species of land planarians that have been found only in a limited part of the country, the flatworm Obama nungara is reported from an area representing three quarters of metropolitan France.

Land flatworms are predators of soil animals, including earthworms and molluscs, and thus are a possible threat to the biodiversity of native animals and to soil ecology, although the ecological impact has yet to be studied.

To date, the presence of Obama nungara has been occasionally recorded from several countries in Europe, including Spain, Portugal, UK, Italy, and Belgium. However, in none of these countries has a study of the extent of the occurrence of O. nungara been performed.

Continued

How Do We Prevent Pets from Becoming Exotic Invaders? – via Herp Digest

Outlawing possession does not appear to stem the release of alligators, snakes and other problematic species

Scientific American 10/6/19

This summer a professional trapper caught an alligator in a lagoon in Chicago’s Humboldt Park, following a weeklong search that drew crowds of onlookers and captured national headlines. Dubbed “Chance the Snapper,” after a local hip-hop artist, the five-foot, three-inch reptile had likely been let loose by an unprepared pet owner, say experts at the Chicago Herpetological Society (CHS). This was no anomaly: pet gators have recently turned up in a backyard pool on Long Island, at a grocery store parking lot in suburban Pittsburgh (the fourth in that area since May) and again in Chicago.

Keeping a pet alligator is illegal in most U.S. states, but an underground market for these and other exotic animals is thriving—and contributing to the proliferation of invasive species in the U.S. and elsewhere. As online markets make it steadily easier to find unconventional pets such as alligators and monkeys, scientists and policy makers are grappling with how to stop the release of these animals in order to prevent new invasives from establishing themselves and threatening still more ecological havoc. 

New research suggests that simply banning such pets will not solve the problem and that a combination of education, amnesty programs and fines might be a better approach. Many people who release pets may simply be unaware of the dangers—both to the ecosystem and the animals themselves—says Andrew Rhyne, a marine biologist at Roger Williams University who studies the aquarium fish trade. People may think a released animal is “living a happy, productive life. But the external environment is not a happy place for these animals to live, especially if they’re not from the habitat they’re being released into,” he says. “The vast majority of [these] species suffer greatly and die out in the wild.”

EXOTICS TO INVASIVES

Owners sometimes release alligators, as well as other exotic pets such as snakes and certain varieties of aquarium fish, when they prove too big, aggressive or otherwise difficult to handle. But unleashing them on a nonnative habitat risks letting them establish themselves as an invasive species that can disturb local ecosystems. According to one estimate, nearly 85 percent of the 140 nonnative reptiles and amphibians that disrupted food webs in Florida’s coastal waters between the mid-19th century and 2010 are thought to have been introduced by the exotic pet trade.

A study published in June in Frontiers in Ecology and the Environment found this trade is already responsible for hundreds of nonnative and invasive species establishing themselves in locations around the world. Examples range from Burmese pythons—which can grow more than 15 feet long and dine on local wildlife in the Florida Everglades—to monk parakeets, whose bulky nests atop utility poles and power substations around the U.S. cause frequent fires and outages. And because of the growth of direct-to-consumer marketplaces on Web sites and social media, “the trade in exotic pets is a growing trend,” both in terms of the number of individual animals and the variety of species kept, says study leader Julie Lockwood, a Rutgers University ecologist. “Together, those increase the chances that this market will lead to an invasion” of an exotic species, she says.

To date, the main way officials have tried to combat the problem is with laws that simply prohibit keeping certain categories of animals as pets. But the effectiveness of this approach is unclear. Even though Illinois has outlawed keeping crocodilians as pets for more than a decade, Chance is just one of many CHS has had to deal with this year alone, says its president Rich Crowley. He likens the problem to illegal fireworks, noting that bans on exotic pets are inconsistent from one state to the next. For Illinois residents, “there’s still a supply that is readily available, legally, across the border” in Indiana, he says. “There are people out there who are willing to take the chance of skirting the law because the reward of keeping [these] animals is worth the risk.”

New research published recently in Biological Invasions underscores this point, finding that banning the sale and possession of invasive exotic species in Spain did not reduce their release into urban lakes in and around Barcelona. “For these invasive species, legislation for the management of invasions comes too late,” because they have already established themselves in the local environment, says University of Barcelona ecologist Alberto Maceda-Veiga, the report’s lead author.

Phil Goss, president of the U.S. Association of Reptile Keepers, says that instead of blanket bans, he would like to see ways for responsible pet owners to still possess exotic species—with laws targeting the specific problem of releasing animals into the wild. “We’re certainly not against all regulation,” he says. “What we’d like to see is something that will punish actual irresponsible owners first rather than punishing all keepers as a whole.”

TRAINING AND TAGGING

Instead of bans, Maceda-Veiga’s study recommends educating buyers of juvenile exotic animals about how large they will eventually grow and taking a permit-issuing approach that requires potential owners to seek training and accreditation. “You need a driving license to drive a car,” and people should be similarly licensed to keep exotic pets, Maceda-Veiga says. He and his co-authors contend that licensing, combined with microchips that could be implanted in pets to identify owners, could curb illegal releases.

Rhyne agrees that giving buyers more information would likely help. “I think the education part is really important,” he says. “We should not assume that the average consumer understands (a) how big the animal will get once it’s an adult and (b) what the harm could be if it got out in the wild.” Crowley concurs and says CHS has worked with municipal authorities to make sure pet owners who might have a crocodilian that is getting too big for the bathtub are referred to the organization for assistance. Also, some state agencies offer alternatives to dumping an animal in the wild that protect owners from legal repercussions. 

Lockwood says devising responsible ways for owners to relinquish such pets could help. But for this to work, “you need to make it as easy as possible” to turn in an animal, she says. In 2006 Florida’s Fish and Wildlife Conservation Commission (FWC) established an amnesty program that allows owners to surrender their exotic pets with no questions asked. So far more than 6,500 animals have been turned over to the program, says Stephanie Krug, a nonnative-species education and outreach specialist at FWC. A few other states have followed Florida’s lead in establishing amnesty initiatives.

Rhyne says some of the onus for controlling exotic animals should fall on the pet industry itself. “If you don’t regulate yourself and make sure you’re doing your best not to trade in species that are highly invasive, you’re going to create a problem that [lawmakers] are going to fix for you,” he adds. Mike Bober, president of the Pet Industry Joint Advisory Council, says the pet care community is considering ways to proactively address the problem. “We look at that being primarily based in education and partnership,” he says.

As for what became of Chance, the erstwhile Windy City denizen is acclimating to his new home at the St. Augustine Alligator Farm Zoological Park in Florida. An aerial photograph of the Humboldt Park lagoon adorns his enclosure—but he is back where he belongs.

Study shows invasive blue catfish can tolerate high salinities

NOVEMBER 6, 2019

by David Malmquist, Virginia Institute of Marine Science

A new study by researchers at the Virginia Institute of Marine Science warns that blue catfish—an invasive species in several Chesapeake Bay tributaries—tolerate salinities higher than most freshwater fishes, and thus may be able to expand their range downstream into mainstem Chesapeake waters, and from there into new Bay tributaries and even Delaware Bay.

Conducting the study, reported in the November 5th issue of PLOS ONE, were Ph.D. student Vaskar Nepal of William & Mary's School of Marine Science at VIMS and VIMS fisheries professor Mary Fabrizio.

Nepal and Fabrizio undertook the study to better constrain the salinity tolerance of blue catfish in their non-native Chesapeake Bay habitat. The value used in the 2014 report that currently guides management of invasive Bay catfishes was based on a study of blue catfish from their native range: the fresh waters of the Mississippi River basin. Evidence suggests that populations of "blue cats" and other fishes may become more salt tolerant when exposed to brackish estuarine waters.

"We wanted to see how long blue catfish can survive at a given salinity to help us better understand the extent to which they can colonize areas other than those where they were originally stocked," says Nepal.

Continued

Tegu lizards threaten native species around Riverview- Tampa, Florida – via Herp Digest

The invasive lizards, which can reach five feet in length, are well established in east Hillsborough.

TAMPA — The Argentine black and white tegu lizard isn’t something you’re likely to forget if you see one in your yard, not only because of its vivid pattern but also because of its size; a full-grown tegu can stretch five feet from the tip of its snout to the tip of its tail.

The invasive species is well established in two Florida locations, the Homestead area of South Florida and the Riverview area of east Hillsborough County.

Though it has a mean bite if aggravated or cornered, it’s not venomous. But it joins a host of exotic reptiles, especially the Everglades’ Burmese pythons, that are wreaking havoc on the Florida ecosystem, said Todd Campbell, a University of Tampa biologist and expert on both the tegu and the monitor lizard, a three- to seven-foot long carnivore that has overrun the city of Cape Coral.

“We’ve got pythons, over 50 species of lizards, a couple of frogs — the Cuban tree frog, the greenhouse frog and the cane toad — so in terms of reptiles and amphibians, Florida is the most invaded area on earth that I know of,’’ Campbell said.

The tegu is an omnivore. It eats fruits, vegetables, dog and cat food, insects and small animals. But because it especially loves eggs, it’s devastating to turtles, alligators and ground-nesting birds. Of course, it will happily eat the live babies, too.

The tegus work the environment almost like a bear, Campbell said. “Think about a bear. They eat nuts and berries, they forage for food, and then if they’ve got a chance to get a mammal, to kill something, they will. They’re opportunistic that way.’’

The state’s biggest population is in extreme South Florida. “They are completely infested in there. They’ve caught hundreds of these animals,’’ Campbell said.

It’s harder to get a sense of how many are foraging around east Hillsborough County. The Florida Fish and Wildlife Conservation Commission has compiled reports of 307 tegu sightings, according to a spokeswoman, and have trapped and removed 128, but it has no estimate of how many are really out there. Captured lizards are euthanized.

Campbell thinks the Riverview population numbers in the thousands. He suspects they were well established there by the year 2000.

"It’s proven difficult to sort of manage them, figure out where we’re going to trap, find the little routes where we could trap them,’’ he said.

Researchers figure these invasive animal species get established in Florida after escaping from or being released by a pet owner or pet dealer. A sudden explosion of an invasive species population in an area indicates that a bunch were released at once, possibly by a dealer who has gone bankrupt and decided to set the inventory free, Campbell said.

In 2007, Campbell called on scientists to make a full-bore effort to save the state from invasive amphibians and reptiles.

  

"Amphibian and reptile introductions are reaching epidemic proportions in Florida, largely due to irresponsible behavior by pet owners and the pet industry, but also due to ineffective preventive policies and actions,'' he stated in a paper delivered at a symposium on managing vertebrate invasive species.

 "Prevention of additional amphibian and reptile introductions in Florida will require a comprehensive approach involving legal restrictions of certain problematic species, a massive public education effort, and a well-funded and staffed Early Detection and Rapid Response (EDRR) program.’'

Campbell said he worries that if the invasive species aren’t eradicated, it could lead to eventually to what he calls “biotic homogenization.’’

He can imagine it happening around the world. "As we transport critters all around the planet, and those critters we transport cause the extinction of critters in those new locations, we’re just going to end up with one big globe of sameness. That’s a little dramatic, but you could make a logical leap to that end point: we’re going to end up with a couple of hundred species that are very, very dominant everywhere on earth.’’

To get a better grasp of the threat to the state and develop strategies to fight it, the Florida Fish and Wildlife Conservation Commission has set up a toll-free number for people to call if they see an invasive reptile or amphibian – 1-888-IVE-GOT1 (888-483-4681). From those reports, scientists can determine the size of the problem in a given area.

The Voracious and Invasive Lionfish Is Taking Over the Atlantic. Here's Why.

By Grant Currin - Live Science Contributor 2 days ago Animals

This is one hungry fish.

One of the most notorious invasive species around, the lionfish, is known for its voracious appetite and can literally eat its competitors out of an ecosystem. And that's what the striking fish is doing, feasting its way through waters that stretch from the Gulf of Mexico to the Eastern Seaboard.

Now, scientists and startups are crafting methods for capturing and killing the hungry invaders. But while these new ideas show promise, tried-and-true spearfishing seems to be the most effective way to eradicate lionfish, scientists told Live Science.

"It's actually hard to describe how a lionfish eats because they do it in a split second," said Kristen Dahl, a postdoctoral researcher at the University of Florida. Lionfish use a complex series of tactics that no other fish in the world is known to employ. In the blink of an eye, a lionfish goes from silently hovering above its prey to flaring its fins, firing a disorienting jet of water from its mouth, unhinging its jaw and swallowing its meal whole, scientists reported in a study published in 2012 in the journal Marine Ecology Progress Series. The attacks happen so quickly that nearby fish don't seem to notice.

"It's actually nice when I'm looking at gut contents," Dahl said, "because if something has been freshly eaten, it's in immaculate condition."

Read on

Department of Biological Sciences helps target invasive species (The Tegu Lizard now in Georgia digging up Gopher Tortoise Eggs) - via Herp Digest

The George-Anne-Georgia Southern University 

by Nathan Woodruff , Aug 26, 2019

Statesboro, GA — Faculty and students at the Georgia Southern University Department of Biological Sciences are helping state and federal agencies target the Tegu lizard, an invasive species in Tattnall and Toombs county. 

An invasive species is one that is not native to a specific location and that has a tendency to spread to a degree believed to cause damage to the environment, human economy or human health. 

Lance McBrayer, Ph.D., professor of General Biology and Herpetology, graduate student Jada Daniels and undergraduates Michael Brennen and Noah Osterhoudt are involved on the project. 

The Tegu lizard has been deemed a threat because they are especially good at hunting and finding eggs, specifically that of the gopher tortoise, which is listed as a vulnerable threatened species, as well as small animals. 

"We are worried about losing our already threatened species and they will go and hunt other small animals as well that we should be concerned about,” Brennen said.

The GS team is using several approaches, including posting flyers on ATV trails, social media outreach, with over 70,000 people reached. The second thing they are doing is using chicken eggs to bait the lizards and use a camera to spot the lizards.

“We’ll bait a trap and leave it closed, so we don’t catch anything but then have a game camera on that trap so if something comes by and smells it or trips the sensor then we realize they are there,” McBrayer said. “We are going to increase our efforts in that kind of trapping.”

The sightings cover about 150 square miles which are confirmed through sightings on the game cameras. Eyewitness reports have also helped pinpoint the lizards’s exact location. Sightings of the Tegu lizard can be reported at the Georgia Invasives website.

The idea among area officials is that this problem was caused by pet releases and perhaps relocations.

“Most of them this far north are pet releases,” McBrayer said. “Someone was probably raising them in outdoor pens, that was the rumor we have, and then they let them all go.”

Reduction or eradication of the Tegu population in Georgia before more damage is done is the ultimate goal of the program.

The lizard is native to Argentina and Brazil, and it has found a home in Georgia because it is on a similar latitude in the Northern Hemisphere that the lizard’s habitat would be in in the Southern Hemisphere.

New model predicts impact of invasive lionfish predators on coral reefs

Date:  June 6, 2019

Source:  University of Alberta

A new model is providing insight into the impact of invasive lionfish on coral reefs in the Atlantic Ocean and Caribbean Sea. The venomous predatory fish has invaded more than 7.3 million square kilometres in the Atlantic and Caribbean, wreaking havoc among native fish populations.

The method, developed and tested with coral reef fish in the Bahamas through an international collaboration of scientists in Canada, the United States, and United Kingdom, is based on the behaviours used by prey to avoid being eaten by predators that use different hunting tactics.

"Many scientists have speculated that invasive lionfish are so successful in the Atlantic because prey don't recognize them as a predator," explained Stephanie Green, assistant professor in the University of Alberta's Department of Biological Sciences and lead author.

Stephanie Green, assistant professor in the Department of Biological Sciences, swims alongside a lionfish.

Continued

New plan would fight invasive Asian carp with air bubbles, electric shocks, noise

MAY 27, 2019

by Todd Spangler, Detroit Free Press

The head of the Army Corps of Engineers has signed off on a $778 million plan to stop the spread of Asian carp toward the Great Lakes with air bubbles, electric shocks and noise, sending it to Congress for approval.

The plan sent by Lt. Gen. Todd Semonite would block the invasive species' advance toward Lake Michigan at a key choke point at the Brandon Road Lock and Dam along the Des Plaines River in Illinois.

It would:

- Put in place additional electric barriers in the waterway to stop most Asian carp from moving through the lock and dam.

- Use special underwater speakers while ships were moving through the locks to blast sound waves at decibels and frequencies sufficient to make Asian carp species uncomfortable enough to turn back.

Read on

North-east squirrel spotters to take note as reds fight back

by Emma Morrice

 18/05/2019, 12:34 pm

Saving Scotland’s Red Squirrels encourages more people to log sightings of red and grey squirrels across the country.

NEW data shows an invasive species of squirrel has almost been eradicated in the north-east thanks to the work of a charity and members of the public.

During the past 10-15 years the number of non-native, invasive grey species has reduced.

They are only being spotted in Aberdeen city now, as opposed to the wider region.

Grey squirrels push the native red species out, taking over their habitats and food.

Saving Scotland’s Red Squirrels encourages more people to log sightings of red and grey squirrels across the country to promote awareness.

In Scotland more than 2,100 animals have already been added to the website.

Last year, 8,393 were tallied, compared with 5,311 in 2017.

In the north-east there has been a huge reduction in grey squirrels, which has allowed the red ones to thrive.

Since the start of the year more than 120 squirrels in Aberdeen City have been added to the map, with the majority of these red, and many more have been logged across Aberdeenshire.

Many have been spotted in Hazlehead Park, near the crematorium, and at Seaton Park. Remaining greys have been seen along the River Don.

Read on

Wild pigs invade Canadian provinces—an emerging crisis for agriculture and the environment

MAY 13, 2019

by University of Saskatchewan

Wild pigs—a mix of wild boar and domestic swine—are spreading rapidly across Canada, threatening native species such as nesting birds, deer, agricultural crops, and farm livestock, research by the University of Saskatchewan (USask) shows.

The first-ever published survey of the wild pig distribution in Canada has found a rapid expansion in the invasive species' range, which is increasing by nine per cent a year.

"Wild pigs are ecological train wrecks. They are prolific breeders making them an extremely successful invasive species," said Ruth Aschim, a Ph.D. student who led the research published today in Nature Scientific Reports. "Wild pigs can cause soil erosion, degrade water quality, destroy crops, and prey on small mammals, amphibians and birds."

Wild boar were brought from Europe in the late 1980s and early 1990s to diversify Canadian livestock production. Others were imported as 'penned game' for shooting.

The hybrid wild pigs have rapidly multiplied and spread, making them the most prolific invasive mammal in Canada.

By 2017, they had spread exponentially across Canada, from British Columbia to Ontario and Quebec, with the majority in the south-central half of Saskatchewan. Their territory has increased by 88,000 square kilometres per year, on average, over the last decade.

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Invasive species are Australia's number-one extinction threat

MAY 10, 2019

by Andy Sheppard, The Conversation

This week many people across the world stopped and stared as extreme headlines announced that one eighth of the world's species – more than a million – are threatened with extinction.

According to the UN report from the Intergovernmental Science-Policy Platform for Biodiversity and Ecosystem Services (IPBES) which brought this situation to public attention, this startling number is a consequence of five direct causes: changes in land and sea use; direct exploitation of organisms; climate change; pollution; and invasion of alien species.

It's the last, invasive species, that threatens Australian animals and plants more than any other single factor.

Australia's number one threat

Australia has an estimated 600,000 species of flora and fauna. Of these, about 100 are known to have gone extinct in the last 200 years. Currently, more than 1,770 are listed as threatened or endangered.

While the IPBES report ranks invasive alien species as the fifth most significant cause of global decline, in Australia it is a very different story.

Australia has the highest rate of vertebrate mammal extinction in the world, and invasive species are our number one threat.

Cats and foxes have driven 22 native mammals to extinction across central Australia and a new wave of decline – largely from cats – is taking place across northern Australia. Research has estimated 270 more threatened and endangered vertebrates are being affected by invasive species.

Introduced vertebrates have also driven several bird species on Norfolk Island extinct.

Continued

Biological changes among invasive species

Date:  April 8, 2019

Source:  University of Plymouth

A remote island in the Caribbean could offer clues as to how invasive species are able to colonise new territories and then thrive in them, a new study suggests.

Scientists from the University of Plymouth have recently completed extensive research into a lizard population on the Cayman Islands.

Up until the mid-1980s, there had never been a recorded sighting of the Maynard's Anole (Anolis maynardi) on Cayman Brac island despite it being less than 10km from its native territory, Little Cayman.

However, since the species was first discovered on Cayman Brac in 1987 -- in what is thought to have been a human-assisted colonisation -- its population has spread right across the 39km² island.

For this study, recent graduate Vaughn Bodden and Lecturer in Conservation Biology Dr Robert Puschendorf conducted a detailed analysis of the invasive species.

They wanted to assess whether individuals at the forefront of the invasion have developed distinct biological traits that are advantageous for dispersal, and compared their findings to animals in the area of first introduction and the native population on Little Cayman.

They discovered the Cayman Brac population has diverged morphologically from the native population, and within the invasive range there was trend of increasing forelimb length from the core to range edge areas. This ran contrary to the expected findings that longer hindlimbs would be the trait selected as a dispersal-related phenotype.

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Invasive round gobies may be poised to decimate endangered French Creek mussels

APRIL 1, 2019

by Pennsylvania State University

The round goby—a small, extremely prolific, invasive fish from Europe—poses a threat to endangered freshwater mussels in northwestern Pennsylvania's French Creek, one of the last strongholds for two species of mussels, according to researchers.

French Creek flows from southwest New York state about 117 miles to the Allegheny River at Franklin, Pennsylvania. It is the most species-rich stream in Pennsylvania and is nationally recognized for its biodiversity, with more than 80 species of fish and 29 species of freshwater mussels.

Four of the mussels in French Creek are listed under the Endangered Species Act: northern riffleshell, snuffbox, clubshell and rayed bean. Northern riffleshell and clubshell mussels are considered critically imperiled and have lost 95 percent of their historic global range—but they appear to have stable populations in French Creek.

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Broad impacts from lake trout invasion in Yellowstone

Date:  March 20, 2019

Source:  University of Wyoming

     

Introduction of nonnative lake trout in Yellowstone Lake has affected organisms from the microscopic level in the lake to large animals in the region, according to newly published research.

Zooplankton, cutthroat trout, river otters, osprey, bald eagles, bears and likely elk are among the creatures whose numbers, diet and behavior have been altered as a result of the presence of the invasive fish, says an article that appears today in the scientific journal Science Advances.

The authors include Lusha Tronstad, research scientist with the Wyoming Natural Diversity Database at the University of Wyoming; National Park Service scientists Todd Koel, Jeffrey Arnold, Kerry Gunther, Doug Smith and Patrick White; and John Syslo of the Montana Cooperative Fishery Research Unit at Montana State University.

The scientists analyzed data spanning more than four decades, from 1972-2017, and concluded that the impact of lake trout in Yellowstone Lake -- in particular, the decline of native cutthroat trout -- has cascaded across the lake, its tributaries and the surrounding ecosystem.

"Our study illustrates the potential impact of a single, invasive predatory species on otherwise pristine ecosystems," the researchers wrote, providing further support for Yellowstone National Park's efforts to suppress the lake trout population in Yellowstone Lake.

Monitoring over the past three decades has shown a dramatic drop in the numbers of native cutthroat trout that inhabit Yellowstone Lake and spawn in its tributaries, largely as a result of the illegal introduction in the 1980s of lake trout -- which prey on cutthroats and spawn at depths inaccessible to bears, birds and other animals.

Continued

Large lizard from South America has Georgia on its mind (So far four adult Argentine black and white tegus seen) – via Herp Digest

March 16, 2019 SAVANNAH, Ga. (AP) 

A South American lizard could be establishing a breeding population in south Georgia, state wildlife officials say.

The lizards — known as tegus — can grow up to 4 feet (1.2 meters) long.

Talk of large, odd-looking lizards has been circulating in eastern Toombs and western Tattnall counties, The Savannah Morning News reported.

People have reported seeing the reptiles crossing dirt roads, and they've shown up on trail cameras.

The Georgia Department of Natural Resources has documented at least four adult Argentine black and white tegus in the state. Also, there have been 20 sightings in the stretch of forest, farmland and streams from the south Georgia town of Lyons to Reidsville.

The agency is encouraging residents to report sightings as biologists investigate their possible expansion into Georgia.

"We think there's something going on. But we need to know more," said John Jensen, a senior wildlife biologist with the Department of Natural Resources.

Argentine black and white tegus are an invasive species that grows large, reproduces fast and eats lots of things, from fruit to eggs, birds and small mammals, the Savannah newspaper reported.

Tegus would pose a threat to native wildlife, including gopher tortoises, a candidate for Endangered Species Act listing. Tegus have been documented using gopher tortoise burrows and eating tortoise eggs and the young. Tegus will also eat vegetables, pet food and chicken eggs.

If tegus are reproducing in the wild in south Georgia, catching them early is crucial.

Once the lizards are established — as they are in Florida's two known populations — the only effective response is to try and stem their numbers and spread, officials said.