Stories tagged invasive species

MinuteEarth digs into the tricky balance of trying to manage invasive species.


Numbered days?: Zebra mussels totally cover a piece of underwater equipment from Lake Michigan.
Numbered days?: Zebra mussels totally cover a piece of underwater equipment from Lake Michigan.Courtesy M. McCormick
For more than 20 years, zebra mussels have gone unchecked in midwest waters. Introduced to North America as stow-away passengers on the bottoms of Great Lakes shipping vessels that came from Europe, the invasive species have exploded to fresh waters in 34 states at an alarming rate.

But their days may be numbered. A New York-based researcher has discovered a bacterium that can kill zebra mussels (and also the related invasive species quagga mussels) without disrupting the rest of the food web.

After rounds of lab testing, the Environmental Protection Agency has okayed the commercial production of Pseudomonas fluorescens strain CL145A, which can then be applied to waters and kill the menacing mussels. In lab tests, the bacterium killed over 90 percent of the the invasive mussels in came in contact with.

Along with pushing out other species in the waters, the invasive mussels have also become a nuisance by clogging up intake pipes at water plants and attaching themselves to docks, piers and other submerged water equipment. Plans are still being developed on how to apply this new bacterium to the waters. All wise zebra mussels might want to start packing their bages and heading back to Europe before they find out what this new bacterium has in store for them!

Invasive species in Minnesota lakes is an ongoing problem. But this story – an alligator shot by Minnesota game officials in a Scandia-area lake – may just take the cake. Oh, and they think there might be one or two more gators still in the lake.


Asian carp jumping: Asian carp not only take over river ecosystems, but can furiously "fly" out of the water.
Asian carp jumping: Asian carp not only take over river ecosystems, but can furiously "fly" out of the water.Courtesy The Theater of Public Policy
Preliminary information from a study of river water DNA samples done two years ago cranked up concerns about the presence of Asian carp in Minnesota sections of the Mississippi River and also the St. Croix River. But new and deeper analysis of the data shows that the menacing fish haven't been regular residents of those waters, and that local authorities have plenty of time to plan ways of keeping the invasive species away.

What changed? Last year researchers used more precise methods of identifying the DNA, they found that the earlier DNA samples were most likely not from Asian carp.

It's all good news in the short term. The Asian carp have been slowly migrating up the Mississippi River, upsetting the eco-balance of those waters for many years. The fish are aggressive and actually can "jump" out of the water and into anglers' boats. They also are aggressively eating foods that are the diets of native fish.

This new information isn't slowing down plans to try to halt the spread of the fish upstream, authorities added. Among the plans are to install underwater noise and bubble barriers at the Ford Dam on the Mississippi River in the heart of the Twin Cities.

I'm not typically one for computer games, but with the tagline "Be a Sea Grant super sleuth," Nab the Aquatic Invaders! looked so neat I couldn't pass it up. (It brought back fond memories of my old Carmen San Diego computer game, circa 1995.)

Players can choose their skill level from "junior detective" to "super sleuth" as they meet the suspects, collect clues, and book the bad guys: invasive species. It's a great way to learn about

"the unusual species that create real problems in the Atlantic, Pacific, Gulf, and Great Lakes regions."

Rules of play might be a little tricky for younger children, but the game comes with a guide for assisting teachers (or parents).

Asian Carp
Asian CarpCourtesy kate.gardiner
ScienceBuzz is covering the danger Asian carp present to the Great Lakes. Last week a 19.6-pound, 34.6-inch bighead carp became entangled in a fishing net about six miles from Lake Michigan.

“Asian carp are like cockroaches; when you see one, you know it’s accompanied by many more you don’t see,” said Henry Henderson, of the Natural Resources Defense Council.

You can learn more in The New York Times


Kudzu: A kudzu infestation of a wooded area near Port Gibson, Mississippi. Note that the kudzu has completely overgrown several of the trees in this picture.
Kudzu: A kudzu infestation of a wooded area near Port Gibson, Mississippi. Note that the kudzu has completely overgrown several of the trees in this picture.Courtesy Gsmith
Chances are good that if you're reading this post from North of Kentucky or West of Louisiana, you've never heard of kudzu. Down here in Charlotte and the rest of the Southeast, we're very, very familiar with this plant.

Kudzu is an invasive species of vine indigenous to Japan and parts of China. As with many invasive species, kudzu was brought to America as a problem solver. Kudzu grows exceptionally fast, does a great job preventing erosion, and can be used as a feed for animals like goats and sheep. Humans can even eat kudzu flowers in the form of jelly.

Unfortunately, the growth of Kudzu soon spun out of control. With no natural consumer or pest to keep population in check, the fast growing plant began to spread, strangling trees and entire fields of low lying plants in its way. Today, the entire Southeast United States is effected, with no real solution available.

Well, a recent study by scientists from The Earth Institute at Columbia University just added another entry to the list of reasons to pull out the industrial sized weed-whacker: air pollution.

Another reason kudzu was so sought after is its ability to take nitrogen from the air and introduce or "fix" it into the soil. There, microbes turn the nitrogen into fertilizer for other plants. Huge mats of kudzu are so good at fixing nitrogen that they're upsetting the chemical balance of the ecosystem, which in turn results in increased levels of hazardous ozone gas.

Using the data they collected near areas of dense kudzu growth, the team of scientists were able to predict that in an extreme scenario, kudzu growth could contribute heavily to ozone warning days in the vicinity.

For lots more information about kudzu infestation and control, check here.

Minnesota state officials have announced that ash trees infested with Emerald Ash Borer(EAB) beetles have been found in Minneapolis. This destructive insect pest had already been confirmed in St.Paul in 2009, so officials were not surprised to find that it had spread. A quarantine has been in place for much of the past year, restricting the movement of ash in and out of Hennepin and Ramsey counties. Minnesota has one of the largest concentrations of ash trees in the United States, making it particularly vulnerable. You can see a map here that shows where in Minnesota the EAB has been found, and can read more about how to detect or prevent the spread of this tree-killing pest in ARTiFactor's earlier post.


Viral hemorrhagic septicemia: a fish infected with the virus
Viral hemorrhagic septicemia: a fish infected with the virusCourtesy Dr. Mohamed Faisal
No… not a rock bass (even though it has a red iris). Nor any normal walleye you might be lucky enough to snag. This fish you might not even need to actually catch. It could be floating next to the boat along with most of the other fish in your favorite river, lake, or reservoir. That is if the dreaded VHS continues to spread and strike us deep in the land of 10,000 lakes. Move over zebra mussel, Eurasian milfoil, and the Asian carp, VHS is viral hemorrhagic septicemia and the latest migrant in the spread of invasive species.

Viral hemorrhagic septicemia (VHS) is a virus. It is a small invading critter that can be quite infectious. Not all fish will show obvious signs. Those that do can exhibit hemorrhaging in the eyes, around the fins, or on the gills. Bloating, erratic behavior, bulging eyes, or even lesions could also be present. On the inside, the disease will attack the liver, kidneys, spleen or swim bladder. Those fish that do survive can still be infected and spread the disease. Blood, urine and even the reproductive fluids of infected fish can pass on the virus. Larger fish can get it from eating smaller infected fish.
Fish kill: sights like this are all the more possible with the new viral invader
Fish kill: sights like this are all the more possible with the new viral invaderCourtesy JoelDeluxe

The disease can be wide spread and is known to affect up to 28 different species of fish. Some of the fish kills have numbered in the tens of thousands. Many of our popular game fish are susceptible. Walleye, Northern Pike, Muskellunge, Smallmouth Bass, Perch, Crappies, Bluegills, Sheepshead and many others are on the list. Even some species of shiner bait fish have been found to carry the disease. While deadly for many fish, the disease is of no harm to humans. The warmth of our bodies is too hot for the virus to survive.

The virus has been known for many decades, but until recently was mainly a scourge of European fish farms. Viral hemorrhagic septicemia was first detected in American coastal waters in 1988, among the salmon populations of the Pacific Northwest. Then in 2005, tested fish showed up positive between Lake Huron and Lake Erie, and were confirmed in samples harvested two years earlier. Now, local news just recently reported on a Cornell study that found VHS diseased fish in the bay waters of the Duluth-Superior harbor on the western edges of Lake Superior. Make no mistake… the ‘bleeding fish’ disease is here at our doorstep.

Guests of the inland waterways will be reminded to be vigilant in safe boating and fishing practices by local resource managers. Be mindful not to transport fish, plants, or bait from one water body to another. Keep those live-wells empty, and dry or rinse that boat! It will fall upon all of us to remain vigilant. Let’s not allow this disease to become a crippling blow to our native fisheries. If we do, it is possible that we’ll witness many seasons of massive fish kills.

More good VHS information:
Wisconsin Dept. of Natural Resources

Univ. of Wisconsin Sea Grant


Alien, immigrant, visitor...: Whatever you want to call them, jaguars are not native to the US.
Alien, immigrant, visitor...: Whatever you want to call them, jaguars are not native to the US.Courtesy Joachim S. Mueller

I’m not sure where to put this one. On the one hand, we’ve had a long discussion on the dangers of introducing non-native species into America’s wild habitats. That was about cheetahs; this is about jaguars; but the idea (a bad one) remains the same.

OTOH, Bryan wants us to keep track of scientific decisions made by the administration, to make sure they hold to the pledge made in Obama’s inaugural address to base scientific decisions on scientific observation and data. This story could certainly go there as well.

Since I can’t make up my mind, I may as well start a new thread:

US Fish and Wildlife Service ignores scientists, takes initial steps toward introducing non-native jaguars into US.