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Entries in invasive species (184)

Friday
Mar212014

Stop Blaming the 'Villagers'

Today’s biology lesson is about the life cycle of zebra mussels. As an added bonus, I’m going to provide a little instruction in the lost art of journalism.

First, read this excerpt from an article about the exotic shellfish on the KAAL website in Minnesota:

 * * *

"Say you've pumped in 100 gallons of water off Lake Minnetonka and it comes in now and then pumps out, any villagers that happen to be in that tank can't get out either,” said Larry Meddock with the Water Sports Industry Association. The villagers are trapped. That's important because the filter reduces the risk of any hitchhikers being transported from one lake to another through ballast tanks on boats.

* * *

Now here’s the journalism lesson: Know what you’re talking about.

And here’s a clue to the biology lesson: “Villagers” don’t live in water; they live in a village. And they are people, not zebra mussels.

What, then, are the “villagers” that the KAAL author is referring to? Had she bothered to do any research, she would have discovered that the correct term is “veligers.”

Here’s what you need to know about zebra mussels and what that article failed miserably to explain:

Veligers are the microscopic, free-swimming larvae of zebra and other mussels. They can drift in the water for several weeks, before settling onto hard surfaces to grow into hard-shell adults.

They likely were introduced to the Great Lakes as veligers in the ballast water of ocean-going ships. They also are being spread within the United States in ballast, as well as in bilges, livewells and any other water left in a boats as they leave infected waterways.

As adults, they can hitchhike by attaching to boat hulls, props, and trailers, surviving out of water for a week or so.

That’s why it’s so important that you clean, drain, and dry your boat after leaving any water infected with zebra or quagga mussels. And the failure of many to take these precautions is a major reason that these problematic shellfish have spread out from the Great Lakes, and, in recent years even crossed the Continental Divide.

Aside from outcompeting native species for oxygen, food, and habitat, they clog water and hydropower plants, costing the nation’s economy more than $1 billion a year in damages and associated control costs annually.

Stop the spread of “veligers,” and leave the “villagers” alone.

Monday
Mar172014

Another Troublesome Invasive Plant Is Spreading

A pilot project in Michigan has resulted in the discovery of an increased threat to fisheries posed by European frog-bit, an exotic floating plant.

Statewide monitoring by the Early Detection Rapid Response coalition revealed European frog-bit in Saginaw Bay, Munuscong Bay, and around Alpena on Lake Huron. Previously, it was thought to be established in just a few localized sites in the southeastern Lower Peninsula.

“Responding quickly to a new invasive species is critical to increasing our chances of success, and it requires a well organized, collaborative effort between multiple agencies and other partners,” said Russ Mason, chief of the Wildlife Division for the Department of Natural Resources (DNR).

Thanks to grant funding for the project through the federal Great Lakes Restoration Initiative, control measures were quickly implemented, including physical removal and trial treatments with herbicides. By mid September, 1,500 pounds of the invasive had been pulled out of the infected areas.

Additionally, education, outreach, and future control activities are being planned with angling groups and other stakeholders.

European frog-bit resembles a miniature lily pad, with leaves about the size of a quarter. Forming dense mats, it shades out beneficial submerged native plants, disrupts natural water flow, and inhibits access.

It originally was accidentally released into Canadian waters during the 1930s, spreading throughout Ontario and into New York, Vermont, and other eastern states.

(This article appeared originally in B.A.S.S. Times.)

Wednesday
Mar122014

Asian Carp Eggs Found in Upper Mississippi River

 

Just when we think that we know what is going on with Asian carp . . . 

The U.S. Geological Survey (USGS) says that researchers found eggs, including late-stage embryos, in samples collected last summer from the Upper Mississippi River, as far north as Lynxville, Wisc. 

Here's more from the USGS:

"This discovery means that Asian carp spawned much farther north in the Mississippi than previously recorded," said Leon Carl, USGS Midwest Regional Director. "The presence of eggs in the samples indicates that spawning occurred, but we do not know if eggs hatched and survived or whether future spawning events would result in live fish."

The Asian carp eggs and late-stage embryos were discovered two weeks ago while processing samples that were collected in mid-May and mid-June, 2013. The samples were taken as part of a larger research project designed to identify Asian carp spawning habitats. The eggs and late-stage embryos were 250 river miles upstream of previously known reproductive populations in the river. Spawning would have occurred upstream from this site.

Once the scientists visually identified the eggs, they examined other samples taken from the Mississippi River and found Asian carp eggs at seven locations between Pool 19 near Keokuk, Iowa, and Pool 9 of the main channel of the Upper Mississippi River near Lynxville. Iowa, Missouri, Illinois, Minnesota and Wisconsin border the navigation pools where these samples were collected.

The eggs and late-stage embryos were identified as bigheaded carps — either bighead carp or silver carp — through visual analyses of specific features of the eggs and embryos. It is also possible that some eggs could be from grass carp, although no eggs were visually identified as such. The USGS attempted genetic analyses to definitively determine which species of Asian carp the eggs belong to, but the results were inconclusive. Additional steps are being completed to attempt genetic confirmation, and those results are expected in one to two weeks.

The research project that collected these eggs is being coordinated by the USGS in collaboration with Western Illinois University. Scientists plan to collect additional samples from the Mississippi River in 2014 as part of their on-going research project.

"Invasive Asian carp could pose substantial environmental risks and economic impacts to the Upper Mississippi River if they become established," Carl said. "Further research will help us to better understand their habitat requirements and inform integrated control efforts."  

Wednesday
Mar122014

Fish Pass Through Electric Barrier

The last line of defense against Asian carp entering Lake Michigan isn’t impenetrable, according to a new report by the U.S. Army Corps of Engineers and the U.S. Fish and Wildlife Service.

Fish can pass through the electric barrier unharmed when they get caught in the wakes of barges passing through. And that’s not all. Metal barges can deplete the charge, and small fish aren’t always susceptible.

"Initial findings indicate that vessel-induced residual flows can trap fish and transport them beyond the electrical barriers, and that certain barge configurations may impact barrier electric field strength,” says an interim report based on laboratory and field experiments.

“Additionally, the preliminary (sonar camera) findings identified the potential for small fish (between 2-4 inches in length) to pass the barrier array in large groups, or schools."

The Corps emphasizes that the findings are preliminary, with more work to be done with the barge community and the Coast Guard to see how the barrier can be strengthened.

“There is no evidence that Asian Carp are bypassing the barriers; nor is there any indication Asian carp are in the vicinity of the barriers,” the agency says. “The closest adult Asian carp found in the Illinois River are about 55 miles from Lake Michigan, and no small Asian carp have been observed closer than 131 miles from Lake Michigan.”

Critics point out that water samples taken near the barrier and in a canal on the lake side of the barrier have tested positive for the exotic fish. Plus, poisoning of the canal in 2009 revealed an Asian carp carcass.

Read more here.

(This article appeared originally in B.A.S.S. Times.)

Tuesday
Feb182014

Exotics Take a Bite Out of Wetlands

Nutria photo from Louisiana Department of Wildlife and Fisheries website.

Most anglers know that Asian carp are harming this nation’s fisheries, from the Upper Midwest down to the Gulf Coast and eastward through the Ohio River watershed.

What many do not realize, however, is that other exotics also are doing severe damage. They don’t receive as much publicity because their range is more limited.

But in Louisiana, the nutria, a large rodent, is devouring the wetlands, destroying spawning and nursery habitat for a multitude of important sport fisheries. In fact, the state estimates that damage at any given time is about 46,000 acres, as about 5 million of the web-footed animals with large, orange teeth feed on the roots and stalks of aquatic plants.

Additionally, the giant apple snail also is taking a giant bite out of the wetlands. They’ve been banned from the state since 2012, but that was too late to keep them from becoming a destructive force, courtesy of irresponsible hobbyists who dumped their aquariums into waterways.

“They eat a ton of plant material, anything they can get their tiny little mouths on,” said Michael Massimi of the Barataria-Terrebonne National Estuary Program. “You are converting a water body from one dominated by plants to one dominated by algae.”

Asian carp, tiger prawns, water hyacinth, and giant salvinia also are among the exotic species doing damage to Louisiana’s coastal system.

Some limited good news is that the state’s nutria control plan, implemented in 2002, has lessened the impact of these furbearers, which were imported during the 1930s and promoted as a way to combat water hyacinth and other invasive plants during the 1940s.

Giant apple snails also are gobbling up wetlands.

Still the cumulative effect of these invaders is significant for an ecosystem already under siege. First came decades of habitat degradation and mismanagement, most of it originating from development and water diversions. These actions accelerated erosion and saltwater intrusion, which are crumbling away the equivalent of a football field every hour.

Then came the Deepwater Horizon oil spill and its aftermath, which added to the peril of an ecosystem that is critical for sustaining the food web of the Gulf of Mexico.

Fortunately, the spill also provided impetus for passage of the RESTORE Act, which provides a rare opportunity to restore and enhance the Delta and its wetlands. Guiding that restoration is a multi-state, multi-agency group known as the Gulf Coast Ecosystem Restoration Council.

And a coalition known as Vanishing Paradise is working to make sure that Council members remember the importance of habitat restoration, which can drive and support economic recovery.

“The people, business, communities, and economy of this region are undeniably reliant upon a healthy and productive Gulf, and ecosystem restoration should be the top priority,” said spokesman Ben Weber.

Sadly, passing legislation and creating coalitions will do little to counter the damage already being done by established exotic species, including the nutria and giant apple snail.

But something could be done to lessen the likelihood of future harmful invasions in Louisiana’s marshes and wetlands, as well as other waterways nationwide. Congress needs to strengthen the Lacey Act, which prohibits the import and trade of harmful species.

Here is how bad the problem is: Since the act’s implementation more than a century ago, only about 40 animal groups have been prohibited, and that usually occurred long after they were imported, escaped into the wild, and started doing damage.

By modernizing the Lacey Act, Congress could empower the U.S. Fish and Wildlife Service to first assess the potential risks associated with a species proposed for import before deciding whether to allow or prohibit its trade in the United States. The ineffectiveness of the current law is easily evidenced by Burmese pythons in the Everglades, Asian carp threatening the Great Lakes, and giant apple snails joining nutria in gobbling up Louisiana’s wetlands.