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Entries in invasive species (195)

Tuesday
Feb242015

Mussels Could Be Contributing to Toxic Algae Blooms

Proposed reductions in phosphorous runoff from agricultural lands might not be enough to counter Lake Erie’s increasing susceptibility to toxic algae blooms, according to University of Michigan researchers.

"Our results suggest that current phosphorus loading targets will be insufficient for reducing the intensity of cyanobacteria blooms to desired levels, so long as the lake remains in a heightened state of bloom susceptibility," said lead author Daniel Obenour of the university’s Water Center.

That “heightened state” led to nearly half a million Ohio and Michigan residents being deprived of drinking water for several days in early August because of a cyanobacteria bloom containing the toxin microsystin.

The problem seems to be that the blooms are becoming more sensitive to phosphorus, according to the scientists.

But what has caused this and the corresponding increase in size of cyanobacteria blooms since the mid 1990s? That’s not so easy to explain.

Computer modeling revealed that a special form of phosphorus, DRP (dissolved reactive phosphorus) is more readily absorbed by algae, but it did not explain increased bloom susceptibility. Also, late-summer surface water temperatures did not increase enough to exacerbate the problem.

Exotic quagga and zebra mussels, however, could be a factor. The filter-feeding shellfish gorge on many species of phytoplankton, but avoid those that produce toxins. In other words, the latter now have less competition for nutrients, including phosphorus.

"We tested to see if the increase in the DRP fraction could be the cause, and it did not pass the test. It also does not look like water temperature is driving the increased susceptibility,” said Don Scavia, co-author and aquatic ecologist. “We're thinking it may have been the increase in mussels.

"As long as the lake remains in this heightened state of susceptibility, this problem is likely to persist,” he added. “That means we need to better understand what is driving the increased susceptibility and whether it can be controlled, or if deeper phosphorus reductions are needed.”

Wednesday
Feb182015

How About a Nice, Cold Beer Brewed With Zebra Mussel Shells?

Slowly but surely, the public is awakening to the value of Asian carp as food.

And what possibly could go better with a carpburger than mussel beer?

More specifically, a Milfoil Lakehouse Saison Ale, brewed with zebra mussel shells and Eurasian watermilfoil by Excelsior Brewing Co. on Lake Minnetonka. The beer with the “exotic, invasive flavor” is promoted as a way to heighten public awareness about the problems caused by exotic species.

This past fall, Grumpy’s Limited Action Beer Fest challenged breweries to develop beer using only Minnesota ingredients, and Excelsior decided it wanted to push the envelope. It blended Minnesota wild rice, Minnetonka honey, and local hops with a small dollop of aquatic hitchhikers.

“We thought, ‘We’re going to take this to the extreme,’” said Paul Awad, a spokesman for the brewery. “It ended up being a really great beer.”

He explained that only tiny amounts of milfoil and mussel shells were used, and filtering prevents beer drinkers from finding a trace of the ingredients in their glasses. “Neither of them adds a lot of flavor. It’s more the novelty of it,” he said, adding that the brew tastes like many Saisons, with fruity, spicy overtones.

Ryan Anderson from MNbeer.com wasn’t particularly surprised by the mussel/milfoil beer. “There are some breweries out there trying some crazy things,” he said.

For example, seaweed as an added ingredient is becoming more common, while other micro breweries are trying things like fish bladders and oyster shells.

“It’s definitely a kind of interesting thing,” he said of the Excelsior beer. “But stranger things have happened.”

Meanwhile, a spokesperson for the Department of Natural Resources said the exotic brew “sounds really unusual.”

Before this latest offering, Excelsior already created beers that honored its lakeside location, including Big Island Blond Ale. Additionally, 1 percent of its profits support the popular fishery via donations to organizations such as the Freshwater Society.

Meanwhile, in the Cafeteria . . . 

The University of Missouri is testing recipes and gathering reactions as it considers adding the invasive Asian carp to the menu in its dining halls.

About 40 students tried different recipes using the fish during recent taste tests at the Sabai Culinary Development Kitchen on the Missouri campus, and their reactions will help the culinary staff decide whether to serve the fish.

Monday
Jan192015

Divers Capture Another Invader in Florida Waters

Surgeon fish photo by Deb Devers

Congratulations to two divers who had the good sense to report and then capture an exotic fish. Their actions might have prevented its establishment in Florida waters.

The two first noted the small, bright yellow fish while SCUBA diving beneath Palm Beach County’s Blue Heron Bridge, and realized that they never had seen one like it. They took photos and later reported what they had seen to the Reef Environmental Education Foundation (REEF), a non-profit that keeps track of exotic marine fish species.

According to the Miami Herald, REEF identified the fish as a mimic lemon peel surgeonfish, also known as a chocolate surgeonfish. It’s native to the Indo-Pacific, and this was its first sighting in Florida waters. Upon learning that, the divers returned to where they had first seen the fish and captured it.

"We don’t know what the effects would have been if the fish had become established and began reproducing,” REEF said. “But if we wait to find out, then it’s too late.”

Taking out the surgeonfish could prove to be the fourth preemptive strike against a non-native marine fish species in Florida coastal waters, according to the organization.

In 1999 and 2002, REEF staff and volunteers captured four large Indo-Pacific batfish from Molasses Reef in Key Largo. In 2009, they removed a whitetail dascyllus damselfish from the east side of the Blue Heron Bridge. In 2012, Miami divers Greg Caterino and Wayne Grammes speared an exotic humpback grouper on a reef off Biscayne National Park and turned the carcass over to REEF. None of those three species are known to have reappeared in Florida waters since their removals.

“Some people might say, ‘Oh big deal, we took this little fish out of the water,’” REEF said. “But that’s the way the lionfish got started. If only we could have taken the first few lionfish out of the water in the first place. We’re relying on divers, snorkelers and fishermen to be our eyes and ears on the water. It’s a perfect example of how early detection and rapid removal can be successful in stemming an invasion.”

Anyone who spots a strange-looking fish that they suspect is invasive is advised to take a photo and report the sighting to REEF.

Friday
Oct242014

Finding Ways to Tame Lionfish

Years ago, Missouri wildlife managers decided to reduce an exploding deer population in a St. Louis suburb. But instead of culling the herd humanely, they bowed to pressure from animal lovers, and, at great expense, trapped and moved deer to a more rural area.

Follow-up research revealed that those deer died of starvation. They had grown so accustomed to eating tulips, roses, and other domesticated plants that they did not recognize wild forage.

Besides showing the folly of trying to manage wildlife by emotion instead of science, this example reveals one of the reasons that exotic species can become so prolific and troublesome in their new habitats. Native species do not see them as food, and, consequently, their populations are free to grow unchecked by predation.

Down in the Caribbean, divers are trying to do something about that by teaching sharks to eat invasive lionfish. The latter are gobbling up native species, especially reef fish.

“From a scientific point of view, we don't know how successful the project is. But, apparently, recent videos show native top predators are starting to eat lionfish without them being previously speared by divers,” says a marine biologist. (Go here to see some great photos of sharks eating lionfish.)

Meanwhile, lionfish populations have declined around Jamaica because another species is eating the invaders --- man.

Dayne Buddo, a Jamaican marine ecologist who focuses on marine invaders at the Caribbean island's University of the West Indies, attributes much of the local decrease in sightings to a growing appetite for their fillets. He says that Jamaican fishermen are now selling lionfish briskly at markets. In contrast, a few years ago island fishermen "didn't want to mess" with the exotic fish with spines that can deliver a very painful sting.

The same strategy eventually may help us control Asian carp in the nation’s rivers and impoundments. Go here to check out my post about that.

Friday
Oct172014

Ground Zero for Asian Carp Invasion

Havana, Ill., is Ground Zero for the Asian carp invasion, according to the Illinois Department of Natural Resources. On the Illinois River, it’s about 200 miles south of Lake Michigan and 120 miles north of the Mississippi.

“You find more carp per acre, per mile of river, tan nearly anyplace else in the world,” says Kevin Irons, DNR’s Asian carp program director.

If you doubt that, check out this video.

Based on electrofishing surveys, bighead and silver carp now account for about 60 percent of the fish biomass in that stretch of the river. That means native species have declined dramatically because the exotics outcompete them for food and habitat.

And peaceful boat rides are a thing of the past because of silver carp, which go airborne when startled.

“People have been hit and seriously injured,” says DNR’s Matt O’Hara. “I know there have been some cases of broken noses and jaws.

“Pretty distressing when you come out here and you’re looking for native fish, and all you see is invasive Asian carp,” he adds.