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Entries in zebra mussels (64)

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
May262014

Zebra Mussels Benefit Lakefront Property Owners

The damage done to fisheries and water supply infrastructures by zebra mussels has been documented for decades.

But now one researcher has discovered that these exotic shellfish are benefiting a few lucky waterfront property owners, even as they wreak havoc on ecosystems.

“We find that property values generally are higher on lakes with zebra mussels,” said Martin Meder, a University of Wisconsin economics student who decided to analyze state data for 400 lakes.

With the assistance of Marianne Johnson, a College of Business economics professor, he looked at property assessments for sale of houses on lakes known to be infested with zebra mussels.

Meder added that his research doesn’t address the causation, but “with statistical certainty, I can say that zebra mussels are associated with an approximately 10 percent increase in lakefront property prices.”

He theorized that the increased water clarity that comes with a zebra mussel infestation is one reason for the increase.

And, he added, “Some research has shown that they (zebra mussels) disadvantage some unpopular fish species. They blanket the bottom of the lake bed so carp can’t feed . . .

“They also seem to be advantageous to fish species that people like, like smallmouth bass.”

Friday
Mar282014

Mapping the Invasion

This screen shot shows zebra and quagga mussel invasion as of 2006.

Nature Conservancy has produced some great interactive maps showing how invasive aquatic species have spread out across the country from their point of introduction.

Featured species include bighead and silver carp, zebra and quagga mussels, Eurasian ruffe, round goby, sea lamprey, and black carp.

Also, in late 2012, the organization released a report saying that aquatic invasive species “cost businesses and consumer in the Great Lakes region hundreds of millions of dollars annually in direct costs and even more from indirect costs related to removal, maintenance, and management of those species.

“Meanwhile, state and federal governments are currently forced to spend additional millions as they attempt to control the impacts and prevent the spread of AIS (aquatic invasive species).”

According to the report, the largest industry affected by AIS in the Great Lakes is tourism and recreation, which is responsible for employing more than 90,000 people in the region, generating $30.3 billion annually in revenue. Costs range from monitoring and controlling AIS to lost revenue from beach closings affecting hotels, restaurants and other tourism-related businesses.

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.