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"Invasive Mussels Threaten Great Lakes"


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#1 Guest_az9_*

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Posted 22 April 2011 - 07:46 PM

Mussels Threaten Great Lakes
April 22, 2011



Invasive mussels feed on single-celled plants called diatoms, which until recently bloomed each spring and were used as an indicator of overall algal production in the Great Lakes. (Credit: Mark Edlund).

The invasion of two species of mussels is causing massive ecosystem-wide changes by stripping two of the planet's largest freshwater lakes of life-supporting algae.

Previous studies have linked the zebra and quagga mussels to far-reaching changes in Lake Michigan's southern basin. New research finds the same dramatic changes are now occurring in northern Lake Michigan and throughout Lake Huron, as well, endangering the multi-billion dollar U.S. commercial and recreational fishing industries.

"These are astounding changes, a tremendous shifting of the very base of the food web in those lakes into a state that has not been seen in the recorded history of the lakes," says Mary Anne Evans, research fellow of natural resources and environment at the Univ. of Michigan. "We're talking about massive, ecosystem-wide changes."

The study is reported in the journal Environmental Science & Technology.

Because the changes are so profound and are happening so rapidly, the Great Lakes management agencies should consider reviewing and perhaps revising policies so they can respond more quickly.

"New strategies for managing the lakes are urgently needed. Ecological changes that formerly occurred over decades are now happening in just a few years, so we need to adapt our management policies to this new reality," says Donald Scavia, professor of natural resources and environment and civil and environmental engineering.

This recommendation is especially relevant in the context of the current review of the Great Lakes Water Quality Agreement by the International Joint Commission, Scavia says. The United States and Canada jointly manage the Great Lakes through the IJC.

Though the zebra mussel is better known to the public, over the past decade it has largely been overshadowed by the quagga mussel, which can thrive far from shore in deep, mud-bottomed waters. Each of the fingernail-size quagga mussels filter about a quart of water a day, and billions of them now blanket the bottoms of lakes Michigan and Huron down to depths of nearly 400 feet.

They feed on algae, including single-celled plants called diatoms that are encased in glass-like shells made of silica, which the diatoms extract from lake water. Until recently, the diatoms "bloomed" each spring in the Great Lakes, and the level of silica in upper lake waters dropped as diatoms built their protective shells, then sank to the lake bottom, taking the silica with them.

The drop in silica levels due to the spring diatom bloom, known as the seasonal drawdown, has long been used as an indicator of overall algal production in the Great Lakes.

A review of records of silica levels in lakes Michigan and Huron collected over the past 30 years by the Environmental Protection Agency, shows that algal production throughout the two lakes was about 80 percent lower in 2008 than it had been in the 1980s.

In Lake Michigan, the decrease in the seasonal drawdown coincided with an explosion in the quagga mussel population and its expansion to greater depths, which began in 2004. The same changes occurred a few years earlier in Lake Huron, where quagga mussels greatly increased in abundance between 2000 and 2003.

"For years, all the talk was about the zebra mussels. And then its close cousin comes in, the little quagga mussel, and wreaks even more havoc on these huge offshore systems," says Gary Fahnenstiel, senior ecologist with the National Oceanic and Atmospheric Administration.

"These changes are unprecedented," he says. "In terms of algal abundance and water clarity, lakes Michigan and Huron are now similar to Lake Superior."

By filtering out the algae, the mussels are robbing other organisms of the food they need to survive. Of particular concern is the plight of Diporeia, a tiny shrimplike creature that was one of the pillars supporting the base of the Great Lakes food web.

Nearly every fish species in the Great Lakes relies on Diporeia at some point in its life cycle. But Diporiea populations have crashed in lakes Michigan and Huron, and the change is already impacting Great Lakes commercial fisheries and the sport-fishing enterprise.

"The big question now is how large the quagga mussel population will get," Evans says. "And when it gets as big as it can get, will it stay at that level or will it die back because it has decimated its own food supply? We don't really know what to expect at this point."

The work was funded in part by NOAA's Center for Sponsored Coastal Ocean Research.

Source: Univ. of Michigan

I have to question the naiveity of thinking there could be some way to "manage" an invasive species in such large bodies of water. Why can't we just close the damn barn door (as in ship ballest water) before the next invasive exotic or pathogen makes its way in?

#2 Guest_fundulus_*

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Posted 22 April 2011 - 08:55 PM

Nice repost. But the answer to your question is that the shipping industry doesn't give a poop about invasives and can generate lots of sympathy for that position among elected officials for all the usual reasons.

#3 Guest_wargreen_*

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Posted 23 April 2011 - 06:41 PM

I have to question the naiveity of thinking there could be some way to "manage" an invasive species in such large bodies of water. Why can't we just close the damn barn door (as in ship ballest water) before the next invasive exotic or pathogen makes its way in?
[/quote]

No, they could......I just dont know if they will.

#4 Guest_wargreen_*

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Posted 23 April 2011 - 06:47 PM

Nice repost. But the answer to your question is that the shipping industry doesn't give a poop about invasives and can generate lots of sympathy for that position among elected officials for all the usual reasons.



Maybe the answer in controlling these invasives is stocking more Pumpkinseed sunnies and Freshwater Drums. Has their been any research into what natives eat the Quagga mussels veligers?

Edited by wargreen, 23 April 2011 - 07:07 PM.


#5 Guest_EricaWieser_*

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Posted 23 April 2011 - 07:54 PM

Zebra mussels have been in the Great Lakes since 1988 (source: http://www.glu.org/c...ves/zebramussel ). This isn't a new issue or anything we can really change at this point. I'd be interested to see what sort of native species eat zebra mussels, though. It would be nice to reintroduce some of the extirpated species back into Lake Erie and have their population be sustainable again by eating the mussels. Here's a list of the fish of Lake Erie if anyone wants to point out some big mussel eaters: https://kb.osu.edu/d....pdf?sequence=1

#6 Guest_fundulus_*

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Posted 23 April 2011 - 09:25 PM

One or two native duck species are the best predators of zebra and quagga mussels. Now that you mention it I'm not sure about the mussels' reproductive biology. It could be that they spawn out of sync with possible native predators of their veligers so that there's relatively little mortality at this stage? But that's a handwave.

#7 Guest_az9_*

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Posted 23 April 2011 - 10:24 PM

delete

Edited by az9, 23 April 2011 - 10:25 PM.


#8 Guest_az9_*

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Posted 23 April 2011 - 10:24 PM

Nice repost. But the answer to your question is that the shipping industry doesn't give a poop about invasives and can generate lots of sympathy for that position among elected officials for all the usual reasons.


Repost?

#9 Guest_ashtonmj_*

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Posted 25 April 2011 - 07:42 AM

How about a title change moderators to invasive mussels?

#10 Guest_farmertodd_*

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Posted 25 April 2011 - 10:11 AM

Ducks only browse the invading species in shallow water. Turtles, crayfish and a HOST of fish species (both native and exotic) have been shown to eat dreissenids, and may be a large part of the naturalization of these species. The trouble in the upper lakes is that these fish species are not grossly abundant (drum, channel catfish, carp) as they are in the more southern portions, and lake sturgeon haven't had time to get through multiple recruiting series because it's so long to maturity.

I have a list of references about species who eat dreissenids in a recent paper about the native Unionid mussels showing up in huge densities in western Lake Erie. I'd be glad to post that in the library if people feel that would be beneficial.

This all said... Be careful what you infer from Great Lakes Fisheries research. I will literally walk out of a talk if they start a rant again about diporea crashing because of dreissenid invasion - they've been giving talks (ie not writing papers which are peer reviewed) for a decade now on the correlation of the crash with incidence of the invading mussels. There have been no lab tests, enrichment test, mass balance tests of these hypotheses, and so the inference might just be another "Flying Spaghetti Monster", so to speak. If they would at least TRY to get into the mechanisms beyond inference, I'd be happy to listen again. In my opinion, and a few others that I've been starting to run into, there is a tendency to completely ignore human contributions to any trend (what part of 35 million pounds of annual Coregonid harvest ISN'T catching their attention?) or have any regard for historic community assemblages, levels of system productivity and how those two topics relate across scales of time. A more cynical part of me feels... well, I don't need to say any of that in public ;)

That said... Close the damn locks already!!!

I also agree with Matt that the title of this thread should be modified.

Todd

#11 Guest_fundulus_*

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Posted 25 April 2011 - 03:36 PM

The title refers to an article being reposted here, so as such it's accurate. The science may be dubious or inexact, but that's a different issue.

#12 Guest_az9_*

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Posted 26 April 2011 - 12:33 PM

The title refers to an article being reposted here, so as such it's accurate. The science may be dubious or inexact, but that's a different issue.



But i don't recall this title being posted before, certainly not by me. Not a big deal just missing something here I guess.

#13 Guest_wargreen_*

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Posted 29 April 2011 - 11:07 AM

Zebra mussels have been in the Great Lakes since 1988 (source: http://www.glu.org/c...ves/zebramussel ). This isn't a new issue or anything we can really change at this point. I'd be interested to see what sort of native species eat zebra mussels, though. It would be nice to reintroduce some of the extirpated species back into Lake Erie and have their population be sustainable again by eating the mussels. Here's a list of the fish of Lake Erie if anyone wants to point out some big mussel eaters: https://kb.osu.edu/d....pdf?sequence=1



That was such a good idea that I did some research over a couple of days (when I wasnt working); and yes there is a species that is native to the St. Lawrence river that has been found to eat small Dreissena mussels, has a long life span, high growth rate and very large Pharyngeal teeth and is considered rare in its native range......(Im letting the tension build :-& )..... its the Moxostoma hubbsi, the Copper redhorse. Im thinking about e-mailing USGS Great Lakes Science center and asking if they currently have any hatcheries raising mussel eaters to help reduce the damage the invasive mussels are causing.

#14 Guest_mywan_*

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Posted 05 May 2011 - 12:15 PM

Even if the Copper redhorse has a minimal effect on the mussels it would still be cool to get some reseeding of the diversity of the great lakes following such an extensive trophic rearrangement. I also wonder if the mussel population will ever fall back some when they reach their food supply limit and what the zooplankton level will be at an equilibrium with the mussels.

The fact sheets all over the internet tend to bullet an all or nothing mentality in defining what is so bad, sometimes leading to some outright false claims. Consider this USGS zebra mussel FAQ where it says:

http://fl.biology.us...ussel_faqs.html

Most people assume that this increased visibility in the water must mean the water is "cleaner". Not true. All they have done is filter out all the algae which normally would be food for native microscopic organisms.


As a matter of fact when a mussel filter it does not discriminate between food and nonfood. Everything big enough to fit and gets stuck in the mucous. The food particles are transported to the mouth while the nonfood gets ejected, still contained in the mucous trap, as pseudofeces, which remains on the floor of the lake. So as a matter of fact the water column is indeed 'cleaner'. These pseudofeces are then form an enriched benthic food chain, and what is not consumed as food gets layered over in sediment burying the contaminates that would have otherwise remained in the water column. Also, the eggs and free swimming larvae appear to have been overlooked when considering mussel predators. From the perspective of theoretical ecology the zebra mussels have the potential to multiply the biodiversity of the ecosystem many times, but would require a significant and diverse number of mussel predators which tends to be somewhat limited for an invasive species like zebra or quagga mussels.

I am not trying to make a case for zebra mussels, or any invasive, but it is irritating to see presumptions based on the law of the excluded middle to be presented as facts. I would love to see a more serious comparison in the structures are densities of zooplankton and related ecosystem variances throughout the water column before and after mussel invasions. Sometimes we just have to get past good and bad and look at the facts.

#15 Guest_wargreen_*

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Posted 15 May 2011 - 08:54 AM

Even if the Copper redhorse has a minimal effect on the mussels it would still be cool to get some reseeding of the diversity of the great lakes following such an extensive trophic rearrangement. I also wonder if the mussel population will ever fall back some when they reach their food supply limit and what the zooplankton level will be at an equilibrium with the mussels.

The fact sheets all over the internet tend to bullet an all or nothing mentality in defining what is so bad, sometimes leading to some outright false claims. Consider this USGS zebra mussel FAQ where it says:

http://fl.biology.us...ussel_faqs.html


As a matter of fact when a mussel filter it does not discriminate between food and nonfood. Everything big enough to fit and gets stuck in the mucous. The food particles are transported to the mouth while the nonfood gets ejected, still contained in the mucous trap, as pseudofeces, which remains on the floor of the lake. So as a matter of fact the water column is indeed 'cleaner'. These pseudofeces are then form an enriched benthic food chain, and what is not consumed as food gets layered over in sediment burying the contaminates that would have otherwise remained in the water column. Also, the eggs and free swimming larvae appear to have been overlooked when considering mussel predators. From the perspective of theoretical ecology the zebra mussels have the potential to multiply the biodiversity of the ecosystem many times, but would require a significant and diverse number of mussel predators which tends to be somewhat limited for an invasive species like zebra or quagga mussels.

I am not trying to make a case for zebra mussels, or any invasive, but it is irritating to see presumptions based on the law of the excluded middle to be presented as facts. I would love to see a more serious comparison in the structures are densities of zooplankton and related ecosystem variances throughout the water column before and after mussel invasions. Sometimes we just have to get past good and bad and look at the facts.


I completely agree that we need to focus more on the facts, (and even what would eat their pseudofeces or if it becomes part of the permament lake sediment); and I think now would be the best time to start reintroducing native fish to help control these invasive mussels (copper redhorses, freshwater Drum and Pumpkinseed sunnies), I didnt find alot of research on what fish would eat Zebra and Quagga mussel veligers, but I believe from my reading that Paddlefish and Gizzard shad eat the veligers of other mussels and would be good candidates.

#16 Guest_don212_*

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Posted 16 June 2012 - 09:22 PM

last time i was on the st lawrence a new invasive, a gobie was everwhere, and the talk was they were reducing the mussel population, is that true, for divers zebras zebras improve vis remarkably, but you have to wear gloves or suffer a thousand papercuts, also they destroy historic wooden wrecks.




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