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The Saga of the Quagga

Separating the invasive species science from the hyperbole
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SCIENTIFIC STUDIES

Below is a list of studies on the quagga and zebra mussels, and several links to studies referenced in the article. Click on the titles to view the full study or report.

Quagga Mussel Risk Assessment An experiment test of quagga mussel survival and reproductive status using Lake Tahoe water with a prediction of invasion into Western water bodies

Inventory of aquatic invasive species and water quality in lakes in the Lower Truckee River Region: 2012

The Ecological Society of America survey (pdf download) “A calcium-based invasion risk assessment for zebra and quagga mussels” commissioned by the U.S. Environmental Protection Agency: This study puts Lake Tahoe, Donner Lake, and surrounding lakes in the “very low risk” category for quagga and zebra mussel invasion. Less than 10 percent of the country is categorized as “very low risk.”

Potential Distribution of Zebra Mussels and Quagga Mussels Phase 1 Report A Report for the California Department of Fish and Game: “Researchers have generally used or recommended the use of 12-15 mg/L [ppm] of calcium or sometimes lower concentrations … However, the records at the lower calcium levels probably represent either misidentifications, limited or inaccurate calcium data, or non-reproducing sink populations recruited from upstream in higher calcium waters.”

Examination of Calcium and pH as Predictors of Dreissenid Mussel Survival in the California Water Project Prepared for the Department of Water Resources: “12 mg/L [ppm] is given as a threshold for possible long-term survival of adult dreissenid mussels, provided the pH is above 7.8. This conservative calcium value is based on experience from Lake Superior where the pH ranges from 7.9-8.2 but the average calcium level is 13 mg/L [ppm]. Lake Superior has only isolated pockets of dreissenid mussels along the shoreline, despite the fact that the first mussels were documented in Duluth Harbor more than 20 years ago”

Short-term survival and potential grazing effects of the New Zealand mudsnail in an uninvaded Western Great Basin watershed

Truckee Regional Aquatic Invasive Species Prevention Program 2011 Annual Report


CALCIUM CONTENT OF LOCAL LAKES

Lake Tahoe (springtime nearshore average) - 9.16 ppm
(Note: Nearshore calcium levels are typically higher than the rest of the lake, and springtime calcium levels can also be elevated, since this is the period where runoff loads the nearshore with minerals and nutrients.)
Donner Lake- 5.16 ppm
Boca Reservoir – 3.09 ppm; 6.6 ppm
Stampede Reservoir- 2.75 ppm; 6.1 ppm
Prosser Reservoir- 4 ppm; 6.7 ppm
Martis Creek Reservoir- 5.5 ppm; 8.7 ppm
Independence Lake- 4 ppm
Marlette Lake- 3 ppm; 3.9 ppm
Spooner Lake- 25.9 ppm; 28.6 ppm

(Note: Where two readings are shown, they represent an early summer average reading and a late summer/early fall average reading in 2012.)
Source:
Inventory of aquatic invasive species and water quality in lakes in the Lower Truckee River Region: 2012, UNR

For nearly five years, the campaign against invasive species in the Lake Tahoe area has been spurred by the specter of the environmental devastation created by two mollusks — small, aggressively invasive bivalves called quagga and zebra mussels.

But an in-depth review of national scientific studies reveals that the poster child for local invasive species programs has almost no chance of surviving long-term in local waters. Millions of dollars have been spent trying to keep mussels out of Lake Tahoe, Donner Lake, and surrounding reservoirs, despite the fact that scientific studies suggest the prolific little bivalve can’t colonize these calcium-poor bodies of water.

A new examination of this science has derailed a mandatory boat inspection program that was scheduled to take effect this summer at Donner Lake. After passing an ordinance mandating fee-based inspections last August, Town of Truckee officials have backtracked and are now recommending that the mandatory inspections be put on hold as they investigate the scientific underpinnings of the program. Voluntary boat inspections are still scheduled to take place this summer at Donner Lake and Boca, Prosser, and Stampede reservoirs as they have in years past.

But the science also raises larger questions — questions about how limited and poorly funded local scientific research was able to trump national scientific studies on mussel invasion risks; and questions about how invasive species program advocates have taken limited and conflicting scientific information and, according to one critic, generated a distorted picture of a lake under imminent threat of mussel invasion.

THE SCIENCE
The most critical factor for zebra and quagga mussel survival — and the reason Lake Tahoe and Donner Lake are among the nation’s most inhospitable lakes for mussel invasion — is the calcium content of the water.

Mussels thrive in calcium-rich waters, filtering out the element and using it to build their shells and support their basic metabolic function. Lake Mead, the southern Nevada water body where some of the dire, worst-case-scenario examples of mussel infestations have occurred, has calcium levels of 80 parts per million (ppm) and water hardness levels of 288 ppm. In these conditions, quagga mussels grow large, reproduce rapidly, and colonize aggressively.

But Lake Tahoe has calcium levels that are merely one eighth those of Lake Mead, and Donner Lake’s calcium levels are even lower —  less than half of the nationally recognized minimum calcium threshold for mussel survival. An average of three calcium readings last fall put Donner Lake’s calcium levels at 5.2 ppm, or about 15 times lower than Lake Mead’s concentrations. Despite those average calcium readings, the concentrations do fluctuate throughout the season and vary in different parts of the lakes. Some small areas of Tahoe’s shoreline have registered higher concentrations, including readings of 12.4 ppm at the Tahoe Keys Marina and localized elevated calcium readings of 24.1 ppm taken from the sediment of Asian clam beds in the Ski Run Marina. Spooner Lake is the lone local lake with lake-wide calcium levels high enough to support mussel invasion.

Numerous scientific studies say that zebra and quagga mussels cannot survive at calcium levels below 12 ppm. And even at 12 ppm calcium levels, test cases across the nation show that mussels do not flourish. In places like Lake George and Lake Superior, where borderline calcium levels of 12 and 13 ppm exist, mussels have been introduced, but have not colonized either lake.

But for years, Tahoe residents heard little about the science that showed Lake Tahoe and Donner Lake were at very low risk of mussel invasion. Instead, they heard stories about Lake Mead, with photos of quagga-encrusted boat propellers from the southern Nevada reservoir that is a starkly different habitat than the Sierra Nevada, and stories about the tens of millions of dollars of damage the creatures create. And when the public did hear about scientific studies, they heard mostly about one 51-day, low-budget study that for the last four years has heavily influenced invasive species policy in the Lake Tahoe region.

THE MUSSEL RISK ASSESSMENT   
In 2008, with the science pointing to Lake Tahoe as being at “very low risk” of mussel invasion, according to the Environmental Protection Agency-commissioned “A Calcium-Based Invasion Risk Assessment for Zebra and Quagga Mussels” (see sidebar), a team of scientists received $20,000 to do a local experiment on the mussel’s ability to survive in Lake Tahoe water. Led by Dr. Sudeep Chandra, an associate professor of limnology and conservation ecology at the University of Nevada, Reno, the team transported eight mussels from the waters of Lake Mead to the UNR lab, and placed them in water taken from the Tahoe Keys in South Lake Tahoe. Tahoe Keys water is among the warmest, most calcium-rich and nutrient-laden water you can find anywhere in Lake Tahoe. Despite the fact that one mussel died and the rest were losing body weight by the end of the experiment, the study reported that, “The possibility exists for at least adult quagga to survive, grow, and reproduce in the Lake Tahoe environment …  the diligent monitoring of recreation vehicles (the major pathway for transfer of invasive mussels to inland lakes) putting into western lakes-of-interest is prudent. The assumption that western oligotrophic waterbodies low in calcium are at very low to low risk of quagga mussel invasion is not necessarily supported.”

The report did not research the full life cycle of quagga mussels, including the ability of vulnerable mussel offspring (called veligers) to survive in Tahoe. Studying the ability of mussels to reproduce in an environment is the true measure of risk, since the threat of mollusks is directly tied to their rapid colonization of an environment. A non-reproducing “sink population” of mussels would only survive for the animal’s three- to five-year lifespan.

Steve Urie, a long-time Donner Lake homeowner who has extensively researched the quagga mussel issue, studied the scientific process of Chandra’s laboratory experiment and found flaws in the process.

“The ‘study’ and its conclusion is equivalent to raising tomatoes in a Sacramento greenhouse, transplanting them in a Meyers’ garden in July, and noting that because the tomatoes were still alive on Labor Day that the Tahoe Basin would be a fine area for tomato farming,” wrote Urie in an article submitted to Moonshine Ink.

The report did recognize some of its own shortcomings. The risk assessment said: “It is possible that the individuals collected from Lake Mead had sufficient reserves for survival, and even moderate growth, in any (non-toxic) environment for the 51-day duration of the experiment.”

The fact that adult quagga mussels could survive in Lake Tahoe water for 51 days should not have been surprising. Tahoe’s own invasive species education material says that the mussels can survive for up to a month completely out of water.

“In Tahoe, adult quagga mussel can survive out of water for as long as 30 days!” says the website of Tahoe Keepers, a kayak and non-motorized watercraft inspection group affiliated with the Tahoe Regional Planning Agency.

The study even theorized that the mussels were possibly cannibalizing their own shells to generate enough calcium for survival.

[pagebreak]

But those messages did not make it into the mainstream. Following the 2008 research and 2009 publication of the report, media and press release material portrayed Lake Tahoe as susceptible to widespread mussel invasion.

Statements like this one, posted on the University of Nevada, Reno website under the headline “Researcher Finds Quagga Mussel Can Survive In Tahoe” were common: “If established, the mussels could forever alter the lake’s sensitive ecology; they could clog water intakes, encrust boats and docks, and cover now-pristine beaches with sharp and reeking shells.”

By the time the message made it to the media, the picture of Lake Tahoe’s mussel threat became even more distorted. An August 2009 San Jose Mercury News article led off: Scientists say a new study shows invasive quagga mussels can survive and possibly reproduce in Lake Tahoe.

“This could potentially be catastrophic for the lake,” said Ted Thayer, natural resource and science team leader for the Tahoe Regional Planning Agency.

Despite the ambiguous results, limited scope, and short timeframe of the study, Chandra’s 2009 risk assessment has been the lone, local science on the quagga mussel survival matter for the last four years.

“It is scientifically unconscionable that an inconclusive, four-year-old laboratory study that did not meet minimum comparative or scalability standards should justify spending millions to prevent an extremely unlikely problem from occurring,” wrote Urie.

And that is not the only limited, short-term report that Chandra had published on local invasive species threats. Chandra was one of the authors of a 2011 report on the ability of the New Zealand mudsnail to survive in the Truckee River watershed and Lake Tahoe.

That experiment only lasted two weeks, even though the study’s own introduction stated, “The ability of [New Zealand mudsnails] to survive for up to three weeks out of water contribute to the species’ ability to expand its range.”

Later on the report said: “Ideally, the experiment would have occurred over more than 14 days, but the need for immediate information to assist with ongoing management decisions as well as funding limitations necessitated the short duration of the experiments. In fact, results from this, as well as other studies in the region, led to the establishment of new guidelines for boat permitting and inspection at Lake Tahoe to proactively reduce the likelihood of nuisance aquatic species introductions.”

When questioned about why further study of the mussel risk was not completed, Chandra said that until now funding was not available to complete studies on the mussel’s full life cycle in Lake Tahoe, or to conduct an experiment that included more than one site, or lasted more than 51 days.

That has now changed. Chandra and a team of researchers were recently funded to complete a more in-depth study this summer, and results should be released this fall. The study will last between 120 and 160 days, Chandra said. It will use water from the Cave Rock area as well as the Tahoe Keys. And it will study the entire life cycle of the animals.

DONNER LAKE: MANDATORY INSPECTIONS ON HOLD
If it were not for the more than 500 hours of intense scientific research that Truckee resident Steve Urie has conducted over the past several months, all watercraft entering Donner Lake would likely have to undergo mandatory inspections, and each boat would have been charged a boat inspection fee this summer.

Urie, a retired businessman with a degree in civil engineering, was intimately familiar with Donner Lake, having lived on the lake for 30 of the 40 years he has been a local resident.

His interest in invasive species was first sparked when he heard California Sen. Dianne Feinstein say in a speech at the 2010 Lake Tahoe Summit: “If you organized all the Asian clams currently in the lake end to end, it would stretch 3.5 miles long.”

Being an engineer, Urie began calculating how many clams it would take to organize a single-file line of clams 3.5 miles long, and concluded that quantity of clams would likely fit into the back of a pickup truck.

“It just did not make sense to me. The reports that came out were so exaggerated,” said Urie.
The more Urie investigated the issue, the more intrigued he became. He read dozens of studies and reports on the calcium requirements of mussels, conversed with experts across the state, and researched years of Tahoe and Donner Lake water studies.

After the equivalent of more than two months of full-time research, he delivered a seven-page, sourced position paper to the Town of Truckee. Urie’s stance was summed up in one of the last sentences of the paper: “No legitimate AIS [aquatic invasive species] threats to Donner Lake have been identified, and until one is, it is illogical and impractical to implement a needless fee-based program that inconveniences residents and visitors alike.”

After an April Town of Truckee invasive species working group meeting where Urie and Chandra had a spirited debate over the topic, the Town of Truckee decided to recommend that the mandatory boat inspection ordinance not be enforced this summer, and that voluntary inspections continue.

“It was the right result. It is exactly what they should have done,” said Urie. “If they had taken off with this, we would have had a boat inspection program at Donner Lake forever. It is one of those government programs that once it gets going, you can never pry it away from them.”
One of the issues the Town of Truckee faced was that the ordinance they passed specifically identified mussels as the invasive species that was being targeted, and declared that the mussels were an “imminent” threat.

“There is obviously not a significant or imminent threat,” said Dan Olsen, the Town of Truckee’s animal services and code compliance manager, following the decision by the town to not recommend mandatory inspections this summer.

CHANDRA'S RESPONSE
Chandra emphasizes that while zebra and quagga mussels have made all the headlines, “it is not all about the mussel. If we make this just about mussels, we are in very deep trouble.”

Chandra lists a number of invasive threats to the region, including curlyleaf pondweed, Brazilian elodea and hydrilla. Curlyleaf pondweed is already growing in Lake Tahoe.

But Urie says that Donner Lake and the reservoirs in the area would be unlikely targets for an invasion of these plants. The annual fluctuations of the water bodies’ levels exposes bare ground along a significant portion of the shoreline to freezing temperatures, greatly reducing the risk of large-scale exotic plant invasions.

And many of the invasive species that can impact an ecosystem — creatures like Asian clams and crawdads — have already established in Donner Lake.

[pagebreak]

But Chandra is essentially erring on the side of caution. With inconclusive and incomplete science on invasive species, he said his approach has been to “be protective first, and back away from protection later.”

“We actually don’t have a handle on these species and the plasticity of them,” said Chandra, noting that more research is needed for the science to be able to more accurately pinpoint invasive species threats.

“That is unfortunately how the science has not caught up,” he said. “We have not caught up to tell you, plant-by-plant, what might invade an area.”

ARE INSPECTIONS AN EFFECTIVE BARRIER?
Donner Lake and other local lakes have long been exposed to invasive species. And even today, the voluntary inspections are a patchwork that leaves hundreds of boats to launch uninspected in local waters each year. At Donner Lake, boat inspections have only occurred at Donner Lake’s public boat ramp. The other two heavily used ramp facilities — Tahoe Donner’s marina and a homeowners’ launch on the west end — have had no boat inspections.

Even at local reservoirs, boaters can simply drive to the edge of the lake off of a dirt road and back an uninspected boat into the water.

“There is no way to control that unless you shut off access to the lake,” said Truckee Animal Control Manager Olsen.

So far, the costs of the voluntary inspections have been borne by the Truckee River Fund, a group supported by the Truckee Meadows Water Authority, which has given the Tahoe Resource Conservation District nearly $1 million over the last four years to conduct boat inspections. That funding is dwindling, and the Tahoe Resource Conservation District was expecting inspection fee revenue to begin to pay for some of the costs beginning this summer.

Tahoe pays nearly $1.5 million a year to run its boat inspection program. Only about half the program is funded by fees; the other half comes from public money.

In Truckee, Urie believes that putting the mandatory inspection on hold as the science and risk is evaluated is the proper procedure. At the final invasive species working group meeting, Urie asked about a Donner Lake risk assessment noted by one presenter. When he was told the risk assessment was not published, and later told that the risk assessment was simply notes from meetings and presentations that had not even been compiled into a complete document, he wondered how a program could be put in place.

“You are asking the Town of Truckee to put in place pretty invasive procedures, and you are basing it on a risk assessment that has not been published?” he asked. “I think there is some real dereliction to ask to put in place a program that there are no facts to support.”

The Town of Truckee and the Tahoe Resource Conservation District say they are willing to re-examine the science behind the program.

“I am not opposed to this discussion happening right now,” said Kim Boyd, the assistant district manager with the Tahoe Resource Conservation District. “I think this is a great time to have this discussion and really evaluate the risks.”

But Brian Hanley, a local boater, said he thinks that if Urie had not spent 500 hours investigating the science behind invasive species, the outcome of the boat inspection program process would have been much different.

“I think if Steve [Urie] had not been there, the science may have been ignored,” said Hanley.

~ Comment on this story below.

 

Reader comments so far...

Rosamond's picture

Rosamond
Nevada Division of Wildlife has confirmed that they have found the invasive New Zealand Mudsnail in the Truckee River. http://www.rgj.com/article/20130514/NEWS/305140055/Invading-snails-discovered-Truckee-River-watch-video-?nclick_check=1 New Zealand Mudsnails have made a mess of aquatic ecosystems all over the West since their invasion into Idaho in the 80s. As Dr. Sudeep Chandra has repeatedly stated, the need for inspections of boats coming into our region is not simply an issue of a single invasive species, but rather, it is a necessary program that should reduce the probability of any number of invasives making it into the lake and its surrounding water bodies. Unfortunately, your paper has chosen to use its pages to promote doing away with the inspection process in our area. I can only hope that your vociferous but myopic position on these matters is disregarded by the state agencies responsible for protecting our waterways. Ultimately, these ecosystems do not belong to us; they belong to our grandchildren. And I believe we as a society should do what we can to avoid squandering our grandchildren's inheritance. Apparently, you disagree.

dbunker
Chris, Thank you for commenting on this article, and for the recent column you contributed to Moonshine Ink. I am glad that you, as a biologist and researcher, have lent your perspective to this issue. Unfortunately, I think you misunderstand and misinterpret the role of Moonshine Ink, and myself as the author of this article, in the discussion over invasive species. As a journalist, I am relaying the scientific background on invasive species, telling the story of the mandatory boat inspection program at Donner Lake, and relating the history of the local science that has been conducted on the issue. I do not "promote doing away with the inspection process in our area" or hold a "vociferous but myopic position" on the issue. I do, however, believe that public agencies and non-profits funded by taxpayer money should be responsible for answering questions about the scientific backing for enacting regulatory, fee-based programs. There are certainly very legitimate issues about how the invasive species program has been marketed to the public that deserve some questioning. The Town of Truckee passed an ordinance that said quagga and zebra mussels were an "imminent" threat to Donner Lake and surrounding waters. As a biologist with a technical understanding of water chemistry, you know this is incorrect. Perhaps more, not fewer, questions about the scientific justification of the program should have been asked at the outset of this process. Equally, the mandatory inspection program itself deserves some scrutiny. If invasive species truly are a grave threat to the ecosystem of Donner Lake, perhaps we should inspect more than one of the three boat launches at Donner Lake. Finally, I think a discussion of the thoroughness of the local science that has been conducted on the issue is in the interest of the public. Should we base a $1.5 million-dollar-a-year mandatory boat inspection program at Lake Tahoe on a $20,000 study that was conducted for 51 days on mature mussels that have proven they can live for nearly 30 days entirely out of water? Should we base a New Zealand Mudsnail risk level on a two-week study of a mud snail that has proven it can live out of water for three weeks? In my opinion, these are legitimate questions. If your opinion on the matter is that there are a lot of invasive species that may or may not be able to live at Donner Lake, our local reservoirs and in the Truckee River, and we should instate mandatory boat inspections to be safe rather than sorry, I respect that opinion. But even with that position there are many questions that remain. If Donner Lake is under imminent threat of invasive species invasion, should each paddle boarder and kayaker be inspected? What about wintertime boat inspections? As opposed to the unfounded allegations in your comment that I am somehow advocating the "squandering of our grandchildren's inheritance," I do care deeply about our ecosystem. Hyperbolized attacks and inaccurate statements like that comment about me are, in my opinion, one of the problems with the invasive species campaign to date. If we could stick to a constructive discussion about the actual threats to our local ecosystem, the science about invasive species, and the best methods to guard our local waterways from degradation, I believe the community would be much better served. Thanks for commenting on the article. I appreciate the dialogue. David Bunker
Rosamond's picture

Rosamond
The native mussels, Anodonta californiana, and Margaritifera falcata, have survived and evolved in our Northern Sierra waters for millennia. Of these, Anodonta was found in both Tahoe and Donner Lakes. I ate a few of these rubbery creatures as a kid, when we lived on the east end of Donner. They’ve become quite rare in Donner, (hopefully not due to my adolescent appetite in the 60s), and CDFG has not found any native mussels at all in their mussel surveys of Tahoe to my knowledge. Margaritifera still occurs in the Truckee and Walker rivers, in very low numbers. The genetic variability between the remaining small, highly localized populations of Margaritifera falcata is sufficient that, if they were mammalian species, we might be considering whether to call them separate subspecies or even species. Of course, in the event of a successful introduction of non-native mussel species, the aforementioned 2 genera would be competing with the non- natives. Extirpation (localized extinction) is an all too common result when specialized, non-compeitive western aquatic taxa have attempted to compete with aggressive generalist non-natives. Frankly, though, I suspect that these taxa may well be wiped out of Donner within my lifetime due to human disturbance of their habitat anyway. I mostly bring these genera up as an introduction to the concept of DEMES; localized populations with little genetic flow among populations or sub-populations, resulting in localized adaptations and, sometimes, speciation. The Quagga mussel shows a definite tendency toward genetic/physiological variability among regional invasive populations, which is stated in the study of Chandra et. al, but not reported in your articles in Moonshine Ink. Stepien et al (2002) showed that genetic variability is high in Quaggas, with marked genetic divergence between native European populations and invasive North American populations, as well as high variability among North American populations. https://www.utoledo.edu/nsm/lec/pdfs/Stepienetal2002.pdf As it turns out, the variation between North American and European populations is putatively expressed in variability between these populations’ Calcium requirements, with the Eastern North American populations exhibiting substantially lower Calcium requirements (20mg/L) than those of European populations (28mg/L) . The Chandra report explained this issue very clearly, but was ignored in your and Steve Urie's quagga articles for Moonshine ink. I'll be charitable and presume you simply forgot to point this out. This well documented variability is one very weighty reason that we should be cautious, and not presume that physiological requirements of populations in the most recently invaded Western North American habitats are identical to those of eastern North American Populations. As for your protestations regarding the cost of the Invasives program in Tahoe, David, approximately 1.5 billion Tourism dollars are spent within the Tahoe basin annually, which generates something to the tune of 150 million state and local tax dollars annually. Do I think that we should spend 1% of that money to reduce the probability of aquatic invasive species being brought into the most unique lake in North America via recreational boats? You betcha. I’ll continue to deconstruct your and Steve Urie’s assumptions, assertions, and misunderstandings in a series of posts as soon I have the time. Expect my presence in this forum for quite some time. Just the facts.

dbunker
I am not quite sure what your argument is here, Chris. Are you saying that we should have boat inspections because quagga mussels might evolve into a species that can live in Donner Lake in the future? I am aware that the Eurasian quagga and the North American quagga have differing habitat requirements, but it should be noted that quagga mussels have been shown to have a higher calcium threshhold than zebra mussels (Jones, Ricciardi, 2005). Donner Lake's latest calcium readings were at 5 ppm. All reputable national science on the species says that quagga mussels cannot live in an environment with that little calcium. It is a question of public policy whether the Town of Truckee or other municipalities would want to enact regulations and enforcements based on the possibilities of future genetic mutations of an invasive species. I do think the issue of the genetic variability of the species would be a rich subject for future research.
Rosamond's picture

Rosamond
David, the thesis of your article is that there is "virtually no possibility of Quagga invasion" in Tahoe. I am merely laying the groundwork as to why the reading public and management agencies should not simply take your opinion article as an unequivocal account of the factual information. I'm not sure how you interpreted what I wrote as an advocacy of management decisions based on potential "future genetic changes" of Quaggas. The high degree of EXISTING genetic variability in Quaggas is in fact an important and to some extent unknown variable in the equation. As Chandra's paper explicitly stated, we do not know enough about the genetics and physiologic tolerances of the most recent Western North American invasion of Quaggas to be able to say with much certainty what the risk is of an invasion without experimental data from those actual organisms. This is, of course, why his group is being funded for the current round of studies on the matter. Lastly, I would like to ask you directly, as you've gone to some effort to repeatedly remind the reading public that you object to 1.5 million dollars being spent annually on boat inspections/aquatic invasive intervention in the Tahoe basin; Given the fact that tourism dollars alone in the Tahoe basin produce ~150 million dollars of state and local tax revenue annually, why would you object to spending what amounts to only 1% of that tax revenue to protect the lake from invasives? If you object to that level of funding for boat inspections, what, if any, level of funding would you deem "reasonable"? I have a number of other points to make regarding your opinions and interpretation of the conclusions of the Chandra study, which I'll get to later, but today is a rock climbing day.

dbunker
Chris, If you are making the case that existing genetic variability in quagga mussels is creating a breed of quagga mussel that can live in low calcium water, you should probably back that up with some science. While you denigrate my article as an "opinion article," I have thoroughly researched and cited numerous nationally published scientific studies to back up the statements I made in my article. While you cited one study on the genetic variability, you have shown no evidence that this relates in any way to the quagga's ability to live in low-calcium waters. On the public funding issue, perhaps this will make sense to you. Being a journalist is similar in some ways to being a scientist. We research and present fact independent of our own personal opinions on topics. You completely misread me, when you say I "object to 1.5 million dollars being spent annually on boat inspections/aquatic invasive intervention in the Tahoe basin." My personal opinions on the topic are not injected into my article. I would hope the same of scientists. As a professional journalist, however, it is my job to ask questions about public policy when there is legitimate cause for question. Contrary to what you say, I believe that if $1.5 million is truly protecting Lake Tahoe from environmental destruction, that is clearly a very small price to pay. If, however, scientific evidence shows that the species we have been protecting ourselves from to the tune of $1.5 million a year is unable to live in Lake Tahoe or surrounding lakes and reservoirs, then I do think there are some legitimate questions about the program. Happy rock climbing Chris. I enjoy the discussion. David Bunker

West Shore Gal
Regardless of if the Quagga and zebra mussel can survive and reproduce in the waters of Donner and Lake Tahoe doesn't mean that we should halt the inspections since there are plenty of other aquatic invasive species (AIS) that can be introduced into our lakes. It seems to me that David is just trying to point out that the public has possibly been mislead by what the actual threat of an invasive mussel infestation could be, since these mussel have become the "poster child" for the AIS program in our region. I don't know specifically what AIS Donner Lake already has in it besides for the Asian clam, but Tahoe has invasive weeds that can be spread between the two lakes very easily. Then there's Fallen Leaf Lake, which has a mandatory washing stations for all boats including non-motorized to keep Tahoe's invasive species out of Fallen Leaf Lake. Of course, there's the New Zealand Mud Snail being found in the Lower Truckee River, where does the water in the Truckee come from??? Maybe the snail should be the new "poster child". I'd like to know what the calcium levels of the Boca/Stampede/Prosser reservoirs are. Reservoir systems are very different from natural lakes, and Lake Mead is a reservoir.

West Shore Gal
I just saw the calcium levels listed above. No need to answer that question.

TruckeeObserver
What was the Truckee Council's logic when they imposed inspections on Truckee's public town ramp, but neglected to require inspections on privately owned boat ramps? Groupthink? Do invasive species somehow not attach to boats owned by members of private homeowner associations (HOA's)? Are there any financial or other connections (or conflicts of interest) between the Town Council members and the private HOA's in town? "At Donner Lake, boat inspections have only occurred at Donner Lake’s public boat ramp. The other two heavily used ramp facilities — Tahoe Donner’s marina and a homeowners’ launch on the west end — have had no boat inspections."

Denise Klempay
Thank you, Mr. Rosamond, for understanding the scientific process, and attempting to painstakingly point out to this "journalist" that one cannot simply find a few articles that are convenient to ones point and call it research. I especially like when the "journalist" attempts to put you down for only citing one article, while he has found a few. Does he want an "attaboy"? Sure, journalism and science could potentially be comparable, but not in this case. Science requires accountability and the compilation of all available data, not just one set of numbers taken out of context. It is your job as a journalist to provide all of the facts. Perhaps you are finding yourself a little out of your league here? As for Steve Urie, the only thing he, and the writer of this article, have managed to articulate is that the need for science education in this country is astounding. These "articles" was deeply upsetting to me as a scientist, intelligent woman, and Tahoe area resident. They should be discounted by all who read them. If you are reading this, and would like to find out more information about invasive species, please turn away from these articles and check out invasivespecies.gov or any of the amazing local agencies around the Tahoe area! Thank you, again, Mr. Rosamond, for your shared passion on the subject. Denise Klempay, BS Zoology Kent State University.

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September 12, 2014