Opinion: Quiet demise of TRPA’s Asian clam program
By Steve Urie
In a recent Voices post, (Collaborate over good policy, Lake Tahoe News, Nov. 28), I criticized the Tahoe Regional Planning Agency for carpeting acres of Lake Tahoe with rubber mats in a futile attempt to eradicate Asian clams. Since 2008, millions have been spent on the failed project that killed many more animals native to Lake Tahoe than the nonnative clams. Mercifully, when the 35 tons of mats that covered 5 acres of Emerald Bay were rolled up last month, the project was placed on hold, and there is no plan to reuse the mats.
In the November post, I wrote that Asian clam shells don’t create high-calcium microzones where quagga mussels can survive, a reason that TRPA and UNR Professor Sudeep Chandra used to justify the eradication program. I also said that the clams slightly decrease dissolved calcium by absorbing it from the water to build their shells and for muscle function.
Steve Urie
A respondent to the article, who identified himself as Cosa Pescado, wrote: “Living [Asian clams] absorb calcium, yes. And the dead ones leave shells that release calcium. Baseline calcium is low for Tahoe. What is also telling about your understanding of science is that you mentioned limestone as a source of background calcium. It certainly is … the remnants of living organisms are responsible for the calcium in limestone.”
Although Cosa Pescado’s response appears logical and some aspects of his argument are correct, the science is wrong. He says that baseline calcium is low for Lake Tahoe — about that he’s correct, it’s exceptionally low. Tahoe’s average shore zone dissolved calcium is 9.16 parts per million. (The minimum calcium threshold for survival for Asian Clams is 6.5 ppm and for quagga and zebra mussels it’s 12 ppm — only 9 percent of all U.S water bodies have dissolved calcium less than 12 ppm.) Whittier, et al., 2008
Cosa Pescado also accurately points out that the remnants of living organisms are responsible for the calcium in limestone. But he then inaccurately implies that clam shells add to calcium concentrations in the water column, creating what Chandra calls “calcium hot zones.”
For all practical purposes, the total amount of calcium in Lake Tahoe is constant. There is a tiny increase from concrete leaching and natural sources, but the vast quantity of Tahoe’s water quickly dilutes it, and the average annual increase from external sources is minute. Asian clams and the half dozen native Tahoe mollusks filter calcium to build their shells, which reduces the lake’s dissolved calcium and proportionately increases the solid calcium — but the total calcium remains the same.
Measurable reduction of calcium in the water column by mollusks has occurred in the Great Lakes. In a research report, Long-term trends of Great Lakes major ion chemistry, scientists attribute slightly decreased dissolved calcium in the lower Great Lakes water to zebra mussels.
Like all mollusks, zebra and quagga mussels need calcium to build their shells, and they get it from the water. Hypothetically, how much calcium is needed to raise Lake Tahoe’s dissolved calcium from 9.16 ppm to 12 ppm? It would take approximately, 1.48 million tons of pure limestone (CaCO₃) to raise the lake’s dissolved calcium by 2.84 ppm. That’s enough limestone to fill a freight train stretching for 80 miles from Oakland to Sacramento — it is estimated that all of the Asian clam shells in Lake Tahoe would fit in a large dumpster.
Cosa Pescado also takes issue with my statement that because “Asian clams live on detritus and algae that they filter from the water, they actually improve water quality and clarity,” and he writes that that the clams “fecal matter concentrates nitrates,” which degrades water quality. That is true, but the logic error is similar to that which he makes with dissolved calcium — the clams remove more waste than they create.
All of Tahoe’s native mollusks and Asian clams are prodigious filter feeders, and steadily remove pollutants, micro-particles, algae, bacteria, and waste from the water; convert it to shell material and use it for muscle energy and function. Unarguably, they measurably improve clarity and water quality. This has been demonstrated over the last 20 years in Lake Michigan where water clarity is greater than at any time since the 1950’s. That Asian clams improve water quality was even acknowledged in a study in which Chandra was a principal investigator: Natural and Human Limitations to Asian Clam Distribution and Recolonization.
But looking at the larger picture of whether the Asian clam control program was not only a colossal waste of money, but also environmentally destructive, in 2013 Chris Rosamond, a freshwater biologist at UNR’s Desert Research Institute and a colleague of Chandra’s, wrote: “I would concur [with the] disdain for the ‘Keep Tahoe Blue by putting big blue tarps all over the bottom and killing everything’ approach that has been used these last few years.
“In addition to the initial shock of suffocating whatever native benthic organisms there are in these locations, the anoxic conditions under these tarps will alter nutrient dynamics in the benthic substrates, particularly phosphorus and nitrogen cycling. Recall that nitrogen and phosphorus are our two greatest pollution concerns in the basin. In short, sterilizing the floor of Tahoe’s shallow habitats through suffocation is probably not a viable long-term solution.”
Last month at Emerald Bay, Rosamond was proven to be correct.
The Wittmann study also states: “Costs of Asian clam treatment in Lake Tahoe were approximately $210,000 per acre. A hypothetical 100-acre area for treatment indicates that total costs of treatment can range [up to] $26 million and will neither achieve eradication, nor the maintenance of low density populations of Asian clams in Lake Tahoe.”
In other words, suffocating clams with rubber matting is prohibitively expensive, even if it were effective.
The quiet demise of the Asian clam control program won’t be as hyped as its rollout was, but it is long past due, and Tahoe is the better for it.
Steve Urie is a 40-year Tahoe-Truckee resident and is the author of “Tessie, Quagga Mussels, and Other Lake Tahoe Myth’s. To learn more about Tahoe’s AIS programs go online.
A note to Cosa Pescado: “The Science” reference in my November post was not put in quotes to cheapen science or employ sarcasm, but to direct the reader to “The Science” tab on the website, where science studies and articles relevant to the Asian clam program and other TRPA AIS prevention and control programs can be found. Since you have an obvious interest in the subject, but aren’t willing to spend $10 to buy the book, please use “Contact” on the website to send me a postal address, and I will send you a complimentary copy.
“But he then inaccurately implies that clam shells add to calcium concentrations in the water column, creating what Chandra calls “calcium hot zones.””
Usually when a writer ends a paragraph with something like that they follow it up with some analysis.
[Ca] is higher on shell beds.
Your evidence that it is not: (conveniently missing, insert rehash of previous letter)
What is the real reason behind this disinformation campaign?
Who is this guy?
Okay, I’ve got a question. I’m obviously no scientist, nor am I promoting some screwball view of science or politics.
But if clams are surviving in the Lake and building their shells out of the calcium that exists in the Lake, it sounds like pretty much of a zero sum situation. They might be drawing the calcium out of some calcium rich compound, but long run, it seems to me that the clams are developing their shells from the natural calcium that exists in the Lake. And, somewhere in the great circle of life (appropriately, borrowing from Disney) the calcium returns to the Lake sometime after the clams move to clam heaven, leaving their calcium remains behind to eventually return to the ecology of the Lake.
It appears to me that any increase in Lake calcium has to be coming from outside streams and plant life and tourists using the old Tums hangover cure. From the arguments I’m reading on Kae’s life work, the clams are only cycling the calcium through several of its various iterations.
So, before I see another Disney movie to sharpen my scientific knowledge, someone ‘splain to me why, absent what’s carried into the Lake by streams, calcium, at least among clams, isn’t a zero sum equation.
Don’t worry; I’m not a Republican. I don’t include “faith” in any discussion.
Cosa Pescado, you ask: What is the purpose behind this disinformation campaign? It’s to get the science right. Copper is correct when he says that total calcium in the lake is “a zero sum equation.”
Since 2008 TRPA has spent millions to kill Asian clams by suffocating them with rubber matting. It didn’t work. The clams cause no harm, but TRPA continues to promote that they increase dissolved calcium. They don’t.
Why then does UNR professor Sudeep Chandra and TRPA promote that they do? It’s because an explanation is needed as to how Tahoe’s calcium can reach 12 ppm — the minimum threshold for quagga mussel survival.
At last spring’s AIS Forum, a question was asked whether boat inspections are unnecessary because the calcium levels in the lake are too low to support a mussel population.
TRPA’s Dennis Zabaglo answered: “While calcium levels in the middle of the lake are extremely low, in discreet and isolated areas such as around Asian clam beds, calcium is at a level where they can establish.”
Those “discreet and isolated areas” are the “calcium hot zones” Chandra says will support quagga. There is no area in Lake Tahoe that can support quagga, and that is why there is disinformation about Asian clam shells.
Even though the rubber mat method of eradicating clams failed, another study is investigating whether electric rakes or bottom-scraping machines will kill the clams. (I don’t know about you, but I wouldn’t want to be the volunteer raking the shoreline to kill clams.)
It’s a complicated issue that can’t be explained in a few paragraphs, and my offer stands to send you a free copy of the book, or it’s available on Amazon.
I’m not sure why Mr. Urie is criticizing the process of the science around “matting” the clams. Many things have been tried to eradicate invasive species. Rubber mats seem relatively benign compared with adding invasive predator species, or poisoning the clams.
So you try something new, spend some money, and find out if it does, or doesn’t work, and if it doesn’t, you pull the plug on the project. But you don’t mock the scientist who tried something new. This experiment followed the path of good science, which often results in experiments that don’t have the results that were hoped for.
But Mr. Urie seems to mock the process. Did Mr. Urie know beforehand that it wouldn’t work through some divine revelation? Or is he just self promoting.
AS for the clams, filter feeders do clarify the water, which is good, but they also clarify the waters of fish, which is not good. So focusing on calcium concentrations ignores the bigger picture of the disruption of benthic and midwater species that occurs. For an example, just look at the decreased sport fishing in the clarified Great Lakes.
RP, I just had to laugh with the term “good science” in regard to Lake Tahoe.
The following questions “What is the real reason behind this disinformation campaign? Who is this guy?” Should be directed to cosa pescado.
Everyone, Lake Tahoe conservation is entering a new paradigm, one without multi million dollar boondoggles. To move into a fiscally sustainable future, accept what didn’t work and consider Steve’s opinion piece. It’s well researched and worthy of thoughtful review. For an anonymous blogger to question who Steve is, well that’s funny strange
It is my understanding that the mats are quite effective at killing milfoil. I hope that they will be repurposed in the Tahoe Keys and marina at a reasonable cost to the homeowners and association.
To steve urie: So your saying that Chandra and Zabaglo are not using water quality sampling results to support their theory for calcium hot zones. Next we will find out that matts have never worked anywhere to control clams! I will get your book- thanks.
Yes Steve, the mats haven’t worked anywhere to kill the clams. Only New York’s Lake George has tried the method, and it didn’t work there either. When they were found in a 4-acre site in Lake George in 2010, Ted Thayer from TRPA and Chandra went there and convinced them to try to control the clams with the rubber mat method. Since then the clams have spread to multiple sites more than 20 miles apart. This fall Lake George also admitted defeat and rolled up their mats for the last time too.
Kurt, your idea of using the mats to kill weeds in the Keys is an excellent idea.
RP, it is too long to completely recount, but in fact there were at least four tests before the Emerald Bay project began. Population surveys of the clams from a pilot that was done in Marla Bay showed that the clams repopulated to near 100% within 22 months — less time than the mats were down in Emerald Bay to kill them. That knowledge was known by the researchers before they carpeted the bay with the rubber matting.
You write: “Focusing on calcium concentrations ignores the bigger picture of the disruption of benthic and mid-water species that occurs. For an example, just look at the decreased sport fishing in the clarified Great Lakes.”
The greatest negative impact to sport fishing in the Great Lakes was not by mollusks, but by lamprey eels. In fact, University of Michigan researchers claim that zebra mussels in the lakes are returning them to their more natural benthic state. But that can’t happen at Lake Tahoe because there isn’t enough dissolved calcium to support zebra or quagga mussels.
But the real travesty with the method is that it kills all life under the mats, including at least a dozen native species. And I not only mock the method, but I ridicule the science and TRPA for not being more diligent in how they use public money and the efficacy of their AIS programs.
And anyone who has plowed through this exchange this far and wants to read the book, please send your mailing address through “Contact” on the website linked in the article. I’ll send you a free copy.
Ok Steve, what “exactly” are your qualifications in regards to Invasive Species and what to do about them?
Those “discreet and isolated areas” are the “calcium hot zones” Chandra says will support quagga. ***There is no area in Lake Tahoe that can support quagga***, and that is why there is disinformation about Asian clam shells.
You are creating BS hot zones that support your disinformation.
Steve Urie is misrepresenting science. I don’t know why. It doesn’t seems like general ignorance. This is intentional. They are assuming that you haven’t read the research papers, and won’t. Banking on ignorance, so they can twist the facts to support whatever it is they are up to. I suspect it is political, given the amount of effort that has gone into this disinformation.
Don’t buy their book and don’t take their word for anything until you have read the research papers. And then compare the research against what Urie is saying, and see if he is misrepresenting the science. I highlighted two simple examples that I believe misrepresent the science. That asian clam shells increase Ca availability in beds, and that because of this there are places where Q/Z mussels can establish. I know there are many more gaping holes in Urie’s argument.
I don’t have the time to address all of them. I just wanted to give the readers a heads up that this guy might be an unreliable source of information.
copper: The presence of shells is a local concentration of calcium that would otherwise be distributed more or less evenly in all of Lake Tahoe. The Ca input into the lake is effectively zero, the concentration is overall low. But once the clams establish the calcium in the local system becomes more available. Shells dissolve in water and release Ca. The closer you are to shells, the more Ca is available.
You should read the research papers. The material can be dense and boring but you can do it.
rock: I am glad you showed up. No one needs a specific degree to discuss this, just a basic understanding of science. College experience would be helpful, research papers are unfamiliar territory for most people.
Rock4tahoe, I have a degree in environmental engineering, but it’s not necessary to have studied anything beyond high school chemistry, biology, and English to understand the study reports that are linked in the main article.
Whittier, et al., 2008 was done for the U.S. EPA by a team of Oregon State researchers. The study evaluated 15 major dreissenid mussel studies and correlated five to 10 years of calcium data from 3,091 U.S. streams and rivers and established calcium thresholds for quagga and zebra mussel survival, colonization, and infestation. Neither species can survive in water with less than 12 ppm. Tahoe’s nearshore, where calcium is greatest, averages 9.16 ppm. The rest of the lake is about 8 ppm.
Whittier established the guidelines that are used by the nation’s 40-plus management programs to assess the threat of potential mussel infestations in their regions. One AIS management program — Lake Tahoe’s — ignored the Whittier study and did its own.
There are also easy to read articles and reports that are linked on “The Science” tab on the website that is linked in the main article.
Cosa Pescado, by saying that you don’t have time to read the science and don’t know why what I say is wrong but know that it is BS saves me a lot of time in responding. However, you do write: “The closer you are to shells, the more calcium is available.” Google “Why doesn’t calcium carbonate dissolve in water.” Pure limestone is calcium carbonate. Mollusk shells are approximately 40% calcium carbonate. Calcium carbonate does dissolve, but very slowly.
You also write: “The presence of shells is a local concentration of calcium that would otherwise be distributed more or less evenly in all of Lake Tahoe.” True, but it’s not dissolved and when it is dissolved it quickly distributes. That’s easy to observe. Buy a food color tablet and drop it in the lake – you will see how fast dissolution works. If you come up with anything other scientific theory, let me know. And encouraging that no one buy a book that you haven’t read will certainly hurt sales — typically, after reading all of the information, thinking people like to make up their own minds about what is true and what is misrepresented. Regardless, I’ve already promised anyone who asks for a free copy that one will be sent.
What is the calcium concentration on mussel beds?
You conveniently left that number out.
“Cosa Pescado, by saying that you don’t have time to read the science”
I never said that. You are ‘putting words in my mouth’. That’s a pretty dishonest and intellectually lazy tactic.
I read the research papers years ago and was at two different Tahoe Science Consortium conferences where the research was presented. I know what I am talking about, you foolishly thought you could slip one past people like me. I don’t have time to take on all of your misrepresentation. Limnology and biology in general is not my thing, I have other research papers to read and only so much time.
You really need to elaborate on this earlier statement:
‘There is no area in Lake Tahoe that can support quagga’
Is this your opinion? Is this based on research you didn’t cite? Do you have anything to back that up (specific paper, pages, figures, etc)?
Do you have plans to submit your book to the Tahoe Science Consortium?
Cosa Pescado, there are no mussel beds in Lake Tahoe. TRPA and Chandra claim the dissolved calcium above the clam beds is slightly higher than other areas in Tahoe, but that is inconclusive, and even if it were the case it makes no difference. Quagga veligers (larvae) drift for about a month as they develop shells before they attach to a surface. Drop a weighted fishing bobber above a clam bed in Lake Tahoe and see how far it drifts in a day.
You are right. You didn’t say that “you don’t have time to read the science.” You said, “I know there are many more gaping holes in Urie’s argument. I don’t have the time to address all of them.” I falsely assumed you were addressing the science I cite and had read it. Sorry.
Yes, I stand by the statement that “there is no area in Lake Tahoe that can support quagga.” Since you claim to have read Whittier, you know that a lake has to have dissolved calcium of at least 20 ppm to support dreissenid colonization – and you know that no area of Lake Tahoe has a concentration nearly that high.
No Dam = no clams
No dam = no clams?
Ok Steve. Many years ago, I went down to Round Hill Pines beach and was appalled by the fluorescent green “stuff” floating in the water like some sort of algae bloom. I believe the green “stuff” was linked to the Asian clams.
Note: lookup “asian clam algae bloom in Lake Tahoe” for images.
Later, the mats were placed as an experiment to kill of the Clams. Just this past summer, on various trips to Round Hill Pines beach, I saw no green “stuff” as before. However, at Pope Beach you can collect all the Clam shells you want just about twenty feet off shore. They are pretty small but also pretty visible. I am no expert, but I am guessing they are Asian. I have been swimming at Pope Beach for over forty years now and have not found clam shells there until very recently.
All this talk of Calcium and research is fun, but is Lake Tahoe better off with Asian Clams? In my opinion no. Is using mats to kill Asian Clams effective, seems to have worked at Round Hill Pines Beach to me. Is there a better way to rid Lake Tahoe of Asian Clams? I don’t know.
As for the Quagga Mussel ability to live in Lake Tahoe. I have read articles that say yes. You say they can’t. Do you want to take the gamble?
Whole lotta guessing and assuming goin’ on here, r4t.
I’ve only been to RH Pines a few times over the years, but never saw any slime. So if I assumed the same way you do, I’d say there is no problem and has never been one.
But I try not to make such assumptions based on so little evidence.
Dog. Again, search “asian clam algae bloom in Lake Tahoe” for images on the internet.
Also, I was good friends with a Boat Captain that used to work out of Round Hill Pines on daily tours and he was the one that told me about the slime in the first place.
“Cosa Pescado, there are no mussel beds in Lake Tahoe”
Sorry, I meant clam beds.
What is the calcium concentration on **ASIAN CLAM** beds?
You conveniently left that number out.
Steve, on clam beds [Ca] is greater than 20.
“Since you claim to have read Whittier, you know that a lake has to have dissolved calcium of at least 20 ppm”
The minimum calcium threshold for survival for Asian Clams is 6.5 ppm and for quagga and zebra mussels it’s 12 ppm — only 9 percent of all U.S water bodies have dissolved calcium less than 12 ppm.) Whittier, et al., 2008 “The minimum calcium threshold for survival for Asian Clams is 6.5 ppm and for quagga and zebra mussels it’s 12 ppm — only 9 percent of all U.S water bodies have dissolved calcium less than 12 ppm.) Whittier, et al., 2008
Which one is it Steve. It looks like you are ‘moving the goal posts’ to support your opinion because it is very weakly supported by data.
Are there areas with elevated calcium levels in the lake?
Are those areas on clam beds?
The science shows that both answers are ‘yes’.
So how can you deny ‘calcium hot spots’?
I haven’t read the book, nor will I because the author’s academic integrity is suspect, but I imagine it would be a great case study in pseudoscience and disinformation. Submit it to the Tahoe Science Consortium, see if they take you seriously.