The Mystery of the SRALP: "No Physa acuta were found."

Editor's Notes - If you’re just joining us.  This is the fourth and final installment in my 2013 series on the Snake River Physa controversy.  It won’t make any sense unless you back up and read February, March and April first.  I’m serious, I mean it, and I’m in no mood to be trifled with, this month in particular.

This essay was subsequently published as: Dillon, R.T., Jr. (2019d) The Mystery of the SRALP: No Physa acuta were found.  Pp 187 - 192 in The Freshwater Gastropods of North America Volume 4, Essays on Ecology and Biogeography.  FWGNA Press, Charleston.

Over two years have passed since the Dixie-cup showdown in Boise, and I will admit that I have been anticipating the formal publication of the Gates & Kerans report with mixed emotions.  On the one hand, I was pleased to see that the replacement of the Minidoka Dam spillway was approved shortly after our meeting in September of 2010 [1] and that actual construction got underway in November of 2011.  On the other hand, the “Record of Decision” published by the USBR after our September meeting contained language strongly implying that its water management options had been significantly narrowed by the presence of putatively endangered physids in the Minidoka tailwaters.  And a regular program to monitor physid populations has been continued through the duration of the spillway replacement project, to the present day.

So the Gates & Kerans paper was published online in late December, with old-fashioned paper publication following in February of 2013 [2].  And I was initially encouraged to see that a substantial volume of fresh sequence data has been added since 2010, and that the authorship has been expanded to include John Keebaugh, Steven Kalinowski, and Ninh Vu [3]. But my heart sank when I read these five words: “No Physa acuta were found.”

As I flipped through the pages of the PDF reprint I recognized much that was familiar: the heroic 2006-08 survey of the Minidoka Dam tailwaters yielding 274 small, oddly-shaped physids, the anatomical observations “courtesy of John B. Burch,” and the mtDNA gene trees with outgroups fished from GenBank, none sampled closer than Wyoming.

In addition, the authors reported an expansion of their mtDNA survey to include a very peculiar sample of physids collected hundreds of miles downstream from the Minidoka Dam (RM 675), all the way across southern Idaho.  Here is the single line from their methods section relevant to this enlarged sampling effort, quoted verbatim: “Museum dredge samples collected from the Snake River between RK 322 (RM 200) and RK 948 (RM 589) from 1995 to 2003 were re-examined to determine species distribution.”  The authors did not offer any explanation regarding the gear or methodology used for “dredging,” but one might infer that samples thus obtained came from deeper water, not from the shallows.

The (N=19,427!) individual physids in this “museum dredge sample” were screened for their match to Taylor’s [4] original description of the P. natricina shell: “small size (maximum of 4.8 – 6.9 mm shell length, plotted above), ovoid shape, inflated body whorl, well-impressed suture, broadly rounded anterior end with a wide aperture making the greatest width anterior to the midlength of the shell, microsculpture of oblique growth lines, and a series of parallel spiral lines consisting of curved arcs with their concavity toward the shell aperture.”  Through this elaborate winnowing process passed 52 individuals (collected from RM 559 to RM 368), 15 of which yielded mtDNA sequence data.  All 15 of the new, downstream mtDNA sequences matched the sequences previously recorded from the Minidoka tailwaters and referred to Physa natricina in 2010.

Gates and colleagues concluded, “Our results confirm the original description of P. natricina as an endangered species and expand the extant distribution” some 200 river miles downstream from the range suggested by Taylor, all the way across Idaho into Hells Canyon on the Oregon border.

And you found no Physa acuta?  Did you even consider getting off I-84 anywhere between Twin Falls and Boise, driving five miles south, wading ankle-deep, bending over and simply picking up any of the plain, ordinary, crappy, acuta-like Physa that you have been repeatedly told for five years [5] are as common as cockroaches in that river?  Or did you gin up a meticulous sampling scheme cynically designed to exclude the 99.7% of the snails in your sample that might possibly be identified as a Physa acuta?

No Physa acuta were found?  Did you even look on Sunday morning, 19Sept10, when we visited the Minidoka tailwaters together [6]?  Or did three of you literally turn your backs on me and spend hours sampling a habitat where you knew no Physa acuta (of any standard morphology) could possibly be found, in an overt and calculated effort not to find them?

No Physa acuta were found?  What did you do with the 30 snails I handed you [7] on Monday morning, 20Sept10, before God, the Bureau of Reclamation, the US Fish & Wildlife Service, and the choir of malacologists invisible?  Flush them down the toilet?

No Physa acuta were found?  Carve it on the tombstone of the misbegotten excuse for a science that calls itself “Conservation Biology.” 

Science and politics do not mix.  When they have bastard children, science is recessive.  Gates, Kerans and their colleagues may have positioned themselves well to write new proposals, win new grants, train more students and perpetuate their wretched enterprise in the waters of the Snake River for years to come.  But I am done with it.

Notes

[1] A nice selection of documents having to do with the Minidoka Dam Spillway Replacement project, including the Environmental Impact Statement and the Record of Decision, are available from the USBR website here: [USBR Minidoka page]

[2] Gates, K. K., B. L. Kerans, J. L. Keebaugh, S. K. Kalinowski & N. Vu (2013) Taxonomic identity of the endangered Snake River physa, Physa natricina (Pulmonata: Physidae) combining traditional and molecular techniques.  Conserv. Genet. 14: 159-169.  [html]

[3] I was surprised not to find the name of John B. Burch among the authors.  On 21July09 I was in the audience for a seminar given by Prof. Burch at the AMS meeting in Ithaca, where he presented a great deal of background information on P. natricina as the senior author of a paper with John Keebaugh and Taehwan Lee.  And at the Boise meeting of 20Sept10 he defended the morphological observations as though they were his own.

[4] Taylor, D. W. (1988) New species of Physa (Gastropoda: Hygrophila) from the western United States. Malac. Rev. 21: 43-79.

[5] Rogers, D. C. & A. R. Wethington (2007) Physa natricina Taylor 1988, junior synonym of Physa acuta Draparnaud, 1805 (Pulmonata: Physidae). Zootaxa 1662: 45-51.

[6] The Mystery of the SRALP: A twofold quest!  [1Mar13]

[7] The Mystery of the SRALP: Dixie-cup showdown!  [2Apr13]

SFS Meeting Jacksonville, May 19 - 23

To the FWGNA Group:

This is a cordial invitation to any of our friends who might be packing for next month's meeting of the society formerly known as NABS.  Please stop by to see me at the "Taxonomy Fair" Wednesday afternoon!  And feel free to bring any problematic samples of freshwater gastropods you may have accumulated in your cabinet drawers.

Looking forward to it,
Rob

The Mystery of the SRALP: Dixie-Cup Showdown!

Editor's Notes - If you’re just joining us.  This is the third installment in my 2013 series on the Snake River Physa controversy.  It won’t make any sense unless you back up and read my February and March posts first.  I’m serious, I mean it.

This essay was subsequently published as: Dillon, R.T., Jr. (2019d) The Mystery of the SRALP: Dixie Cup Showdown!  Pp 181 - 185 in The Freshwater Gastropods of North America Volume 4, Essays on Ecology and Biogeography.  FWGNA Press, Charleston.

So the highly-improbable team of Newman, Keebaugh, Burch and Dillon reunited at the Bureau of Reclamation’s Boise field office on Monday morning, September 20, 2010, for the purpose of reviewing the Gates & Kerans Report.  In addition to the four of us fresh from our adventures in the tailwaters of the Minidoka Dam, and authors Gates & Kerans themselves, also present for the meeting were four additional Bureau of Reclamation personnel and five representatives of the US Fish & Wildlife Service, for a total of 15 participants. 

And Ms. Gates, for her part, did a fine job with the presentation.  My general impression of her (and of her advisor, Dr. Billie Kerans) was that they are two earnest and hardworking researchers trying to do their jobs as best they can with the tools God gave them, bless their hearts.

Their survey of the Minidoka tailwaters, which was (after all) the job they were paid to do, was marvelously well-executed.  But with the publication of the Rogers and Wethington paper in late 2007 [1], their study was “overtaken by events” [2].  At that point the only appropriate control for any datum they might have collected became the population Physa indistinguishable from P. acuta inhabiting the Snake River shallows (the “SRALP”), and none of their observations can have any meaning without that appropriate control.

So throughout Ms. Gates’ presentation, the 25-30 acuta-like Physa that I had collected at Snake River Mile 600 the previous afternoon were blissfully crawling about in the drinking cup on the conference table in front of us.  And when my turn came to comment on her report, I transferred my cup of SRALP-snails to Prof. Keebaugh, who had been serving as curator for the project.  Here, I announced to the 15 biologists and managers assembled, is the appropriate control for the research we have just heard presented.

Might the sample of 274 little physids heroically recovered from the Minidoka tailwaters by Gates & Kerans match my sample of SRALP from RM 600, genetically and morphologically?  I stressed that this question is not merely academic; that it has management implications.  If no, then more water should be released from Minidoka Dam to better match the habitat of an endangered “Physa natricina” narrowly adapted to deep rapids, and less should go to the potato fields fed by the irrigation canals leading north and south.  But if yes, and if indeed one wanted more trash snails like those crawling about on the conference table in front of us, as much water as possible should be sent to the potatoes, and as little as possible through the gates of the dam.  Then the tailwaters of the dam would pond up, warm, and more closely approximate the acuta-friendly habitats downstream.  I concluded that since the Gates & Kerans report did not address this question, no recommendations were possible at that time.

Rising to the defense of the Gates & Kerans report was Prof. John B. Burch.  It was Prof. Burch’s opinion that Physa acuta do not inhabit the Snake River, nor indeed is P. acuta even native to North America.  He asserted that Physa acuta is a European species, rarely introduced to the New World, if at all.  With regard to the breeding data from my lab suggesting otherwise [3], he was dismissive, failing to see the relevance of experiments “done in Dixie cups.”  Our culture vessels are 12-ounce drinking cups of clear plastic, I corrected him.  That our experiments have been conducted in Charleston is the only Dixie thing about them.

What, I asked Prof. Burch, is the anatomical difference between the 274 little physids recovered by Gates & Kerans and invasive pest populations of Physa acuta from any of six continents he’d like to name, other than size?  I challenged him to put his finger on the anatomical drawings to show me one, single distinction.  Gates & Kerans screened their sample by restricting shell heights to no greater than 6.9 mm, the maximum specified by Taylor [4].  Did Prof. Burch have any comparable observations on 6.9 mm Physa acuta?

The exchange between Prof. Burch and myself was rather heated at times.  In retrospect it must have been quite a show for the roomful of natural resource managers assembled to see such passion exercised over such arcane subject matter.

We, the outside experts were excused at 10:00 AM, leaving the managers to reconvene after a break for decision-making.  Burch, Keebaugh, Newman and Dillon shook hands in the parking lot, although the pleasantries may have been a bit strained.  John Keebaugh departed with the container of acuta-like Physa I had collected at RM 600, which I felt certain he would convey to Gates & Kerans and whoever their collaborators might be for sequencing.  And setting aside all the controversy of the morning, the mystery of the SRALP should at last be solved.

Or will it?  Join us again next time for the final installment in the Mystery of the SRALP… “No Physa acuta were found.”

Notes

[1] Rogers, D. C. & A. R. Wethington (2007) Physa natricina Taylor 1988, junior synonym of Physa acuta Draparnaud, 1805 (Pulmonata: Physidae). Zootaxa 1662: 45-51

[2] This is a term I learned during my AAAS fellowship year on Capitol Hill.  It means “obsolete” without the harsh connotation.

[3] Dillon, R. T., A. R. Wethington, J. M. Rhett and T. P. Smith.  (2002)  Populations of the European freshwater pulmonate Physa acuta are not reproductively isolated from American Physa heterostropha or Physa integra.  Invertebrate Biology 121: 226-234. [PDF]

Dillon, R. T., A. R. Wethington and C. Lydeard (2011) The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail Physa.  BMC Evolutionary Biology 11: 114. [PDF]

See also my post of [12July11] "What is a Species Tree?"

[4] Taylor, D. W. (1988) New species of Physa (Gastropoda: Hygrophila) from the western United States. Malac. Rev. 21: 43-79.

The Mystery of the SRALP: A Twofold Quest!

Editor’s Notes – If you're just joining us.  This is the second installment in my 2013 series on the Snake River Physa controversy.  It won’t make any sense unless you back up and read my February installment first.  It might also help to read my essays of March 2008 and September 2010, but the most important thing is to read last month’s post, before trying to read this one.  I’m serious, I mean it.

This essay was subsequently published as: Dillon, R.T., Jr. (2019d) The Mystery of the SRALP: A Twofold Quest.  Pp 173 - 180 in The Freshwater Gastropods of North America Volume 4, Essays on Ecology and Biogeography.  FWGNA Press, Charleston.

The rendezvous was set for 9:00 Sunday morning, September 19, 2010, at a gas station by the interstate near Burley, Idaho.  We were four biologists of strikingly different agendas, drawn together on a twofold quest.  And I suppose I should not have been surprised, but I was.

When I first suggested a field trip to the Minidoka Dam to Mr. Ryan Newman, my Bureau of Reclamation host, I had imagined that I would go alone.  I thought perhaps he’d call the staff on duty for me, maybe get somebody to open a gate on a Sunday morning, and I’d be fine.  I was pleased (of course) to discover that he was willing to accompany me as my native guide, and pleased again to see our good friend John Keebaugh’s email address on the CC line.  John works out of the Orma J Smith Museum at the College of Idaho in Caldwell, about 150-200 miles west, back near Boise.  But the fourth member of our party, chauffeured in by Mr. Newman as John Keebaugh and I stood chatting in the parking lot that morning, was a surprise.  Dr. John B. Burch, all the way from Ann Arbor.

Dillon, Burch & Keebaugh

My agenda on the Snake River that morning was simple – to test the hypothesis I first advanced in my essay of March 2008 [1].  Based on the observations of Rogers & Wethington [2], it seemed likely to me that Physa acuta, or some snail not immediately distinguishable from Physa acuta (which we are calling the Snake River acuta-like Physa, or “SRALP”) should inhabit the shallow backwaters downstream from Minidoka Dam.  This would be consistent with the greater hypothesis, that outliers on the margins of acuta-like populations may have colonized more rapid midstream environments of the Snake River, inducing the phenotype we identify as Physa natricina.

It materialized that my three colleagues, on the other hand, were bent on sampling the deeper waters for additional specimens bearing the natricina phenotype.  The rationale for this behavior escaped me, as the existence of small-bodied physid populations bearing wide apertures in the deeper Minidoka tailwaters had already been well-established by the heroic survey of Gates & Kerans, which prompted this field trip in the first place. One would think, if the little things were indeed elements of an endangered species, we would leave them alone.  But no.

John Keebaugh had brought a long-handled dipper with which, wading into the river waist deep and extending to full length, he was able to retrieve cobbles from some rather great depth.  Ryan Newman and Jack Burch sorted through trays of these dredgings, looking for physids.

Meanwhile, I enjoyed a fresh, sunny morning wading around in the Snake River shallows all by myself, looking for the sorts of ponds and protected backwater areas that one might think of as typical Physa acuta habitat.  And finding slick-rock nothing.

It turns out that the Snake River below Minidoka Dam is a really crappy habitat, for snails or indeed for macroinvertebrate benthos of any sort.  Our team visited three sites, from River Mile 675 just below the spillway to River Mile 670 at the Jackson Bridge.  And throughout that five mile stretch, it was my impression that river levels are terribly impacted by the generation schedule at the dam.  On the September day of our visit we found a couple vertical feet of cobble beach exposed, and I would estimate that the water levels regularly fall another 3-4 vertical feet below that.  So even wading knee deep and squinting as far as I could into the dark, roiling river, I probably couldn’t see to any bottom that hadn’t been dewatered last May, and wouldn’t be dewatered again come December.

I did find a few Physa gyrina in the shallows – mostly on sticks and organic debris – probably washed in from little side tributaries [3].  In fact, the only really nice snail population I saw all morning was the Physa gyrina in a seep near the base of the spillway [4].  But I found no acuta-like Physa in the Minidoka tailwaters [5].  That turned out to be a really, really crappy habitat.

So we ate lunch and I bid my colleagues adieu.  And I hopped back into my rental car and turned my attention toward a (rather poor) roadmap I found in the glove compartment.  And began planning a blitzkrieg survey of the Snake River further downstream, on my return trip west, back toward Boise.

Snake R from the US93 Bridge

At this point a brief orientation might be helpful.  The Snake River runs east to west like a giant smiley-face across the bottom of Idaho, then north along the Oregon border through Hells Canyon to join the Columbia River at Kennewick, Washington, there designated “Snake River Mile 0.”  So Minidoka Dam is in eastern Idaho, at river mile RM 675.

Rogers & Wethington [2] never promised us any Physa acuta as high as RM 675.  They reported that their sample of 211 physids collected between RM 573 and 340 contained 94% of the “Physa acuta group.”  Nor did Dwight Taylor list any localities upstream as high as Minidoka County in his original description of Physa natricina [6].  His natricina localities were in Gooding, Elmore, and Owyhee counties, roughly RM 571 – 525.

It looked to me as though the Milner Dam (located at RM 639) backed the Snake River up almost to the Jackson Bridge, where I sat parked early that Sunday afternoon.  So I rather arbitrarily set my course for the US 93 bridge near Twin Falls, further downstream at RM 611.  The river turned out to be inaccessible from the US 93 bridge, but I was able to follow signs down to a public access at the Magic Valley Hatchery, RM 600.

The Snake River at RM 600 had taken an entirely different character from the flashy, sterile thing I’d waded around in all morning.  It was broad and warm and shallow and rich [7].  And the rocks on the quiet margins were covered with SRALP-snails, indistinguishable to my eye from Physa acuta.  It didn’t take me ten minutes to squat down and collect at least 25 – 30 individuals in a drinking cup, which I resolved to carry with me to the meeting in Boise Monday morning.

Thousand Springs area

Then I got back into my rental car and continued driving east, enjoying the lovely weather and the countryside all quite exotic to my eastern eyes.   I made three additional stops, all brief: at the Owsley Riverfront Park (RM 582), at Bliss (RM 565) and at Glenns Ferry (RM 538), just as the sun was setting.  The river looked rich at all these spots, with a nice, diverse pulmonate fauna.  The population of Potamopyrgus (“New Zealand Mud Snails”) at Owsley was strikingly dimorphic, which was interesting [8].  And I enjoyed the big Fluminicola population at Bliss, the first I’d ever seen on the hoof.  And at all three spots I found SRALP-snails at least moderately common.  I picked up a few at each site and kept going.  I saw no Physa gyrina anywhere in my quick tour of the Snake River between RM 600 and RM 538 at all.

Back in Boise that night I slept soundly, my sample of SRALP crawling peacefully around the drinking cup at my bedside.  Surely, I thought, everybody at the big Bureau of Reclamation meeting on the morrow would see the importance of these snails to the answer of our ultimate question.  Does the strange little physid population in the Minidoka tailwaters that Gates & Kerans refer to “Physa natricina” indeed represent an endangered species?  Or might they be ecophenotypic variants of an otherwise common species, nevertheless endemic to the Snake/Columbia system?  Or might the Gates & Kerans sample simply constitute 274 ecophenotypic variants of the invasive pest Physa acuta, found everywhere on six continents?

How naïve could I be?  Join us again next time, for … Dixie-Cup Showdown!

  

Notes

[1] Red Flags, Water Resources, and Physa natricina [12Mar08]

[2] Rogers, D. C. & A. R. Wethington (2007).  Physa natricina Taylor 1988, junior synonym of Physa acuta Draparnaud, 1805 (Pulmonata: Physidae)  Zootaxa 1662: 45-51.

[3] To be as complete as possible.  I did collect approximately 15 - 20 juvenile and subadult Physa from the Minidoka tailwaters that I thought, on the morning of 19Sept10, might be Physa acuta.  I brought them home with me to Charleston, reared them to adulthood, and then dissected them.  Nope, they were all Physa gyrina.

[4] One of the strongest memories I have from my very brief introduction to the Minidoka tailwaters on a bitterly cold morning in December of 2005 was the high density of Potamopyrgus.  But on my return visit in September of 2010 I found exactly N=0 in several hours of effort.  The river levels were significantly higher in 2010, so it’s possible that I simply missed them.  Or has there been a flush/crash?

[5] So my hypothesis of 3/2008 was incorrect.  Physa gyrina seems to be washing into the shallows below Minidoka Dam, not Physa acuta.  My new hypothesis is that the little population of snails that Gates & Kerans are calling “Physa natricina” is the relict of a much larger acuta-like population comparable to those inhabiting the Snake River further downstream, but now extinguished from the shallows by operations at the dam.

[6] Taylor, D. W. (1988)  New species of Physa (Gastropoda: Hygrophila) from the western United States.  Malacological Review 221: 43-79.

[7] Although similar in outward appearances, P. acuta and P. gyrina have diverged strikingly in their life history adaptation.  Populations of P. acuta are weedy or “ruderal” – their rapid growth, quick maturity and high reproductive output (relative to body mass) adapted to exploit rich, although often unpredictable habitats.  Physa gyrina are more stress-tolerant (like a cactus), adapted to nutrient poor but nevertheless predictable habitats.  See my book (Dillon 2000) pp 131-136 and Fig 8.10 for more.  In southern Idaho, these life history differences seem to be reflected in the distributions of the two species – acuta in the main river (further downstream) and gyrina in the tributaries.

[8] The presence of two strikingly different shell forms in a single Potamopyrgus population would seem to suggest sexual reproduction.  The Snake River gastropod fauna really does offer a wealth of opportunity for important scientific research, if serious scientists could get beyond all the politics and confusion.  Such a shame.

The Mystery of the SRALP: A Bidding...

Editor’s Note – This essay was subsequently published as: Dillon, R.T., Jr. (2019d) The Mystery of the SRALP: A Bidding...  Pp 165 - 171 in The Freshwater Gastropods of North America Volume 4, Essays on Ecology and Biogeography.  FWGNA Press, Charleston.

The invitation arrived by email on 19Aug2010.  Mr Ryan Newman of the US Bureau of Reclamation (USBR) was curious to know whether I might be available to join a working group convening in Boise to review a report by K. Gates & B. Kerans entitled, “Snake River Physa, Physa (Haitia) natricina, survey and study.”  And so began one of the greater malacological adventures of my life, professional or otherwise.

Faithful readers may remember my post of March 2008 regarding the federally-endangered Physa natricina [1].  Described by Dwight Taylor (1988) in one move of an (ultimately successful) effort to thwart the impoundment of the last free-flowing section of the Snake River in southern Idaho, the species was for many years a phantom – no precise localities known, even the type specimens lost.  Its habitat seemed to be unique among physids, “on boulders in the deepest accessible portion of the Snake River near rapid margins” [2].  The adults were unusually small-bodied (shell length “5.4 – 6.9” mm), bearing an unusually wide aperture.  See note [3] for more about the photo below.

Taylor went to some length to distinguish his Physa natricina from Physa gyrina – the former having a one-part penial sheath (“type-c”) and the latter a two-part sheath (“type-b”).  But in late 2007 Rogers and Wethington [4] pointed out that Taylor’s anatomical description was not sufficient to distinguish P. natricina from the worldwide invasive P. acuta*, another type-c physid apparently common in the shallows throughout most of the Snake.  Since stunted size and an odd aperture might simply reflect ecophenotypic responses to life in a habitat to which physids are marginally suited at best, Rogers and Wethington synonymized Taylor’s nomen natricina under P. acuta.  One might think this would end the matter.

But a controversy every bit as political as that which prompted the 1992 listing of Physa natricina had been simmering for some years in the Snake River tailwaters below Minidoka Dam, 20 miles upstream (NE) of Burley.  There macrobenthic surveys conducted in the mid-1990s by biologists working for the Bureau of Reclamation had returned small, oddly-shaped physids identified by consultants in 2004 as Physa natricina.  This prompted the US Fish & Wildlife Service to issue a “Biological Opinion” in March of 2005 [5] affecting the USBR’s management [6] of Minidoka Dam.  So in August of 2005 the USBR commissioned a study [7], which by August of 2010 had yielded fruit.  And I was being invited to review the result.

The 87-page Gates & Kerans report attached to Mr. Newman’s bidding comprised three sections – a survey, a morphological study, and a DNA sequence study.  The survey section spun a ripping-good yarn of suction dredges and tethered scuba divers, ultimately triumphing in the recovery of a remarkable 274 small, oddly-shaped type-c physids from the roiling waters of the Snake River below Minidoka Dam.  The second section reported a conventional study of the shell and anatomy of six of these small snails, featuring a photo of a couple living individuals (“courtesy of John B. Burch”).  And the third section, contributed by collaborators at both Montana State and the University of Michigan, reported an average 19.7% mtDNA sequence divergence between approximately 30 of these little snails (combined over both labs) and a sample of Physa gyrina.

And here’s the headline.  Gates &  Kerans reported an eye-popping 17.1% average sequence divergence between their sample of small, oddly-shaped type-c physids and Physa acuta sequences retrieved from Genbank.

But alas.  Gates & Kerans seemed entirely ignorant of (or worse, dismissive of?) the Rogers and Wethington report of Physa acuta* in the Snake River.  And the nearest P. acuta sequence available for comparison in GenBank had been sampled 500 km NE of the Minidoka Dam, on the other side of the Rocky Mountains in Wyoming.  And Gates & Kerans had not (apparently) felt called to sample their own.

Granted, the Rogers and Wethington study was not published until after the 2007 field season, by which time two years of data were already in the can.  But it seemed to me that, as soon as the existence of P. acuta* in the Snake River became known, those populations became the only appropriate control for the study of P. natricina, not P. acuta sampled across the continental divide 500 km northeast, and certainly not P. gyrina. The relevant morphological comparison would be between the population of small, oddly-shaped type-c Physa at mid-river in the Snake and equally small P. acuta* sampled from its shallows.  Gates and Kerans needed DNA samples from Snake River acuta*; neither Snake River gyrina nor Wyoming P. acuta were germane.

At this point in our malacological adventure I find it convenient to introduce a new term, “Snake River acuta-like Physa,” or SRALP for short.  And request that my readership mentally replace all five instances of the binomen "Physa acuta” marked with asterisks above with “SRALP.”  And find it necessary to reverse the flow of my narrative once again, back to an essay I wrote in September, 2010 [8].

That particular essay was prompted by the de-listing of Valvata utahensis and Pyrgulopsis robusta, two of the other four freshwater gastropod species politically listed in 1992 to block the Snake River impoundment.  In that 2010 essay I made reference to what seemed like a logical progression of three hypotheses – narrow endemic, regional endemic, and nonendemic – and lamented how natural resource politics had for 20 years short-circuited the (otherwise orderly) examination of all three.  And toward the end of that essay I pointed out that, in the case of Physa natricina, nobody seems to have given any study to “Hypothesis #2 (of 3)” at all.

The Gates & Kerans report was on my desk at the time I wrote my 2010 essay, and the timing was not a coincidence.  Does the Gates & Kerans sample of 274 small type-c Physa come from a narrowly endemic species, restricted to “boulders in the deepest accessible portion of the Snake River,” best identified as Physa natricina?  Or perhaps those 274 snails are simply ecophenotypic variants of the nonendemic P. acuta, otherwise common in the Snake River backwaters and elsewhere throughout the world?  Or might the Snake River be home to a regional endemic – locally common and practically indistinguishable from acuta in the calm backwaters, but rare, stunted and misshapen in the rapids?  The names concolor (Haldeman 1843) and columbiana (Hemphill 1890) are already in the literature for this second (of the three) possibilities. 

The answer to these questions and more would rest in the SRALP.  What exactly is that population of type-c physids reported common in the Snake River by Rogers and Wethington?  And what might their relationship be to the 274 odd little physids heroically retrieved by Gates & Kerans?  Tune in next time, as we journey to southern Idaho, on a quest!

Notes

[1] Red flags, Water Resources, and Physa natricina [12Mar08]

[2]  The “deepest accessible portion” quote comes from Taylor’s (1982) “Status Report on Snake River Physa Snail” (USFWS, Portland).  Taylor’s formal description of 1988 did not include habitat notes of any sort, oddly.

[3] The shell labelled "natricina" was dead-collected in the "drift" on one of the rocky beaches below the Minidoka Dam on 19Sept10.  Its collector was John Keebaugh, who identified it and made a gift of it to me.  I myself had collected the P. gyrina from a seep near the Minidoka Dam spillway earlier that morning.  And I also collected the individual labelled "SRALP" (Snake River acuta-like Physa) later that same day from the Snake River at Owsley (RM 582).  More in our next installment.

[4] Rogers, D. C. & A. R. Wethington (2007)  Physa natricina Taylor 1988, junior synonym of Physa acuta Draparnaud, 1805 (Pulmonata: Physidae).  Zootaxa 1662: 45 – 51.

[5] USFWS (2005)  Biological Opinion for Bureau of Reclamation Operations and Maintenance in the Snake River Basin Above Brownlee Reservoir.  This and all the other documents regarding the 2004-05 Minidoka controversy (including the implementation plan for a Physa study) are available from the Bureau of Reclamation here: [USBR 2004 Biological Assessment].

[6]  All the 2005 fussing (that came to my ears, anyway) focused on the annual schedule of water release from the Minidoka Dam, the FWS pressing for something closer to natural flow.  It also turns out that the USBR had been studying the complete replacement of the Minidoka Dam spillway since at least 2000, although I didn’t hear about that element of the controversy until 2010.  Here is the USBR page with all the documents relating to the spillway replacement: [USBR Spillway Replacement].

[7] To be as complete and fair as possible.  My first visit to Minidoka Dam came in December of 2005 as a member of a “Snake River Physa Technical Team” convened by the Bureau of Reclamation to provide recommendations for their study (documents at Note 5 above).  At the time, there was real concern that even if any small, misshapen type-c physids might be recovered from the Minidoka tailwaters, nobody could positively confirm their identity as P. natricina.  And I had not heard another word about the project as of 12Mar08, hence the reference to “a day which never arrived” in my 2008 blog post. 

But (in fact) the Gates & Kerens study was already into its third year by the spring of 2008.  I was invited to a second meeting of the Snake River Physa Technical Team on 1May2008, although not offered any funding to get me there.  So I told Mr. Newman that “if I happen to be in Boise on May 1, I’ll drop by.”  I would nevertheless have been happy to read a written progress report, had Mr. Newman offered one in 2008, which he did not.  Thus the desirability of standards and controls in scientific investigation was not called to the attention of Gates & Kerans until the fall of 2010, by which time there seems to have been little opportunity for a remedy.

[8] Valvata utahensis and Hypothesis #2 (of 3)  [14Sept10]

The Clean Water Act at 40

Editor’s Note. This essay was subsequently published as: Dillon, R.T., Jr. (2019d) The Clean Water Act at 40.  Pp 201 - 205 in The Freshwater Gastropods of North America Volume 4, Essays on Ecology and Biogeography.  FWGNA Press, Charleston.

I was born and raised in the Shenandoah Valley of Virginia, in a geographical oddity known as Waynesboro, 100 miles from everywhere.  But near enough, by happy fortune, to the South River (a tributary of the South Fork Shenandoah) as it cascaded freshly down from the Blue Ridge, and slowed upon entry into the verdant valley below [1].  And I spent some of the happiest days of my youth swimming, fishing, rafting, and grabbing everything slick and squirmy I could grab out of those gentle waters, from snakes and turtles to crayfish, bugs, and (of course!) snails.

In the riffles the benthic macrofauna was dominated by the pleurocerid Leptoxis carinata, with Physa common in the pools, limpets occasional and Helisoma anceps rare.  I remember being frustrated, even at the age of twelve, that I could not identify the freshwater snails of the South River.  I had a tremendous infatuation with the natural world around me, and could find guidebooks to help with the birds and reptiles, the trees and the wildflowers, and most shells – certainly the marine ones.  But not the freshwater snails.

In any case, the economy of Waynesboro was not as agricultural as I have made it sound above.  During the 1920’s two major textile-related plants joined a number of smaller factories already humming in the town – DuPont (manufacturing acetate fibers such as nylon, orlon & lycra) and Crompton (corduroy, velveteen & nylon velvets).  The attractions of this otherwise rural setting included cheap land, an eager work force, good rail transport, and (alas!) the South River to dump crap into.

The DuPont and Crompton plants (and several others, to be fair) stretched by the river for about a mile along the east side of town.  DuPont discharged large quantities of elemental mercury in among a witch’s brew of other chemical wastes generated as a consequence of routine manufacturing processes, over quite a number of years.  The several Waynesboro plants also featured very tall smokestacks that dumped huge amounts of black smoke into the sky.  I didn’t like it – nobody did.  But waste seemed like an inevitable consequence of economic prosperity [Photo below, Note 2].

By now you will have gathered that The Dillons lived upstream from the DuPont plant.  My friends and I occasionally rafted inner tubes a mile or so downstream to the Hicks Bridge, at the south entrance of the plant.  I don’t remember any signs specifically warning us of hazardous conditions further downstream – I think this was generally understood.  But in any case, had I ventured to gather any personal observations regarding the benthic macrofauna of the South River below the Hicks Bridge at any time in my young life, my mother would have found out quite promptly, which would have been hazardous enough, to my backside.

The Clean Water Act was signed into law on October 18, 1972.  I was a senior in high school by that time, and the next summer off to college at Virginia Tech, never to live in Waynesboro again.  Although my wife and I still have family in the area, I have lost that intimate connection I developed with the South River in my youth, carried away by other rivers less gentle.

The rebirth of the river downstream from the Waynesboro plants, in my absence, has been astonishing.  Mercury contamination was discovered in fish samples taken from the South River in 1976, precipitating a legal battle between DuPont and the state ultimately resolved in 1984.  As part of the settlement DuPont agreed to fund a “South River Science Team” [3] to serve as a focal point for technical and scientific issues concerning mercury contamination.  By 1989, the water quality had improved to such an extent that the state began stocking the South River at Waynesboro with brown and rainbow trout.  Waynesboro is now home to two annual celebrations of the South River, the Virginia Flyfishing Festival and the Waynesboro “Riverfest” [4].

Last summer I launched my kayak at the Apple Acres bridge near my childhood home and paddled through the entire City of Waynesboro, passing the DuPont site and the sites of several other industries only slightly less spectacular [5], emerging to call my brother-in-law at Bridge Avenue, about five miles downstream.  The most memorable features of my trip were the fly fishermen quietly angling in the shadows of the industrial smokestacks. 

The river looked pristine to casual inspection – Leptoxis carinata uniformly abundant through the river section I paddled.  Downstream from Waynesboro I pulled out and collected six species: Leptoxis, Physa acuta, Ferrissia fragilis, Helisoma anceps, H. trivolvis and Lymnaea humilis.  So in addition to the four species that have likely recolonized from upstream refugia, we seem to have added two species from downstream.  The freshwater gastropod fauna of the South River is today indistinguishable from that of any other similar-sized river in the upper Shenandoah Valley.

The Clean Water Act worked.  Sometimes I fear that the environmental community has earned a reputation for shrillness – always focusing on impending disaster, prophesying the end of the world.  It might help our credibility a bit if we acknowledged the real successes of the last 40-50 years and admitted, as bad as things might look today, we have seen worse.

This past summer I spent a couple weeks surveying the freshwater gastropods of New Jersey.  So prior to my departure I mapped a grid of sample sites to cover the various physiographic regions and drainages of The Garden State, mixing lotic and lentic habitats, large and small.  I paid attention to access, of course, preferring boat ramps, parks, and public spaces if possible.  Water quality concerns did not, however, enter my mind.

And so the afternoon of September 11, 2012 found me at a public park on the bank of the Raritan River in Manville, NJ.  The water was clear, apparently clean, and inviting.  The luxuriant macrobenthic fauna included 11 gastropod species, making it the second-richest site I was to visit that entire week.  Only a subsequent conversation with a passing fisherman reminded me of the history of that place, the site of the former Johns-Manville manufacturing facilities for asbestos insulation [6].

Happy Birthday, Clean Water Act.  And keep up the good work!

Notes

[1] The black & white photo above is a 1966 image of the South River as it enters Waynesboro.  That’s the old “Apple Acres” bridge in the background.  Scanned from Massie, E.S. and C. Skinner (2009)  Images of America: Waynesboro.  Arcadia Publishing.

[2] The South River runs around the right edge of this photo, from top to bottom.  The DuPont plant is featured in the middle of the photo (on the right descending bank) with the Crompton-Shenandoah plant shown at right, on the left descending bank.  This photo from the South River Science Team site, see note [3].

[3] South River Science Team [html]

[4] Waynesboro Riverfest [html]

The Virginia Flyfishing Festival [html]

[5] The Crompton plant went out of business in 1984, and has now largely been demolished.  DuPont sold its Waynesboro plant to the InVista Corporation a few years ago, and manufacturing operations continue at a reduced scale.

[6] I don’t have any independent knowledge of the Johns-Manville situation on the Raritan River in New Jersey, but here’s a link to the Wikipedia entry [html].

On Getting Clappia in Tennessee

Editor’s Note – This essay was subsequently published as: Dillon, R.T., Jr. (2019c) On getting Clappia in Tennessee.  Pp 199 - 204 in The Freshwater Gastropods of North America Volume 3, Essays on the Prosobranchs.  FWGNA Press, Charleston.

The Powell River is one of my favorite places on Earth.  Running gently through a rich, narrow valley from southwest Virginia into East Tennessee, the Powell is home to about 17 species of freshwater gastropods, and perhaps twice that number of unionid mussels.  I first dipped a boot toe into those magical waters in the summer of 1975, as an hourly employee of the TVA working on mussel surveys, and have returned many times since.  I always see something new.

The Powell as it flows south into Tennessee is choked with pleurocerid snails – Leptoxis, Io, and three species of Pleurocera jostle each other for every square millimeter of benthic habitat.  This actually makes gathering observations on any other freshwater gastropod species extra-challenging.  As much as I love pleurocerids, I sometimes find myself wishing that they would all disappear for about an hour, so I could find anything else.

So I patted myself on the back in the summer of 2007 when I was able to confirm a population of Somatogyrus parvulus in the Powell River (marked “S” in the figure below).  Adult Somatogyrus are essentially indistinguishable from juvenile Leptoxis in the field (“L”), unless held up to close examination.  Their habitat was an important clue for me standing knee deep at midstream – I noticed a few suspicious little snails crouched Somatogyrus-like under rocks, when most of the Leptoxis population was grazing on top.

Then in 2008 I found a couple individuals of a second, more mysterious hydrobiid species in the Powell (C, below).  Again, they were mixed with a high density of Leptoxis, but this second population was more associated with woody debris in marginal pools than rocks at midstream.  Initially I thought they might be Amnicola (A), which does range through East Tennessee drainages, although not as commonly encountered as in Ohio drainages further north.  But back in the lab, they simply did not look like Amnicola.  I recorded them as “Birgella” in my database, which didn’t look right either, because the mystery snails were too small, and figured to come back to them in the future.

In 2010 I found samples of the same mysterious hydrobiid (C) at two sites in the upper Sequatchie River, another lovely mid-sized tributary of the Tennessee about 250 km SW of the Powell.  The Sequatchie also boasts a wonderfully diverse fauna of freshwater mollusks – certainly including Amnicola as well as a dense population of Leptoxis.  And again, to recover a completely vanilla 3 mm prosobranch gastropod from the waters of the Sequatchie that is neither a juvenile Leptoxis nor an Amnicola required something akin to divine intervention.  And once again, I labeled the mysterious little snails Birgella-with-a-question-mark and set them aside for future study, really rather distracted by the other 37 species of freshwater gastropods in the upper Tennessee drainage at the time.

So two years passed.  Then at the AMS meeting this past June I ran into my old buddy Bob Hershler, and he agreed to take a look at my (now three) samples of mysterious East Tennessee hydrobiid, and together we sorted the situation out. 

Bob confirmed a simple, unlobed “lithoglyphine” penial morphology for the mystery populations, firmly ruling out Birgella and Amnicola, and suggested Somatogyrus.  But Somatogyrus are more heavily-shelled and found midstream – witness the population of S. parvulus in the Powell River rapids not two meters from the marginal pool favored by our mystery species. The mystery hydrobiids bear a lighter, slightly more inflated shell with an umbilicus.  A Somatogyrus with an umbilicus?  Does that ring any bells?

Last month we reviewed the life and work of Bryant Walker (1856-1936), touching at some length on Walker’s research interest in the hydrobiid genus Somatogyrus [1].  Attentive readers may recall that between 1904 and 1909 Walker described 22 species of Somatogyrus, including 21 that were indistinguishable and one that looked different.  That different one, “remarkable for its round, deep umbilicus,” Walker removed to a new genus Clappia in 1909 [2].

Clappia umbilicata was originally described from the Coosa River of Alabama, and has not subsequently been collected elsewhere.  In 1965 Bill Clench reported an additional population of Clappia inhabiting a tributary of the Coosa River perhaps 50 km west of the type locality of C. umbilicata, which he described as Clappia cahabensis, honoring the strict one-drainage-per-species rule enforced throughout the Mobile Basin [3].

But the sad fate of the Mobile Basin gastropod fauna will be well known to most of my readership [4].  Thompson based his 1984 review of the lithoglyphine hydrobiids on a museum lot of Clappia, considering C. umbilicata "apparently" extinct and opining that C. cahabensis "may also be extinct" [5].  Both species were more recently listed as extinct by Lydeard & Mayden [6] and designated as such on the IUCN Redlist.  Our colleague Stephanie Clark enjoyed 15 minutes of fame for rediscovering C. cahabensis alive back in 2005 [7].

Now it has become apparent that the range of Clappia extends well beyond Alabama, to include at least two mid-sized rivers in East Tennessee [8]. And given how lightly the freshwater gastropods of Tennessee have been surveyed, and how difficult such diminutive hydrobiids may be to find in the high densities of pleurocerids that characterize the entire region, it seems quite likely that additional Clappia populations yet remain undiscovered.

We know less about the freshwater gastropod fauna of some parts of the United States than we do about the surface of Mars.  At this writing NASA’s “Curiosity Rover” is firing laser beams at the Martian surface [9] and transmitting data through 100 million kilometers of space to rooms-full of the world’s greatest engineers, at a mission cost of $2.5 billion, delivered.  NASA scientists know what they don't know.

But it seems possible that I may be the first person ever to hold those little snails in my hand – not the juvenile Leptoxis, not the Amnicola, not the Somatogyrus, not the Birgella - the other little 3 mm snail with the vanilla shell and the vanilla penis in the organic debris in the quiet backwaters of the Powell River as it flows into East Tennessee.  Nobody knows what we don't know about North American freshwater snails.

I do not begrudge NASA its $2.5 billion budget [10].  I would simply like to point out that we do not need to travel 100 million km to dip our boot toes into the magical waters of the unknown.

Notes

[1] Bryant Walker's Sense of Fairness [9Nov12]

[2] Walker, B.  (1909)  New Amnicolidae from Alabama.  Nautilus 22: 85-90.

[3] Clench, W. J. (1965)  A new species of Clappia from Alabama.  Nautilus 79: 33-34.  The primary difference between Walker's C. umbilicata and Clench's C. cahabensis seems to be body color, black for the former and white for the latter.  The mantles of the Tennessee populations do (generally) seem to bear black pigmentation.

[4]  For references on the conservation status of the Mobile Basin gastropod fauna see:

• Influential publications in freshwater gastropod conservation [3May10]
• Mobile Basin I: Two pleurocerids proposed for listing [24Aug09]

[5]  Thompson, F. G. (1984)  North American freshwater snail genera of the hydrobiid subfamily Lithoglyphinae.  Malacologia 25: 109-141.

[6] Lydeard, C & R. L. Mayden (1995) A diverse and endangered aquatic ecosystem of the southeast United States.  Conservation Biology 9: 800-805.

[7] Ivory-billed Freshwater Gastropods [9May05]

[8] A distribution map is available from the new Clappia umbilicata page on the FWGNA site: [Clappia umbilicata]

[9] Since 1898 there has been a narrative in western culture featuring an invasion by Martians, often involving robotic landers and death rays.  So now it materializes that NASA has mounted a laser gun on our most recent Martian Rover.  Apparently we kicked all the Nazi ass we can find, and kicked all the Commie ass we can find, and now we're up in space, kicking little green Martian ass.  USA! USA!

[10] This is because I cannot imagine any scenario where the subtraction of a single dollar from the NASA budget might yield even a penny for any funding source to which I might conceivably apply.  I don't understand money, at all.  But I think that funding for space research may be motivated by a combination of national pride, military paranoia, and Buck Rogers romanticism.  Although NASA takes the money and does some science with it (among other things), NASA's appeal is not primarily, or secondarily, or even tertiarily scientific.  But I do not understand money, at all.