The Twelve Phascinating Physa of Bliss

Editor’s Note – This is the third episode in a three part series on the Snake River Physa controversy, prompted by the recent paper of M. K. Young and colleagues [1].  If you’re new to this blog, and seriously interested in the science, I would recommend that you back up two months and read my essays of [14May24] and [11June24] before continuing onward.  I’ve also written six older posts on the subject 2008 – 2013, but no point in going back that far, screw it.

In August of 1979 the Idaho Power Company (IPC) received a permit to study the construction of a proposed A. J. Wiley Hydroelectric Project on the Snake River at RM 565, about 1.5 miles west of the little town of Bliss [2].  The proposed dam would have impounded a narrow reservoir as deep as 85 feet nearly eight miles upstream, to the foot of the Lower Salmon Falls Dam.  Inundated would have been the childhood home of a lichen biologist named Dr. Peter Bowler.

By 1992, Bowler had developed a second career as a malacologist, thick as thieves with Dwight Taylor, Terry Frest, and Ed Johannes.  A new species of Physa had been described, Physa natricina, which although found as a fossil throughout northern Utah and southern Idaho, was known alive only from RM525 to RM571 of the Snake River [3].  The “Snake River Physa” had been fast-tracked onto the Federal Endangered species list [4], and the A.J. Wiley Project had been permanently shelved.

The Snake River at RM 570

So last month we reviewed the exciting story of heroic efforts by IPC biologists working in the tailwaters of the Swan Falls Dam, RM 420 – 449, ultimately yielding hundreds of small physids matching the Physa natricina phenotype in at least some respects [11June24].  Because the IPC sample was taken 76 miles downstream from the type range, however, we referred to this population as “Snake River natricina-like Physa,” or SRNLP for short.  Ultimately, the SRNLP from RM 420 – 449 proved a genetic match with Physa acuta, a trash snail invasive on five continents [1].

This is not the situation at RM 675, however.  Previously we have reviewed very similar efforts by biologists engaged by the U.S. Bureau of Reclamation in the tailwaters of the Minidoka Dam 100 miles upstream of the type range of Physa natricina [5].  There, the SRNLP bear a unique mtDNA haplotype, not matching Physa acuta.

Between the Swan Falls Dam and the Minidoka Dam, in the actual type range of Physa natricina, previous research results have been equivocal.  Rogers and Wethington examined hundreds of physids sampled from this stretch of river by IPC biologists 1995 -2007, ultimately unable to distinguish the entire lot from Physa acuta [6].  John Keebaugh disagreed, selecting a small subsample as bona fide Physa natricina.  But the genetic results from the Keebaugh subsample were dubiously reported and never vouchered [7].

Are there no reliable genetic data for Snake River physids sampled between RM 525 and RM 571?  Well, yes, there are.  Twelve very interesting and extraordinarily diverse mtDNA sequences from the tailwaters of the Bliss Dam at RM 559, to be precise.

The Snake River in Idaho, modified from Gates et al [7]

It materializes that the Idaho Power Company has interests that extend beyond the conservation biology of freshwater gastropods.  Sport fishing is an important part of the local economy of the small communities along the Snake River, for example, and mercury levels in the game fish a matter of some concern to the IPC [8].  IPC biologists also have an ongoing project to survey mercury levels in the macrobenthos, as a component of the diet of the white sturgeon.

And so it came to pass that on 17Sept19 a team of IPC and USFWS biologists gathered to sample macrobenthos from the tailwaters of the Bliss dam at RM 559 with a suction dredge.  Their sample came from wadable depths – not the middle of the river – and Physa were not the target [9].  But the 12 individual Physa recovered as bycatch were sent to Mike Young and colleagues at the National Genomics Center for Wildlife and Fish Conservation in Missoula for analysis, along with that big sample of P. acuta from the Swan Falls tailwaters we obsessed over last month [1].  And the results were fascinating:

P. gyrina, Snake R. [10]

N = 1 Physa gyrina.  This is the most widespread of the Snake River physids, inhabiting the main stem throughout the state of Idaho, upstream beyond the Minidoka Dam and into many of the tributaries.  Populations of P. gyrina are not as invasive as P. acuta, however, demonstrating slower growth rates, larger sizes at first reproduction, and lower fecundities per unit body mass.  The CO1 sequence similarity between the singleton P. gyrina recovered by IPC biologists at Snake River mile 559 (SRP199 = OK510769) and the type P. gyrina sequence from Council Bluffs, Iowa (AY651187) is 99.0%.  Good.  No surprises there.

N = 5 Physa acuta.  Arbitrarily selecting the first-listed of the five sequences in this most common category of physids recovered from the Bliss tailwaters, the divergence of SRP001 (= OK510580) from the P. acuta type sequence (River Garonne, AY282589) is 4.7%, and the divergence with our typical P. acuta sequence from the Swan Falls tailwaters (SRP051 = OK510624) is 3.4%.  Apparently, a population of very ordinary, typical [11] Physa acuta was found, again.  This is additional confirmation, if any was needed, that the range of a trash snail invasive on five continents does in fact extend 76 miles up the Snake River from Swan Falls to the type locality of Physa natricina.  Fine.  No surprises there, either.

N = 4 Snake River Candidate Species 3 (“SRCS3”).  Four individual physids sampled from the Snake River at RM 559 bore a haplotype so divergent from all other sequences in the worldwide database that Mike Young, bless his heart, considered the evidence “consistent with their assignment to a separate genus.”  Ultimately, however, Mike decided simply to nominate this subset of four as #3 in his slate of 18 new “candidate species” for the physinine malacofauna of North America.

P. acuta, Snake R. [13]

Picking the first SRCS3 sequence from my buddy Mike’s Supplementary Table 2 as typical (SRP206 = OK510774), we can immediately confirm nearly negligible CO1 sequence similarities of 76.1% with Bliss acuta (OK510580) and 75.8% with Bliss gyrina (OK510769).  Indeed, blasting OK510774 against the entire NCBI GenBank database, we discover that Mike’s SRCS3 is more similar to Indoplanorbis exustus from Bangladesh than to (essentially) any other physid sampled from anywhere else in the world, with five phascinating exceptions.

Mike Young’s SRCS3 sequences are 93.2% similar to a pair of CO1 sequences uploaded by Ting Hui Ng and colleagues from their famous survey of freshwater gastropods in the ornamental pet trade of Singapore (KP182981 and KP182982).  I reviewed Ting Hui’s paper shortly after its 2016 publication [14], adding a footnote to her earlier paper focusing on Singapore Physa in particular [15], and a footnote connecting the Singapore Physa to the situation in the Snake River of Idaho, which now looks genuinely prophetic [16].

Mike Young’s SRCS3 sequences are also 92.1 – 93.9% similar to a set of three sequences very recently uploaded to GenBank by Gantshe Molaba and colleagues [17] from a 2023 parasitological study in South Africa (ON953193, ON953197, ON953200).  The South African sequences and the Singapore sequences are virtually identical.

What is going on here?  In Singapore and in South Africa and now in the Snake River, physids bearing an extravagantly divergent haplotype have been recovered together with Physa acuta bearing a typical haplotype, and in none of these cases did the authors of the papers report any corresponding morphological distinction between divergent and typical snails.

This situation looks precisely like the situation in France, and indeed right here in Charleston, South Carolina, elegantly demonstrated by our good friend Patrice David and his colleagues [18] to be a signature of cytoplasmic male sterility.  Patrice has hypothesized that mutation in some component of the mitochondrial DNA repair mechanism has simultaneously increased mitochondrial mutation rates in such lines and robbed their bearers of fertility in the male function.  But because they retain female function and mate freely with typical P. acuta (serving as male), they have not speciated.  They are still Physa acuta.

From David et al. [18]

Male-sterile variants of P. acuta are also at least as invasive as typical P. acuta, possibly even more so.  It is impossible to resist pointing out that the middle Snake River Valley is home to scores of fish hatcheries and fish farms, jostling each other for every cubic foot of the spring water that gushes forth from its scenic canyon walls, yielding truckloads of rainbow trout, cutthroat trout, salmon and steelhead.  It was almost certainly these hatcheries, and the fisheries they support, that introduced Potamopyrgus into the American West back in 1987.  Surely, they could bring exotic Physa into this country as well, yes?

Sure, maybe.  But we should also immediately note that Physa acuta is a North American native, and it is just as likely that we exported a male sterile variant to Singapore as Singapore exported one to us.  And the Snake River strain is not the Singapore strain.  They are 6.8% different, as though they sprang from a single mitochondrial mutation, and have subsequently diverged.

And the hypothesis that SRCS3 really is a valid biological species cannot be ruled out.  I’ve been footnoting the possibility of a second acuta-like Physa in the Pacific Northwest for years now – even suggesting Haldeman’s (1843) concolor as a possible name for the critter [19].  Wouldn’t it be great to do some old-fashioned breeding studies here?  Informed by old-fashioned nuclear markers – allozymes, microsatellites, anything?  I have a dream.

N = 2 Snake River Form 14 (“SRF14”).  Mike Young, bless his heart, declined to nominate the two individual snails (SRP200 and SRP201) recovered from the Bliss tailwaters bearing CO1 sequence OK510770 as a “candidate species” unto themselves, instead referring to them as “Form 14” of the 34 “forms” of physinine snails he ultimately distinguished in his stupendous gene tree.  His OK510770 sequence is 92.6% similar to Bliss gyrina (OK510769) and just 83.6% similar to Bliss acuta (OK510580).

Blasting the CO1 sequence Mike Young obtained from his two SRF14 individuals against the entire NCBI GenBank database, we discover that OK510770 is 95 - 96% similar to a set of 13 sequences obtained by University of Michigan (UMMZ) researcher A. C. Moore, with Jack Burch and Tom Duda, from a “highly restricted freshwater snail lineage” they introduced to the world in 2014 as the “Owyhee Wet-Rock Physa,” or OWRP for short [20].

The Owyhee River enters the Snake River in eastern Oregon at RM 395, downstream 165 miles from the Bliss Dam.  (See map below.)  It would be quite the adventure, but if one could float those 165 miles down the Snake to the Oregon border then pioneer back up the Owyhee approximately 130 miles through deep, arid canyons one would arrive at a geothermal spring complex inhabited by a population of Physa that apparently reminds everybody, both in their morphology and in their life habit, of the federally endangered Physa zionis of Utah.

Fig 1 of Moore et al [20] modified

Both the Owhyee Wet-rock Physa and Physa zionis are tiny, stunted little things, with grotesquely expanded body whorls, even more stunted and even more grotesque than Physa natricina.  What is the chance that Mike Young’s SRF14 might be Dwight Taylor’s long-sought and much-endangered species?

The evidence does not point in that direction.  As most of my (highly specialized) readership will be aware, pulmonate snails of the family Physidae bear several distinct types of penial morphology.  The most common type was called “Type C” by George Te in 1975 [21] – bearing a one part, muscular penial sheath.  Type C physids include Physa acuta, Physa natricina [22], and Physa zionis.  Also quite common in North America are physids bearing “Type B” penial morphology – a two part penial sheath – such as demonstrated by Physa gyrina.  If that distinction is unfamiliar to you, and you have more than a casual interest in the Snake River Physa controversy, I would assign the 2007 paper of Wethington & Lydeard [23] for homework.

Wethington & Lydeard showed that penial morphology correlates with molecular phylogeny.  So, although neither the IPC/USFWS team that fished them from the Bliss rapids nor Mike Young, bless his heart, dissected any of the 12 fascinating physids under discussion here, nor (indeed!) did the UMMZ group dissect any of their Owyhee Wet Rock Physa, it turns out that both the SRF14 sequence and the 13 OWRP sequences all clustered together with Type B Physa gyrina, not with Type C Physa acuta/natricina/zionis.

So, the next four paragraphs will be a digression, but indulge me.  The UMMZ group sequenced 13 Owhyee Wet-rock Physa for three genes, ultimately obtaining five slightly different CO1 sequences (KF305393 – 405).  While a match to P. zionis was not confirmed, those sequences did demonstrate a 95% match to a set of 11 CO1 sequences (KF305406 – 416) obtained from a population identified as Physa gyrina inhabiting Aqua Fria Creek, about 20 miles west of Yosemite National Park in central California.

And in 2018, four years after the publication of the OWRP paper, our hardworking friends at the Centre for Biodiversity Genomics (CBG) in Guelph uploaded to GenBank a “Physidae sp.” sequence collected from a beaver pond by the Similkameen River in southern British Columbia (MG421809) that also demonstrated a 95% match to the OWRP.  The Similkameen River flows south into the Okanogan River, joining the Columbia River in central Washington.

Now for the punch line.  It materializes that Mike Young’s SRF14 sequence, collected by IPC/USFWS biologists from the Bliss Rapids of the Snake River, is a stunning 99.7% similar to that “Physidae” sequence collected by the CBG from the beaver pond by the Similkameen 500 miles to the northwest.

Do the four populations mapped above, inhabiting wet rocks on the eastern edge of Oregon, a creek in central California, a beaver pond in southern British Columbia, and now discovered in the Bliss rapids of the Snake River of Idaho, represent a single previously unrecognized species of Type B Physa, extraordinarily variable, widespread across western North America?  Or might they have evolved from a male-sterile variant of Physa gyrina, as SRCS3 seems to have evolved from Physa acuta?

Again, as was the case with SRCS3 and P. acuta, Mike Young’s SRF14 population is sympatric with a population of Physa gyrina of the typical phenotype, bearing mitochondria of the typical haplotype.  Dare I dream that some worthy and industrious graduate student might someday survey these populations for variation at some sort of nuclear marker or markers and look for reproductive isolation, or lack thereof?  Followed by some breeding studies, perhaps?

There was a time in my career when I could have answered every question posed in this entire essay with a day in the field, four days in the lab, and $100 for reagents and expendable supplies.  Get a nice, big sample of Physa from the Bliss Dam tailwaters, paying attention to microhabitat.  Examine their anatomy and shell morphology critically, sort them into Type B and Type C subsets.  Within those subsets, are nuclear markers segregating in Hardy-Weinberg equilibrium?  How many biological species of Physa are we dealing with here?  Give me another six months and a student or two, and the breeding experiments done would have been done.  How many million dollars and years of wandering in a wilderness of ignorance and superstition might timely reference to a scientist, who actually knows something about the biology of the living, breathing animals he is studying, have saved?

N = 0 Minidoka SRNLP.  Although otherwise bearing a stunningly diverse array of mitochondria, our little sample of 12 physids from the tailwaters of the Bliss Dam did not include any bearing a CO1 sequence matching that of the peculiar little misshapen Physa recovered from the Minidoka Dam tailwaters 116 miles upstream, ascribed by Gates, Kerans and Keebaugh to Physa natricina [7].  True, the IPC/USFWS biologists did not sample midstream, where Physa bearing such haplotypes were recovered at Minidoka.  This is a weak test, indeed.

But these are all the relevant data we have, for 18 years of effort by multiple teams of hardworking, well-meaning biologists and millions of dollars flushed down the toilet.  So, since Physa acuta do indeed appear to be common in the shallows of the Snake River in the type range of Physa natricina, and since populations identified as Physa natricina in the Swan Falls tailwaters, both in the shallows and at midstream, are synonymous with P. acuta, the strongest hypothesis at present remains that the population Dwight Taylor described as Physa natricina in its RM 525 – 571 type range is a junior synonym of Physa acuta, as suggested by Rogers and Wethington in 2007.  And the SRNLP population in the roiling tailwaters of the Minidoka Dam is Something-Else-God-Knows-What.

To summarize.  On [12Mar08] I posted the following overly optimistic observation:

“Science is a self-correcting process. It is gratifying to see two of our own, Rogers and Wethington, designing the research program and publishing the paper that has turned us back from our 20-year blunder. But at such a cost! Literally millions of dollars have been wasted monitoring, managing, and protecting a snail that anyone on six continents could find in the ditch behind his local McDonalds, licking special sauce off the hamburger wrappers.”

Now 16 more years have passed, the Rogers and Wethington paper ignored, and millions of additional dollars wasted.  In 2008 I was laboring under the assumption that the world of science and the world of public policy could find some common frame in which to communicate.  Although I went on to write, “Science and politics do not mix,” in retrospect, I should have written that science and public policy cannot mix.

I am playing bluegrass music.  The natural resource agencies are playing baseball [24].  And the Idaho Power Company, just trying to run a business heaven help them, is standing in the batter’s box with a fiddle.

Notes

[1] Young, M.K., R. Smith K.L. Pilgrim, and M.K. Schwartz (2021)  Molecular species delimitation refines the taxonomy of native and nonnative physinine snails in North America.  Scientific Reports 11: 21739. https://doi.org/10.1038/s41598-021-01197-3

[2] Malde, H. E. (1981)  Geologic factors pertinent to the proposed A. J. Wiley Hydroelectric Project, No. 2845, Bliss, Idaho.  U.S. Department of the Interior, Open File Report 81-569.  75 pp.

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

[4] US Fish & Wildlife Service (1992). Endangered and threatened wildlife and plants; Determination of endangered or threatened status for five aquatic snails in south central Idaho. 50 CFR Part 17. Federal Register 57(240)59244-57. (December 14, 1992)

[5] Gates, K. K., and B. L. Kerans (2010) Snake River Physa, Physa (Haitia) natricina, Survey and Study.  Report to the US Bureau of Reclamation under agreement 1425-06FC1S202.  87 pp.  For a review of this report, see:

• The Mystery of the SRALP: A bidding… [5Feb13]
• The Mystery of the SRALP: A twofold quest! [1Mar13]
• The Mystery of the SRALP: Dixie Cup showdown! [2Apr13]

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

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

[7] 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. For reviews, see:

• The Mystery of the SRALP: No Physa acuta were found [2May13]
• The SRALP and the SRNLP: A New Hope [14May24]

[8] Willaker, J.J., C.A. Eagles-Smith, J.A. Chandler, J. Naymik, R. Myers and D.P. Krabbenhoft (2023) Reservoir stratification modulates the influence of impoundments on fish mercury concentrations along an arid land river system.  Environmental Science & Technology. DOI: 10.1021/acs.est.3c04646

[9] This is a personal communication from my friend Jim Chandler at IPC.  No reports or publications are as yet available for the sturgeon/food web/methylmercury research project.

[10] The specimen of P. gyrina figured above was collected by RTD from wetlands below the Minidoka Dam on 19Sept2010.

[11] Actually, I think the Snake River population of P. acuta may represent the “Clade B” form of Ebbs, Loker, and Brant [12].  The sequence similarity of OK510580 to Clade B sequence MF694449 from Montana was 98.2%.

[12] Ebbs, E.T., Loker, E.S. & Brant, S.V. (2018) Phylogeography and genetics of the globally invasive snail Physa acuta Draparnaud 1805, and its potential to serve as an intermediate host to larval digenetic trematodes. BMC Evol Biol 18, 103. https://doi.org/10.1186/s12862-018-1208-z

[13] The specimen of P. acuta figured above was collected by RTD from the Snake River at Bliss, 19Sept2010.

[14] Ng, Ting Hui, Tan SK, Wong WH, Meier R, Chan S-Y, Tan HH, Yeo DCJ (2016) Molluscs for Sale: Assessment of Freshwater Gastropods and Bivalves in the Ornamental Pet Trade. PLoS ONE 11(8): e0161130. https://doi.org/10.1371/journal.pone.0161130.  For a review, see:

• What’s Out There? [9Oct17]

[15] Ng, T.H., Tan, S.K. & Yeo, D.C. (2015) Clarifying the identity of the long-established, globally-invasive Physa acuta Draparnaud, 1805 (Gastropoda: Physidae) in Singapore. BioInvasions Rec. 4, 189–194.

[16] If you write five crazy things per month for 25 years, eventually at least one will turn out to be a prophecy.  See footnote [6] of my [9Oct17] post for an example.

[17] Molaba, G.G. et al. (2023) Molecular detection of Fasciola, Schistosoma and Paramphistomum species from freshwater snails occurring in Gauteng and Free State provinces, South Africa.  Veterinary Parasitology 320: 109978.  https://doi.org/10.1016/j.vetpar.2023.109978

[18] David, Patrice, Cyril Degletagne, Nathanaëlle Saclier, Aurel Jennan, Philippe Jarne, Sandrine Plénet, Lara Konecny, Clémentine François, Laurent Guéguen, Noéline Garcia, Tristan Lefébure, Emilien Luquet (2022) Extreme mitochondrial DNA divergence underlies genetic conflict over sex determination.  Current Biology 32: 2325-2333.  https://doi.org/10.1016/j.cub.2022.04.014.  For a review, see:

• Cytoplasmic Male Sterility in Physa! [9June22]

[19] The hypothesis “that some physid bearing a type-C penial morphology, but not correctly identified as either P. natricina or as P. acuta, might inhabit rivers of the Pacific Northwest” was Hypothesis #2 (of 3) in my post of [14Sept10].

[20]  Moore, A.C., J.B. Burch, and T.F. Duda Jr. (2015) Recognition of a highly restricted freshwater snail lineage (Physidae: Physella) in southeastern Oregon: convergent evolution, historical context, and conservation considerations.  Conservation Genetics 16: 113 – 123.

[21] Te, G. A. (1975) Michigan Physidae, with systematic notes on Physella and Physodon (Basommatophora: Pulmonata).  Malacological Review 8: 7-30.  For a review, see:

• To Identify a Physa, 1975 [6May14]

[22] Figure 6 in Dwight Taylor’s original description [3] clearly shows a type-C penial morphology.  And Jack Burch’s Fig 2.3 confirms that the SRNLP population in the Minidoka tailwaters are also type-C Physa [5].

[23] Wethington, A.R., & C. Lydeard (2007) A molecular phylogeny of Physidae (Gastropoda: Basommatophora) based on mitochondrial DNA sequences.  Journal of Molluscan Studies 73: 241 - 257. For a review, see:

• The Classification of the Physidae [12Oct07]

[24] The relationship between the worldview of science and the worldview of public policy is analogous to the relationship between music and sports.  They have different languages, cultures, and values.  They are not “compatible” in any sense, neither are they “incompatible” in any sense, because they are absolutely, utterly different.  Nothing I have written in this essay, nor indeed  any scientific findings of any sort, can ever have any effect on public policy.  I play the banjo, and the USFWS plays baseball.

Most of advocates for science in public policy are harmless naïfs, enamored of big government, Democrats the lot of them.  I worked with a building full of that sort 1982-83, as a AAAS Congressional Fellow on Capitol Hill.  They write reports which nobody reads.  No harm in that.

But should any person step forward, claiming to be a scientist, promising to conduct research to inform some issue of public importance, in exchange for contract money or grant, beware!  This is a charlatan, and pseudoscience is his snake oil.