Dr. Rob Dillon, Coordinator

Thursday, May 2, 2013

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.


[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]