To the FWGNA group:
This past December brought the publication of a brief paper by our
colleagues Christopher Rogers and Amy Wethington synonymizing the
federally listed “Snake River Physa” (Physa natricina) under the cosmopolitan P. acuta (1).
How a local population of an invasive pest came to be protected under
the Endangered Species Act is but one blunder in the sad history of
fumbles and missteps that has characterized the record of American
Malacology in the Snake River Canyon of southern Idaho. Can
anything be learned to prevent such embarrassments in the future?
The misadventure began in the early 1980s, when Idaho Power Company
proposed the construction of six new hydroelectric projects on the
middle Snake River, perhaps to impound the last free-flowing reaches of
a 122 mile section already tightly controlled by 11 dams.
Environmental groups rose up in opposition (2),
and I would freely confess sympathy for their cause. I have a
visceral love of rivers and the lotic biota, and hate impoundments
because they are ugly, stinking blights, all too rapidly infested with
Bud-swilling bass fishermen.
But insults to the public aesthetic will never be as compelling to the
permitting agencies as hydropower, irrigation, and jobs, no matter how
egregious the choice of beer. Thus it is not a coincidence that
within ten years of the announcements by Idaho Power, five species of
endangered freshwater gastropods were discovered in the middle Snake
River. Pyrgulopsis idahoensis, Valvata utahensis, Taylorconcha serpenticola, Physa natricina,
and the undescribed "Banbury Springs lanx" were added to the federal
list of endangered and threatened wildlife on December 14, 1992 (3). The Idaho Power hydro projects were shelved.
About "Pyrgulopsis idahoensis" we have written much in recent years (4). Although originally believed endemic to the Snake River, it proved to be a junior synonym of P. robusta, its actual range extending over four states. Far from being endangered, the Snake River population of P. robusta may be the largest single population of freshwater gastropods on earth. Taylorconcha and V. utahensis are also not rare, and are currently being studied for delisting as well (5). And now published is the paper by Rogers & Wethington 
sinking Physa natricina.
Physa natricina was described in 1988 by Dwight Taylor, a reclusive millionaire whose 44-page obituary will appear in the next Malacologia (6).
Although perhaps better qualified as a paleontologist, Taylor often
published on the modern terrestrial and freshwater malacofauna of the
American West. He is best remembered for his fanciful treatments
of the Physidae (7) and the Cuatro Cienegas hydrobiids (8), imagining more higher taxa than valid biological species actually exist to sort into them.
To be fair, Taylor’s 1988 work (9)
conformed to the same 19th century standards of practice under which
most elements of America's molluscan fauna have been described.
He did distinguish his Physa natricina from P. gyrina,
a strikingly different animal which is very common in the Snake
River. But the brief comparison he offered between his new
species and P. integra, the synonym for acuta most commonly applied in the upper Midwest, should have raised a red flag. Taylor wrote that the penial sac of P. integra
"is more slender, with a kink near its distal end, and is not bent near
the middle." Kinks and bends in mollusk anatomy? Was Taylor
nuts? (10) One need not
be a malacologist - one need only to have eaten an oyster - to realize
that anybody who would distinguish the internal anatomy of a gastropod
by reference to kinks and bends is simply unqualified for his
profession.
Taylor's work was generally characterized by false precision. For
example, in his introductory description of the (entire!) subgenus Physa,
he stated that the "spawn capsule...is up to about 10 mm long with 20
eggs." But even under controlled conditions here in my
laboratory, we commonly record individual Physa
egg masses ranging from over 100 embryos to fewer than 1.
Meanwhile, about truly important matters Taylor seems to have been
careless at best. His statement that the natricina
holotype was deposited in the Los Angeles County Museum ("LACM 2256")
seems to have been a fabrication. Christopher Rogers was finally
able to track down Taylor's P. natricina holotype at the California Academy of Sciences, where it was not deposited until 1999.
And here's another red flag - the hypothesized rarity of the new
species. Taylor's original description was based on but two
live-collected animals, "despite arduous effort" to obtain more.
But species do not exist as individuals - they exist in
populations. Any generally-trained biologist might well wonder
how a population as sparse as P. natricina seems to have been for over 20 years could remain viable.
In late 2005 I was pleased to accept an invitation from the Bureau of Reclamation to visit the Minidoka Dam (photo above) on the Snake River east of Rupert, Idaho, for a Physa
strategy meeting. Also present were our colleagues Amy
Wethington, John Keebaugh, Steve Lysne, and several others. The
product of that meeting was a consensus that a sequencing project
should be undertaken as soon as the next fresh P. natricina individual might be recovered from the river – a day which never arrived (11).
But on the basis of what I was able to learn about that elaborately
managed river system, together with my own limited observations of the
environment and my general experience with the biology of physids, I
offer the following hypothesis (12).
I suggest that the two individual P. acuta from which Taylor described his “Physa natricina”
in 1988 may have been flushed into the main Snake River from irrigation
ditches. In addition to power generation, many of the Snake River
dams serve to divert irrigation water to the surrounding farm
land. This is done seasonally, and both the peak diversions and
the peak release flows back to the river can be high. I suggest
that irrigation waters may sporadically carry elements of the
canal-dwelling macrobenthos into the Snake River, including occasional
individual Physa acuta.
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. Can
we avoid even the first step down such paths in the future?
Yes, if we watch for red flags. And the biggest red flag waving over the Physa natricina
blunder was not the vacuous description, the false precision, or the
biological implausibility of the phantom snail's very existence.
The biggest red flag was that this entire research program was
motivated, from its very inception, by water resource politics.
You have heard me preach this sermon before - science and politics do not mix.
When the two worldviews collide, compromises must be made, and it's
always the science that suffers, in my experience. Malacology was
corrupted at least four times by water resource politics in the middle
Snake River 20 years ago. And science continues to be corrupted
in our professional organizations, from the AAAS to the NAS, on matters
ranging from global climate to stem cells. But when we see that
red flag fly, we must stop.
And keep in touch,
Rob
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.
A pdf reprint can be requested from the author:
<crogers@ecoanalysts.com>
(2) Wuerthner, G. (1992) No Home for Snails. Defenders May/June 92: 8 - 14.
(3) 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)
(4) 28Apr05 - Idaho Springsnail Showdown.
23Dec05 - Idaho Springsnail Panel Report.
30Jan06 - When Pigs Fly in Idaho.
4Oct06 - FWS finding on the Idaho springsnail.
(5) 14Jun07 - Snake River gastropods studied for delisting
(6) Kabat, A. R. & R. I.
Johnson (in press) Dwight Willard Taylor (1932-2006): His life
and malacological research. Malacologia.
(7) Wethington, A. R.
& C. Lydeard (2007) A molecular phylogeny of Physidae
(Gastropoda: Basommatophora) based on mitochondrial DNA
sequences. J. Moll. Stud. 73: 241-257.
(8) Hershler, R.
(1985) Systematic revision of the Hydrobiidae (Gastropoda:
Rissoacea) of the Cuatro Cienegas Basin, Coahuila, Mexico.
Malacologia 26: 31 - 123.
(9) Taylor, D. W. (1988) New species of Physa (Gastropoda: Hygrophila) from the western United States. Malac. Rev. 21: 43-79.
(10) Yes.
(11) See the Bureau of Reclamation's web site
for the "Physa Amendment" to its "2004 Biological Assessment and
Opinions for Operations and Maintenance of Reclamation Projects in the
Snake River Basin above Brownlee Reservoir." There's also an
(8/05) "Implementation Plan for Proposed Snake River Physa Surveys"
available toward the bottom of the page.
(12) I don’t
remember who first advanced this hypothesis – it was very likely
in existence long before my introduction to the matter. And
I’m pretty sure I’m not the only one who holds it, but I
wouldn't presume to speak for anybody else.
Return ... to the FWGNA project