Dr. Rob Dillon, Coordinator

Monday, May 3, 2010

Influential Publications in Freshwater Gastropod Conservation

Back on April 22 I forwarded the following email from our good friend Bob Hershler to the FWGNA group:
We are preparing a paper on “Molluscan conservation over the past 50 years” for the upcoming UNITAS conference and toward that end we are asking the malacological community to help us identify the most important/influential publications on the subject between 1960-2010. If you have the time and interest, please send us a short list of no more than 5 publications that you consider to be in this category. Thanks very much in advance!

Bob Hershler
Rob Cowie (cowie@hawaii.edu)
Bob indicated that he will be accepting nominations through the first week of May. So there's still a bit of time to send him your suggestions, if you hurry.

I myself struggled with this assignment. Freshwater gastropod faunas are fundamentally regional, as are we researchers who study them, as are the conservation communities that rise to their defense, as are state agencies, as indeed even is the US Fish and Wildlife Service. There is no reason to expect that an inventory of gastropod species facing extinction from impoundments in Alabama, for example, should have any influence on livestock degradation of springs in New Mexico, no matter how compelling.

So I decided to subdivide my nominations by region. As of 5/2010, the US endangered species list includes 9 freshwater gastropods from the Mobile Basin of Alabama, 5 from the arid southwest, 5 from the Snake River, 2 from Tennessee, and 1 from Missouri. My initial idea was to gauge the "influence" of candidate publications by examining the literature cited sections of the entries in the Federal Register in which these 22 species were proposed, perhaps according more importance to the earlier references than to the later ones.

But a dichotomy immediately presented itself. Here in the East, the publications that seem to have influenced gastropod conservation all advance the argument, "Species X was common, and is now rare." So the proposals in the Federal Register for Alabama and Tennessee species cite 19th-century works of taxonomy, 20th-century alarms of a general nature, and unpublished status reports documenting the specific conservation situation. But in the West, species arrive rare. The Federal Register cites 20th-century works of taxonomy leading directly to unpublished status reports, skipping the general calls to alarm.

Ultimately I decided not to offer any recommendations for The West. I have very little experience in western regions, and (from the outside) was unable to identify any publications of even regional influence. Within the East I have divided my nominees into the Tennessee region, the Alabama region, and a special category from the Northeast.

First Place, Tennessee Region
Stansbery, D. H. (1970) Eastern Freshwater Mollusks (I) The Mississippi and St. Lawrence River Systems. Malacologia 10: 9-22.

This was the most lengthy contribution to the "Symposium on Rare and Endangered Mollusks of North America" organized by Arthur Clarke for the 1968 AMU meeting in Corpus Christi. Clarke edited the proceedings of the entire symposium for publication as a unit in the 1970 Malacologia 10: 3 - 56. That symposium featured contributions by 14 prominent malacologists of the day (1), and might justifiably be cited as a single work.

Dave Stansbery was primarily a unionid worker, but directed some attention in his paper to the status of pleurocerid populations in the eastern and central regions of North America. He specifically highlighted Io fluvialis ("A few relic populations remain") and Athearnia ("Eurycaelon - a few populations of at least one species yet survive.") In subsequent papers (2) Stansbery went on to document the elimination of Io from the North Fork Holston River, its type locality.

As the symbol of the American Malacological Society, Io fluvialis is literally "iconic." The alarm bell rung by Stansbery in 1970 was followed by the successful transplant efforts of Ahlstedt (3) ultimately keeping Io off the endangered species list (4).

Second Place, Tennessee Region
Bogan. A. E., & P.W. Parmalee. 1983. Tennessee’s Rare Wildlife, Volume II: The Mollusks. Tennessee Wildlife Resources Agency, Nashville. 123 pp.

The only Tennessee drainage freshwater gastropods to reach the Federal list have been Pyrgulopsis ogmorhaphe and Athearnia anthonyi, both in 1994. A review of the 5Aug93 issue of the Federal Register in which those two species were formally proposed for endangered status shows the work of Bogan and Parmalee cited prominently. This is certainly a much more complete work than that of Stansbery, although appearing later on the scene.

First Place, Alabama Region
Stein, C.B. 1976. Gastropods. Pp. 1-41 in Endangered and Threatened Plants and Animals of Alabama. H. Boschung (ed.). Bull. Alabama Museum of Natural History 2: 21- 41.

The first freshwater gastropod to enter the Federal Endangered Species list was Tulotoma magnifica in 1991. The review of Stein (1976) appears as the primary (published) reference in the 11July90 Federal Register proposing that endangered status. And even though at least four additional calls to alarm on behalf of the Mobile Basin fauna have been issued more recently (5), Stein's work may still be the most thorough.

Second Place, Alabama Region
Athearn, H. D. (1970) Discussion of Dr. Heard's paper. Malacologia 10: 28-31.

A batch of six Mobile Basin gastropods were added to the Federal list in 1998. The Federal Register of 17Oct97 cited six references in support of the statement that "During the past few decades, publications in the scientific literature have primarily dealt with the apparent decimation of this fauna" - Goodrich 1944, Athearn 1970, Heard 1970, Stein 1976, Palmer 1986, and Garner 1990. The work of Goodrich 1944 is a bit old for our fifty-year window, but the Athearn 1970 / Heard 1970 pair certainly does seem to have had an impact.

These papers were both contributed to that same (1968) symposium that also featured the Stansbery paper cited above. Bill Heard’s paper, entitled "Eastern freshwater mollusks, the South Atlantic and Gulf Drainages," was rather vague and general. But the "Discussion” by Herb Athearn, appearing in print as a simple four page list of "now rare and endangered, or possibly extinct" species, seems to have had a significant influence on Carol Stein's more complete review and the regulations that followed in the 1990s.

Harman, W. N. & J. L. Forney (1970) Fifty years of change in the molluscan fauna of Oneida Lake, New York. Limnology & Oceanography 15: 454-460.

The quality of the science in all four of the works cited for Tennessee and Alabama above is anecdotal at best. In fact, the papers of Stansbery and Athearn do not even rise to the level of the anecdote. For their 1970 paper in L&O, by contrast, Harman and Forney rigorously resampled Oneida Lake at the same spots originally sampled by F. C. Baker in 1917 (6), using similar gear. They documented significant reductions in gastropod abundance, species richness and diversity, and striking faunal shifts with the introduction of the invasive Bithynia tentaculata.

Harman and Forney’s work inspired me as a graduate student to reanalyze Baker’s data for a paper I published in The American Naturalist in 1981 (7), carrying forward to Chapter 9 of the book I published in 2000 (8). Harman also followed his 1970 study with a third study in 1992-95, documenting another 31% reduction in species richness with the introduction of zebra mussels (9).

Nominally driven to extinction in the 50 years between 1917 and 1967 were three nominal species nominally endemic to Oneida Lake, Amnicola bakeriana, A. clarkei, and A. oneida. Henry Pilsbry differentiated these three taxa from other much more widespread hydrobiids on the slenderest of threads (10). Nevertheless, the phantom New York hydrobiids of Baker and Pilsbry are no less valid than the phantom Alabama pleurocerids that Athearn listed without comment down the left margin of Malacologica Volume 10 in 1970 (11).

But Harman’s call to alarm has been of no consequence to freshwater gastropod conservation whatsoever. That a rigorous work of scientific research should disappear completely from the public conscience, while an unsubstantiated faunal list reaches the Federal Register to impact the laws of the land, should surprise none of my faithful readership (12). Science and Public Policy are two entirely different things.

Pushing on in the former, nonetheless,


(1) Stansbery, Clarke, Heard, Athearn, Dwight Taylor, Murray, Clench, Dundee, Allyn Smith, Abbott, Rosewater, Keen, Emerson, and Joe Morrison.

(2) Stansbery, D. H. (1972) The mollusk fauna of the North Fork Holston River at Saltville, Virginia. Bull. AMU 1972: 45-46. Stansbery, D. H. & W. J. Clench (1974) The Pleuroceridae and Unionidae of the North Fork Holston River above Saltville, Virginia. Bull. AMU 1974: 33-36. Stansbery, D. H. & C. B. Stein (1976) Changes in the distribution of Io fluviatilis in the upper Tennessee River system. Bull AMU 1976: 28-33.

(3) Ahlstedt, S. A. (1991) Reintroduction of the spiny riversnail Io fluvialis into the North Fork Holston River, southwest Virginia and northeast Tennessee. Amer. Malac. Bull. 8: 139-142.

(4) The reintroduction of Io into the NF Holston depended on much more than a few papers in the Bulletin of the AMU. The snails (and indeed, most of the benthic fauna of the river) were eliminated by pollution from the Olin-Mathieson Chemical Company in Saltville, which was closed by the EPA in 1971-72. Our good friend Steve Ahlstedt tells me that his Io transplant project was an outgrowth of water quality monitoring projects that started in the mid-1970s with mussels in barbeque baskets.

(5) Mobile Basin I: Two Pleurocerids Proposed for Listing [24Aug09]

(6) Baker, F. C. (1918) The productivity of invertebrate fish food on the bottom of Oneida Lake, with special reference to mollusks. NY State Coll. Forestry Tech. Publ. 9. 264 pp.
For more about this remarkable man and his work, see
The Legacy of Frank Collins Baker [20Nov06]

(7) Dillon, R.T. (1981) Patterns in the morphology and distribution of gastropods in Oneida Lake, New York, detected using computer-generated null hypotheses. American Naturalist 118: 83-101. [PDF]

(8) Now available in paperback! [Dillon 2000]

(9) Harman, W. N. (2000) Diminishing species richness of mollusks in Oneida Lake, New York State, USA. Nautilus 114: 120-126.

(10) Pilsbry, H. A. (1918) New species of Amnicolidae from Oneida Lake, New York. pp 244-246 in F. C. Baker, cited in (6) above. We'll never know, but from Pilsbry's descriptions it looks to me like Amnicola bakeriana may be a synonym of A. limosa, Amnicola clarkei is Lyogyrus granum, and Amnicola oneida is Marstonia lustrica.

(11) See my four-part series on the Mobile Basin pleurocerids:
I. Two Pleurocerids Proposed for Listing [24Aug09]
II. Leptoxis Lessons [15Sept09]
III. Pleurocera Puzzles [12Oct09]
IV. Goniobasis WTFs [13Nov09]

(12) See for example: Red Flags, Water Resources, and Physa natricina [12Mar08] and references cited therein.