SPECIES FACT SHEET

Scientific Name: Vorticifex neritoides (Baker, 1945)Common Name: Nerite Rams-hornPhylum: MolluscaClass: GastropodaOrder: BasommatophoraFamily: Planorbidae(ITIS 2018; NatureServe 2018)

Conservation Status: Global Status: G1Q – Critically imperiled/Questionable taxonomy (Last reviewed 01 Jun 2000)National Status (United States): N1 (Last reviewed 01 Jun 2000)State Status: SH (Oregon), S1S2 (Washington)(WHNP 2017; NatureServe 2018) IUCN Red List Category: Not assessed

Taxonomic Notes:1. The type specimen for this species was originally described as

Parapholyx effusa neritoides (Baker 1945). Frest and Johannes (1995) describe this taxon as Vorticifex neritoides, and not as a subspecies of Vorticifex effusus/effusa. NatureServe (2018) lists the taxonomy of this gastropod as Questionable. Furthermore, Johnson et al. (2013) and ITIS (2018) do not recognize Vorticifex neritoides (Baker) as a valid species, and it was overlooked by Burch (1989).

2. Rib patterns have been used in the past for describing species in this genus, but the character is unreliable and there is much variation within species (Hanna 1963; Albrecht et al. 2007). In the past, the male copulatory organ and radula have been found to be the most important structures for phylogenetical studies in Planorbidae (Hubendick 1955); however, this family is morphologically heterogeneous and intraspecific differences in several structures can make this group very confusing (Albrecht et al. 2007). Planorbid phylogenetic relationships remain problematic and controversial even after more recent molecular studies provide some insight into phylogenetic relationships (see Morgan et al. 2002; see Jørgensen et al. 2004; see Albrecht et al. 2007); therefore, additional research and revisions are needed for unresolved taxonomic problems (Albrecht et al. 2007).

Technical Description: Some freshwater mollusks can be difficult to identify properly due to their small size and limited understanding of their taxonomy. Species in the family

1

Planorbidae can often only be identified by internal anatomy (the radula and male copulatory organ being the most important morphologic structures) as shell features often overlap between species (Baker 1945; Hubendick 1955). Planorbid snails have discoidal shells (coiled in one plane and flattened like a disc) (Burch 1982) and are mostly orb-shaped, wheel-shaped, or disc-shaped (Baker 1945). While the shells of the genus are apparently dextral (coiled to the right), their respiratory, excretory, and reproductive systems are sinistral (terminating on the left side); a sinistral animal with a dextral-appearing shell is a condition known as pseudodextral (Baker 1945; Burch 1982; Dillon 2004). Vorticifex species are often large and thin-shelled with whorls that rapidly expand and an aperture that is wide and expanded (Baker 1945; Frest and Johannes 1999). However, the shell of V. neritoides is small, thick, and neritiform (hemispherical, with few rapidly enlarging whorls; spire very reduced, and aperture restricted and thickened around the entire periphery) (Frest and Johannes 1999). Its thick, brownish-yellow shell with restricted aperture resembles the overall appearance of some marine neritid species (Frest and Johannes n.d.)

The shell of this species is similar to that of V. effusa, but smaller, with a lower, much reduced spire, few whorls, and a comparatively thicker shell (Frest and Johannes 1999).

See Appendix (Attachment 4) for images of the shell of this species.

Life History:The Vorticifex genus is a member of the Planorbidae family, a group of pulmonate freshwater snails commonly known as ramshorn snails. The Planorbidae are one of the most diverse of the families of aquatic pulmonate snails (Baker 1945). As pulmonates, planorbids have a modified lung supplemented by a pseudobranch, or false gill, which they use to breathe while submerged in water. Freshwater pulmonates are simultaneous hermaphrodites, and though most are believed to be capable of self-fertilization, it is rare in the group (Dillon 2004). Vorticifex spp. generally lay eggs in tough, flat, circular gelatinous masses that may be attached to most firm substrates in protected areas in lotic habitats (Frest and Johannes 1992; 1999). Members of the genus are believed to lay egg capsules that contain from 6-30 embryos (Frest and Johannes 1999).

Very little is known about the life history of V. neritoides, and basic life history information is also lacking at the genus level. Inferring basic life history information specific to the members of Planorbidae is met with caution since taxa of the genus Vorticifex are atypical in ecology and life history for the family, and compared with other pulmonates (Frest and Johannes 2002). In fact, most pulmonate snails in the family are

2

characterized as more tolerant of unfavorable environmental conditions compared with other mollusks, with some planorbids persisting in alkaline, saline, or eutrophic waters because of their modified lung (Baker 1945; Dillon 2004). However, some members of the genus Vorticifex are strongly nonconforming for planorbids—being more similar in ecological preferences to prosobranch snails—which use a gill for breathing dissolved oxygen in water (more commonly in lotic environments) (Dillon 2004). As a Pacific Northwest endemic group, most taxa in this genus are adapted to cool oligotrophic waters dominant in this region (Frest and Johannes 1999). Thus, this species is found in cold, well-oxygenated, primarily lotic habitats (Frest and Johannes 1995). Because they prefer such habitats, members of this genus do not need to surface for air like most other pulmonate snails that live in shallow, warm water environments (Dillon 2004).

V. neritoides has been described as a lithophile and is likely a perilithon grazer (Frest and Johannes 1995). As a perilithon grazer, V. neritoides feeds primarily by scraping algae and diatoms on the surface of rocks (Frest and Johannes 1995). Additionally, members of the family have been observed grazing on floating and submerged plant leaves and various types of algae and may consume other small organic particles such as detritus, bacteria, and fungal hyphae (Baker 1945; Frest and Johannes 1995; Dillon 2004). Perilithon grazers like Vorticifex spp. are considered relatively sessile snails—they may not freely travel far during their lifetime—rarely moving far from their place of birth (Frest and Johannes 1993; 1995). The individual life span of this species and for planorbids in general is unknown; however, life history traits of Vorticifex spp. indicate they are annual and semelparous, living for one year during which they breed, lay eggs, and then die (Frest and Johannes 1992; reviewed in Furnish and Monthey 1998; reviewed in Pyron and Brown 2015). Their annual, semelparous life cycle is considered atypical for the family, since many planorbids live for several years and reproduce in successive years (Frest and Johannes 1992).

Range, Distribution, and Abundance:Type Locality: “Lower Columbia River” probably at the Dalles, Wasco Co., OR (Frest and Johannes 1995).

Range: This species has been reported in the Lower Columbia River. It is believed to be a strict Columbia River endemic known from multiple sites in this region, including near The Dalles Dam and Bonneville Dam (Frest and Johannes 1995).

Distribution: Vorticifex neritoides is endemic to the Columbia River Basin in Oregon and Washington (Frest and Johannes 1995). Syntypes of this species were originally described from The Dalles, Wasco County, Oregon (Coan and

3

Roth 1987; Frest and Johannes 1995). It has been documented at very few sites, and, like other locally endemic sensitive species with type localities here, has been documented as a part of comprehensive surveys of the Columbia Basin (see Frest and Johannes 1995). These surveys have revealed only one occurrence of this species, as it may be extinct at the type locality (Frest and Johannes 1995). Collection sites are vaguely described, but Frest and Johannes believe the original distribution to include Clark, Cowlitz, Klickitat, Skamania, and Wahkiakum Counties in Washington and Clatsop, Columbia, Hood River, Multnomah, and Wasco Counties in Oregon (Frest and Johannes 1995). Additionally, Frest (2005, pers. comm.) contends that, based on similar habitat, colonies may also occur in the lower Willamette River (Oregon City and north to the Columbia-Willamette confluence), though none have been collected here (Johannes 2009, pers. comm.). Despite additional surveys, it has not been found again at the Dalles type locality, and only one new location on the Columbia (near Abernathy, Washington) was found during 1988 surveys and has not been found since (Frest and Johannes 1995; Frest 2005, pers. comm.).

BLM/Forest Service Land: Documented: Vorticifex neritoides is not documented on Forest Service or BLM lands.

Suspected: It is suspected in the Columbia River Gorge National Scenic Area in Oregon and Washington.

Abundance: This species has rarely been encountered and specific abundance estimates are not available (Frest and Johannes 1995).

Habitat Associations: This species occurs in relatively large deep rivers (Frest and Johannes 1995). While locality descriptions are vague and this species has rarely been encountered, the general habitat for this species likely includes well-oxygenated deep river habitat near rapids with boulder-gravel substrate in unimpounded stretches at low elevations (Frest and Johannes 1995). Of the dozen or so extant Vorticifex taxa described in Oregon, most are restricted to habitat with relatively unpolluted, cold, and clear flowing water with high dissolved oxygen (DO) content (Frest and Johannes 1995; 1999; n.d.). However, while most Vorticifex taxa are found in small rivers and spring-influenced lake habitat, this species appears to prefer large rivers and is considered a Lower Columbia River endemic (Frest and Johannes (1995).

The ecology of members in the genus is much more similar to the limpet-shaped lancids (than members of Planorbidae), with which Vorticifex often co-occurs (Frest and Johannes 1995; 1999). This species has been collected

4

from low elevation sites at 15-122 cm (6-48 in) depth with substrates composed of cobbles and a mixture of sand and silt with no macrophytes (Frest and Johannes 1995). Other mollusks restricted to the Columbia River drainage system (and found in the lower reaches of the river), but now thought to be extinct due to habitat modifications include: Physella columbiana, Fisherola nuttalli, and Fluminicola columbiana. (Frest and Johannes 1995; n.d.). Physella columbiana is a BLM Strategic Species in Oregon (BLM ISSSSP Database 2015).

Threats:Freshwater gastropods presently have the highest extinction rate of any organism relative to their background extinction rate; this is likely a result of their limited dispersal abilities, endemism, and high vulnerability to habitat loss and degradation (Johnson et al. 2013). Mollusks with narrow ranges and ecological requirements like Vorticifex neritoides in particular have a high risk of extinction. Consequently, taxa in the genus are sensitive to substantial quantities of pesticides, nitrates, or phosphates; habitats with unstable, soft substrate or substantial quantities of suspended fine sediment; hypoxic conditions; and areas subject to frequent water level fluctuations (Frest and Johannes 1993; 1995; 1998). Their local endemism and hydrological requirements make them especially vulnerable in large river systems that have experienced widespread hydrologic and geomorphic alterations and suffer from pollution (Frest and Johannes 1995).

The Columbia River’s natural channel morphology has been extensively modified due to hydropower operation, bank stabilization structures, and flood protection measures (Simenstad et al. 2011). Hydropower facilities may degrade the system by altering sediment transport and flow regimes (OR DEQ 2012). Other deleterious impacts for gastropods may result from silt accumulation, loss of shallow water habitat from the creation of navigation channels, stagnation, and accumulation of pollutants. Furthermore, the Columbia River has been impacted by a host of hazardous contaminants from polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), and pesticides that exceed thresholds, impair the water, and impact aquatic life (LCREP 2007).

Sites in the Columbia River in Washington where this species has been documented are managed as reservoirs, which may at times exceed thermal tolerances for aquatic life (LCREP 2007; OR DEQ 2012). As a result of hydroelectric development, riverine habitat in the Columbia River has been reduced to 13% of what existed pre-impoundment (Dauble et al. 2003); in fact, this river system is one of the most fragmented and regulated among the world’s large rivers (Nilsson et al. 2005). River systems managed as reservoirs in the West create slow water habitat, which can be detrimental to

5

species that depend on cold, flowing water. Indeed, river impoundments have been known to be detrimental for benthic aquatic life (Poff and Schmidt 2016), and for mollusks in particular (McAllister et al. 2000; reviewed in Watters 2000). Furthermore, construction of dams themselves has been known to drive some gastropod species to extinction (Lydeard and Mayden 1995) and even impact lentic species adapted to slower flowing habitats (McAllister et al. 2000; Strong et al. 2008). Frest and Johannes (1995) note that this species has not been found from the type locality nor has it been relocated at the one site they collected this species in 1988 within the Columbia River near Washington. Thus, it may be extinct or near extinction due to its intolerance for impoundments and turbid and slack water.

Conservation Considerations:Research: The Columbia River hosts a diversity of taxa that are of special conservation concern, including Vorticifex neritoides and other endemic gastropods like Physella columbiana, Fisherola nuttalli, and Fluminicola spp. now thought to be extinct or near extinction (Frest and Johannes 1995). Research in the Columbia River is needed to determine current distribution of this species as well as its population status and other species-specific information, including basic biology and life history traits (density and abundance). Research is needed to assess the tolerance range of this species to environmental change and impacts to river flow and habitat modification.

Inventory: No known collections of this species have occurred in the Columbia River area since 1988 (Frest and Johannes 1995). Johannes (2009, pers. comm.) recommends surveys within the entire Columbia River range for this species. Surveys in the future could provide a better understanding of the current status, range, and population characteristics of this and other sensitive mollusk species that are known from the lower Columbia River. Continuing to monitor associated river habitats will provide information on disturbance events and introduced species, and provide a general understanding of endemic species dependent upon this large river system. Initial surveys are recommended at known historic sites in the Columbia River where the status of this species needs re-evaluation. Surveys for this species could occur at additional suitable habitat in the Lower Columbia River system.

Management: The high endemism of Vorticifex neritoides makes it particularly vulnerable to threats from development and habitat modification and degradation. Management for this species could include mitigating damage to rivers in this area from impoundment and river regulation to help meet ecosystem needs (see Poff and Schmidt 2016), since a return to pre-dam conditions is not feasible.

6

Nonpoint source pollution, including urban or agricultural runoff and pesticides, may also reduce water quality. Land managers could monitor activities associated with pollutants and sediment contamination near urban and industrial areas. Threats that degrade water quality and quantity for this species can be mitigated by managing and limiting habitat modifications and preventing erosion and sedimentation. These management actions can ensure better quality of rivers in this area, which can help provide important habitat. Additional management activities could include monitoring the introduction of exotic mollusks. Future surveys would help provide a basis for determining the most appropriate management to support populations.

Version 2Prepared by: Michele BlackburnThe Xerces Society for Invertebrate ConservationDate: February 2018

Edited by: Candace FallonThe Xerces Society for Invertebrate ConservationDate: March 2018

Version 1 (Duncan 2009)Prepared by: Nancy Duncan Date: April 2008

Edited by: Rob Huff Date: April 2009

ATTACHMENTS:[1] References[2] List of pertinent or knowledgeable contacts [3] Map of known records in Oregon and Washington[4] Photographs of Vorticifex neritoides[5]Aquatic Gastropod Survey Protocol, including specifics for this

species

ATTACHMENT 1: ReferencesAlbrecht, C., K. Kuhn, and B. Streit. 2007. A molecular phylogeny of Planorboidea (Gastropoda, Pulmonata): insights from enhanced taxon sampling. Zoologica Scripta 36(1): 27-39.

Baker, F.C. 1945. Descriptions of new species and new varieties. In the molluscan family Planorbidae. University of Illinois Press, Urbana, IL. pp. 218-

7

233. Available online at Biodiversity Heritage Library: http://www.biodiversitylibrary.org/ia/molluscanfamilyp00bake#page/20/mode/2up [Accessed 22 February 2018].

BLM ISSSSP Database. 2015. FINAL OR/WA State Director Special Status Species List, July 13, 2015.

Burch, J.B. 1982. Freshwater snails (mollusca: gastropoda) of North America. Environmental Monitoring and Support Laboratory. U.S. Environmental Protection Agency. Contract No. 68-03-1280. Cincinnati, Ohio.

Burch, J.B. 1989. North American Freshwater Snails. Malacological Publications, Hamburg, MI. 365 pp.

Dauble, D.D., T.P. Hanrahan, D.R. Geist, and M.J. Parsley. 2003. Impacts of the Columbia River hydroelectric system on main‐stem habitats of fall Chinook salmon. North American Journal of Fisheries Management 23(3): 641-659.

Dillon, R.T. 2004. The ecology of freshwater molluscs. Cambridge University Press. Cambridge, United Kingdom. 509 pp.

Duncan, N. 2009. Vorticifex neritoides. Species Fact Sheet. Interagency Special Status/Sensitive Species Program. Unpublished document. Available on ISSSSP intranet site.

Frest, T. 2005. Personal communication with Ms. Tyler, North Cascades National Park. Consultant, Deixis Consultants, SeaTac, Washington.

Frest, T.J. and E.J. Johannes. 1992. Distribution and ecology of the endemic and relict mollusc fauna of Idaho TNC's Thousand Springs Preserve. Yearly Report prepared for The Nature Conservancy of Idaho. Deixis Consultants, Seattle, Washington. 346 pp.

Frest, T.J. and E.J. Johannes. 1993. Mollusc species of special concern within the range of the Northern Spotted Owl. Final Report: Forest Ecosystem Management Working Group USDA Forest Service, Portland OR. 145 pp.

Frest, T.J. and E.J. Johannes. 1995. Interior Columbia Basin mollusk species of special concern. Final report: Interior Columbia Basin Ecosystem Management Project, Walla Walla, WA. 286 pp.

Frest, T.J. and E.J. Johannes. 1999. Field guide to survey and manage freshwater mollusk species. Bureau of Land Management, Oregon State Office. 128 pp.

8

Frest, T.J. and E.J. Johannes. [n.d.]. Northwestern U.S. sensitive nonmarine mollusks. Unpublished document. Available from E. Johannes.

Furnish, J.L. and R.W. Monthey. 1998. Revised by N. Duncan, 2005. Conservation Assessments for Mollusk Species associated with springs and spring runs: Fluminicola new species 2, 3, 11; Vorticifex klamathensis sinitsini; Juga (Oreobasis) new species 2; and Lyogyrus new spp. 1. USDA Forest Service Region 6 and USDI Bureau of Land Management, Oregon and Washington. Unpublished Document. Available on ISSSSP Intranet Site.

Hanna, G.D. 1963. Some Pleistocene and Pliocene freshwater mollusca from California and Oregon. California Academy of Sciences. 43:1-20.

Hubendick, B. 1955. Phylogeny in the Planorbidae. Transactions of the Zoological Society of London. 28(6): 453-542.

[ITIS] Integrated Taxonomic Information System. 2018. Integrated Taxonomic Information System (ITIS) Report: Vorticifex Meek, 1870 Taxonomic Serial No.: 76673 [website]. Available at: http://itis.gov [Accessed 21 February 2018].

Johannes, E. 2009. Personal communication with Sarah Foltz Jordan, the Xerces Society for Invertebrate Conservation. Consultant, Deixis Consultants, SeaTac, Washington.

Johnson, P.D., A.E. Bogan, K.M., Brown, N.M. Burkhead, J.R. Cordeiro, J.T. Garner, P.D. Hartfield, D.A.W. Lepitzki, G.L. Mackie, E. Pip, T.A. Tarpley, J.S. Tiemann, N.V. Whelan, and E.E. Strong. 2013. Conservation Status of Freshwater Gastropods of Canada and the United States. Fisheries. 38(6): 247-282.

Jørgensen, A., T.K. Kristensen, and J.R. Stothard. 2004. An investigation of the ‘Ancyloplanorbidae’ (Gastropoda, Pulmonata, Hygrophila): preliminary evidence from DNA sequence data. Molecular Phylogenetics and Evolution 32: 778–787.

[LCREP] Lower Columbia River Estuary Partnership. 2007. Lower Columbia River and Estuary Ecosystem Monitoring: Water Quality and Salmon Sampling Report. Portland, OR. 76 pp.

McAllister, D.E., J.F. Craig, N. Davidson, S. Delany, and M. Seddon. 2000. Biodiversity impacts of large dams. Prepared for Thematic Review II.1: Dams, ecosystem functions and environmental restoration. A contributing paper to

9

the World Commission on Dams on behalf of IUCN, the World Conservation Union. 66 pp.

Morgan, J.A.T., R.J. DeJong, Y. Jung, K. Khallaayoune, S. Kock, G.M. Mkoji, and E.S. Loker. 2002. A phylogeny of planorbid snails, with implications for the evolution of Schistosoma parasites. Molecular Phylogenetics and Evolution 25: 477–488.

NatureServe. 2018. “Vorticifex neritoides.” NatureServe Explorer: An online encyclopedia of life [website]. Nov. 2016. Version 7.1. NatureServe, Arlington, Virginia. Available at: http://www.natureserve.org [Accessed 21 February 2018].

Nilsson, C., C.A. Reidy, M. Dynesius, and C. Revenga, 2005. Fragmentation and flow regulation of the world’s large river systems. Nature 308: 405–408.

[OR DEQ] Oregon Department of Environmental Quality. 2012. Regional Environmental Monitoring and Assessment Program: 2009 Lower mid-Columbia River Ecological Assessment Final Report. Hillsboro, OR. 100 pp.

Poff, N.L. and J.C. Schmidt. 2016. How dams can go with the flow. Science 353(6304): 1099-1100.

Pyron, M. and K.M. Brown. 2015. Introduction to Mollusca and the Class Gastropoda in Ecology and General Biology: Thorp and Covich’s Freshwater Invertebrates (J.H. Thorp and A.P. Covich, eds.). Academic Press, San Diego, CA. pp.383-421.

Simenstad, C.A., J.L. Burke, J.E. O'Connor, C. Cannon, D.W. Heatwole, M.F. Ramirez, I.R. Waite, T.D. Counihan, and K.L. Jones. 2011. Columbia River estuary ecosystem classification—concept and application (No. 2011-1228). US Geological Survey. pp. i-54.

Strong, E.E., O. Gargominy, W.F. Ponder, and P. Bouchet. 2008 Global diversity of gastropods (Gastropoda; Mollusca) in freshwater. Hydrobiologia 595: 149-166.

Watters, G.T. 2000. Freshwater mussels and water quality: A review of the effects of hydrologic and instream habitat alterations. Proceedings of the First Freshwater Mollusk Conservation Society Symposium 1999: 261-274.

[WNHP] Washington Natural Heritage Program. 2017. Washington Natural Heritage Program list of animal species with ranks. October 2017. Available

10

at: https://www.dnr.wa.gov/publications/amp_nh_animals_ranks.pdf?bmzu7g. [Accessed 22 March 2018].

ATTACHMENT 2: List of pertinent, knowledgeable contacts

Ed Johannes, Consultant, Deixis Consultants, Seattle-Tacoma Washington.

Tom Burke, Retired, Regional Mollusk Expert, Pacific Northwest.

ATTACHMENT 3: Map of known records

Records of Vorticifex neritoides in Oregon and Washington relative to Forest Service and BLM lands.

11

ATTACHMENT 4: Images of Vorticifex neritoides (Baker, 1945)

Shells of Vorticifex neritoides (Baker 1945). Syntype collected by H. Hemphill from the Columbia River at The Dalles, Oregon. Used under Fair Use Law, information provided by the National Museum of Natural History, Smithsonian Institution, 10th and Constitution Ave. N.W. DC 20560-0193. (http://www.nmnh.si.edu/). USNM Number: 36615.

ATTACHMENT 5: Aquatic Gastropod Survey Protocol, including specifics for this species:

Taxonomic group: Aquatic Gastropoda

How to survey:

Please refer to the following documents for detailed mollusk survey methodology:

1. General collection and monitoring methods for aquatic mollusks:

12

See documents under the heading “Invertebrates – Mollusks” on the Interagency Sensitive and Special Status Species web page: https://www.fs.fed.us/r6/sfpnw/issssp/inventories/identification.shtml

2. Standard survey methodology that can be used by field personnel to determine presence/absence of aquatic mollusk species in a given waterbody, and to document species locations and habitats in a consistent format:

Duncan, N. 2008. Survey Protocol for Aquatic Mollusk Species: Preliminary Inventory and Presence/Absence Sampling. Version 3.1. Portland, OR. Interagency Special Status/Sensitive Species Program. U.S. Department of Interior, Bureau of Land Management, Oregon/Washington and U.S. Department of Agriculture, Forest Service, Region 6. 52 pp. [Available at: http://www.fs.fed.us/r6/sfpnw/issssp/species-index/fauna-invertebrates.shtml].

3. Inventory information for mollusk site surveys:

Inventory and Monitoring protocol page, with NRIS/Geobob field forms. Available at: http://www.fs.fed.us/r6/sfpnw/issssp/species-index/fauna-invertebrates.shtml

ID services page, with current versions of field tags. Available at: http://www.fs.fed.us/r6/sfpnw/issssp/inventories/identification.shtml.

Species-specific survey details:Vorticifex neritoides

How to survey: Aquatic snails may occur in a variety of habitat types, including springs, rivers and streams, and lakes and ponds. Seek out key habitat features known to be utilized by the target species. Record geographic coordinates and key habitat features for each site surveyed. Standardized abundance estimates for this species at new and known sites would assist future conservation efforts, since population size is important in evaluating the stability of a species at a given locality.

A variety of methods may be used to sample for aquatic snails, including hand and dip-net collection, kick-net collection, and the use of surber samplers, grab samples, dredges, and wire-basket benthos samplers. Dip-netting and dredging are appropriate survey techniques for this species

13

(Deixis MolluscDB 2009). Duncan et al. (2008) outline methods appropriate for typical aquatic habitats. Sample procedures should limit impacts to sensitive habitats, particularly springs and streambeds. Surveyors should avoid use of chemicals such as bug repellant or sunblock, which may wash off into the water. Surveyors should also take steps to disinfect gear prior to sampling and reduce risk of transferring invasive species among sampling sites (Duncan et al. 2008). More information on invasive species and prevention strategies can be found at: http://www.fs.usda.gov/detail/r6/forest-grasslandhealth/invasivespecies/?cid=stelprdb5302184.

Where: Surveys for Vorticifex neritoides are recommended in the Columbia River in Oregon and Washington. The habitat preferences for V. neritoides are not well known since few individuals have been collected, but the general habitat for this species likely includes well-oxygenated river habitat near rapids with boulder-gravel substrate. This species has been collected from low elevation sites at 15-122 cm (6-48 in) depth with substrates composed of cobbles and a mixture of sand and silt with no macrophytes (Deixis MolluscDB 2009). According to Frest and Johannes (1995), this species is one of several aquatic mollusks likely driven to extinction or near extinction from dams and their effects, and the lower Columbia River populations, including the type locality, are largely extirpated. Further surveys, however, are strongly recommended for this species; Johannes (2009, pers. comm.) recommends surveys within the entire suspected Columbia River range. Johannes (2009, pers. comm.) also suggests searching appropriate areas in the lower Willamette River.

When: Sampling can be conducted any time of year, though surveys for this species are best conducted in the fall when the water levels in the Columbia River are lower (Johannes 2009, pers. comm.). Collections of this species have occurred in September and November. Although this species is present all year, it is likely not active in winter (Duncan 2008). Surveys in flowing waters should be conducted after water levels and flows have decreased and survey conditions are safe. The sampling schedule must be planned to avoid tidal influences in the lower stretches of the river as well as periods when water is being released from the dams (Johannes 2009, pers. comm.). These and other recommendations are outlined further in Duncan et al. (2008).

References (Survey Protocol only):Deixis MolluscDB database. 2009. An unpublished collection of mollusk records maintained by Ed Johannes.

14

Duncan, N. 2008. Survey Protocol for Aquatic Mollusk Species: Preliminary Inventory and Presence/Absence Sampling. Version 3.1. Portland, OR. Interagency Special Status/Sensitive Species Program. U.S. Department of Interior, Bureau of Land Management, Oregon/Washington and U.S. Department of Agriculture, Forest Service, Region 6. 52 pp. [Available at: http://www.fs.fed.us/r6/sfpnw/issssp/species-index/fauna-invertebrates.shtml].

Frest, T.J. and E.J. Johannes. 1995. Interior Columbia Basin mollusk species of special concern. Final report: Interior Columbia Basin Ecosystem Management Project, Walla Walla, WA. 286 pp.

Johannes, E. 2009. Personal communication with Sarah Foltz Jordon, the Xerces Society for Invertebrate Conservation. Consultant, Deixis Consultants, SeaTac, Washington.

15