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SECTION NO. 3
Fluminicola seminalis

Draft Management Recommendations
for
Nugget Pebblesnail (Fluminicola seminalis), a ROD Mollusk Species
associated with Sacramento River habitats.

v. 2.0

by

Joseph L. Furnish,
USDA Forest Service,
San Francisco, California

and

Roger W. Monthey
USDI Bureau of Land Management
Salem, Oregon

December 1998


TABLE OF CONTENTS

EXECUTIVE SUMMARY 1
I. NATURAL HISTORY 3
A. Taxonomic/Nomenclatural History 3
B. Species Descriptions 3
1. Morphology 3
2. Reproductive Biology 3
3. Ecology 3
C. Range, Known Sites 4
D. Habitat Characteristics and Species Abundance 4
II. CURRENT SPECIES SITUATION 5
A. Why Species is Listed under Survey and Manage Standards & Guidelines 5
B. Major Habitat and Viability Considerations 5
C. Threats to the Species 5
D. Distribution Relative to Land Allocations 6
III. MANAGEMENT GOALS AND OBJECTIVES 6
A. Management Goals for the Taxon 6
B. Specific Objectives 6
IV. HABITAT MANAGEMENT 6
A. Lessons from History 6
B. Identification of Habitat Areas for Management 7
C. Management within Habitat Areas 7
D. Other Management Issues and Considerations 8
V. RESEARCH, INVENTORY, AND MONITORING NEEDS 8
A. Data Gaps and Information Needs 8
B. Research Questions 9
C. Monitoring Needs and Recommendations 9
VI. REFERENCES 10

EXECUTIVE SUMMARY

Species: Fluminicola seminalis (Nugget pebblesnail)

Taxonomic Group: Mollusks (Phylum Mollusca; Class Gastropoda; Subclass Prosobranchia; Family Hydrobiidae)

ROD Components: Survey and Manage Strategies 1 & 2 and listed in the Standards and Guides for protection from grazing.

Other Management Status: None

Range: Pit River and McCloud River basins. Currently known on federal lands from only 2 sites in Shasta National Forest and 3 sites in Whiskeytown-Shasta-Trinity National Recreation Area.

Specific Habitats: Fluminicola seminalis prefers gravel-cobble substrate and clear, cold flowing water. It typically is found in large streams and rivers. However, it is also found in a very few large spring pools with soft, mud substrates (Frest and Johannes 1995).

Threats:

  • Chemical spills and other forms of water pollution (e.g., livestock use of stream channels and springs, sewage contamination from recreation use) resulting in effects such as: 1. direct mortality of species as evidenced by the recent Cantara Spill (1991) on the upper Sacramento River, and 2. deleterious habitat alterations resulting from factors such as: eutrophication caused by excessive nitrogen and phosphorus levels, reduced dissolved oxygen levels, or elevated water temperatures.
  • Dam construction that submerges cold springs, slows current velocities, lowers the availability of oxygen, and allows fine sediments to accumulate. Existing dams on the Sacramento River (e.g., Shasta Dam, dams creating Whiskeytown Reservoir and Siskiyou Lake) and the Pit River have already caused extensive destruction of suitable habitat.
  • Reductions in water flow by water diversions resulting in elimination or reduction of aquatic habitat for this snail.
  • Excessive sedimentation from a variety of activities such as logging, mining, road and railroad grade construction, and grazing may smother preferred substrates and may impair egg-laying or survivorship of eggs or young.

Management Recommendations: All sites occupied by this snail should be protected and monitored. Specific recommendations include:

  1. Avoid all types of water pollution (e.g., chemical and sewage contamination resulting in excessive fertilization)
  2. Maintain water temperatures below 18oC (65oF) to avoid thermal stress and ensure adequate availability of oxygen. (18oC represents the critical threshold for trout.)
  3. Maintain dissolved oxygen levels at or near saturation levels.
  4. Maintain and/or restore native riparian plant communities that aids in maintaining cool water temperatures (i.e., below 18oC) by providing shade, reducing sedimentation impacts by providing a vegetative filter, and providing litter fall nutrients essential to energy pathways in stream ecosystems.
  5. Avoid or mitigate for activities (e.g., logging, grazing, mining, construction activities) that could significantly increase sedimentation or potential for eutrophication of occupied sites.
  6. Avoid water diversions or other activities that may reduce water flow below levels necessary to sustain viable populations. This level should be determined on a site specific basis but this species generally needs flowing water.
  7. Avoid or mitigate for the construction of dams that may have the following impacts: submersion of cold springs, slowing of current velocities, lowering of dissolved oxygen, and increased sedimentation.

Information Needs: Additional surveys should be conducted to locate populations in areas with potential suitable habitat. More monitoring or research is needed on habitat requirements of these species. Develop a collection of voucher specimens for appropriate administrative units within the range of these species. Provide additional training opportunities for identifying mollusk species and conducting surveys within the appropriate administrative units. Monitor water temperature and other environmental parameters (e.g., sedimentation, dissolved oxygen) that potentially affect this species. Determine the minimum instream flow requirements necessary to maintain environmental conditions within physiological limits.

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I. NATURAL HISTORY

A. Taxonomic/Nomenclatural History

Synonyms - Paludina seminalis Hinds, 1842; Melania seminalis (Hinds) Lea, 1856; Bithinia seminalis (Hinds) Carpenter, 1857; Amnicola seminalis (Hinds) Cooper, 1860; Lithoglyphus cumingii Frauenfeld, 1863; Melania (Paludina) seminalis (Hinds) Carpenter, 1864; Paludina cumingii Frauenfeld, 1864; Lithoglyphus cumingi [sic] (Frauenfeld) Pilsbry, 1899; Fluminicola seminis [sic] (Hinds) Wenz, 1939; Fluminicola seminaris [sic] (Hinds) Wenz, 1939; Lithoglyphus seminalis (Hinds) Taylor, 1966, 1981.

B. Species Description

1. Morphology

For detailed description of shell and anatomy, see Hershler & Frest (1996). This species has a medium-high conic spire, ranging to about 4 mm in height; adults have about 4.5 whorls. The shell is thick and green; the protoconch is small and flattened; the shell apex is blunt; later whorls are even and moderately convex. The aperture is bluntly ovate; the entire margin is thickened more or less evenly (except possibly the base), but the columellar callus is rather narrow. There is a narrow umbilical chink and small basal crescent that does not extend to the base of the columella. A similar but distinct species occurs in the Klamath drainage in Oregon. For illustrations of this species see Frest & Johannes (1993a, fig. 3b; 1995, fig. 6B); and Hershler & Frest (1996, figs. 6b, 13b, c; 15a-f; 17a-c).

2. Reproductive Biology

Information on life history is very sparse, but Fluminicola seminalis is probably similar to other Fluminicola species that have been better studied. Typically, members of the family are dioecious (i.e., have separate sexes) and semelparous (i.e., breed only once in their lifetime and then die). Individuals have a life span of one year, with 90 percent or more of the population turning over annually. Surviving individuals are generally those that do not breed during their first year. Eggs are laid in the spring and hatch in approximately 2-4 weeks. Sexual maturity is reached by late summer after a few months of growth. Individuals overwinter as adults and do not disperse widely so populations remain very localized in their distribution.

3. Ecology

Fluminicola seminalis is a rare aquatic snail belonging to the family Hydrobiidae. A common name for this family is "spring snails", which is an allusion to the type of habitat where they are primarily found. All hydrobiid snails have gills that makes them dependent upon dissolved oxygen in the water column. It is very intolerant of pollution, and is extremely sensitive to warm water, sedimentation, and low oxygen levels.

F. seminalis is a riparian associate and is a cold water, perilithon (e.g., the algal and microbial film on rock surfaces) feeder, like most other Fluminicola species. This amniphilic (preferring stream environments) and crenophilic (preferring spring environments) species could be a detritivore.

F. seminalis often co-occurs with Juga (Juga) occata, J. (Calibasis) acutifilosa, J. (Oreobasis) nigrina, and Lanx patelloides. It also commonly occurs with widely distributed species like Vorticifex effusa, Gyralus parvus and Physella gyrina.

C. Range, Known Sites

According to Hershler and Frest (1996), this species is a typical river-dwelling hydrobiid of the Upper Sacramento River system where it is endemic. However, in a recent survey of 231 sites in the potential area of occurrence, Frest and Johannes (1995) reported that they could not locate it in the Upper Sacramento system. Presumably, this species was recently extirpated by the Cantara Bend herbicide spill. F. seminalis is moderately common in the Pit and McCloud Rivers and their tributaries. Frest and Johannes collected it from 22 sites, in a confined portion of the Pit drainage. Five of these sites are on federal land: 2 in the Shasta National Forest and 3 in the Whiskeytown-Shasta-Trinity National Recreation Area.

D. Habitat Characteristics and Species Abundance

F. seminalis prefers cool, clear, flowing water and gravel-cobble substrate. It is typically found in large creeks and rivers (Taylor 1981). In addition, it can occur on soft, mud substrates in large spring pools (Frest and Johannes 1993a, 1995). The latter authors provided a general description of the habitat for F. seminalis in the Upper Sacramento system. Most of the Upper Sacramento system should be appropriate habitat for the species. The terrain of this area is steep, moist, and comparatively well vegetated. Rivers and creeks are perennial, have relatively large discharges, and flow through deep, incised, shaded canyons. Vegetation is primarily coniferous and soils are thin and nutrient poor. Aquatic environments generally have clear, cold, well oxygenated, flowing waters that have relatively low concentrations of dissolved nitrogen and phosphorus. Macrophytes such as Potamogeton, Rorippa, and Ceratophyllum occur in patches at some occupied sites. Substrates are primarily characterized by coarse boulders, cobbles and gravel mostly derived from metamorphic and igneous parent material with some sedimentary lithologies. There are a few occupied lake and marsh habitats. Frest and Johannes (1993a, 1995) found F. seminalis at elevations ranging from 365 to 3305 feet.

Frest and Johannes (1995) recorded densities for F. seminalis at 2000-3000 per m2 in the Pit and McCloud Rivers. Under such circumstances it may constitute the major invertebrate biomass at a site.

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II. CURRENT SPECIES SITUATION

A. Why Species is Listed Under Survey and Manage Standards and Guidelines

The FEMAT analysis concluded this species has a low likelihood of attaining stable, well distributed populations (USDA, Forest Service, and USDI, Bureau of Land Management 1994a) based on the following factors. F. seminalis is considered rare since it occurs at a few, highly localized sites in restricted habitats. It is endemic to the Upper Sacramento River system. Historically, it has suffered from habitat degradation so it is appropriate to protect surviving populations. Recent events like construction of dams, the spill of the herbicide metam sodium (Vapam) in the Cantara spill of 1991, and the Burney fire of 1992 and subsequent salvage logging, have caused significant impacts to the population. The species is now about 95 percent extirpated from its former range in the Sacramento River (USDA, Forest Service, and USDI, Bureau of Land Management, Appendix J2 1994b).

B. Major Habitat and Viability Considerations

Fluminicola species, like most hydrobiid snails, are highly sensitive to oxygen deficits, elevated water temperatures, and sedimentation. F. seminalis is only found in river reaches and springs that have cold, well oxygenated, clear water, generally with cobble and/or boulder substrates. Any activities that degrade these parameters will adversely impact this species.

The life history traits of F. seminalis also put it at risk. Individuals apparently breed only once in a lifetime and then die. Usually 90 percent of the population turns over annually so any condition that impairs egg laying, or survivorship of eggs or young may result in extirpation.

C. Threats to the Species

  • Chemical spills and other forms of water pollution (e.g., livestock use of springs and channel bottoms, sewage contamination from recreational use) resulting in effects such as: 1. direct mortality of species as evidenced by the recent Cantara Spill (1991) on the Upper Sacramento River, and 2. deleterious habitat alterations resulting from factors such as eutrophication caused by excessive levels of nitrogen and phosphorus, reduced dissolved oxygen levels, or elevated water temperatures.
  • Dam construction that submerges cold springs, slows current velocities, lowers the availability of oxygen, and allows fine sediments to accumulate. Existing dams on the Sacramento River (e.g., Shasta Dam, and dams creating Whiskeytown Reservoir and Siskiyou Lake) and the Pit River have already caused extensive destruction of suitable habitat.
  • Reductions in water flow by water diversions resulting in elimination or reduction of aquatic habitat for this snail.
  • Excessive sedimentation from a variety of activities such as logging, mining, road and railroad grade construction, and grazing may smother substrates preferred by these species and may impair egg-laying or survivorship of eggs or young.

D. Distribution Relative to Land Allocations

Populations in the upper Sacramento River basin are located in areas allocated as Late-Successional Reserves. For more precise locations of known sites relative to land allocations, field units should refer to the Survey and Manage Database, and maps of Late-Successional Reserves and other allocations in their administrative area.

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III. MANAGEMENT GOALS AND OBJECTIVES

A. Management Goals for the Taxon

The overall management goal is to assist in maintaining species viability.

B. Specific Objectives

  • Maintain water quantity (as determined on a site specific basis) and water quality (e.g., high dissolved oxygen at or near saturation levels, stream temperatures below 18oC or 65oF) at levels suitable for sustainability of this species.
  • Maintain native riparian plant communities to help maintain desired ecological attributes.
  • Maintain integrity of streambed substrates preferred by this species by minimizing sedimentation (i.e., avoid smothering of suitable substrates).

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IV. HABITAT MANAGEMENT

A. Lessons from History

Historically, over the last century, this species has suffered significant negative impacts from mining, logging, grazing, pollution, road and railroad grade construction, and water manipulations. For example, hydraulic mining in the 1800s caused extensive damage by removal of riparian vegetation and by bank destruction, resulting in elevated water temperatures and excessive sedimentation of aquatic habitats. In addition, the need for lumber to sustain mining operations increased logging activities resulting in similar impacts. Road and railroad grade construction in riparian areas also added to these effects. Grazing operations have primarily impacted aquatic habitat by 1. diverting, channelizing, or damming water flow, thus affecting the quantity and quality of habitat, and 2. livestock trampling of stream channels and springs resulting in sedimentation and water pollution.

Work initiated as part of the Central Valley Project (after 1937) and the California Water Project (in 1960) have resulted in major habitat modifications. Dam construction on the Sacramento River (e.g., Shasta Dam, dams creating Whiskeytown Reservoir and Siskiyou Lake) and Pit River by Pacific Gas and Electric have caused extensive destruction of suitable habitat. For example, dam construction submerges cold springs, slows current velocities, lowers the availability of oxygen, and allows fine sediments to accumulate. Existing populations have been decimated and become fragmented and isolated as a result.

In July 1991 any remaining populations in the Upper Sacramento River appear to have been destroyed when railroad cars carrying the herbicide metam sodium (Vapam) derailed at Cantara Bend and spilled into the river, causing major impacts in the lower 40 miles of the river. Only the upper 3 miles were unaffected by the spill.

Salvage logging in the aftermath of the Burney fire of 1992 caused significant impacts to populations by increasing sedimentation and elevating water temperatures.

B. Identification of Habitat Areas for Management

All populations on Forest Service or BLM administered lands are considered important to maintain the viability of these species. Other sites on which populations are located in the future should also be managed.

Identify the habitat areas around known site locations, including all habitat features that contribute to the environmental conditions important to the species at the known site.

In most cases, the Riparian Reserve standards and guides for buffer widths and meeting Aquatic Conservation Strategy objectives will be sufficient for management within these areas. In situations where RRS and ACS do not apply or are not considered sufficient (e.g., wetlands less than 1 acre, springs and seeps) apply the standards and guides for perennial stream widths to determine the size of the area. Where wind firmness is a problem, habitat area widths may need to be increased to protect species habitat conditions.

C. Management Within Habitat Areas

All sites occupied by these snails should be protected. Specific recommendations include:

  1. Maintain water temperatures below 18oC (65oF) to avoid thermal stress and ensure adequate availability of oxygen. (18oC represents the critical threshold for the trout.)
  2. Maintain dissolved oxygen levels at or near saturation levels.
  3. Maintain and/or restore native riparian plant communities at site and upstream that aid in maintaining cool water temperatures ( i.e., below 18oC) by providing shade, reducing sedimentation impacts, and providing litterfall nutrients to energy pathways in stream ecosystems.
  4. Avoid or mitigate for activities that could significantly increase sedimentation, pollution, or potential for eutrophication of occupied sites (e.g., logging, grazing, mining, construction activities).
  5. Avoid water diversions or other activities that may reduce water flow below levels necessary to sustain viable populations. This level must be determined on a site specific basis, but these species generally need flowing water.
  6. Avoid or mitigate for the construction of dams that may have the following impacts: submersion of cold springs, slowing of current velocities, lowering of dissolved oxygen, and increased sedimentation.

D. Other Management Issues and Considerations

If reestablishment is considered for this species, Frest and Johannes (1993a, 1995) advised that relatively pure colonies of this species should be reintroduced in formerly occupied sites using fairly large numbers (i.e., in the range of several hundred to several thousand individuals per reintroduction site). Formerly occupied sites may be established by consulting museum records. No other management issues and considerations are identified at this time.

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V. RESEARCH, INVENTORY, AND MONITORING NEEDS

The objective of this section is to identify opportunities for additional information which could contribute to more effective species management. The content of this section has not been prioritized or reviewed as to how important the particular items are for species management. While the research, inventory, and monitoring information is not required, these recommendations should be addressed by a coordinating body at the Northwest Forest Plan level.

A. Data Gaps and Information Needs

The following items would enhance our knowledge of this species:

  • Conduct surveys to locate populations in areas identified as potential suitable habitat. Surveys to reliably establish patterns of distribution have only recently been initiated (Frest and Johannes 1993a, 1995). Thus, it is appropriate to conduct additional surveys in suitable habitats of the Sacramento River and Pit River basins prior to undertaking activities that may adversely impact this species.
  • Conduct monitoring or research on habitat requirements of this species.
  • Develop a collection of voucher specimens for appropriate administrative units within the range of this species.
  • Provide additional training opportunities for identifying this species and conducting surveys within the appropriate administrative units.
  • Monitor water temperature at or in the vicinity of occupied sites using continuous reading thermometers, or at least maximum-minimum thermometers, to assure compliance.
  • Monitor other environmental parameters (e.g., sedimentation, dissolved oxygen) that potentially affect this species.
  • Determine the minimum instream flow requirements necessary to maintain environmental conditions within physiological limits.
  • Develop keys and descriptions that allow field offices to accurately identify these species.

B. Research Questions

  • Where did viable populations of this species occur prior to the Cantara spill? Can this species be reestablished at sites occupied prior to the spill?
  • Are survey and manage provisions effective? If not, why? What should be done differently?
  • What is the condition of existing populations with regard to absolute size and density?
  • What are the dispersal mechanisms of this species?
  • What are the specific habitat requirements of this species?
  • How does this species respond to changes in water quality conditions and other disturbances?
  • What implications, if any, does management for this species have on other species?

C. Monitoring Needs and Recommendations

Protocols for monitoring presently known populations and conducting surveys. At a minimum, the following variables should be monitored to track habitat quality: 1. water temperature, 2. dissolved oxygen, 3. sedimentation, 4. nitrogen and phosphorus levels, and 5. flow in streams.

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VI. REFERENCES

Frest, Terrence J. and Edward J. Johannes. 1993a. Freshwater Molluscs of the Upper Sacramento System, California with Particular Reference to the Cantara Spill. Deixis Consultants, 1992 Yearly Report. Unpublished report prepared for the State of California, Department of Fish and Game, Contract #FG2016R1. 101 pp. and 2 appendices.

___________. 1993b. Mollusc Species of Special Concern within the Range of the Northern Spotted Owl. Deixis Consultants, Final Report. Unpublished report prepared for the Forest Ecosystem Management Working Group, U.S.D.A. Forest Service; Pacific Northwest Region; Portland, OR. 98 pp. and 1 addendum.

___________. 1995. Freshwater Molluscs of the Upper Sacramento System, California with Particular Reference to the Cantara Spill. Deixis Consultants, 1994 Yearly Report. Unpublished report prepared for the State of California, Department of Fish and Game.

Hershler, R., and T. J. Frest. 1996. A Review of the North American Freshwater Snail Genus Fluminicola (Hydrobiidae). Smithsonian Contributions to Zoology, No. 583. 41 pp.

Hinds, R. B. 1842. Descriptions of new shells. Annals & Magazine of Natural History, Ser. 1, 10:81-84.

Taylor, D. W. 1966. Summary of North American Blancan Nonmarine Mollusks. Malacologia 4:1-172.

___________. 1981. Freshwater Mollusks of California. California Fish and Game, 67(3):140-163.

USDA, Forest Service, and Department of the Interior, Bureau of Land Management.1994a. Final Supplemental Environmental Impact Statement on Management of Habitat for Late-Successional and Old-Growth Forest Related Species within the Range of the Northern Spotted Owl, Appendix A, Forest Ecosystem Management: An Ecological, Economic, and Social Assessment. Portland, OR.

___________. 1994b. Final Supplemental Environmental Impact Statement on Management of Habitat for Late-Successional and Old-Growth Forest Related Species within the Range of the Northern Spotted Owl, Appendix J2. Results of Additional Species Analysis.


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