Species Status Assessment Report for Beaverpond Marstonia

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Species Status Assessment Report

For

Beaverpond Marstonia (Marstonia castor)

Marstonia castor. Photo by Fred Thompson

Version 1.0

September 2017

U.S. Fish and Wildlife Service Region 4 Atlanta, Georgia

This document was prepared by Tamara Johnson (U.S. Fish and Wildlife Service – Georgia Ecological Services Field Office) with assistance from Andreas Moshogianis, Marshall Williams and Erin Rivenbark with the U.S. Fish and Wildlife Service – Southeast Regional Office, and Don Imm (U.S. Fish and Wildlife Service – Georgia Ecological Services Field Office). Maps and GIS expertise were provided by Jose Barrios with U.S. Fish and Wildlife Service – Southeast Regional Office.

We appreciate Gerald Dinkins (Dinkins Biological Consulting), Paul Johnson (Alabama Department of Conservation and Natural Resources), and Jason Wisniewski (Georgia Department of Natural Resources) for providing peer review of a prior draft of this report.

Suggested reference:

U.S. Fish and Wildlife Service. 2017. Species status assessment report for beaverpond marstonia. Version 1.0. September, 2017. Atlanta, GA. 24 pp.

Species Status Assessment Report for Beaverpond Marstonia (Marstonia castor)

Prepared by the Georgia Ecological Services Field Office U.S. Fish and Wildlife Service

EXECUTIVE SUMMARY

This species status assessment is a comprehensive biological status review by the U.S. Fish and Wildlife Service (Service) for beaverpond marstonia (Marstonia castor), and provides a thorough account of the species’ overall viability and extinction risk. Beaverpond marstonia is a small spring snail found in tributaries located east of Lake Blackshear in Crisp, Worth, and Dougherty Counties, Georgia. It was last documented in 2000.

Based on the results of repeated surveys by qualified species experts, there appears to be no extant populations of beaverpond marstonia. Failure to detect the species in surveys to date in beaverpond marstonia’s type locality and similar habitat in surrounding areas indicates that the species is likely extinct.

We used the best available information to describe the species’ viability. We have assessed the overall species status including the species’ needs, current condition, and future condition with respect to three factors of viability (Table ES-1). The three factors of viability – resiliency, redundancy, and representation – are currently absent, which leads us to conclude that the beaverpond marstonia has no viability and appears to be extinct.

Table ES-1. Overall species status assessment summary for beaverpond marstonia.

3Rs Needs Current Condition Future Condition (Viability) Resiliency  Functioning spring  No known  No resiliency (Large ecosystems current populations able  Adequate flow for populations to withstand stochastic streams  Historical events)  Known populations locations  Habitat with dewatered submerged vegetation Redundancy  Multiple  No known  No (Number and populations populations redundancy distribution of throughout the populations to range of the species withstand catastrophic events)

Representation  Genetic variation  No known  No known (genetic and exists between populations representation. ecological populations diversity to maintain  Ability to survive adaptive under different potential) habitat conditions

Table of Contents

EXECUTIVE SUMMARY...... 4 CHAPTER 1. INTRODUCTION...... 7 CHAPTER 2. BIOLOGY AND LIFE HISTORY...... 9 2.1 Taxonomy...... 9 2.2 Morphological Description...... 10 2.3 Life History...... 10 2.4 Reproduction...... 10 2.5 Ecology...... 11 2.6 Habitat...... 11 CHAPTER 3. CURRENT CONDITION...... 13 3.1 Range and Distribution...... 13 3.2 Current Condition of Historical Locations...... 15 3.3 Current Condition of Populations...... 15 3.4 Current Beaverpond Marstonia Habitat Conditions...... 13 3.5 Summary of Current Conditions...... 14 CHAPTER 4. FACTORS INFLUENCING VIABILITY...... 15 4.1 Introduction...... 16 4.2 Natural Stochastic Events...... 16 4.3 Drought ...…………...... 16 CHAPTER 5. SPECIES VIABILITY...... 17 5.1 Introduction...... 17 5.2 Resiliency...... 17 5.3 Redundancy...... 17 5.4 Representation...... 17 5.5 Status Assessment Summary...... 17 LITERATURE CITED...... 19

CHAPTER 1. INTRODUCTION

Beaverpond marstonia (Marstonia castor) was historically found only in Georgia, at its type locality, Cedar Creek (over Coney Road) in Crisp County, and in two additional locations; 1) in Swift Creek, Worth County and 2) Mercer Mill Creek, Dougherty County.

The beaverpond marstonia had previously been considered for listing under the Endangered Species Act of 1973, as amended (Act), and has been assigned status as a category 2 candidate species. A category 2 candidate species was one for which there was some evidence of vulnerability, but for which additional biological information was needed to support a proposed rule to list as endangered or threatened. This system of categories was discontinued in 1996 (December 5, 1996; 61 FR 64481) in favor of maintaining a list that only represented those species for which we have on file sufficient information on biological vulnerability and threats to support a proposal to list as endangered or threatened, but for which preparation and publication of a proposal is precluded by higher priority listing actions.

On April 20, 2010, Center for Biological Diversity (CBD) and others petitioned the Service to list the beaverpond marstonia as endangered or threatened under the Act as part of the mega- petition to list 404 species in the southeastern United States. The petition identified habitat destruction, inadequacy of existing regulatory mechanisms, water pollution, and stochastic genetic and environmental events as threats to the species. On September 27, 2011, the Service published a substantial 90-day finding for 374 species, including the beaverpond marstonia. On December 30, 2015, the Service received a notice of intent to sue from CBD to compel the Service to issue a 12-month finding as to whether the listing of the beaverpond marstonia under the Act is warranted, not warranted, or warranted but precluded. On August 30, 2016, the Service entered into a stipulated settlement agreement with specifying that they would submit the 12- month finding to the Federal Register by April 1, 2017.

This document constitutes the Service’s 12-month finding on the April 20, 2010 petition to list the beaverpond marstonia as endangered under the Act.

This Species Status Assessment (SSA) Report was completed using the best available scientific information on the beaverpond marstonia to evaluate the species’ needs, current condition, and anticipated future condition. Based on the results of repeated surveys by qualified species experts, there appear to be no extant populations of beaverpond marstonia. It does not appear that the beaverpond marstonia is actually still extant, but rather is extinct; however, extinction of a species is difficult to prove, and there is inherent uncertainty in drawing an absolute conclusion of extinction.

This SSA reviews the species’ biology and threats, evaluates its biological status, and assesses the resources and conditions needed to maintain long-term viability. The SSA Report will be updated if new information becomes available that warrants the listing of the beaverpond marstonia under the Act, and will be used to support all functions of the Service’s Endangered Species Program including, but not limited to, Candidate Assessment, Listing, Consultations, and Recovery. This SSA Report is a living document upon which listing rules, recovery plans, and 5- year reviews are based if the species warrants listing under the Act.

This SSA Report solely provides a review of the available information related to the biological status of beaverpond marstonia. Importantly, the SSA Report does not result in a decision by the Service on whether this species should be proposed for listing as a threatened or endangered species under the Act. The Service will make a listing decision after reviewing this document and all relevant laws, regulations, and policies, and the results of the decision will be announced in the Federal Register, with opportunities for public input if appropriate.

CHAPTER 2. BIOLOGY AND LIFE HISTORY

This chapter provides basic biological information about the beaverpond marstonia, including its taxonomy and relationships, morphological description, reproductive and other life history traits, and physical environment. Due to the lack of biological and ecological information for the beaverpond marstonia, we gathered and used information from similar species of spring snails that, based on genetic analysis, are closely related, especially those within the family Hydrobiidae.

2.1 Taxonomy

The family Hydrobiidae is found within the subclass Caenogastropoda of class Gastropoda (superfamily Rissoidea). Characteristics of hydrobiids include gills located near the front of their body, a spirally coiled shell, and a mantle cavity near the head that contains sensory organs and excretory organs (Kabat and Hershler 1993, p. 5). Members of Hydrobiidae are understood to be found in freshwater habitats. Although the family constitutes a large group of approximately 170 known species of aquatic snails with worldwide distribution, especially in North America and Australia (USFWS 2015, p. 1), many species within the family appear to have restricted distributions, often associated with springs, and even more are known only from their respective type locality (Watson C.N. 2000, p. 233). Information on hydrobiids is lacking in comparison to other mollusks, due to their small size and the need to differentiate between species morphologically, primarily by the male genitalia.

Beaverpond marstonia belongs to the Nymphophilinae subfamily of Hydrobiidae, one of the largest groups of aquatic mollusks in North America. These species align with hydrobiid characteristics, including limited dispersal abilities and adherence to narrow distribution in local drainage systems. Members of this subfamily often live in small springs and other fragile habitats (Hershler et al. 2003, p. 357). Recent studies found the most likely single feature of the clade is the presence of surficial glandular fields on the penis of males (with a few species in the Pyrgulopsis genus being the exception) (Hershler et al. 2003, p. 362). The genus Marstonia is composed of 15 small (shell height <5.0 mm) ovate to elongate-shelled species that are distributed in springs, streams, and lakes in eastern North America (Hershler 2011, p. 2). Marstonia was first described by F.C. Baker in 1926 as a subgenus to Amnicola, and Berry elaborated on that finding, basing the distinction on the differing penis structures of the two genii (Baker 1926, Berry 1943).

Hershler and Thompson expanded and redefined the genus, eventually merging it with Pyrgulopsis based on the morphological similarity of the male genitalia (Hershler and Thompson 1987, p. 29). However, subsequent studies found significant morphological contrast between the eastern Pyrgulopsis species and the western counterparts. Marstonia is distinguished in that the oviduct and bursal duct join well in front of the posterior pallial wall. Marstonia is further distinguished from Pyrgulopsis by the more coarsely pitted protoconch sculpture, incomplete inner shell lip across the parietal wall, banded pattern of mantle pigmentation, narrowly vertical oviduct coil, and bursal duct largely or entirely imbedded in (as opposed to superficial to) the albumen gland (Hershler 1994, p. 11). Hershler and Thompson withdrew the merger and again recognized Marstonia as a distinct genus (2002, p. 269), with evidence that it is a well-supported

sub-clade within its subfamily based on mtDNA sequences (Hershler et al. 2003, p. 360).

2.2 Morphological Description

To date, little is known about the beaverpond marstonia. It was first described by Fred Thompson (1977, p. 130). The tan-colored shell of beaverpond marstonia is ovate-conic, and it typically has less than 3-5 whorls and is less than 4 mm in length. The operculum (gill cover) is oval-shaped, very thin, well-formed, a light amber color, with a light indentation along the outer edge (Thompson 1977, p. 130), see Figure 2.2.1.

Beaverpond marstonia shares morphological characteristics with members of its family, Hydrobiidae. Hydrobiids are strictly aquatic, relying on an internal gill for respiration (Martinez et al. 2006, p. 8) and typically have a strong, mobile foot that is able to retract into its shell. Mucous glands that discharge from a narrow groove across the anterior edge of the foot allow movement by ciliary gliding. The eyes of hydrobiids are found at the base of its cephalic tentacles, typically in discrete swellings on outer sides. These tentacles are usually symmetrical, often with patches or tracts of ciliary tufts (motile and non-motile) on dorsal and/or ventral surfaces. Both the mantle edges and mantle cavities of hydrobiids are smooth, lacking protuberances. Hydrobiids also usually have a trapezoidal central tooth, surrounded by cusped lateral and marginal teeth (Hershler 1994, p. 5).

Commonly identified by their internal organs, hydrobiids have stomachs with well-differentiated anterior and posterior chambers, with a single opening to the digestive gland. The hypobranchial gland, a mucus-producing structure common in mollusks, is typically either absent or modestly developed (Hershler 1994, p. 5). The rectum of the hydrobiid is usually straight, and it often overlaps with the gonoducts (gamete passageway), and the anus opens near the edge of the mantle (Hershler 1994, p. 5).

Figure 2.2.1. Marstonia castor. Fred Thompson (1977)

2.3 Life History

The average life span of beaverpond marstonia is unknown, though the average lifespan of hydrobiids is 9 to 15 months (USFWS 2015, p. 5). Beaverpond marstonia achieve maturity between November and March, when they are at their largest size (J. Wisniewski, pers.comm., 2016). Limited mobility based on the topographical features of the spring ecosystem makes migration unlikely. Therefore, they usually spend their entire lives within a restricted system. Evidence suggests aquatic snails have sometimes dispersed by attaching to the feathers of migratory birds (USFWS 2015, p. 5).

2.4 Reproduction

Hydrobiid females are oviparous, and deposit their egg capsules on hard substrates, where it completes its larval stage. Upon hatching, small snails crawl out into their adult habitat (USFWS 2015, p. 5).

2.5 Ecology

Fine particulate organic matter and periphyton are the primary food sources for hydrobiids. Perphyton is a broad term defining primary producers that attach to stream substrate, and are directly affected by physical and chemical changes over time (USEPA 2016, p. 12). The term includes algae, which has a rapid reproduction rate and often informs the amount of nutrient enrichment in a stream. Primary producers play a vital role in the spring ecosystem as they are directly affected by the steady state of its metabolism, temperature, and major chemical constituents (Knight et al. 2008, p. 25). This means that any change due to influences, anthropogenic or otherwise, can cause nutrient loading, and disrupt the equilibrium needed for highly endemic snail species to survive (Knight et al. 2008, p. 2).

2.6 Habitat

Beaverpond marstonia were primarily found by on clumps of vegetation of the Najas and Chara genii, in shallow, clear water that only had a slight current (Thompson 1977, p. 130). The family Hydrobiidae is known for diversity in the habitats its species occupies, including springs, large rivers, and a variety of diverse aquatic systems, but particularly spring ecosystems that produce running water (USFWS 2015, p. 5). These spring systems are areas where groundwater is exposed, with a close source from the water table to the Earth’s surface. These springs are perennial, and are typically rich in dissolved nutrients and gases from the continual supply of inorganic and organic materials in dissolved and particulate forms (Knight et al. 2008, p. 24). The enriched water quality undergirds the biodiversity of aquatic flora and fauna found in these areas (Knight et al. 2008, p. 3).

Stability from a relatively constant groundwater source, physical limitations from topography and terrestrial features (Knight et al. 2008, p. 22), and geological events that influence evolution of local species, are all factors that influence a high level of endemism among freshwater species, especially snails, which have the most restricted dispersal ability of all major freshwater groups (Strayer 2010, p. 346, P. Johnson, pers. comm. 2017).

CHAPTER 3. CURRENT CONDITION

The following describes the current condition of the beaverpond marstonia and its habitat, including references to potential habitat outside of the historically known range.

3.1 Range and Distribution

Beaverpond marstonia were historically found only in Georgia, at its type locality, Cedar Creek (near Coney Road) in Crisp County, and in two additional locations in Swift Creek, Worth County and Mercer Mill Creek, Dougherty County. The two additional locations were recorded by Thompson in the Florida Museum of Natural History database (UF 244510 and UF 278962, respectively). The streams are located east of Lake Blackshear, a man-made 8,500 acre impounded reservoir on the Flint River. Thompson (1977, p. 130) reported habitat at the type locality as a small clear creek with submerged vegetation, slowly flowing through a cypress slough and draining into Lake Blackshear, and the exact coordinates are estimated to be at Slade Bridge Road in Cedar Creek, Crisp County, Georgia. Based on the habitat description of the type locality of beaverpond marstonia, suitable habitat found outside of that initial site is limited.

A historical summary of survey results for beaverpond marstonia near Lake Blackshear is provided in Table 3.1.1 and a map designating the historical range of the beaverpond marstonia within southwest Georgia is provided as Figure 3.1.1. Details of findings in the 2016 Wisniewski survey are provided in Figure 3.1.1 and in Table 3.1.2.

Table 3.1.1. Historical Survey results for beaverpond marstonia near Lake Blackshear (1973 to 2016).

Year Location Number of Specimens Surveyor Citation Surveyed

1973 351 specimens found Thompson Thompson 1977, Cedar Creek (undesignated locations per p. 130 Figure 3.1.1)

1995 specimens found, unknown Thompson Wisniewski 2016, Swift Creek number (undesignated p. 2 locations per Figure 3.1.1)

Cedar Creek 2000 0 (undesignated locations Watson Watson 2000, p. 7 per Figure 3.1.1)

Mercer Mill 2000 specimens found, unknown Thompson Wisniewski 2016, Creek number (undesignated p. 2 locations per Figure 3.1.1)

Cedar Creek 2014 0 (undesignated locations Johnson Johnson 2014, per Figure 3.1.1) pers. comm.

Cedar Creek 2016 0 (designated locations per Wisniewski Wisniewski 2016, Figure 3.1.1) p. 3-4

Gully Creek 2016 0 (designated locations per Wisniewski Wisniewski 2016, Figure 3.1.1) p. 3-4

Swift Creek 2016 0 (designated locations per Wisniewski Wisniewski 2016, Figure 3.1.1) p. 3-4 Mercer Mill Creek 2017 0 specimens found Wisniewski Wisniewski 2017

Jones Creek 2017 0 specimens found Wisniewski Wisniewski 2017 Big Abrams Creek 2017 0 specimens found Wisniewski Wisniewski 2017

Table 3.1.2. Sites sampled for Marstonia castor with location and site conditions during August and November 2016 (Figure 3.1.1). Site Stream Name Location Site Conditions Site Conditions Number August 2016 November 2016 1 Gully Creek GA 300 Dry Dry 2 Gully Creek Slade Road Dry Dry 3 Gully Creek Crossroad Store Road Dry Dry 4 Gully Creek Coney Road Dry Dry 5 Gully Creek Pine Road Wet with vegetation Dry 6 Gully Creek Lake Blackshear Reservoir embayment Drawn down 7 Gully Creek Lake Blackshear Reservoir embayment Drawn down 8 Cedar Creek Lake Blackshear Reservoir embayment Drawn down 9 Cedar Creek Slade Bridge Road Not examined Dry 10 Cedar Creek Byrds Mill Road Wet Wet 11 Cedar Creek Pateville Road Dry Dry 12 Cedar Creek, unnamed tributary Pateville Road Dry Dry 13 Cedar Creek, unnamed tributary GA 33 Dry Dry 14 Swift Creek, North Branch GA 33 Dry Dry 15 Swift Creek, North Branch Pateville Road Dry Dry 16 Swift Creek, North Branch Antioch Road Dry Dry 17 Swift Creek, North Branch Arabi-Warwick Road Good flow Good flow sampled 18 Swift Creek Primrose Bridge Road Good flow Good flow, sampled 19 Swift Creek GA 33 Dry Dry

Source: December 20, 2016, Survey of the Current Status and Distribution of the Beaverpond Marstonia, Marstonia castor (Thompson 1977), Jason M. Wisniewski, Nongame Conservation Section, Wildlife Resources Division, Georgia Department of Natural Resources, December 20, 2016

3.2 Current Condition of Historical Locations

Georgia Department of Natural Resources (DNR) surveyed all access points of Cedar and Swift Creek (streams with beaverpond marstonia occurrences) and Gully Creek (located near those streams and also a tributary to Lake Blackshear) in August and December 2016. The type locality is mostly agricultural and timber lands. Gully Creek and Cedar Creek are historically runoff fed, while Swift Creek is predominantly spring fed and maintains flow during drought periods. It was observed during the 2016 survey that several sites in the Cedar, Swift, and Gully Creek systems were either dry or exhibited low stream flow, due to persistent drought conditions in Georgia. The stream at Slade Bridge Road crossing and downstream was dewatered, with little evidence of recent moisture in the stream bed, which is detrimental to a highly endemic, spring- system dependent species like beaverpond marstonia. Aquatic vegetation was absent from all sampled sites (Wisniewski 2016, p. 4).

In March 2017, GDNR and FWS visited Mercer Mill Creek, the one historical location that was unsurveyed in the most recent efforts. Mercer Mill Creek exhibited steady flow (due to recent rain fall) but no submerged vegetation as described by Thompson (1977). In addition, Jones Creek and Big Abrams Creek, two streams located directly north of Mercer Mill Creek, were sampled due to similarity of habitat and proximity to the type locality. No beaverpond marstonia were found at Mercer Mill Creek. Several snails with morphology similar to beaverpond marstonia were found at the other two sites, but under further morphological and genetic review they were deemed to be other species (P. Johnson 2017, pers. comm,; N. Whelan 2017, pers. comm.).

3.3 Current Condition of Populations

Before the GDNR surveys, the last beaverpond marstonia collection was by Fred Thompson on August 5, 2000. Subsequent surveys for the species, in historical locations and areas surrounding it that are similar to the type locality, have yielded no specimens (Wisniewski 2016, p. 2). The first recorded search after the last sighting stated that there had been residential development on the banks of Cedar Creek at the type locality, but there was still a considerable amount of submerged vegetation in the stream (Watson 2000, p. 239). Based on the results of repeated surveys (Table 3.1.1) by qualified species experts, there appears to be no extant populations of beaverpond marstonia.

CHAPTER 4. FACTORS INFLUENCING VIABILITY

In this chapter, we evaluate the past, current, and future factors that may be affecting the beaverpond marstonia’s viability. We analyzed pathways for each factor and how each factor (stressor) affects the species, and each of the causes is examined for its historical, current, and potential future effects. The current and expected distribution and abundance also determine the viability and vulnerability of the species to extinction.

4.1 Introduction

The most significant stressor to snails from spring-fed systems is the loss of those systems, which is usually directly tied to anthropogenic modification of spring ecosystems and/or water quality (USFWS 2015, p. 34). The type locality of beaverpond marstonia is located within the Lake Blackshear watershed, and is thus vulnerable to the operations of the reservoir facility. Lake Blackshear management prioritizes agriculture, hydropower, and recreational needs, which affects the nearby streams and spring-fed systems that are not replenished as quickly (USFWS 2015, p. 25). Through scheduled maintenance drawdowns and exaggerated conditions from droughts, beaverpond marstonia’s habitat is affected disproportionately, and its short life span and sensitive niche in the ecosystem puts it at greater peril than more tolerant species (Wisniewski 2016, p. 5). No detection of this species for almost seventeen years (2000 – 2016) could indicate that the loss and degradation of beaverpond marstonia’s habitat may have pushed this sensitive species to extinction.

There are currently no regulatory mechanisms that provide conservation benefit or legal protection for beaverpond marstonia.

4.2 Natural Stochastic Events

Spring-dependent organisms like the beaverpond marstonia, whose populations exhibit a high degree of geographic isolation in small populations, are extremely susceptible to random extinction resulting from stochastic natural disasters such as fires, floods, or changes in spring water chemistry.

4.3 Droughts

Droughts are defined as an extended period of decreased precipitation and streamflow (USGS 2000, p. 1). Drought conditions in the southeastern U.S. have reduced flow in perennial streams, while placing stress on spring fed systems that depend on regular water flow (Knight et al. 2008, p. 16). USGS records indicate Georgia has been in extended periods of drought, including from 1998-2001 (when beaverpond marstonia was last detected), 2007, 2010-2012, and 2016 (the latter being when the last survey for beaverpond marstonia was conducted). Dewatering of these systems is likely to lead to major ecological disruptions, including loss of genetic diversity and extirpation (Strayer 2010, p. 349).

4.4 Anthropogenic Effects

Beaverpond marstonia’s range is within the Flint River basin, one of the three major rivers involved in the Tri-State Water Wars between Alabama, Georgia, and Florida. Water needs including agricultural demands and seafood industry sustenance have created legal and political battles that complicate determinations on who has jurisdiction over certain water resources (Mitra et al. 2016, p. 1). Specifically in the Flint River basin, the aforementioned effects of conditions during the most recent droughts were intensified by increased irrigation pumping from groundwater resources for agricultural land use (Mitra et al. 2016, p. 2). Increased pumping reduced stream flow in all three major basins, and thus affected aquatic biota population dynamics within the rivers and their tributaries (Mitra et al. 2016, p. 15).

CHAPTER 5. SPECIES VIABILITY

5.1 Introduction

Based on factors previously mentioned in this report, the survival of beaverpond marstonia would depend on maintaining habitat at its type locality (i.e., water, structure, and food sources), while at the same time avoiding the effects of anthropogenic and natural causes of reduced water flow at its sites. Under these projections, we evaluated the viability of beaverpond marstonia by considering the resiliency, redundancy, and representation of its populations.

5.2 Resiliency

Resiliency describes the characteristics of a species that allow it to recover from periodic disturbance, such as annual environmental variation and stochastic events. From drought disturbances and records of reservoir drawdowns, which have reduced water flow and submerged vegetation, beaverpond marstonia appears to have no resiliency.

5.3 Redundancy

Redundancy is defined for this analysis as having sufficient numbers of populations for the species to withstand catastrophic events. Based on limited information known about the specific habitat requirements of beaverpond marstonia, a catastrophic event is difficult to define. Through knowledge of spring snails and their systems, the loss of spring systems, or the reduced amount of flow, would place the species in jeopardy. Because of drought conditions and the ripple effect of reservoir drawdowns from Lake Blackshear, the beaverpond marstonia appears to have no redundancy.

5.4 Representation

Representation is having the genetic and ecological diversity within the species to be able to adapt to changing environmental conditions. We do not have information to determine a level of genetic diversity, since the species was extant with only a few populations east of Lake Blackshear, none of which have been detected for seventeen years (2000 – 2016). If there are individuals present, there are likely so few that representation is either extremely limited or absent. Beaverpond marstonia appears to have no representation.

5.5 Status Assessment Summary

The goal of this SSA is to describe the viability of the species in a manner that will address the needs of the species in terms of resiliency, redundancy, and representation. We considered the possible future conditions of the species, and we considered the range of potential scenarios that included important influences on the status of the species. Based on the findings of the most recent surveys, the current assessment is that beaverpond marstonia lacks the three factors of viability. Therefore, we cannot project future conditions because there are no known extant populations on which we can project those conditions. Beaverpond marstonia is presumed to be extinct. This status assessment has been reviewed by three species experts of the field, who agree with this conclusion, based on the best science available.

LITERATURE CITED

Baker, F.C. 1926. Nomenclatural notes on American fresh water Mollusca. Transactions of the Wisconsin Academy of Sciences, Arts, and Letters 22:193-205.

Berry, E. G. 1943. The Amnicolidae of Michigan: distribution, ecology, and taxonomy. Miscellaneous Publications, Museum of Zoology, University of Michigan 57:1-68.

Hershler, R.G. A review of North American freshwater snail genus Pyrgulopsis (Hydrobiidae). Smithsonian Contributions to Zoology. Number 554. 124 pp.

Hershler, R.G. and Liu, H-P. 2011. Redescription of Marstonia comalensis (Pilsbry and Ferriss, 1906), a poorly known and possibly threatened freshwater gastropod from the Edwards Plateau region (Texas). ZooKeys 77: 1-16.

Hershler, R.H. and Thompson, F. G. 1987. North American Hydrobiidae (Gastropoda: Rissoacea): redescription and systematic relationships of Tryonia Stimpson, 1865 and Pyrgulopsis Call and Pilsbry, 1886. The Nautilus 101(1): 25-32.

Hershler, R.H. and Thompson, F. G. 2002. Two genera of North American Freshwater snails: Marstonia Baker, 1926, resurrected to generic status, and Floridobia, new genus (Prosobranchia: Hydrobiidae: Nymphophilinae). The Veliger 45(3):269-271.

Hershler, R.H., Liu, H.-P., and Thompson, F.G. 2003. Phylogenetic relationships of North American nymphophiline gastropods based on mitochondrial DNA sequences. Zoologica Scripta 32:357-366.

Johnson, P. 2014. Personal communication. November 13, 2014.

Johnson, P. 2017. Personal communication. September 26, 2017.

Kabat, A. R. & Hershler, R.G. 1993. The prosobranch snail family Hydrobiidae (Gastropoda: Rissooidea): Review of classification and supraspecific taxa. Smithsonian Contributions to Zoology 547: 94 pp..

Knight, R.L. and S.K. Notestein. 2008. Summary and Synthesis of Available Literature on the Effects of Nutrients on Springs Organisms and Systems: Springs as Ecosystems. University of Florida. 52 pp.

Martinez, M.A. and Thome, D. M. 2006. Habitat usage by the Page springsnail, Pyrgulopsis morrisoni (Gastropoda:Hydrobiidae), from Central Arizona. The Veliger 48(1):8-16.

Mitra, S., Srivastava, P., and Singh, S. Effect of irrigation pumpage during drought on karst aquifer systems in highly agricultural watersheds: example of the Apalachicola-

Chattahoochee-Flint river basin, southeastern USA. Hydrogeology Journal 24:1565-1582. 18 pp.

Strayer, D. L. and Dudgeon, D. 2010. Freshwater biodiversity conservation: recent progress and future challenges. Journal of the North American Benthological Society 29(1):344-358.

Thompson, F. G. 1977. The hydrobiid snail genus Marstonia. Bulletin of the Florida State Museum: Biological Sciences 21(3): 113-158.

U.S. Environmental Protection Agency (USEPA). Rapid Biological Assessment Protocols: An Introduction. 34 pp. Accessed October 3rd, 2016.

U.S. Fish and Wildlife Service. 2015. Species status assessment report for the Page springsnail. Albuquerque, NM. 39 pp.

U.S. Geological Survey. 2000. Droughts in Georgia. U.S. Geological Open-File Report 00-380. 2 pp.

Watson, C.N. 2000. Results of a survey for selected species of Hydrobiidae (Gastropoda) in Georgia and Florida. Proceedings of the First Freshwater Mollusk Conservation Society Symposium: 233-244.

Whelan, N. 2017. Personal communication. September 26, 2017.

Wisniewski, J. 2016. Georgia Department of Natural Resources, personal communication, February 25, 2016

Wisniewski, J. 2016. Georgia Department of Natural Resources. Survey of the Current Status and Distribution of the Beaverpond Marstonia, Marstonia castor (Thompson 1977). December 20, 2016.

Wisniewski, J. 2017. Personal communication. February 23, 2017.

Wisniewski, J. 2017. Personal communication. March 14, 2017.