Species Status Assessment Report Scott Riffle Beetle (Optioservus

Species Status Assessment Report

Scott Riffle Beetle (Optioservus phaeus)

Big Spring at Historic Lake Scott State Park. Photo by Kansas Department of Wildlife, Parks, and Tourism.

U.S. Fish and Wildlife Service Mountain-Prairie Region

Kansas Ecological Services Field Office Manhattan, Kansas & Region 6 Ecological Services Lakewood, Colorado

Version 1.0, May 2019

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Species Status Assessment Report for the Scott Riffle Beetle (Optioservus phaeus) Prepared by the Kansas Ecological Services Field Office U.S. Fish and Wildlife Service

Executive Summary

This species status assessment details the results of the comprehensive biological status review by the U.S. Fish and Wildlife Service (Service) for the Scott riffle beetle (Optioservus phaeus) and provides a thorough account of the species’ viability and extinction risk. The Scott riffle beetle is a small freshwater aquatic beetle endemic to only one known type locality: a spring (Big Spring) located in Historic Lake Scott State Park (state park) in Scott County, Kansas. No other populations are known or are thought to exist. There are no known additional historical records for this species of riffle beetle (Ferrington et al. 1991, p. 4).

To evaluate the biological status of the Scott riffle beetle both currently and into the future, we assessed a range of conditions to allow us to consider the species’ resiliency, redundancy, and representation (together, the 3Rs). The future persistence of the Scott riffle beetle is dependent on five fundamental environmental factors associated with Big Spring (its only known habitat). These factors include:

(1) consistent groundwater discharge (2) relatively shallow, unpolluted, oxygenated water (3) coarse substrate such as medium sized rocks or broken concrete (4) abundance of aquatic macrophytes, algae, and periphyton (5) availability of adjacent terrestrial habitat

If the Big Spring ecosystem meets these five conditions, we anticipate the only known Scott riffle beetle population to exist into the future (Table I). As we consider the future viability of the species, it should be noted that only a discovery of a previously undocumented population would lead to a higher overall species viability.

We have assessed the Scott riffle beetle’s levels of resiliency, redundancy, and representation at present and into the future by describing the condition of the one population in its current state and by projecting its condition under multiple future plausible scenarios (Table I). The assessments are qualitative and are based on the knowledge and expertise of the Kansas Department of Wildlife, Parks, and Tourism (KDWPT) and other natural resources professionals.

The most significant future potential stressor to the Scott riffle beetle is groundwater depletion and the subsequent loss of the spring ecosystem within which the larvae and adults need to complete their life history. Groundwater withdrawals from the High Plains Aquifer will continue into the future with depletion and recharge rates depending on regional water usage (Butler et al. 2018, pp. 52-53) and climate change (Crosbie et al. 2013, p. 3949). Anthropogenic activities that could act as stressors, such as surface water contamination, habitat destruction, substrate removal, or the introduction of invasive species are currently minimal at Big Spring due to protective measures implemented by the state park.

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The viability of the Scott riffle beetle depends on maintaining the only known population at Big Spring over time. Given the possibility that groundwater discharge may change into the future and that this variable is fundamental to the survival of the species, we forecasted Scott riffle beetle resiliency, redundancy, and representation under five plausible future scenarios, weighting regional groundwater usage (a proxy for spring groundwater discharge1 and a variable whose impact could increase or decrease depending on the magnitude of climate change) higher than other potential variables:

(1) decreased regional groundwater usage; tree removal to reduce local water stress; decreased groundwater contamination risk; increased site protection; increase in habitat area; establishment of captive population and suitable rearing facility (2) decreased regional groundwater usage; tree removal to reduce local water stress; no change in groundwater contamination risk; increased site protection; no change in habitat area; no captive population established; establishment of suitable rearing facility (3) no change in regional groundwater usage; tree removal to reduce local water stress; no change in groundwater contamination risk; increased site protection; no change in habitat area; no captive population established; establishment of suitable rearing facility (4) no change in regional groundwater usage; tree removal to reduce local water stress; no change in groundwater contamination risk; increased site protection; no change in habitat area; no captive population established; no suitable rearing facility (continuation scenario) (5) increased regional groundwater usage; increased groundwater contamination risk; decreased site protection; possible decrease in habitat area; no captive population established

A Scott riffle beetle management plan written by KDWPT details management actions that have already reduced or are likely to reduce many of the potential risks to the Scott riffle beetle (Hofmeier (a) 2018, pp. 6-7). The plausible future scenarios draw heavily on the management actions contained in this plan. The underlying risk of groundwater discharge reduction as a result of regional groundwater usage, however, may be outside the current scope of this plan.

Our assessment of the future viability (in terms of resiliency, redundancy, and representation) for the Scott riffle beetle is summarized in Table I below. Scenarios one and two are the only scenarios in which we would expect the resiliency of the species to not decline. Species redundancy is expected to be low in all but Scenario one which includes the establishment of one additional population, in this case in captivity. The current population inhabits the entire known range of the species; therefore, establishment of additional populations is limited to captivity. The presence of only one known population in one ecological niche with unknown genetic diversity means representation is projected to remain low under all five scenarios.

1 Historic discharge rates at Big Spring are expected to differ from current discharge rates due to differences in measurement methods and changes in the spring run infrastructure, including the installation of a pipe, the lining of the spring run in concrete, and the subsequent destruction of the concrete lining (Hofmeier (d) pers. comm. 2018). Regional groundwater usage is a variable related to groundwater discharge at Big Spring and is more accurately assessed in a historical context and in plausible management scenarios. KDWPT installed a water quality and quantity monitor in May of 2018. Measurements from this monitor can be used to calibrate regional water usage trends.

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Table I. Species Status Assessment summary for the Scott riffle beetle (Optioservus phaeus).

3Rs Needs Current Condition Future Condition (Viability)

o adequate groundwater o One population assumed Projections based on scenarios: discharge to have medium to high ● Scenario 1 (optimistic) decreased regional groundwater usage; decreased groundwater o sufficient water quality, resiliency contamination risk; increased site protection; increase in habitat area; establishment of including sufficient dissolved captive population and suitable rearing facility. POPULATION EXPECTED TO oxygen EXPERIENCE INCREASE IN RESILIENCY o presence of periphyton and ● Scenario 2 (less optimistic) decreased regional groundwater usage; no change in diatoms groundwater contamination risk; increased site protection; no change in habitat area; o suitable substrate no captive population established; establishment of suitable rearing facility. o terrestrial habitat POPULATION EXPECTED TO EXPERIENCE NO DECLINE IN RESILIENCY Resiliency ● Scenario 3 (more optimistic than continuation) no change in regional groundwater (large populations able to usage; no change in groundwater contamination risk; increased site protection; no withstand stochastic events) change in habitat area; no captive population established; establishment of suitable rearing facility. POPULATION EXPECTED TO EXPERIENCE DECLINE IN RESILIENCY ● Scenario 4 (continuation) no change in regional groundwater usage; no change in groundwater contamination risk; increased site protection; no change in habitat area; no captive population established; no suitable rearing facility. POPULATION EXPECTED TO EXPERIENCE DECLINE IN RESILIENCY ● Scenario 5 (pessimistic) increased regional groundwater usage; increased groundwater contamination risk; decreased site protection; possible decrease in habitat area; no captive population established. POPULATION EXPECTED TO EXPERIENCE RAPID DECLINE IN RESILIENCY o multiple populations o Low redundancy, only one Projections based on scenarios: throughout known range of known population ● Scenario 1 (optimistic) INCREASE IN REDUNDANCY WITH ESTABLISHMENT OF species CAPTIVE POPULATION (because of presumed increased ability to withstand a Redundancy catastrophic event) (number and distribution of ● Scenario 2 (less optimistic) SLIGHT INCREASE IN REDUNDANCY WITH ESTABLISHMENT populations to withstand OF REARING FACILITY catastrophic events) ● Scenario 3 (more optimistic than continuation) SLIGHT INCREASE IN REDUNDANCY WITH ESTABLISHMENT OF REARING FACILITY ● Scenario 4 (continuation) UNCHANGED, LOW REDUNDANCY ● Scenario 5 (pessimistic) UNCHANGED, LOW REDUNDANCY o genetic variation within o only one known Projections based on scenarios: single existing population; population in one ● Scenario 1 (optimistic) UNKNOWN REPRESENTATION, LIKELY REMAINS UNCHANEGED multiple and varied niches ecological niche; genetic ● Scenario 2 (less optimistic) UNKNOWN REPRESENTATION, LIKELY REMAINS Representation occupied diversity unknown UNCHANEGED (genetic and ecological ● Scenario 3 (more optimistic than continuation) UNKNOWN REPRESENTATION, LIKELY diversity to maintain adaptive REMAINS UNCHANEGED potential) ● Scenario 4 (continuation) UNKNOWN REPRESENTATION, LIKELY REMAINS UNCHANEGED ● Scenario 5 (pessimistic) UNKNOWN REPRESENTATION, LIKELY REMAINS UNCHANEGED

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Table of Contents

Chapter 1. Introduction to the Species Status Assessment Framework 1 Chapter 2. Species Description, Life History, and Habitat Needs 3 Taxonomy 3 Morphology 3 Life History 5 Feeding Habits 6 Habitat 7 Range and Distribution 7 Chapter 3. Current Condition 11 Population Data: Historic and Current 11 Chapter 4. Factors Influencing Viability 13 Potential Stressors 13 Regional Groundwater Usage Levels Influencing Groundwater Discharge at Big Spring 13 Physical Habitat (substrate, vegetation, stream run) Alteration 15 Contamination of Above-Ground Spring Water 16 Contamination of Groundwater 16 Predatory and/or Invasive Species 17 Climate Change 18 Cumulative effects of stressors 18 Potential and Current Conservation Efforts 19 Regional Groundwater Usage Levels Influencing Groundwater Discharge at Big Spring 19 Physical Habitat (substrate, vegetation, stream run) Alteration 19 Contamination of Above-Ground Spring Water 19 Contamination of Groundwater 20 Predatory and/or Invasive Species 20 Establishment of Captive Facility and/or Population 20 Chapter 5. Future Condition and Species Viability 21 Appendix A. Core Conceptual Model 28 Appendix B. Condition Category Table 29

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Chapter 1. Introduction to the Species Status Assessment Framework

The Scott riffle beetle (Optioservus phaeus; White 1978, p. 70; Coleoptera: Elmidae) is a freshwater aquatic riffle beetle that is known to occur at one location in Historic Lake Scott State Park in west central Kansas. The Scott riffle beetle has been a candidate for listing under the Endangered Species Act of 1973, as amended (Act), since 2001 (66 FR 54808). The Species Status Assessment (SSA) framework (USFWS 2015, entire) is intended to support an in-depth review of the species’ biology and stressors, an evaluation of its biological status, and an assessment of the resources and conditions needed to maintain long-term viability. The SSA report is a living document that can be updated as new information becomes available and that supports all functions of the Endangered Species Program including Candidate Species Assessment, Classification, Consultation, Recovery, and/or 5-Year Review if the species warrants listing under the Act.

This SSA Report for the Scott riffle beetle is intended to provide the biological support for the decision on whether or not to propose to list the species as threatened or endangered and, if so, where to propose designating critical habitat. Importantly, the SSA Report does not result in a decision by the USFWS on whether this species should be listed as a threatened or endangered species under the Act. Instead, this SSA Report provides a review of the available information strictly related to the biological status of the Scott riffle beetle. The listing decision will be made by the USFWS after reviewing this document and all relevant laws, regulations, and policies, and the results of a proposed decision will be announced in the Federal Register, with appropriate opportunities for public comment.

For the purpose of this assessment, we define viability as the ability of the Scott riffle beetle to sustain its population in natural systems over time. Using the SSA framework (Figure 1.1), we consider what the species needs to maintain viability by characterizing the status of the species in terms of its resiliency, redundancy, and representation (Wolf et al. 2015, entire).

Figure 1.1 Species Status Assessment Framework.

Resiliency describes the ability of populations to withstand stochasticity. We can measure resiliency based on demographic metrics including birth rate, death rate, and population size. Highly resilient populations are better able to withstand disturbances such as random fluctuations in birth rates

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(demographic stochasticity), variations in rainfall (environmental stochasticity), or the effects of anthropogenic activities.

Representation describes the ability of a species to adapt to changing environmental conditions. Representation can be measured by the breadth of genetic or ecological diversity within and among populations and gauges the probability that a species is capable of adapting to long-term changes in the environment. The more representation, or diversity, a species has, the more it is capable of adapting to changes (natural or human caused) in its environment. In the absence of species-specific genetic and ecological diversity information, we evaluate representation based on the extent and variability of habitat characteristics across the geographic range.

Redundancy describes the ability of a species to withstand catastrophic events. Measured by the number of populations, their resiliency, and their distribution (and connectivity), redundancy gauges the probability that the species has a margin of safety to withstand or can bounce back from catastrophic events (such as a rare destructive natural event or episode involving many populations).

To evaluate the biological status of the Scott riffle beetle both currently and into the future, we assessed a range of conditions to allow us to consider the species’ resiliency, redundancy, and representation (together, the 3Rs). This SSA Report provides an assessment of biology and natural history and assesses demographic risks, stressors, and limiting factors in the context of determining the viability and risk of extinction for the species using the best available scientific information.

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Chapter 2. Species Description, Life History, and Habitat Needs

Taxonomy

The Scott riffle beetle, Optioservus phaeus, was first collected by a staff member at the Kansas Biological Survey in the mid-1970’s as part of a statewide inventory of aquatic invertebrates in the state. It was formally described by White (1978) who stated, “The locality of the collection, its larger size, and differences in the male genitalia warrant its separate designation. The type-locality is quite isolated, the habitat consisting of a spring-fed brook which flows but a few meters before joining a larger stream that disappears into a sink. The sink most likely enters into the Missouri River drainage” (White 1978, p. 70).

The holotype is catalogued at the United States Museum of Natural History in Washington D.C. Forty- eight paratype specimens can be found at five other natural history museums in the U.S. (Ferrington et al. 1991, p. 2).

The current accepted classification is:

Class: Insecta Order: Coleoptera Suborder: Polyphaga Family: Elmidae Genus: Optioservus Species: Optioservus phaeus

The Scott riffle beetle is one of approximately 80 known species recorded in North America that are members of the family Elmidae (Elliott 2008, p. 189). Elmid bettles are the most completely aquatic of all beetles (Brown 1987, p. 254). There are thirteen known species in the Nearctic region (North America, including Greenland) belonging to the genus Optioservus (Ferrington et al. 1991, p. 2). No known genetic studies have been completed for the Scott riffle beetle.

Morphology

The Scott riffle beetle is a “small dark brown to black beetle, 2.62-2.90 mm in length [and] 1.22-1.34 mm in width. Some specimens may appear to have faint small light blotches of white or red on the forewings, which are modified as coverings over the membranous hindwings” (White 1978, p. 70) (Figure 2.1). These wings are non-functional, micropterous (small or merely vestigial) wings and not capable of flight (Shepard 2019, entire).

The following description is taken from White (1978, p. 70):

Diagnosis. Length 2.62-2.90 mm, width 1.22-1.34 mm. Immaculate to faintly bimaculate. Parameters short, rounded; processes of basal sheath not deeply notched between. Pronotum. Length 0.75-0.84 mm, width 0.88-0.85 mm. Piceous to black. Punctures uniformly spaced on disk. Sublateral carinae pronounced. Moderately pubescent: hairs short, black to testaceous.

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Elytra. Length 1.86-2.06 mm, width 1.22-1.34 mm. Testaceous to dark brown. Elongate, only slightly diverging to apical third then gently rounded to apex. Heavily pubescent in both males and females, hairs testaceous to brown giving a dull appearance to elytra. Striae well developed with deep punctures. Appearing immaculate: faintly bimaculate in some, with humeral spot small and rounded, apical spot slightly elongate. Venter. Testaceous to dark brown. Pubescence short and thick, golden to testaceous. Male genitalia. Length 0.73-0.75 mm, width 0.27-0.30 mm. Penis tapering in apical half to rounded apex, processes curved outward and pointed. Paramers short, broad, rounded at apex. Processes of basal sheath slightly notched between. Both larvae and adults are well suited for feeding and existence in a flowing environment. Adults have long legs with strong claws that are able to grip the substrate surface. The larvae are elongate and elateriform in shape and have shorter legs than the adults with one prominent apical claw.

The species is closely related to Optioservus castanipennis and O. divergens, though potential future genetic studies should attempt to further elucidate this relationship.

Figure 2.1 Photo of adult Scott riffle beetle (Optioservus phaeus). Photo by Roy J. Beckemeyer (used with permission).

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Life History

Beetles in the family Elmidae generally have distinct egg, larval, pupal, and adult stages, all of which are spent in an aquatic environment except portions of the pupal stage, which are terrestrial. Pupation typically occurs out of the water (Huston and Gibson 2015, p. 521). There are 5-8 larval instars (Figure 2.2) and in most species the final instar larvae leave the water by crawling and will pupate in the soils or under rocks near the water (Elliott 2008, p. 190). After emerging from pupation, the adults, which are incapable of flight dispersal, enter the water permanently. Both adult and larval stages occur together throughout the year (Barr 2018, p. 15).

Figure 2.2 Photo of Scott riffle beetle (Optioservus phaeus) larva. Photo by Roy J. Beckemeyer (used with permission).

There is limited knowledge specific to Scott riffle beetle reproduction and life stages. One study suggested that Scott riffle beetle recruitment begins with eggs laid in the fall that hatch during the fall and possibly throughout the winter (Ferrington 1985, p. 31). Larvae then grow for up to 18 months, reaching the mature instar by the second summer. Pupation occurs during the second summer and possibly into the fall of the second year. It is not known how far from Big Spring the Scott riffle beetle larvae travel after emerging from the water to pupate. Adults emerge after the pupal period, which is presumed to be of relatively short duration as seen in other Elmidae beetles. Studies of other Elmids have shown it is a period of one to three weeks (Elliott 2008, p. 194). Mating is thought to occur during the fall or early winter months (Ferrington 1985, pp. 31-33).

Abundance data collected by the Kansas Department of Wildlife, Parks, and Tourism (KDWPT) suggested there is a high amount of second year or older adult mortality in the winter, with newly emerged adults likely surviving through winter (Hofmeier (b) 2018, slide 14). Reproduction most likely occurs in the fall and into early winter with pupation and emergence likely occurring in the summer and fall months (Hofmeier (b) 2018, slide 14) (Figure 2.3).

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Figure 2.3 The mean number of Scott riffle beetle larvae per rock at Big Spring (Hofmeier (c) 2018, p. 6). Decreased abundance of larvae from 3/15/1984 to 7/24/1984 likely represents natural mortality, possibly coupled with larvae leaving the spring run for pupation. The increase in larvae from September to November might represent eggs hatching or larval instars recruiting into “sampleable” sizes.

Feeding Habits

The presumed food of adult and larval Scott riffle beetles is some mixture of organic matter that live on submerged surfaces in aquatic environments, though the exact dietary preferences are unknown (Layher 2002, p. 12). Ingestion occurs after the periphyton is removed by mouthparts that are able to scrape the substrate surface (Layher 2002, p. 12). In studies of other Optioservus species, detritus was found to be the main food component, other items include microinorganics, diatoms, and plant material (Tavares and Williams 1990, p. 572).

Survival, Growth, and Longevity

The average lifespan of the Scott riffle beetle is unknown, though survey data suggest that the larval phase lasts from one to two years and the adult phase lasts for two or more years (Ferrington 1985, p. 33). Adult Elmid beetles have been maintained in aquariums for more than three years, but this lifespan may not be realistic outside of captivity (Elliott 2008, p. 191).

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Both larvae and adults utilize dissolved oxygen for respiration although each stage has a different strategy for doing so. Adult riffle beetles cannot utilize atmospheric oxygen for respiration nor can they survive short periods of drying (Barr 2018, p. 17). The larvae have tracheal gills that can be retracted and protected by an operculum. Larvae are also able to artificially circulate oxygen rich water over gills. Adults utilize a plastron strategy for respiration. The ventral surface of the adults is composed of densely packed setae (stiff hairs or bristles) which are hydrophobic in nature. The setae are able to maintain a thin layer of gas next to the body. This strategy is very efficient for respiration but is limited to oxygen rich environments. This type of respiration is very vulnerable to the introduction of soap and detergent pollutants (Elliott 2008, p. 189).

Habitat

Specimens are most often encountered on rocks that are submerged in riffle areas of streams or spring runs” (Ferrington et al. 1991, p. 3). Both adult and larval Scott riffle beetles are almost always found clinging to the surface of stones (epilithic) or broken concrete pieces within the Big Spring run (Ferrington 1985, p.7). This is an area characterized by flowing spring water that is cool and well- oxygenated. Larvae are most common on rocks in the range of 64mm to 128mm and 128mm to 256mm in diameter (Ferrington 1985, p. 5). Occasionally larvae are found on the watercress (Nasturtium officinale) plants growing throughout the spring run, though in very low numbers. Larvae densities are positively correlated with areas of faster current velocities (Ferrington 1985, p. 24). It is very unlikely that these beetles would be able to persist in an environment that was not flowing in nature, though there are many Elmid beetle species that are found in lotic systems not directly associated with the emergence of a spring (Elliott 2008, p. 191). The annual temperature range measured at the springhead is not thought to vary more than 4 degrees C, ranging from 14 to 18 degrees C, thus making the environment at Big Spring stenothermic, or defined by a very narrow range of temperatures. It is believed that this species is more tolerant to cooler variations in temperature versus warmer variations due to the inverse relationship of water temperature and dissolved oxygen levels. Past measurements of discharge from the spring have ranged from 350 to 400 gallons per minute (gpm). Maximum depth for the spring run is less than 0.2 meters. Velocity varies from slow to swift with some areas exceeding 30 cm/sec.

The spring run is less than 20 meters long and ends in a pool approximately 3 meters wide with a maximum depth of 1.75 meters near the dam at its terminus (Layher 2002, p. 7). Although no pictures or descriptions of the area prior to construction of the dam exist, it is possible the pool may be inundating sections of the run that could have been habitat for the beetle prior to dam construction. However, the existence of suitable substrate in this area prior to dam construction is unknown. Overflow from the dam eventually enters a large impoundment (Historic Lake Scott).

Range and Distribution

The Scott riffle beetle appears to be a true endemic with the only current and known historic location occurring at Historic Lake Scott State Park located in Scott County, Kansas (Figures 3.1 & 3.2).

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Figure 3.1 Map showing the entire range of the Scott riffle beetle (“Big Spring”).

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Figure 3.2 Aerial image showing Big Spring, including the spring run, pool, and dam (shown in red rectangle) (Image: Hofmeier (b) 2018).

More specifically, the beetle is only found in a small portion of the park known as the Big Spring, and within that portion, the majority of beetles are found in the spring run (Figure 3.3).

Figure 3.3. Photo of the spring run (Image: Hofmeier (b) 2018).

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The park is owned by the State of Kansas and managed by the Kansas Department of Wildlife, Parks, and Tourism and was originally deeded to the state in 1927.

In 1983 Leonard Ferrington began a population study on the Scott riffle beetle (Ferrington 1985, entire). Part of this study included searching 35 locations in several counties in Western Kansas looking for additional populations of Scott riffle beetles. No additional populations were found in Kansas. Supplementary surveys in neighboring states were conducted by the Kansas Biological Survey in 1990- 1991. Fifty-four springs were surveyed in New Mexico, eastern Colorado, eastern Wyoming, and western Nebraska with no additional populations of Scott riffle beetles found. Two other species of the genus Optioservus were found during that effort (O. divergens and O. castanipennis) (Ferrington et al. 1991, pp. 13-17), with the closest known population of genus Optioservus (O. divergens) found on the Nebraska/Kansas border approximately 150 kilometers away from the Big Spring site at Historic Lake Scott State Park.

Figure 3.4 Areas surveyed for Scott riffle beetles (Hofmeier (b) 2018, slide 13).

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Species Needs

Based on current knowledge of the observed habitat and life history of the Scott riffle beetle, the species’ needs include:

Population Data: Historic and Current

In 1983-84, seven sampling events produced 2,096 larvae and 235 adult Scott riffle beetles. Sampling in Big Spring proper only produced low numbers of larvae (Ferrington 1985, p. 13). Substrate in the spring proper consists mostly of sand and silt with watercress and lacks the Scott riffle beetle’s preferred rocks and rubble. Ferrington focused his study on the spring run where numbers of adults and larvae were highest due to the abundance of rocks. Water temperature in the spring run ranged from 15.5 to 16.5 °C across all sampling events. Individuals were counted on a per rock basis while classifying rocks by size and sculpture. Samples were stratified across five distinct habitat zones of the spring run (Figure 3.5).

Figure 3.5 Big Spring broken into five segments for Scott riffle beetle sampling. Image: (Hofmeier (b) 2018, slide 13)

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Zone A is the lower spring run, zone B is the upper edge of zone A to the outlet of the pipe, zone C is the outlet of the pipe to the lower end of the concrete bridge, zone D is under the bridge (originally, the concrete bridge), and zone E is upstream of the bridge to where the spring run merges with Big Spring (Ferrington 1985, p. 9).

Results of Ferrington’s survey effort showed abundance of adults was greatest in the upper reaches of the spring run, zones C and D (Ferrington 1985, p. 15). Larvae abundance was greatest in the spring zones B and C (Ferrington 1985, p. 16). Three distinct larval instars were documented during this effort. Small instars were more aggregated than large instars, which were widely dispersed. This indicates a high habitat specificity of newly hatched larvae, or low dispersal from egg-laying sites after hatching (Ferrington 1985, p. 28). Number of larvae per rock was positively correlated with current velocity (Ferrington 1985, p. 18). Detailed habitat characteristics of adults were not identified due to low sample size (Ferrington 1985, p. 29).

In 2016 and 2017, KDWPT replicated the study that was done by Ferrington, documenting 2,813 larvae and 246 adults across nine sampling efforts (Figure 3.6). Use of a Mann Whitney U test to compare contemporary (2016-2017) results to historical (1983-1984) results indicated differences in numbers of individuals are not statistically significant, suggesting the population has remained stable for over 30 years (Figure 3.6).

Figure 3.6 Comparison of 1983/1984 data with 2016/2017 data (Hofmeier (b) 2018, slide 15).

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Chapter 4. Factors Influencing Viability

The Scott Trough and Unique Characteristics of Big Spring

When considering the future viability of the Scott riffle beetle, it is important to understand the unique characteristics of Big Spring that support viability of the beetle’s habitat itself into the future. Flows from the Big Spring have shown to be resilient for an area that has experienced periods of drought, some severe, for over the last one hundred years. A complete loss of flow has not been documented at Big Spring. The physical location of Big Spring is an important factor regarding what makes it so resilient. The spring occurs in what is known as the Scott trough; where the bedrock of the High Plains Aquifer is much lower than the surrounding aquifer (Wilson 2018, slides 20-21). Big Spring discharges from the bottom of that trough, which is one hundred plus feet deep. Additionally, groundwater that flows to Big Spring comes from the west where groundwater withdraws are significantly less than other parts of the aquifer (Wilson 2018, slides 29 and 35). Because of these unique circumstances, the trough (and Big Spring) would likely continue to flow regardless of drought or groundwater reductions (Wilson 2019 pers. comm., 22 Feb). This is compounded by the fact that surrounding users, situated nearby but outside of the trough, would likely cease being able to draw water from the aquifer ahead of any impacts likely to be seen at Big Spring. A 30-40% reduction in regional groundwater usage would stabilize the spring for the next decade or two (Butler et al. 2018, p. 53); however even if there are no reductions in regional groundwater usage, i.e. the continuation scenario in our future condition analysis, we expect that the spring will maintain flows in all of the projected future scenarios because of the unique location of Big Spring (see Chapter 5).

Although Big Spring is not physically within a groundwater management district, it is adjacent to Kansas groundwater management district #1. The groundwater management district is considering groundwater conservation measures. Any future implementation of additional conservation measures as well as the development of more efficient irrigation technologies into the future will also increase the resiliency of Big Spring and Scott riffle beetle habitat.

Potential Stressors

Regional Groundwater Usage Levels Influencing Groundwater Discharge at Big Spring

Big Spring is located over the bedrock depression of the Scott County Trough where it is fed entirely by the Ogallala Aquifer. In 1947 the spring discharge rate was measured at 400 gpm (Waite 1947, p.77) and in 1998 the spring discharge rate was measured at 350 gpm (Layher 2002, p. 6). Historic discharge rates at Big Spring may differ from current discharge rates due to differences in measurement methods and changes in the spring run infrastructure, including the installation of a pipe, the lining of the spring run in concrete, and the subsequent destruction of the concrete lining (Hofmeier (d) pers. comm. 2018). Ferrington showed a positive correlation between number of larvae and stream velocity (Ferrington 1985, p. 18), though quantifying a “normal” or ideal discharge rate is impossible with the current data set. In addition to the past two flow measurements (recorded in gpm) taken at Big Spring, a pressure transducer was installed in the spring in 2018 to achieve constant flow readings going into the future. The pressure transducer measures the weight of the water above it in pounds per square inch (PSI). Currently the State is not able to make comparisons between the current readings and those readings

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that were taken in 1947 and 1998. Having a pressure transducer permanently in place will allow the State to establish a new baseline for flow and to identify trends in flows from Big Spring moving into the future.

The land surrounding Historic Lake Scott State Park consists of cultivated cropland and herbaceous cover (Figure 4.1).

Figure 4.1: National Land Cover Data (classified in 2011) in Groundwater Management District #1 and in the areas surrounding Historic Lake Scott State Park. Cultivated Crops are defined in the National Land Cover Dataset as “areas used for the production of annual crops, such as corn, soybeans, vegetables, tobacco, and cotton, and also perennial woody crops such as orchards and vineyards. Crop vegetation accounts for greater than 20% of total vegetation. This class also includes all land being actively tilled” (USGS 2014). Herbaceous areas are “dominated by gramanoid or herbaceous vegetation, generally greater than 80% of total vegetation. These areas are not subject to intensive management such as tilling, but can be utilized for grazing” (USGS 2014).

Corn, sorghum, and wheat were the main crops planted in Scott County in 2017 (USDA NASS 2018). Regional groundwater usage in Groundwater Management District #1 includes irrigation, municipal water usage, and non-irrigation stock water.

Discharge rates at Big Spring are likely to be influenced by regional variations in the water table as opposed to direct impairment from specific wells (Wilson 2018, slide 17). Regional groundwater usage

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in the area south of Big Spring, is currently at 30% of authorized levels but is still too large to sustain stable groundwater levels (Wilson 2018, slides 25 and 38). Correlations between annual water-level change and annual water use in the vicinity of the Scott County Index Well, a groundwater observation site equipped to continuously monitor water-levels in the aquifer, indicate 39% reductions in the average pumping amounts would stabilize water levels for the next decade or two (Butler et al. 2018, p. 53). Increases in regional groundwater usage could reduce the amount of water in storage within the aquifer. This, in turn, could reduce discharge rates from the aquifer to Big Spring and surface flows required by the species to complete all life stages. Big Spring is located at the edge of the High Plains Aquifer and is currently outside the geographic area the Kansas Geological Survey monitors, thus there is some level of uncertainty in statements regarding discharge at the site.

Physical Habitat (substrate, vegetation, stream run) Alteration

The physical habitat at the spring was altered in the past before the Scott riffle beetle was described. Some of the alterations included the construction of a concrete bridge as well as the pouring of a concrete lining of the sides of the spring run (Figure 4.2).

Figure 4.2 Historic photo of Big Spring in 1947 (Waite 1947, p. 76).

A pipe installed sometime in the park’s history diverts part of the spring flow and then empties into the run. Ironically, the submerged remaining concrete rubble from the destruction of the concrete lining is used by both adult and larval riffle beetles.

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One of the most common plants in the spring run is watercress, an edible plant, which could have been picked in the past by park visitors. The park entrance sign currently states regulations which allow “the noncommercial gathering of edible wild plants for human consumption,” though swimming in Big Spring is not allowed as stated by a sign leading to the spring.

Contamination of Above-Ground Spring Water

The introduction of contaminants into the habitat of the Scott riffle beetle could be acutely detrimental to water quality. The introduction of herbicides from nearby spraying, sunscreens or bug sprays from human contact, or insecticide from pet shampoo are some potential sources of contamination. Future increases in sedimentation could be detrimental to the Scott riffle beetle though this may be unlikely due to the protections in place at Big Spring.

Certain types of contaminants could interfere with the beetle’s ability to respire, as riffle beetles are highly dependent on oxygen rich water (Elliott 2008 p. 189). No historic contamination event has been documented.

Contamination of Groundwater

Historic Lake Scott State Park is not currently in a Ground Water Management District (GMD) but is less than two miles from GMD #1 (Figure 4.3). GMD’s were established to, among other reasons, conserve groundwater resources.

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Figure 4.3 Map showing Kansas Groundwater Management Districts in proximity to Historic Lake Scott State Park (shown in green).

Future groundwater quality issues could arise from regional herbicide, fertilizers and pesticide use, chemical and biological contamination from confined animal feeding operations, oil and gas development and wastewater disposal, and/or increases in salinity and other minerals from activities on the landscape coupled with decreasing water levels in the High Plains Aquifer. The above mentioned activities have been occurring historically with no known impacts to the Scott riffle beetle as supported by comparing population data from 1983-84 vs. 2016-17. The future quality of groundwater at Big Spring is difficult to predict and the upper and lower tolerances for water quality parameters of the Scott riffle beetle are unknown. Riffle beetles in general rely on highly oxygenated water (near saturation) so any contamination that threatens to diminish this quality would likely have negative impacts to survival (Elliott 2008, pp. 198-199).

Predatory and/or Invasive Species

The appearance of non-native or undesired species has been noted in the pool below Big Spring in the past. Non-native insectivorous fish were collected and removed from the pool in September of 2015. The only fish species to have been collected in the spring run were orangethroat darters (Etheostoma spectabile) (Hofmeier (a) 2018, pp. 6), it is unknown whether these darters actively prey on Scott riffle

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beetle larvae or adults, but plans are in place to collect and dissect a specimen to learn more (Hofmeier (e) pers. comm. 2018).

Terrestrial invasive species could also potentially have impacts to Big Spring. Salt cedar (Tamarix sp.) can be found in at least 49 counties in Kansas and can out-compete native plants over large areas. Salt cedars prefer to grow near water sources and a single large tree can use up to 32 gallons of water in a day (Owens et al. 2007, p. 553). If this species was to become prevalent along waterways in western Kansas it could have an effect on groundwater recharge. Though there are no salt cedars growing in the Big Spring area now, if salt cedars were identified early mechanical control would likely prove effective. If needed, precise spot-treatment using an appropriate herbicide could be employed.

Didymo (Didymosphenia geminata) or “rock snot” is a freshwater diatom that can completely envelope the bottom of flowing waters and choke out naturally occurring plants and invertebrates. It has been found near the Kansas and Colorado state border, but has not been observed in Big Spring or documented in Kansas. For detailed information on Didymo see: https://diatoms.org/species/didymosphenia_geminata

Due to restrictions in place regarding recreation in Big Spring the introduction of Didymo is considered unlikely, but if it was to take hold it would likely have significant impacts on the ecosystem.

Other potential invasive species include: crayfish, aquatic turtles, New Zealand mudsnail, and zebra mussel, though with current park protections in place, these invasive species are not likely to be introduced to Big Spring.

Climate Change

Climate change projections based on global climate models show Kansas summers trending to longer and hotter (EPA 2016, entire) with decreased summer precipitation and increased frequency and severity of droughts (Whittemore et al. 2016, p. 141; Cook et al. 2015, entire). This trend could lead to an increased demand for pumping groundwater. Furthermore, “such conditions will likely lead to an acceleration of water-level declines across all portions of the HPA [High Plains Aquifer] in Kansas” (Whittemore et al. 2016 pp. 141). The Kansas Geological Survey uses radar-based precipitation data sets to characterize climate conditions in western Kansas. In the vicinity of the Scott County Index Well, radar precipitation is strongly correlated (R2=.88) with annual reported water use (Butler et al. 2018, pps. 43-47). A change in climate resulting in less precipitation would likely lead to increased pumping demands on the High Plains Aquifer. If these demands occurred in the region of the aquifer that discharges to Big Springs, surface water outflows could be impacted, though the likelihood of the spring drying is small given its location within the aquifer (see discussion on the Scott Trough within this document).

Cumulative effects of stressors

Climate change directly affects the regional demand for groundwater and the rate of recharge of the High Plains Aquifer. Should climate change result in longer, hotter summers, and more frequent and severe droughts, we would expect to see higher demand on groundwater, a lower rate of groundwater recharge, and the potential for diminishment of groundwater discharge at Big Spring. However, due to uncertainties in future changes in regional temperature and precipitation levels resulting from climate

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change and the effect that may have on water demand and groundwater levels, we are unable to accurately predict level of impact to the beetle. Furthermore, the location of the spring within the aquifer is such that a complete suspension of discharge is unlikely (see discussion on the Scott Trough within this document). That said, we have included a number of plausible future groundwater levels into our future condition scenarios evaluated below. The suite of scenarios provides a cumulative assessment of the stressors, including climate change, with the potential for species level impacts in the future.

Potential and Current Conservation Efforts

Regional Groundwater Usage Levels Influencing Groundwater Discharge at Big Spring

Based on the relationship between average annual reported water use and average annual water-level change from 2008 to 2016 at the Scott County Index Well, a decrease by 30-40% of current usage levels in that region would likely sustain the spring at current discharge rates for at least 10-20 years (Butler et al. 2018, pp. 53).

No groundwater observation wells are located in sufficient proximity to the springs to provide adequate water level measurements, therefore the Kansas Geological Survey has recommended the installation of one or more observation wells to the west and/or southwest of Big Spring in order to better monitor long term trends in the water table at that location (Wilson 2018, Slide 56). This, coupled with onsite water monitoring managed by KDWPT, could help to better quantify the relationship between regional groundwater usage levels and groundwater discharge at Big Spring.

Physical Habitat (substrate, vegetation, stream run) Alteration

A well-designed boardwalk above the concrete bridge does not appear to impact the spring or the run and keeps visitors on the designated path and out of the spring and run. Protections afforded to the beetle from its state endangered status and the designation of critical habitat under State law means a permit would be required for any construction projects that could alter Scott riffle beetle habitat.

Big Spring benefits from its close proximity to the Historic Lake Scott State Park office in that one or more state employees drive by the spring at least 15 times a day. This may be enough to deter vegetation gathering, or any additional substrate disturbance from park visitors.

Increased site protection and conservation efforts, such as the establishment of a no spray area, improvement of groundwater quality and quantity and increased public outreach as proposed under a 2018 Draft Scott Riffle Beetle Management Plan (Hofmeier (a) 2018, p.7) means the potential for future disturbance or loss of physical habitat seem very unlikely.

Contamination of Above-Ground Spring Water

The risk of above-ground contamination is greatly reduced by the protections afforded to the site by park management. The Draft Scott Riffle Beetle Management Plan (Hofmeier (a) 2018, p. 7) restricts the spraying of any pesticides at or near the site and suggests that visitors are closely monitored. The

Scott Riffle Beetle SSA 19 2019

installation of a real time water quality monitor in 2018 at the spring run allows KDWPT biologists to monitor for any surface contamination event.

Contamination of Groundwater

The real time water monitoring station at Big Spring allows KDWPT biologists to identify any sudden or gradual changes in groundwater quality. Should the monitoring suggest a contamination event, KDWPT staff could attempt to salvage individuals from Big Spring until the event subsides, though no formal protocol to do so is currently in place.

Predatory and/or Invasive Species

Unauthorized placement of fish in the pool below the springs is not considered a significant threat. Due to the shallow nature of the spring run it is not suitable habitat for larger fish. According to draft management plans by KDWPT there will be no fish stocking in the future and the pool will be sampled by seine and electrofishing on a regular basis to remove any undesired fish species.

Because unauthorized access is prohibited at Big Spring and the lack of sportfish habitat would not attract anglers, it is unlikely that Didymo would be introduced there, but if it was to establish it could have severe consequences for the Scott riffle beetle.

Establishment of Captive Facility and/or Population

The establishment of a captive population of Scott riffle beetles would improve the species’ ability to withstand a catastrophic event. At present there is no protocol in place for the establishment or long term maintenance of a captive population, nor have any techniques been established on how to create a successful refugium for the Scott riffle beetle in the event of a catastrophic event at Big Spring. At a minimum, the establishment of a holding facility would allow biologists to remove beetles and larvae and place them in holding in the event of a temporary contamination event. In 2018, KDWPT opened a facility called the Kansas Aquatic Biodiversity Center. The primary purpose of the center is to propagate non-game imperiled aquatic vertebrates and invertebrates in a hatchery type environment. The Center was not designed to maintain long-term, captive populations. There has been some success with the establishment of a captive breeding program for the Federally Endangered Comal Springs riffle beetle (Heterelmis comalensis) in Texas, at the U.S. Fish and Wildlife’s San Marcos Aquatic Resources Center in San Marcos, Texas. Development of captive rearing techniques has been ongoing since 1996 and there has been some success in rearing beetles through all life stages (Huston et al. 2015, p. 521). Some of the methods used could very well be applicable for captive propagation of the Scott riffle beetle if it was determined that the need existed.

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Chapter 5. Future Condition and Species Viability

Based on our understanding of historical, current, and expected future conditions, we developed five plausible future scenarios, including a continuation of current conditions, that could impact the resiliency, redundancy, and representation over the next 50 years, focusing on what we identified as the most important stressors and conservation efforts (Table 5.1). The main stressor driving these scenarios is regional groundwater usage, with the understanding that if regional groundwater usage remains the same, groundwater discharge is likely to decrease. These scenarios capture what we believe to be the full risk profile for the species given probable levels of cumulative stressors and conservation efforts that could happen in the future based on the best available information. There is always uncertainty in projecting future effects to species and the actual future for this species in 50 years may not play out exactly as any one of the scenarios described, but the actual future in 50 years is probably somewhere within the range of the five scenarios. We believe some scenarios are more or less likely to happen than others and have provided a relative likelihood of each scenario (as compared to each other) in Table 5.1.

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Table 5.1 Future plausible scenarios taking into account identified stressors and conservation efforts. Stressor/ Stressor/ Stressor/ Stressor/ Scenario Stressor/Conservation Effort Conservation Likelihood Conservation Effort Conservation Effort Conservation Effort Effort dam removal at least one captive with proper regional population and one groundwater techniques to groundwater usage site protection such that risk of substrate suitable rearing contamination risk prevent Scenario 1 decreases by 30%- disturbance, vegetation gathering, or acute facility (in the event lowered through headcutting less likely (optimistic) 40%; tree removal contamination from soaps, pesticides, etc. of temporary acute best management ect. and to reduce local is minimized contamination at practices subsequent water stress spring site) increase in established habitat area regional one suitable rearing groundwater groundwater usage site protection such that risk of substrate facility (in the event contamination risk dam remains; Scenario 2 decreases by 30%- disturbance, vegetation gathering, or acute of temporary acute (less lowered through habitat area likely 40%; tree removal contamination from soaps, pesticides, etc. contamination at optimistic) best management unchanged to reduce local is minimized spring site) practices water stress established regional one suitable rearing groundwater usage Scenario 3 site protection such that risk of substrate facility (in the event remains stable at groundwater dam remains; (more disturbance, vegetation gathering, or acute of temporary acute optimistic 30% of authorized contamination risk habitat area very likely contamination from soaps, pesticides, etc. contamination at than usage quantity; tree unchanged unchanged is minimized spring site) continuation) removal to reduce established local water stress regional groundwater usage site protection such that risk of substrate remains stable at groundwater dam remains; Scenario 4 disturbance, vegetation gathering, or acute no rearing facilities 30% of authorized contamination risk habitat area likely (continuation) contamination from soaps, pesticides, etc. established usage quantity; tree unchanged unchanged is minimized removal to reduce local water stress regional dam remains; groundwater usage groundwater site protection decreased due to staffing Scenario 5 possible no rearing facilities increases above contamination risk changes, management changes, and/or less likely (pessimistic) decrease in established 30% of authorized unchanged budget cuts habitat area usage quantity

Scott Riffle Beetle SSA 22 2019

To evaluate these scenarios, we considered how each would affect the resiliency, redundancy, and representation of the Scott riffle beetle.

Resiliency is the ability of populations to withstand stochastic events. It is measured based on metrics of population health, such as the size and growth rate of populations and how quickly they are able to rebound in numbers after an event results in the loss of individuals or populations. Information on these metrics for the Scott riffle beetle is fairly limited. We assessed Scott riffle beetle resiliency by taking into consideration their very limited geographical range, their apparent ability to persist in one area over a long period of time, population densities from surveys in 1983/84 and 2016/17, current conditions of the spring and the underlying aquifer, and protections afforded to the population from management actions by the State of Kansas. It should be noted that the population has remained unchanged from historic and modern surveys despite having multiple years of below normal precipitation occurring since 1985.

Redundancy is having a sufficient number of populations for a species to withstand catastrophic events. To assess Scott riffle beetle redundancy, we focused on the fact that fairly extensive past surveys failed to find any additional populations of the beetle, and thus it is likely that there is just one population.

Representation is the ability of a species to adapt to changing environmental conditions. It can be measured through ecological diversity (environmental variation) and genetic diversity within and among populations. Because information is lacking or limited for the Scott riffle beetle, we assume a species with a greater diversity of environmental conditions has higher representation. Due to the extremely limited amount of habitat that the Scott riffle beetle occupies one could assume that representation would be low. However there are subtle difference in parameters like water temperature and dissolved oxygen throughout the occupied habitat. These small scale, subtle differences could possibly result in some degree of genetic diversity.

In scenario one, regional groundwater usage decreases by 30%-40% meaning groundwater discharge should remain the same for the next 50 years. Trees are removed locally to further lower the risk of water stress. Groundwater contamination risk is lowered through regional best management practices and the site is well-protected by KDWPT. The dam below the pool is removed using proper techniques to prevent headcutting, etc., restoring the lower reach of the spring run thereby increasing available habitat. At least one captive population is established along with a holding area in the event of temporary contamination at the site. This scenario would likely increase resiliency by ensuring the existing habitat remains unchanged and by growing the population within additional habitat downstream. Redundancy would increase by establishing a captive population and holding/rearing facility. Representation would likely remain unchanged.

In scenario two, regional groundwater usage decreases by 30%-40% meaning groundwater discharge should remain the same for the next 50 years. Trees are removed locally to further lower the risk of water stress. Groundwater contamination risk is lowered through regional best management practices and the site is well-protected by KDWPT. The dam below the pool is kept. A captive holding area is established in the event of temporary contamination at the site. Resiliency would remain unchanged through the next 50 years by ensuring the existing habitat remains unchanged. Redundancy would increase slightly due to the establishment of a holding/rearing facility. Representation would likely remain unchanged.

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In scenario three, regional groundwater usage remains the same, meaning groundwater discharge could diminish over the next 50 years, though the likelihood of the spring drying is small given its location within the aquifer (see discussion on the Scott Trough within this document). Trees are removed locally to further lower the risk of water stress. Groundwater contamination risk is unchanged, but the site is well-protected by KDWPT. The dam below the pool is kept. A captive holding area is established in the event of temporary contamination at the site. Resiliency would decrease under the assumption that existing habitat would decrease as a result of decreased groundwater discharge. Redundancy would increase slightly due to the establishment of a holding/rearing facility. Representation would likely remain unchanged.

In scenario four, current conditions are continued. Regional groundwater usage remains the same, meaning groundwater discharge could diminish over the next 50 years, though the likelihood of the spring drying is small given its location within the aquifer (see discussion on the Scott Trough within this document). Trees are removed locally to lower the risk of water stress. Groundwater contamination risk is unchanged, but the site is well-protected by KDWPT. The dam below the pool is kept. No captive holding area is established. Resiliency would decrease under the assumption that existing habitat would decrease as a result of decreased groundwater discharge. Redundancy would remain unchanged. Representation would likely remain unchanged.

In scenario five, regional groundwater usage increases, meaning a decrease in groundwater discharge is expected to occur over the next 50 years, though the magnitude of the decrease is unknown and complete drying of Big Spring appears unlikely given its location in the aquifer (see discussion on the Scott Trough within this document). Groundwater contamination risk is unchanged and the site is less protected as a result of KDWPT budget cuts or significant staffing and management changes. The dam below the pool is kept, although total wetted habitat area would likely decrease with decreasing groundwater discharge at the spring. No captive holding area is established. Resiliency would decrease under the assumption that existing habitat would decrease as a result of decreased groundwater discharge. Redundancy would remain unchanged. Representation would likely remain unchanged.

Projected habitat conditions under each scenario were scored as high, moderate, and low and then tallied to reach a numeric score (high = 3, moderate = 2, and low = 1) (Table 5.2). Groundwater discharge was weighted three times more than the other habitat metrics to reflect that the presence of adequate water underscores every other habitat variable. Final scores correspond to specific qualitative conditions (Appendix B).

See Table I above for a summary of the overall results of our current and future species condition analysis for the Scott riffle beetle.

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Table 5.2 Projected habitat condition under plausible future scenarios for the Scott riffle beetle at the only population, Big Spring (see Table B.1 for further information). Current & Sufficient Adequate Presence of Total Future DO Water Suitable Terrestrial Condition (indicator of Groundwater Periphyton & Habitat Condition groundwater and Quality Substrate Habitat Score surface water Discharge (x3) Diatoms Area Scenarios contamination risk?)

Current Condition High High High High High High Moderate 26 (H) Future Condition Scenario 1 High High High High High High High 27 (H) (optimistic) Future Condition Scenario 2 (less High High High High High High Moderate 26 (H) optimistic) Future Condition Scenario 3 (more optimistic Moderate Moderate Moderate Moderate Moderate High Moderate 19 (M) than continuation) Future Condition Scenario 4 Moderate Moderate Moderate Moderate Moderate High Moderate 19 (M) (continuation)* Future Condition Scenario 5 Moderate Low Low Low Low Moderate Low 11 (L) (pessimistic) *a continuation scenario would see the continuation of current regional groundwater usage quantities, which will lead to a decrease in groundwater discharge

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Literature Cited

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Brown, H.P. 1987. Biology of Riffle Beetles. Ann. Rev. Entomol. 32:253-73

Butler Jr., J.J. Whittemore, D.O. Reboulet, E. Knobbe, S. Wilson, B.B. Bohling, G.C. 2018. High Plains Aquifer Index Well Program: 2017 Annual Report. Kansas Geological Survey Open-File Report No. 2018- 17. 59 pp.

Cook, Benjamin I. Ault, Toby R. Smerdon, Jason E. 2015. Unprecedented 21st century drought risk in the American Southwest and Central Plains. Science Advances. 1:e1400082.

Crosbie, Russel S. Scanlon, Bridget R. Mpelasoka, Freddie S. Reedy, Robert C. Gates, John B. Zhang, Lu. 2013. Potential climate change effects on groundwater recharge in the High Plains Aquifer, USA. Water Resources Research. Vol 49, 3936-3951.

Elliott, M.J. 2008. The Ecology of Riffle Beetles. Freshwater Reviews. 1:189-203.

Environmental Protection Agency. What Climate Change Means for Kansas. 2016. EPA 430-F-16-018.

Ferrington, L.C. 1985. Population Study of Optioservus phaeus White, a Riffle Beetle of Threatened Status Endemic to Kansas. Reports of the State Biological Survey of Kansas. No 29. 46pp.

Ferrington L.C., Busby W.H., Blackwood M.A. 1991. Status Report on Optioservus phaeus White (Scott Riffle Beetle). 19 pp.

Hofmeier, J. 2018 (a). Kansas Department of Wildlife Parks and Tourism Draft Management Plan for the Scott Riffle Beetle.

Hofmeier, J. 2018 (b). Scott Riffle Beetle Species Status Assessment Presentation. Prepared by the Kansas Department of Wildlife Parks and Tourism. PowerPoint presentation available at the US Fish and Wildlife Kansas Field Office, Manhattan, Kansas.

Hofmeier, J. 2018 (c). Comments received during peer review of Scott Riffle Beetle Species Status Assessment. 6 pp.

Hofmeier, J. 2018 (d). Personal communication. Email: September 20, 2018. Kansas Department of Wildlife, Parks, and Tourism.

Hofmeier, J. 2018 (e). Personal communication. Verbal comments during May, 2018 Big Spring site visit.

Huston, D.C. Gibson, R.J. 2015. Underwater Pupation By the Comal Springs Riffle Beetle, Heterelmis comalansis, Tuff, and Brown, 1988 (Coleoptera: Elmidae), with an update on Culture Techniques. The Coleopterists Bulletin. 69(3): 521-524.

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Layher, B. 2002. Recovery Plan for the Scott Riffle Beetle, Optioservus phaeus Gilbert, in Kansas. Prepared for Kansas Department of Wildlife and Parks. 38pp.

Owens, K.M. Moore, G.W. Saltcedar Water Use: Realistic and Unrealistic Expectations. Rangeland Ecol Manage. 60:553-557.

Shepard, W.D. 2019. Flight wing polymorphisms in Elmidae Curtis and Dryopidae Billberg (Insecta: Coleoptera: Byrrhoidea). The Coleopterists Bulletin 73 (1). Accepted for publication.

Tavares, A.F. Williams, D.D. 1990. Life histories, diet, and niche overlap of three sympatric species of Elmidae (Coleoptera) in a temperate stream. The Canadian Entomologist 122:563–577.

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U.S. Fish and Wildlife Service (USFWS). 2015. USFWS Species Status Assessment Framework: an Integrated Analytical Framework for Conservation. Version 3.3, dated August 2015.

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Whittemore, Donald O. Butler Jr., James J. Wilson, Blake B. 2016. Assessing the major drivers of water- level declines: new insights into the future of heavily stressed aquifers, Hydrological Sciences Journal, 61:1, 134-145, DOI: 10.1080/02626667.2014.959958

Wilson, Blake B. 2018. Groundwater Trends In and Around Scott County State Park. Prepared by the Kansas Geological Survey. PowerPoint presentation available at the US Fish and Wildlife Kansas Field Office, Manhattan, Kansas.

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Appendix A. Core Conceptual Model

Core Conceptual Model

Stressors Needs

Sufficient Demographic Dissolved O2 Invasive Species Metrics

Adequate Groundwater Groundwater Discharge Depletion Abundance

Population Water Quality Resiliency

Water Contamination Age Class Structure Presence of Periphyton & Diatoms Species Viability

Extreme Weather Event/Flooding Suitable Substrate Diagram Key

Substrate Positive Effect Disturbance Terrestrial Habitat Negative Effect

Figure A.1 Core Conceptual Model for the Scott Riffle Beetle. This model shows the positive and negative relationships of stressors to species needs, demographic parameters, and ultimately species viability.

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Appendix B. Condition Category Table

Table B.1 The quantity or characteristic of each demographic and habitat factor that characterize a healthy, moderately healthy, unhealthy, or extirpated population.

Demographic/Distribution Factors Habitat Factors Condition Category Age Class Groundwater Discharge Abundance Substrate Overall Water Quality Total Habitat Area Structure (Water Quantity) greater than or presence of equal to larvae and adults reduction in regional meets established high primarily cobble & High abundance in numbers groundwater usage by 30% groundwater quality rubble (see: Ferrington > 0.3 acre (healthy) measurement greater than or to 40% (Kansas Geological standards (DO, N, salinity, 1985) in water from 1983/1984 equal to Survey, 2018) temperature) study 1983/1984 study current regional decrease in increased groundwater usage remains Moderate abundance from decreases in embeddedness of the same (at 30% of decrease from acceptable 0.3 acre (current (moderately past surveys (by abundance of existing substrate; some authorized usage quantity) standards; slight impairment size as of 2018) healthy) unspecified % at larvae and adults cobble & rubble above (Kansas Geological Survey, this point) water line 2018)

regional groundwater usage primarily fine sediment Low significant missing either increases above 30% of and/or cobble & rubble significant impairment < 0.3 acre (unhealthy) decrease larvae or adults authorized usage quantity above water line

regional groundwater usage all fine sediment and/or increases such that spring total habitat loss missing both no cobble or rubble extremely significant Extirpated absent flow becomes intermittent, during months-long larvae and adults available below water impairment i.e. months-long periods of periods line no flow

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