Lang 1999 Status of Aquatic Mollusks of New Mexico E-20-7.Pdf

Appendix A. Management recommendations for state-listed and federal Candidate species and Species of Concern macro invertebrates of New Mexico, E-20-7. Management Recommendations for State-listed and Federal Candidate Species and Species of Concern Macroinvertebrates of New Mexico under Section 6 Project E-20-7

Noel's Amphipod (Gammarus desperatus)

Status:

Monthly (1995-1998) censuses ofmacroinvertebrates at the Bitter Lake National WildlifeRefuge (BLNWR) documented a second population of G. desperatus in Sago Springs complex. This species was known heretofore only fromBitter Creek ("Lost River"; Cole 1988), and extirpated from North Spring ofthe Roswell Country Club (RCC) and Lander Springbrook, Chaves County (Cole 1981, 1985). From June 1995 to May 1996, the relative abundance of G. desperatus in 2 2 Bitter Creek was 64-8768 amphipods/m compared to lower densities (26-575 amphipods/m ) in Sago Springs complex. A satellite population of G. desperatus was recently documented by Dr. M. E. Gordon in a ditch along the west shore line ofrefugeUnit 6 (B. K. Lang,pers. obs.). Gammarus desperatus appears restricted to wetland habitats ofthe BLNWR, as exploratory aquatic inventories in southeasternNew Mexico during the past fouryears have documented only hyalellid amphipods (NMGF files). Cole (1981, 1985, 1988) considered the species a narrow endemic known only fromisolated populations in Chaves County, New Mexico.

Gammarus desperatus occurs sympatrically with three macroinvertebrate tax.apossessing state and federalstatus (Table 1), the federalendangered Pecos gambusia, and the proposed endangered Pecos pupfish, that inhabit surface waters of Bitter Creek and Sago Springs complex ofthe BLNWR. Potential adverse impacts of oil and gas activities along the Pecos River (USFWS 1997b) underscore the imminence ofthreats (see Appendix B, attached) to the long term viability of G. desperatus populations at the BLNWR.

Management and ConservationOptions:

(1) Recommend routine sampling of G. desperatus in Bitter Creek and Sago Springs complex to monitor the population and to document life history parameters. Inventory is recommended at NorthSpring, which will require permission for site access fromthe RCC; such requests were denied previously.

(2) Continued Section 6 fundingwill facilitate the Project Biologist's effortsto process voucher material collected during monthly censuses (June 1995 to July 1998), compile macro- and microhabitat data, analyze ecological data, and synthesize reports.

Al and Wildlife Service (1997b) rendered jeopardy opinion that potential oil and gas activities along the Pecos River may adversely impact the Pecos bluntnose shiner and Pecos gambusia.

Since all ma9.roinvertebrate species of the BLNWR that possess state and federal status are sympatric with the federal endangered Pecos garnbusia in Bitter Creek and Sago Springs complex, adherence with Section 7 Consultation Reasonable and Prudent AlternativeNo. I (RPA-1) forPecos Garnbusia (USFWS 1997b) is recommended. The RP A-1 states:

"Use the best available hydrologic information to map the source and movement of water that supplies springs occupied by Pecos Gambusia on the Bitter Lake National Wildlife Refuge and Salt Creek Wilderness. Close the lands within the mapped area to oil and gas leasing unless or until the BLM can demonstrate that mandatory protective measures will ensure no aquifer contamination."

This abeyance for exploratory oil and gas well permits on lands referred toin RP A-1 is equally justified for G. desperatus since these two species occur sympatrically, although G. desperatus is even more narrowly distributed than Pecos garnbusia.

(4) In the event that oil and gas activities proceed without demonstrating that mandatory protective measures will ensure no aquifer contamination within the area referencedby RPA-1, then there would be a threatened curtailment and possible destruction of the limited habitat of G. desperatus, thus demonstrating that regulatory mechanisms are inadequate. The species would be in danger of extinction throughout all of its range.

(5) Management practices at the BLNWR might include rehabilitation of vestigial habitat of G. desperatus along the westernditch of refugeUnit 6, and in other impoundments or ditches, providing that such practices do not adversely impact habitats, populations, or management plans forother taxa on the refuge.

(6) It is suggested that the USFWS reclassify G. desperatus from a federal Species of Concernto a Candidate forlisting under the Endangered Species Act (ESA), as factors warranting such a classification forsympatric macroinvertebrates (i.e., Assiminea pecos, Pyrgulopsis roswellensis, Tryonia kosteri) of the BLNWR equally threaten G. desperatus. Imminent threats to the bastion population of this endemic species, now restricted solely to the BLNWR, are listed in the species account of Appendix B (attached).

A2 Assiminea pecos

Status:

Assiminea pecos in New Mexico has been reported live from two populations on the Bitter Lake National WildlifeRefuge (BLNWR): a seepage area along Unit 6 (type locality) and in Bitter Creek ("Lost River") (Taylor 1987). Taylor ( 1983, 1987) reported extirpation of A. pecos from the type locality and from North Spring, Roswell Country Club (RCC), Chaves County, New Mexico.

This aquatic prosobranch snail exhibits behaviors characteristic of pulmonate land snails that colonize mesic habitats, as it frequentswetted muddy stream margins, and occurs most commonly under moist organic material adjacent to flowing water (Taylor 1987). As such, A. pecos has not occurred readily in benthic or tile substrate samples collected during monthly censuses (June 1995-July 1998) at the BLNWR. While only one live A. pecos was collected in each Bitter Creek and Sago Springs complex fromJune 1995 to May 1996, several empty shells occurred as driftspecimens in benthic samples. The paucity of live specimens· in benthic samples likely reflects lack of appropriate sampling effort.

Exploratory survey in May 1998 concentrated on stream margins along ca. 0.75 mile of Bitter Creek and yielded only one live specimen. In spring 1999, search forA. pecos focusedon Sago Springs complex and at select localities along Bitter Creek where specimens were collected previously (i.e., ca. 300 m upstream of the flume, DragonflySpring run). Although no A. pecos were observed along Bitter Creek, the species was abundant in the marsh emergents formingthe perimeter of a sink hole at the terminus of Sago Spring run. Assiminea pecos occurred on wetted stem surfaces at the base of marsh emergents and on muddy surfaceswithin 1 cm of water. The presence of A. pecos at this site is noteworthy as the habitat was burnedin spring 1997. Taylor (1987) attributed extirpation A. pecos to annual burningof marsh emergents in the Bols6n de Cuatro Ciengas, Mexico. It appears that the species is tolerant of fire,and that intensity, duration, and frequencyare principal factorsto consider when prescribing firemanagement practices to control seral succession of habitats where A. pecos occurs.

Assiminea pecos occurs sympatrically with three macroinvertebrate taxa possessing state and federalstatus (Table 1), the federalendangered Pecos gambusia, and the proposed endangered Pecos pupfish, that inhabit surfacewaters of Bitter Creek and Sago Springs of the BLNWR. Habitat and population threats are listed in species accounts of Appendix B (attached). Potential adverse impacts of oil and gas activities along the Pecos River (USFWS 1997b) underscore the imminence of threats (see Appendix B) to the long-term viability of A. pecos populations at the BLNWR.

Management and Conservation Options:

(1) Conduct routine surveys employing stream-side searches in areas of recorded

A3 occurrences, including North Spring, RCC. Access to North Spring will require permission from the RCC; such requests were denied previously.

(2) Continued Section 6 funding will facilitate the Project Biologist's ongoing efforts to process field voucher material, compile macro- and microhabitat data, analyze ecological data, and synthesize reports.

(3) Through formal Section 7 Consultation on threatened and endangered species of the Bureau of Land Management's Roswell Resource Area Draft Resource Management Plan/Environmental Impact Statement (Roswell DRMP/EIS) (BLM 1994), the U.S. Fish and WildlifeService (1997b) rendered jeopardy opinion that potential oil and gas activities along the Pecos River may adversely impact the Pecos bluntnose shiner and Pecos gambusia.

Since all macro invertebrate species of the BLNWR that possess state and federal status are sympatric with the federalendangered Pecos gambusia in Bitter Creek and Sago Springs complex, adherence with Section 7 Consultation Reasonable and Prudent AlternativeNo. 1 (RPA-1) forPecos Gambusia (USFWS 1997b) is recommended. The RPA-1 states:

"Use the best available hydrologic informationto map the source and movement of water that supplies springs occupied by Pecos Gambusia on the Bitter Lake National Wildlife Refugeand Salt Creek Wilderness. Close the lands within the mapped area to oil and gas leasing unless or until the BLM can demonstrate that mandatory protective measures will ensure no aquifer contamination."

This abeyance forexploratory oil and gas well permits on lands referredto in RPA-1 is equally justified forA. pecos since this species occurs sympatrically with Pecos gambusia.

( 4) In the event that oil and gas activities proceed without demonstrating that mandatory protective measures will ensure no aquifercontamination within the area referencedby RPA-1, then there would be a threatened curtailment and possible destruction of the limited habitat of A. pecos, thus demonstrating that regulatory mechanisms are inadequate. The species would be in danger of extinction throughout all its range in New Mexico.

Pyrgulopsis chupaderae

Status:

Pyrgulopsischupaderae is known from Willow Spring (type locality) (Taylor 1987), and a relict

A4 population froman unnamed spring located ca. 0.25 air miles north of Willow Spring, Cienega Ranch, Socon-o County, New Mexico. Monthly monitoring of the P. chupaderae population of Willow Spring spanned the period May 1997 to July 1998. Routine population and habitat monitoring is ongoing.

This species was up listed fromstate Threatened to Endangered due to over-grazing of habitat (i.e., the spring run was devoid of vegetation and trampled to a mud hole) at the northernmost unnamed spring, which decimated the population (NMGF 1996a). During monthly population monitoring (May 1997-July 1998), cattle grazing in the riparian corridor of Willow Spring and in downstream reaches of the wetland complex was minimal. The riparian corridor ofWillow Spring was intact under this level of grazing pressure. While no efforts were observed to improve surface water catchment, water was diverted from an artesian springhead adjacent (i.e., within 4 m) to the source for Willow Spring. Diverted water was returnedto the pond down gradient ofWillow Spring run. This diversion did not appear to affect adversely the habitat or population ofP. chupaderae at Willow Spring.

Willow Spring was visited on 4 occasions under grant Segment 7. In November 1998, the spring rheocrene (flowing "channel") and wetted riparian corridor was reduced notably in width to approximately 1/s to½ the width observed during monthly visits under previous grant segments (6-7). Whether reduced spring discharge was attributed to groundwater withdrawals up-gradient, seasonally diminished flows,or a combination of these factorsremains undetermined. Notwithstanding, reduced spring discharge did not appear to affectadversely P. pecosensis.

Routine population and habitat monitoring in August 1999 revealed removal of woody debris from the riparian corridor ofWillow Spring. These "cosmetic" alterations did not affect habitat of Willow Spring·or the P. chupaderae population. Sampling tiles were removed from the springrun, and a water temperature data logger could not be relocated fordata retrieval. Consequently, minimal population and habitat data was recorded.

In 1999, the Cienega Ranch (ca. 30,000 acres) was sold and renamed "Willow Spring Ranch". Small parcels were placed under land auction in September 1999. The Project Biologist contacted the current owner, in person and with correspondence, to inform the land steward of agency efforts to conserve P. chupaderae and aquatic habitats of Willow Spring. The present status of Willow Spring is undetermined. Site visitation is now pre-arranged with the landowner.

Regional and local groundwater depletion is a primary threat to the extant population ofP. chupaderae. If grazing was controlled for a sufficientperiod oftime, the northernmostunnamed spring might support reintroduction of P. chupaderae once a contiguous marsh emergent plant· community has developed. See draftspecies account in Appendix B ( attached) foradditional information.

Management and ConservationOptions:

A5 (1) Monitor populations of P. chupaderae and habitat of Willow Spring quarterly.

(2) Provide Section 6 fundingto process fieldvoucher specimens and ecological data.

(3) Recommend development ofa habitat management plan in cooperation with the land owner under the "candidate conservation agreement" (USFWS 1997a) that perpetuates aquatic habitat conditions of Willow Spring suitable for P. chupaderae. Such a conservation plan must consider balancing water stewardship wisely to meet the needs of historic land use practices, which, heretofore, have allowed for persistence of the aquatic habitat of Willow Spring that is critical forsurvival of P. chupaderae.

(4) Establish a refugepopulation ofP. chupaderae in an artificial stream system at the Albuquerque Biological Park.

Pyrgulopsisgilae

Status:

Mehlhop (1992, 1993) last reported on status ofhydrobiids of the Gila River Basin, and documented three new populations ofP. gilae in spring and seep discharges on Taylor Creek (two sites), and a spring complex on the East Fork Gila River. The "metapopulation" ofP. gilae consists of 10 widely disjunct populations in the Gila River Basin, New Mexico. Single populations occur on U.S. Forest Service (USFS) lands along the Middle Fork Gila River and Gila River mainstem. The East Fork Gila River sub-basin possesses eight isolated populations: two each on private and dual stewardship (private-USPS) lands, and fourpop ulations on USFS managed lands. The genetic affinitiesof such geographically isolated populations are poorly understood, seldom studied, and must be adequately explored prior to development of proper management prescriptions (Weins 1996). See draft species account in Appendix B (attached) for additional information.

In August 1998, approximately 20 miles ofriparian corridor along the West Fork Gila River were inventoried for suitable spring habitats that might support populations ofP. gilae. Only pulmonate physid snails were collected fromspring-fed backwater habitats of the West Fork Gila River. This sub-basin lacks the abundance ofartesian springheads characteristic ofthe East Fork and Middle Fork sub-basins, and the Gila River mainstem. A single thermal spring on the Middle Fork Gila River, located approximately 0.7 river miles upstream ofthe Gila Visitor Center, was not conducive to successfulcolonization by any mollusk taxa, as the water temperature exceeded 55°C, and the thermal pools were in the riverine floodway.

Management and ConservationOptions:

(1) Initiate population surveys under ongoing project Segment 8 to document biology, land-

A6 use practices, and status of all known P. gilae populations in the Gila River Basin. Expand inventory to unexplored reaches within the basin.

(2) Recommend allocation of Section 6 funding to assess genetic divergence of P. gilae within and among geographically isolated populations throughout the Gila River Basin. Genetic divergence between disjunct populations may warrant taxonomic reevaluation of the species, which in tum could confer specific· management recommendations particular to genetically distinct populations specific to current ownership and land-use practices.

Pyrgulopsis pecosensis

Status:

Taylor (1987) reported two populations of the endemic P. pecosensis fromperennial tributaries of the Black River, Eddy County, New Mexico: Blue Spring (type locality) and Castle Spring. Extirpation of the Castle Spring population is attributed to adverse land-use practices in the watershed (Landye 1981, NMGF 1988, Mehlhop 1992). The habitat and P. pecosensis population of Blue Spring was monitored monthly at two localities from July 1997 to September 1998. Blue Spring was visited twice under project Segment 7. Pyrgulopsis pecosensis of Blue Spring appears stable under current grazing pressure and irrigation withdrawals. See species account in Appendix B (attached) for additional information.

Acquisition of Blue Spring surface water rights (NMSA 1995) and the "lack of oil and gas reserves in the area" prompted reclassification of P. pecosensis from a federalCandidate for listing under the ESA to a Species of Concern (USFWS 1996). Contrary to this reclassification, the Black River Valley has experienced repeated problems of ground-water depletion and contamination. Water levels of domestic and agricultural/range wells in the Black River Valley have lowered and even dried-up (residents of Black River Village and environs,pers. com.). Acquisition of surface water rights of Blue Spring was a temporary state lease (NMSA 1995). Oil and gas operations are ongoing in the Black River drainage basin (BLM 1994)

Richard(1988a, 1988b) and Richard and Boehm (1989a, 1989b) documented ground-water contamination of domestic and agricultural/range wells in the upper Black River Valley (i.e., Washington Ranch, Ballard Wells) by petroleum-derived hydrocarbons and sulfides. Richard and Boehm (1989b) reported "severe" sulfidecontamination of Blue Spring in 1988, the most down-gradient surfacedischarge point for groundwater in the upper Black River Valley. These authors indicated that gas contamination originating up-gradient was likely transported about 20 miles down-gradient to Blue Spring. Such long distance transport of groundwater is common in karst, evaporite rock (White 1995, Martinez et al. 1998), and raises concerns forsurface-water quality of the Blue Spring wetland complex and the Black River,especially considering the concentration of petroleum industry operations in the Black River Valley. Oil and gas extractive practices are ongoing in the Black River sub-basin, including the immediate watershed of Blue

A7 Spring (NMGF files).

Management and Con ervation Options:

(1) Recommend that the U. S. Fish and Wildlife Service explore the possibility of developing a conservation agreement (USFWS 1997a) that provides a vehicle for species and habitat conservation compatible with past and present land-use practices.

(2) Financial support under Section 6 will facilitatethe Project Biologist's efforts to process monthly voucher collections, compile a database, analyze data, and synthesize reports.

(3) Continue routine monitoring of P. pecosensis populations and habitats of Blue Spring.

Pyrgulopsis roswellensis

Status:

Since Taylor (1987) described P. roswellensis fromthe Bitter Lake National Wildlife Refuge (BLNWR), Mehlhop (1992, 1993) documented persistence of the species on the refuge, and spot checked population status at NorthSpring, Roswell County Club, Chaves County. In March 1995, a relict population still occurred in North Spring (P. Mehlhop,pers. com.). Monthly macroinvertebrate population monitoring (June 1995-July 1998) documented a second population of P. roswellensis in Bitter Creek, BLNWR. From June 1995 to May 1996, the abundance of P. roswellensis in Bitter Creek was 64-512 snails/m2 compared to higher densities in Sago Springs complex (1125-27,924 snails/m2).

In 1998, Dr. M. E. Gordon (pers. com.) located a relict population of P. roswellensis in a drainage canal along the west shore line of refugeUnit 6, and commented on a collection of hydrobiid snails fromLake St. Francis, BLNWR, possibly referableto P. roswellensis.

Pyrgulopsis roswellensis occurs sympatrically with three macroinvertebrate taxa possessing state and federal status (Taable 1 ), the federal endangered Pecos gambusia, and the proposed endangered Pecos pupfish, that inhabit surfacewaters of Bitter Creek and Sago Springs complex of the BLNWR. Potential adverse impacts of oil and gas activities along the Pecos River (USFWS 1997b) underscore the imminence of threats (see Appendix B, attached) to the long term viability of P. roswellensis populations at the BLNWR.

Management and Conservation Options:

(1) Recommend biannual (March, October) monitoring of P. roswellensis populations at permanent localities in Bitter Creek (Dragonfly Spring, Lost River confluence, flume, downstream of flume), Sago Springs complex (springhead pools, spring brook), and

A8 North Spring, RCC. Access to North Spring will require permission from the RCC; such requests were denied previously.

(2) Financial support under Section 6 will facilitate the Project Biologist's efforts to process monthly voucher collections, compile a database, analyze data, and synthesize reports.

(3) Through formal Section 7 Consultation on Threatened and Endangered species of the Bureau of Land Management's Roswell Resource Area Draft Resource Management Plan/Environmental Impact Statement (Roswell DRMP/EIS) (BLM 1994), the U.S. Fish and Wildlife Service (1997b) rendered jeopardy opinion that potential oil and gas activities along the Pecos River may adversely impact the Pecos bluntnose shiner and Pecos gambusia.

Since all macroinvertebrate species of BLNWR that possess state and federalstatus are sympatric with the federal endangered Pecos gambusia in Bitter Creek and Sago Springs, adherence with Section 7 Consultation Reasonable and Prudent AlternativeNo. 1 (RPA l) forthe Pecos Gambusia (USFWS 1997b) is recommended. The RPA-1 states:

"Use the best available hydrologic information to map the source and movement of water that supplies springs occupied by Pecos Gambusia on the Bitter Lake National WildlifeRefuge and Salt Creek Wilderness. Close the lands within the mapped area to oil and gas leasing unless or until the BLM can demonstrate that mandatory protective measures will ensure no aquifer contamination."

This abeyance forexploratory oil and gas well permits on lands referred to in RPA-1 is equally justifiedfor P. roswellensis since these two species occur sympatrically, although P. roswellensis is even more narrowly distributed than Pecos gambusia.

(4) In the event that oil and gas activities proceed without demonstrating that mandatory protective measures will ensure no aquifercontamination within the area referenced by RPA-1, then there would be a threatened curtailment and possible destruction of the limited habitat of P. roswellensis, thus demonstrating that regulatory mechanisms are inadequate. The species would be in danger of extinction throughout all of its range.

(5) Management practices at the BLNWR might include rehabilitation of vestigial habitat along the westernditch of Unit 6, and in other impoundments or ditches, providing that such practices do not adversely impact habitats, populations, or management plans of other taxa on the refuge.

Pyrgulopsisthermalis

Status:

A9 Mehlhop (1993) last reported on status of hydrobiid spring snails ofthe Gila River Basin, and documented the persistence of P. thermalis at historic site occurrences (see Taylor 1987) on the East Fork Gila River, and on the main stem ofthe Gila River (type locality), Grant County. Known P. thermalis populations are widely dispersed. The East Fork populations occur on lands under joint stewardship (private-CT. S. Forest Service), and the mainstem population occurs in the Gila Wilderness. The genetic affinitiesof such geographically isolated populations ofare poorly understood, seldom studied, and must be adequately explored before proper management prescriptions can be developed (Weins 1996). See species account in Appendix B (attached) for additional information.

In August 1998, approximately 20 miles ofriparian corridor along the West Fork Gila River were surveyed forsuitable spring habitats that might support populations ofP. thermalis. No hydrobiid snail populations were located, as only pulmonate physid snails were collected from spring-fedbackwater habitats ofthe West Fork Gila River. This sub-basin lacks the abundance ofartesian springheads characteristic ofthe East Fork and Middle Fork sub-basins, and the Gila River mainstem. A single thermal spring on the Middle Fork Gila River, located approximately 0.7 river mile upstream ofthe Gila Visitor Center, was not conducive to successful colonization by any mollusk taxa, as the water temperature exceeded 55°C, and the thermal pools were in the riverine floodway.

Management and Conservation Options:

(1) Continue population surveys under ongoing project Segment 8 to document biology, land-use practices, and status ofall known populations ofP. thermalis in the Gila River Basin. Expand area ofsurvey to malacologically unexplored reaches within the basin.

(2) Recommend allocation of Section 6 funding to assess genetic divergence ofP. thermalis within and among geographically isolated populations throughout the Gila River Basin. Genetic divergence between disjunct population may warrant taxonomic reevaluation of the species, which may in turn confer specific management recommendations particular to genetically distinct populations relative to current ownership and land-use practices.

Tryoniakosteri Status:

Taylor (1987) firstdescribed Tryonia kosteri from Sago Spring, Bitter Lake National Wildlife Refuge(BLNWR), and reported additional populations in Bitter Creek (Lost River) and along the westernperimeter of refuge units 3 and 6. Mehlhop (1992, 1993) documented the persistence of BLNWR populations, and spot-checked the species' status at the Roswell County Club (RCC), Chaves County. Under project segments 4-6, macroinvertebrate populations at the BLNWR were censussed monthly from June 1995to June 1998. During Year I monitoring (June 1995- May 1996), the abundance of T. kosteri in Bitter Creek was 704-89,472 snails/m2 compared to

AlO lower densities in Sago Springs complex (75-512 snails/m2).

Persistence of relict T. kosteripopulations along refuge impoundments 3 and 6 were verified by Dr. M. E. Gordon ( pers. com.), who also extended the range ofthis species south to the northwestern border of Hunter Marsh. These relict populations seem to occupy vestigial habitats where freshwater springs and seeps discharge less saline, more thermally stable waters compared to impounded waters (B. K. Lang,pers. obs.).

Although Taylor (1987) and Cole (1988) reported extirpation of this species from North Spring, a population may still persist there (Mehlhop 1993). Tryonia kosteri in Bitter Creek and Sago Springs complex are stable under present management practices at the BLNWR.

Tryonia kosteri occurs sympatrically with three macroinvertebrate taxa possessing state and federal status, the federal endangered Pecos gambusia, and the proposed endangered Pecos pupfish, that inhabit surface waters of Bitter Creek and Sago Springs complex ofthe BLNWR. Potential adverse impacts ofoil and gas activities along the Pecos River (USFWS 1997b) underscore the imminence ofthreats (see Appendix B, attached) to the long-term viability of T. kosteri populations at the BLNWR.

Management and Conservation Options:

(1) Recommend biannual monitoring (March and October) of T. kosteri populations at permanent localities in Bitter Creek (Dragonfly Spring, Lost River confluence, flume, downstream of flume), Sago Springs complex (springhead pools, spring brook), including North Spring, RCC. Field activities at the RCC will require permission from the private land steward; such requests were denied previously.

(2) Continued Section 6 funding will facilitatethe Project Biologist's efforts to process unsorted voucher material collected during monthly censuses, compile macro- and microhabitat data, analyze ecological data, and synthesize reports.

(3) Through formal Section7 Consultation �n threatened and endangered species of the Bureau ofLand Management's Roswell Resource Area DraftResource Management Plan/Environmental Impact Statement (Roswell DRMP/EIS) (BLM 1994), the U.S. Fish and Wildlife Service (1997b) rendered jeopardy opinion that potential oil and gas activities along the Pecos River may adversely impact the Pecos bluntnose shiner and Pecos gambusia.

Since all macro invertebrate species of BLNWR that possess state and federal status are sympatric with the federal endangeredPecos gambusia in Bitter Creek and Sago Springs complex, adherence with Section 7 Consultation Reasonable and Prudent Alternative No. 1 (RPA-1) forPecos Gambusia (USFWS 1997b) is recommended. The RPA-1 states:

Al l "Use the best available hydrologic information to map the source and movement of water that supplies springs occupied by Pecos Gambusia on the Bitter Lake National Wildlife Refugeand Salt Creek Wilderness. Close the lands within the mapped area to oil and gas leasing unless or until the BLM can demonstrate that mandatory protective measures will ensure no aquifer contamination."

This abeyance forexploratory oil and gas well permits on lands referred to in RP A-1 is equally justifiedfor T. kosteri since these two species occur sympatrically, although T. kosteri is even more narrowly distributed than Pecos gambusia.

(4) In the event that oil and gas activities proceed without demonstrating that mandatory protective measures will ensure no aquifer contamination within the area referenced by RP A-1, then there would be a threatened curtailment and possible destruction of the limited habitat of T. kosteri, thus demonstrating that regulatory mechanisms are inadequate. The species would be in danger of extinction throughout all of its range.

(5) Management practices at the BLNWR might include rehabilitation of vestigial habitat of T. kosterialong the western shore line of refuge impoundments, providing that such practices do not adversely impact habitats, populations, or management of other taxa on the refuge.

Pisidium sanguinichristi

Status:

Taylor (1987) described P. sanguinichristi as a narrowly restricted peaclam endemic to Middle Fork Lake, Questa Ranger District, Carson National Forest (CNF). In 1995, the NMDGF commenced annual population monitoring of P. sanguinichristi in response to a multi-agency conservation effortinitiated by the U.S. Forest Service (1996). Pisidium sanguinichristi has not been collected in New Mexico since Taylor's species description. See draftspecies account in Appendix B ( attached) foran overview of status surveys from 1995 topresent.

Management and Conservation Options:

(1) Continue sphaeriid inventory in high elevation wetland habitats throughout the Sangre de Cristo Mountains. Expand this effortinto the Jemez Mountains under futureproject segments.

(2) Conduct conchological morphometric study of P. sanguinichristi and P. milium, if such an investigation merits the effort. While shell meristics may help resolve outstanding taxonomic questions (NMGF 1996b), significantecophenotypic variation in shell morphology and hinge dentition of sphaeriid clams manifestedby local environmental

A12 influences could render such an effort futile (Herrington 1962).

(3) No change in status appears warranted at this time.

Al3 Literature Cited

Bureau of Land Management. 1994. Draft resource management plan/environmental impact statement for the Roswell Resource Area, Roswell, New Mexico, and draft resource management plan amendment/environmental impact statement for the Carlsbad Resource Area, Carlsbad, New Mexico. Bureau of Land Management, Roswell, NM.

Cole, G. A. 1981. Gammarus desperatus, a new species from New Mexico (Crustacea: Amphipoda). Hydrobiologia 76:27-32.

Cole, G. A. 1985. Analysis of the Gammarus-pecos complex (Crustacea: Arnphipoda)in Texas and New Mexico, USA. Journal of the Arizona-Nevada Academy of Science 20:93-103.

Cole, G. A. 1988. A report on the status of Amphipoda, including Gammarus desperatus in New Mexico. Submitted to the New Mexico Department of Game and Fish Endangered Species Program under Professional Service Contract 519-77-02. 15 pp.

Herrington, H.B. 1962. A revision of the .Sphaeriidaeof North America (Mollusca: Pelecypoda). University of Michigan Museum of Zoology. Miscellaneous Publications No. 18.

Land ye, J. J. 1981. Current status of endangered, threatened, and/or rare mollusks of New Mexico and Arizona. Endangered Species Office, U.S. Fish and WildlifeService, Final Report 13.

Martinez, J. D., K. S. Johnson, and J. T. Neal. 1998. Sinkholes in evaporite rocks. American Scientist 86:38-51.

Mehlhop, P. 1992. Establishment of a rare mollusc inventory and monitoring program for New Mexico. Progress Report. NMGF ProfessionalServices Contract 80-519-52.

Mehlhop, P. 1993. Establishment of a rare mollusc inventory and monitoring program for New Mexico. Year II Progress Report. NMGF Professional Services Contract No. 80-519-52-Amendment 1.

New Mexico Department of Game and Fish. 1996a. Threatened and endangered species of New Mexico: Biennial Review and Recommendations. 122 pp.

New Mexico Department of Game and Fish. 1996b. Status of aquatic and terrestrial mollusks of New Mexico. Final Report submitted to the USFWS.

A14 New Mexico Department of Game and Fish. 1988. Handbook of species endangered in New Mexico. Account: A-299.

New Mexico Statutes Annotated. 1995. Interstate Stream Commission Water Conservation Program: Pecos River Portion. NMSA Supplement 72-5-28.

Richard, M. 1988a. Natural gas contamination at Rattlesnake Springs, Carlsbad Caverns National Park: review of the geohydrology in the vicinity of Rattlesnake Springs and the contamination problem. Report 1. National Park Service Contract RFQ 7029-8-0025.

Richard, M. 1988b. Natural gas contamination at Rattlesnake Springs, Carlsbad Caverns National Park: report of the firstfield investigation, August 1988. Report 2. National Park Service Contract RFQ 7029-8-0025.

Richard, M. and A. Boehm. 1989a. Natural gas contamination at Rattlesnake Springs, Carlsbad CavernsNational Park: report of the second fieldinvestigation, March, 1988. Report 3. National Park Service Contract RFQ 7029-8-0025.

Richard, M. and A. Boehm. 1989b. Natural gas contamination at Rattlesnake Springs, Carlsbad CavernsNational Park: final summary of the investigation. Report 4. National Park Service Contract RFQ 7029-8-0025.

Taylor, D. W. 1983. Endangered Species: Status investigation of mollusks of New Mexico. ProfessionalService Contract Nos. 519-69-01 and 519-69-01-A.

Taylor, D. W. 1987. Fresh-water mollusks fromNew Mexico and vicinity. New Mexico Bureau of Mines & Mineral Resources Bulletin 116.

United States Fish and WildlifeService. 1996. Endangered and threatened wildlife and plants; Review of plant and animal taxa that are candidates for listing as endangered or threatened species. Federal Register 61(40):7596-7613.

United States Fish and WildlifeService. 1997a. Announcement of draftpolicy for candidate conservation agreements. Federal Register 62(113):32183-32188.

United States Fish and WildlifeService. 1997b. Biological opinion on the Roswell Resource Area Resource Management Plans. Section 7 Consultation #2-22-96-102.

United States Forest Service. 1996. Habitat conservation assessment forSangre de Cristo peaclam (Pisidium sanguinichristi).

Al5 Weins, J. A. 1996. Wildlifein patchy environments: metapopulations, mosaics, and management. Pp 53-84, In Metapopulations andWildlife Conservation (Ed. D.R. McCollough). Island Press.

White, W.W., DC. Culver, J. S. Herman, T. C. Kane, and J.E. Mylroie. 1995. Karst Lands. American Scientist 83 :450-459.

Al6 Appendix B. Drafts pecies accounts for state-listed and federal Candidate and Species of Concern macroinvertebrates of New Mexico, E-20-7. Noel's amphipod, Gammarus desperatus Cole, 1981

Listing Status: New Mexico - Endangered (19 NMAC 33.1), listed 9 January 1988 (NMGF Reg. 657); Federal - Species of Concern (USFWS 1996).

Characteristics: The amphipod, Gammarus desperatus, is a member ofthe superorder Peracarida, a large crustacean group characterized by the absence ofa carapace (the "shell" of lobsters, crayfish, and shrimp) and the presence of 7 pairs ofpereopods (legs) (Pennak 1989; Covich and Thorp 1991). Commonly termed scuds, side swimmers, or freshwater shrimp, amphipods are distinguished fromother crustaceans by a laterally flattened body consisting ofa cephalothorax with 2 pair of antennae, 7 freethoracic segments each with a pair of pereopods, a six-segmented abdomen, and a small terminal telson (Pennak 1989, Covich and Thorp 1991). Two families, the Gammaridae and the Hyalellidae, occur in New Mexico (Cole 1981). Gammarus species are distinguished from hyalellid amphipods by the presence of elongate eyes, a 3-7 segmented accessory flagellum (whip-like structure) ofthe first antennae that is longer than the second antennae, a biramous well-developed third uropod (abdominal leg), and a bilobed telson cleft to its base (Holsinger 1976). Elongate reniform (kidney-shaped) eyes, non-calceolate antennae, setiferous (spiny) pereopods, and long C-setae on mandibular palps separate G. desperatus from G. lacustris, the only other known gammarid in New Mexico (Cole 1981). The brown-green body of G. desperatus is flanked with red bands along the thoracic and abdominal segments and oftenpossesses a dorsal red stripe. Males are larger (range = 9.5-14.80 l mm) than females (range = 8.5-12.6 / mm) (Cole 1981, 1985).

Distribution: Of the more than 6000 described species ofAmphipoda in the world, about 1500 are freshwater species. In North America, there are approximately 40 named epigean (inhabiting surfacewaters) species and roughly 100 hypogean (subterranean) species (Pennak 1989, Covich and Thorp 1991).

Cole (1981) described G. desperatus from a 1967 collection ofamphipods fromNorth Spring, Roswell Country Club (RCC), Roswell, Chaves County, New Mexico. Based on morphological similarities, G. A. Cole synonymized Gammarus amphipods ofNorth Spring with an extinct gammarid amphipod of Lander Springbrook that Noel (1954) errantly termed G. fasciatus (Cole 1981). Gammarus desperatus is 1 of3 described species ofthe Gammarus-pecos complex (4 Gammarus sp. remain undescribed) that occur as narrowly restricted, endemic amphipods of the Pecos River Basin near Roswell, New Mexico, south to Fort Stockton, Pecos County, Texas. Amphipods ofthis species complex occur as geographic isolates in freshto moderately-saline waters in areas of eroding marine sediments once overlain by Permian seas. Gammarus desperatus is endemic to Chaves County, New Mexico (Cole 1981, 1985).

Based on similarity ofstructural features, gammarid amphipods from Bitter Creek ("Lost River"), Bitter Lake National WildlifeRefuge (BLNWR), Roswell, New Mexico, are considered conspecific with G. desperatus ofNorth Spring (NMGF 1988, NMGF files). Additional populations of G. desperatus occur in Sago Springs complex and along refuge Unit 7, BLNWR.

Bl Biology: As a group, gammarid amphipods most commonly inhabit shallow, cool, well oxygenated waters of small streams, ponds, ditches, sloughs and springs (Holsinger 1976, Pennak 1989). Being extremely sensitive to light, benthic-dwelling amphipods are most active at night feeding on algae, submergent vegetation, and detritus of the substrata (Holsinger 1976, Pennak 1989, Cole 1988). Juveniles are dependent on microbial foods,such as algae and bacteria, associated with periphyton or aquatic plants (Covich and Thorp 1991). Pennak (1989) reported cannibalism in certain amphipod genera at high population densities.

Like most Peracarida crustaceans, amphipods formbreeding pairs that remain attached for1- 7 days, or until the femaleundergoes a "breeding molt" (Pennak 1989). The Gammaridae have a benthic mating system, whereby breeding pairs remain in copula while continuing routine activities ( e.g., feeding, swimming) near the substrata (Bousfield1989). Adult femalescan reproduce at every stage of molting and may produce multiple broods (iteroparous) during an extended breeding season. Fertilized eggs and developing young are carried in a ventral brood pouch (marsupium) until they are released as fullydeveloped, free-swimmingsub-adults (ovoviviparous). Brood size varies between genera, but ranges fromfew to about 20. Growth is indeterminate and longevity of epigean amphipods typically is limited to 1 year (Holsinger 1976, Pennak 1989, Covich and Thorp 1991).

Lifehistory of G. desperatus is unknown. Noel (1954) reported that G. desperatus was the most abundant macroinvertebrate of Lander Springbrook, with mean densities ranging 2,228- 10,416/m2. During monthly censussing (June 1995- May 1996) at the BLNWR, G. desperatus was most abundant in Bitter Creek (64-8768 amphipods/m2). Benthic estimates from Sago Springs (26-575 amphipods/m 2) are considerably lower than populations observed clinging to submergent macrophyte beds and under indurate gypsum substrata. Physicochemical water conditions at the BLNWR are similar to those recorded at North Spring (Cole 1981) and Lander Springbrook (Noel 1954).

Status: The specific epithet, desperatus, refers to what Cole considered an imperiled situation for the species: reduction of the Gammarus-pecos complex throughextinction of localized populations fromregional groundwater depletion (Cole 1985). The Lander Springbrook population was extirpated between 1951-1960, whereas the North Spring (RCC) population was lost sometime during the period 1978-1988. These extirpations are attributed to regional groundwater depletion and habitat alterations (spring channelization), respectively (Cole 1981, 1988). Consequently, the species was uplisted from state threatened to endangered (NMGF 1990). Gammarid crustaceans have not been documented in recent benthic samples taken from North Spring (Mehlhop 1992, 1993).

While G. desperatus populations of the BLNWR are stable under present refugemanagement practices, habitat loss and alteration ( e.g., artesian spring source diversion, dewatering, capping), groundwater depletion, and ground- and surface-water contaminantsare considered principal causes of decline in amphipods (Cole 1981, 1985; Pennak 1989; Covich and Thorpe 1991). Regional groundwater pumping and oil/gas industry operations ( exploration, transfer, storage,

B2 and refining)are ongoing in the Pecos River Valley (BLM 1994). Such extractive processes and industry operations are known to deplete groundwater aquifersand to contaminate ground- and surface-waters (Hennighausen 1969; Jercinovic 1982, 1984; Longmier 1983; Quarles 1983; Boyer 1986; Richard 1988a, 1988b; Rail 1989; Richard and Boehm 1989a, 1989b; Jones and Balleau 1996; Martinez et al. 1998); which can adversely impact amphipod crustaceans (Eisler 1987, Havlik and Marking 1987, Green and Trett 1989), and threaten extant G. desperatus populations at the BLNWR (USFWS 1997). Increase risk of potential water quality degradation due to domestic sewage contamination (i.e., septic discharge) is posed by encroachment of residential development within aquifer recharge-discharge areas along the western bounds of BLNWR (Bitner and Graves 1992, McQuillan et al. 1989, White et al. 1995). Natural stochastic events, such as prolonged drought, could adversely impact extant populations by reducing discharge through refugesurface waters while concomitantly increasing salinity and concentrating contaminants.

Conservation: Gammarid amphipods are acutely sensitive to water pollution and contamination (Covich and Thorp 1991). Long-term population viability at the BLNWR will be contingent upon protection of surfaceand ground-water quality and quantity. The NMGF, in compliance with Section 17-2-40.1.A-G of the amended WildlifeConservation Act (1995), initiated a conservation plan for4 state-listed invertebrate species ofChaves County, including G. desperatus (NMGF files). Federal water-rights for the BLNWR were secured in 1996 (USDJ 1996).

Literature Cited

Bitner, M. J. And T. Graves. 1992. Effectoflot sizes on potential ground-water contaminants fromconventional septic-tank systems: numerical modeling. Policy Coordinating Committee. 4 7 pp.

Bousfield,E. L. 1989. Revised Morphological relationships with the Amphipoda genera Pontoporeia and Gammaracanthus and the "glacial relict" significanceof their postglacial distributions. Canadian Journal of Fisheries and Aquatic Sciences 46: 1714- 1725.

Boyer, D. G. 1986. Differencesin produced water contaminants from oil and gas operations in New Mexico - implications forregulatory action. Pp. 291-316, In Proceedings of the Conferenceon Southwestern Ground Water Issues (National Water Well Association, Publisher).

Bureau of Land Management. 1994. Draftresource management plan/environmental impact statement for the Roswell Resource Area, Roswell, New Mexico, and draftresource management plan amendment/environmental impact statement for the Carlsbad Resource Area, Carlsbad, New Mexico. Bureau ofLand Management, Roswell, NM.

B3 Cole, G. A. 1981. Gammarus desperatus, a new species fromNew Mexico (Crustacea: Amphipoda). Hydrobiologia 76:27-32.

Cole, G. A. 1985. Analysis of the Gammarus-pecos complex (Crustacea: Amphipoda) in Texas and New Mexico, USA. Journal ofthe Arizona-Nevada Academy of Science 20:93-103.

Cole, G.A. 1988. Noel's amphipod (Gammarus desperatus). NMGF ProfessionalService Contract No.519-77-02. 6pp.

Covich, A.P. and J. H.Thorp. 1991. Crustacea: introduction and Peracarida. Pp. 665- 689, In Ecology and Classification of North American Freshwater Invertebrates (J.H. Thorp and A. P. Covich, Eds.).Academic Press, Inc.

Eisler, R. 1987. Polycyclic aromatic hydrocarbon hazards to fish, wildlife, and invertebrates: a syntopic review. U. S.Fish and WildlifeService. Contaminant Hazard Reviews Report No.11, Biological Report 85 (1.11).

Green, J. and M.W. Trett. 1989. The fateand effects of oil in freshwater. Elsevier Science Publishing Co., Inc., New York.

Havlik, M.E. and L. L. Marking. 1987. Effects of contaminants on naiad mollusks (Unionidae ): a review. U.S.Fish and Wildlife Service, Resource Publication 164.

Hennighausen, F. H. 1969. Meters and their effectsin the Roswell Artesian Basin in Chaves and Eddy counties, New Mexico. Pp. 29-33, In 14th Annual New Mexico Water Conference (Water Resources Institute).

Holsinger, J. R. 1976. The freshwateramphipod crustaceans (Gammaridae) of North America. U.S. Environmental Protection Agency. Biota ofFreshwater Ecosystems, Water Pollution Control Research Series 18050 ELD04/72.

Jercinovic, D.E. 1982. Assessment ofrefinedpetroleum-product contamination problems in surfaceand ground waters ofNew Mexico. Water Pollution Control Bureau, New Mexico Environmental Improvement Division, EID/WPC-82/5.

Jercinovic, D. E. 1984. Petroleum-product contamination ofsoil and water in New Mexico. New Mexico Environmental Improvement Division, EID/GWH84/2.

Jones, M. A. and W. P. Balleau. 1996. Interrelation of groundwater and surface water at Bitter Lake National Wildlife Refuge. Balleau Groundwater, Inc. Report to U.S. Department of Justice, 16 pp.

B4 Longmire, P. A. 1983. Petroleum-product contamination of ground and surfacewater: a literature review. Ground Water Section, Water Pollution Control Bureau, New Mexico Environmental Improvement Division. EID/WPC-83/7.

Martinez, J. D., K. S. Johnson, and J. T. Neal. 1998. Sinkholes in evaporite rocks. American Scientist 86:38-51.

McQuillan, D. M., M. J. Jasper and B. H. Swanson. 1989. Ground-water contamination by septic-tank use: a field studyin the Albuquerque south Valley - West Mesa Region, BernalilloCounty, New Mexico. New Mexico Health and Environment Department, Environmental Improvement Division, Ground Water Bureau.

Mehlhop, P. 1992. Establishment of a rare mollusc inventory and monitoring program for New Mexico. Progress Report. NMGF Professional Services Contract 80-519-52.

Mehlhop, P. 1993. Establishment of a rare mollusc inventory and monitoring program for New Mexico. Year II Progress Report. NMGF Professional Services Contract No. 80-519-52-Amendment 1.

New Mexico Department of Game and Fish. 1988. Handbook of species endangered in New Mexico. Account: A-650.

New Mexico Department of Game and Fish. 1990. Amending the listing of endangered species and subspecies of New Mexico. Regulation No. 682,

Noel, M. S. 1954. Animal ecology of a New Mexico springbrook. Hydrobiologia 6:120-135.

Pennak, R. W. 1989. Fresh-water invertebrates of the United States: Protozoa to Mollusca. John Wiley & Sons, Inc.

Quarles, J. 1983. Groundwater contamination in the United States. University of Pennsylvania Press, Philadelphia.

Rail, C. D. 1989. Groundwater contamination: sources, control, and preventative measures. Techonomic Publishing Company, Inc. Lancaster, PA.

Richard, M. 1988b. Natural gas contamination at Rattlesnake Springs, Carlsbad Caverns National Park: report of the first field investigation, August 1988. Report 2. National Park Service Contract RFQ 7029-8-0025.

BS Richard, M. and A. Boehm. 1989a. Natural gas contamination at Rattlesnake Springs, Carlsbad CavernsNational Park: report of the second field investigation, March, 1988. Report 3. National Park Service Contract RFQ 7029-8-0025.

Richard, M. and A. Boehm. 1989b. Natural gas contamination at Rattlesnake Springs, Carlsbad CavernsNational Park: finalsummary of the investigation. Report 4. National Park Service Contract RFQ 7029-8-0025.

United States Department of Justice. 1996. United States of America's statement of claim for reserved surfacewater and groundwater rights forBitter Lake National WildlifeRefuge. Roswell Basin Section, RAB 923 and 1793, Denver.

United States Fish and WildlifeService. 1996. Endangered and threatened wildlifeand plants; Review of plant and animal taxa that are candidates forlisting as endangered or threatened species. Federal Register 61(40):7596-7613.

United States Fish and WildlifeService. 1997. Biological opinion on the Roswell Resource Area Resource Management Plans. Section 7 Consultation #2-22-96-102.

White, B. W., D. C. Culver, J. S. Herman, T. C. Kane, and J.E. Mylroie. 1995. Karst lands: the dissolution of carbonate rock produces unique landscapes and poses significant hydrological and environmental concerns. American Scientist 83 :450-459.

Wildlife Conservation Act. 1995. Sections 17-2-37 through 17-2-46 NMSA 1978.

B6 Pecos assiminea, Assiminea pecos Taylor, 1987

Listing Status: New Mexico - Endangered (19 NMAC 33.1), listed 22 July 1983 (NMGF Reg. 624); Federal - Candidate (USFWS 1996).

Characteristics: Assiminea pecos (Mollusca: Gastropoda) is a member of the marine snail familyAssimineidae, which like one other freshwater snail familyin New Mexico (Hydrobiidae) possess internal gills forrespiration and an operculum (lid-like structure) covering the shell aperture ( opening) (Pennak 1989). The genus Assiminea is distinguished fromhydrobioid snails by an almost complete lack of tenticles, leaving the eyes within the tips of short ocular peduncles. The thin, chestnut-brown shell of A. pecos is minute (1.55-1.87 l mm), regularly conical with up to 4½ strongly incised (shouldered) whorls, broad ovate aperture, thin parietal lip appressed to the last whorl that passes smoothly into the thick columellar lip, which encroaches slightly on the deeply-invaginated umbilicus. The protoconch (firstshell whorl) is smooth, glossy and abruptly shouldered from the rest of the shell which possesses fineaxial threads. The pale amber operculum is corneous, paucispiral, and slightly concave (Taylor 1987).

Distribution: Assiminea includes 50-60 species typically foundin coastal brackish waters or upper intertidal zones along coastal shore lines in tropical and temperate latitudes worldwide. Inland species of Assiminea in North America occur in California (Death Valley National Monument), New Mexico, Texas (Diamond Y Draw, Pecos County), Utah, and Mexico (Bols6n de Cuatro Cienegas). Assiminea pecos of New Mexico represents the most inland population than any other known occurrence of the genus in the world. Historically, this species occurred in 3 isolated localities within the Pecos River Valley of New Mexico and Texas, and was known sporadically throughout the Bols6n de Cuatro Cienegas, Coahuila, Mexico (see Taylor 1983, 1985, 1987). In New Mexico, D. W. Taylor reported 3 Chaves County populations: 2 fromBitter Lake National Wildlife Refuge (BLNWR), including the species' type locality, and a third extinct population from North Spring, Roswell Country Club (RCC). Taylor (1985) reported on a large population fromDiamond Y Spring, Pecos County, Texas.

Biology: The biology of A. pecos is unknown. The species typically occurs on moist earth or underneath emergent plants within a few centimeters of flowing water, and never in submerged habitats (Taylor 1987). While the genus Assiminea essentially occupies terrestrial habitats, live specimens were taken recently fromwater depths ranging 5-21 cm (NMGF 1996). Food items likely consist of bacteria, detritus, fungi, and algae. Respiration probably occurs by direct air breathing, as the gill is vestigial and the mantle cavity typically entraps an air bubble (Taylor 1983). Assiminea species are egg-laying (oviparous) gastropods (NMGF 1988).

Status: The A. pecos metapopulation shows a pattern of localized extinctions throughout its historic range. In New Mexico, 2 populations have been extirpated in Chaves County: 1 from the RCC and a second population at the BLNWR (Taylor 1983). Control and removal of hydrophytic vegetation represent primary factorsresponsible forextirpation of localized populations in New Mexico and Mexico (Taylor 1987, NMGF 1988).

B7 Extant populations of A. pecos are known froman approximate 0.5 mile reach of Bitter Creek, BLNWR (NMGF 1996). In Spring 1999, the species was abundant in a emergent marsh plant community forming the perimeter of a sink hole at the terminus of Sago Spring run, where A. pecos occurred on wetted stem surfacesat the base of marsh emergents and on muddy surfaces within 1 cm of water. Presence of A. pecos at this site is noteworthy as the habitat was burnedin spring 1997. Taylor (1987) attributed extirpation A. pecos to annual burning of marsh emergents in the Bols6n de Cuatro Ciengas, Mexico. It appears that the species is tolerant of fire, and that intensity, duration, and frequencyare principal factors to consider when prescribing fire management to control seral succession of habitats where A. pecos occurs. Populations of A. pecos at the BLNWR are stable under present firemanagement practices.

Regional groundwater pumping and oil/gas industry operations (exploration, transfer, storage, and refining) are ongoing in the Pecos River Valley (BLM 1994). Such extractive processes and industry operations are known to deplete groundwater aquifers and to contaminate ground- and surface-waters (Hennighausen 1969; Jercinovic 1982, 1984; Longmire 1983; Quarles 1983; Boyer 1986; Richard 1988a, 1988b; Rail 1989; Richard and Boehm 1989a, 1989b; Jones and Balleau 1996; Martinez et al. 1998); which can adversely impact aquatic mollusks (Eisler 1987, Havlik and Marking 1987, Green and Trett 1989), and threaten extant A. pecos populations at the BLNWR (USFWS 1997). Increase risk of potential water quality degradation due to domestic sewage contamination (i.e., septic discharge) is posed by encroachment of residential development within aquiferrecharge-discharge areas along the western bounds of BLNWR (Bitner and Graves 1992, McQuillan et al. 1989, White et al. 1995). Natural stochastic events, such as prolonged drought, could adversely impact extant populations by reducing discharge throughrefuge surface waters while concomitantly increasing salinity and concentrating contaminants.

Conservation: Acquisition of federal water rights forthe BLNWR in 1996 effectivelyensures minimum surface water discharge of Bitter Creek (USDJ 1996). While A. pecos populations of the RCC have not been documented during recent springsnail surveys (Mehlhop .1992, 1993), search efforthas not considered deeper habitats that appear temporarily suitable forthis species at the BLNWR. The NMGF initiated procedures fora conservation management plan for a suite of 4 state-listed Chaves County invertebrates, including A. pecos, under section 17-2-40.1 of the amended Wildlife Conservation Act (1995).

Literature Cited

Bureau of Land Management. 1994. Draft resource management plan/environmental impact statement forthe Roswell Resource Area, Roswell, New Mexico, and draftresource management plan amendment/environmental impact statement forthe Carlsbad Resource Area, Carlsbad, New Mexico. Bureau of Land Management, Roswell, NM.

Bitner, M. J. And T. Graves. 1992. Effectof lot sizes on potential ground-water contaminants fromconventional septic-tank systems: numerical modeling. Policy

B8 Coordinating Committee. 4 7 pp.

Boyer, D. G. 1986. Differences in produced water contaminants fromoil and gas operations in New Mexico - implications forregulatory action. Pp. 291-316, In Proceedings ofthe Conference onSouthwestern Ground Water Issues (National Water Well Association, Publisher).

Eisler, R. 1987. Polycyclic aromatic hydrocarbon hazards to fish, wildlife, and invertebrates: a syntopic review. U.S. Fish and WildlifeService. Contaminant Hazard Reviews Report No. 11, Biological Report 85 (1.11 ).

Green, J. and M. W. Trett. 1989. The fateand effectsof oil in freshwater. ElsevierScience Publishing Co., Inc., New York.

Havlik, M. E. and L. L. Marking. 1987. Effects ofcontaminants on naiad mollusks (Unionidae): a review. U.S. Fish and WildlifeService, Resource Publication 164.

Jercinovic, D. E. 1982. Assessment ofrefinedpetroleum-product contamination problems in surfaceand ground waters ofNew Mexico. Water Pollution Control Bureau, New Mexico Environmental Improvement Division, EID/WPC-82/5.

Jercinovic, D. E. 1984. Petroleum-product contamination of soil and water in New Mexico. New Mexico Environmental Improvement Division, EID/GWH84/2.

Jones, M.A. and W. P. Balleau. 1996. Interrelation ofgroundwater and surface.waterat Bitter Lake National WildlifeRefuge. Balleau Groundwater, Inc. Report to U.S. Department of Justice, 16 pp.

Longmire, P.A. 1983. Petroleum-product contamination ofground and surfacewater: a literature review. Ground Water Section, Water Pollution Control Bureau, New Mexico Environmental Improvement Division. EID/WPC-83/7.

Martinez, J. D., K. S. Johnson, and J. T. Neal. 1998. Sinkholes in evaporite rocks. American Scientist 86:38-51.

McQuillan, D. M., M. J. Jasper and B. H. Swanson. 1989. Ground-water contamination by septic-tank use: a fieldstudy in the Albuquerque south Valley - West Mesa Region, BernalilloCounty, New Mexico. New Mexico Health and Environment Department, Environmental Improvement Division, Ground Water Bureau.

B9 Mehlhop, P. 1992. Establishment of a rare mollusc inventory and monitoring program for New Mexico. Progress Report. NMGF ProfessionalServices Contract 80-519-52.

Mehlhop, P. 1993. Establishment of a rare mollusc inventory and monitoring program for New Mexico. Year II Progress Report. NMGF ProfessionalServices Contract No. 80-519-52-Amendment 1.

New Mexico Department of Game and Fish. 1988. Handbook of species endangered in New Mexico. Account: A-295.

New Mexico Department of Game and Fish. 1996. Status of aquatic and terrestrial mollusks of New Mexico, E-20(1-4). Final Report submitted to the U.S. Fish and WildlifeService.

Pennak, R. W. 1989. Fresh-water invertebrates of the United States: Protozoa to Mollusca. John Wiley & Sons, Inc.

Quarles, J. 1983. Groundwater contamination in the United States. University of Pennsylvania Press, Philadelphia.

Rail, C. D. 1989. Groundwater contamination: sources, control, and preventative measures. Techonomic Publishing Company, Inc. Lancaster, PA.

Richard, M. 1988b. Natural gas contamination at Rattlesnake Springs, Carlsbad Caverns National Park: report of the firstfield i nvestigation, August 1988. Report 2. National Park Service Contract RFQ 7029-8-0025.

Richard, M. and A. Boehm. 1989a. Natural gas contamination at Rattlesnake Springs, Carlsbad Caverns National Park: report of the second fieldinvestigation, March, 1988. Report 3. National Park Service Contract RFQ 7029-8-0025.

Richard, M. and A. Boehm. 1989b. Natural gas contamination at Rattlesnake Springs, Carlsbad Caverns NationalPark: finalsummary of the investigation. Report 4. National Park Service Contract RFQ 7029-8-0025.

Taylor, D. W. 1983. Endangered species: status investigation of mollusks of New Mexico. ProfessionalService Contract Nos. 519-69-01 and 519-69-01-A.

Taylor, D. W. 1985. Status survey of aquatic mol1uscs in Diamond Y Draw, Pecos County, Texas. Unpublished Report to Bitter Lake National WildlifeRefuge, 24 pp.

Bl0 Taylor, D. W. 1987. Fresh-water mollusks fromNew Mexico and vicinity. New Mexico Bureau of Mines & Mineral Resources, Bulletin 116.

United States Department of Justice. 1996. Annotated abstract of water-rights administration Bitter Lake National Wildlife Refuge. Balleau Groundwater, Inc., Albuquerque, NM.

United States Fish and WildlifeService. 1996. Endangered and threatened wildlife and plants; Review of plant and animal taxa that are candidates forlisting as endangered or threatened species. Federal Register 61(40):7596-7613.

United States Fish and WildlifeService. 1997. Biological opinion on the Roswell Resource Area Resource Management Plans. Section 7 Consultation #2-22-96-102.

WildlifeConservation Act. 1995. Sections 17-2-37 through 17-2-46 NMSA 1978.

Bl 1 Chupadera pyrg, Pyrgulopsis chupaderae Taylor, 1987

Listing Status: New Mexico - Endangered (19 NMAC 33.1), listed 22 July 1983 (NMGF Reg. 624); Federal - Candidate (USFWS 1996).

Description: Pyrgulopsis chupaderae (Mollusca: Gastropoda) is a prosobranch snail ofthe freshwaterfamily Hydrobiidae, which differfrom all but 1 aquatic snail family (Assimineidae) in New Mexico by the presence ofinternal gills forrespiration and an operculum (lid-like structure) covering the aperture (shell opening). Hydrobiid snails are distinguished from Assiminea pecos by the presence ofeyes on long antennae and a globose to narrowly conical shell. The Hydrobiidae comprise a major faunalelement ofNorth American freshwaters, numbering approximately 28 genera and 148 species (Burch and Tottenham 1980). In such a large family, species recognition has been problematic since intra- and inter-generic affinitiesof taxa have been uncertain owing to significant overlap and variation in shell characteristics. Most genera are distinguished by anatomical features, namely penial morphology and structure (Taylor 1987, Pennak 1989). Hershler and Thompson (1987) revised the Hydrobiidae in southwestern North America, and allocated the genus Fontelicella Gregg and Taylor, 1965 to Pyrgulopsis Call and Pilsbry, 1886.

The tan to brown shells ofP. chupaderae are elongately ovoid with a short convex spire, whorls are convex to slightly shouldered with a weak suture, peristome usually adnate Goined) or sometimes free. The operculum is dark reddish-brown without a notable spiral trace. Distinctive penial morphology includes a freeportion containing conspicuous melanin granules, but not the dense core as in other Pyrgulopsis species (Taylor 1987).

Biology: The biology ofP. chupaderae is unknown. Most freshwater gastropods are herbivorous or detritivores that consume algae, bacteria, and decaying organic material, or that passively ingest small invertebrates while grazing periphyton. Respiration in hydrobiid snails is strictly aquatic via an internal gill with some oxygen absorption through the mantle (softbody). Hydrobiid snails are sexually dimorphic, femalesare characteristically larger and live longer than males. Most prosobranch snails are annual species that reproduce several times (iteroparous) during the breeding period (spring-fall)with varying degrees ofreplacement of generations. The

B12 femaleslay adhesive egg masses (oviparous) attached to the substrate. Growth is indeterminate for most hydrobiids. While longevity is variable, most prosobranch snails live 9-15 months (Taylor 1987, Pennak 1989, Brown 1991).

Status: Populations of P. chupaderae at Willow Spring have persisted despite intensive land use (e.g., grazing, groundwater pumping, springrun impoundment) over the last several decades (Taylor 1983, NMGF 1988, Mehlhop 1993). In 1996, significant grazing impacts were noted at both springhead habitats, including effortsto maintain pump facilities and improve water delivery systems near the Willow Spring population (NMGF files). Repeated sampling (1995- 1997) at the northernmost spring source yielded no snails. This spring was heavily trampled by cattle, devoid of riparian vegetation, and springrun gravels were covered with soil and manure. Consequently, the species was uplisted fromstate threatened to endangered (NMGF 1996).

In 1999, the Cienega Ranch (ca. 30,000 acres) was sold and renamed "Willow Spring Ranch". Small parcels were placed under land auction in September 1999. The current status of Willow Spring is undetermined, including plans to develop water resources on once contiguous ranch lands.

Regional and local groundwater depletion, springrun dewatering, and riparian habitat degradation represent principal threats to extant P. chupaderae of Willow Spring (NMGF 1988, NMGF 1996). Natural stochastic events, such as prolonged drought, could adversely impact this population by reducing flow through the system, thereby manifestingincreased grazing pressure.

Conservation: Persistence of this species is contingent upon protection of the riparian corridor immediately adjacent to the springrun, and sustenance of perennial, oxygenated flowing water (Taylor 1983, Mehlhop and Vaughn 1994, Mehlhop 1996) within the species' required thermal range. Long-term conservation effortswill likely require maintenance of a refugepopulation at the Albuquerque Biological Park.

B13 Literature Cited

Burch, J. B and J. L. Tottenham. 1980. N01ih American freshwater snails: species, list, ranges and illustrations. Walkerana, Volume 1, Transaction of the POETS Society No.3.

Brown, K. M. 1991. Mollusca: Gastropoda. Pp. 285-314, In Ecology and Classificationof North American Freshwater Invertebrates (J. H. Thorp and A.H. Covich, Eds.). Academic Press, Inc.

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

Mehlhop, P. 1993. Establishment of a rare mollusc inventory and monitoring program for New Mexico. Year II Progress Report. NMGF ProfessionalServices Contract No. 80-519-52-Amendment 1.

Mehlhop, P. 1996. Ecology and conservation needs of hydrobiid snails. The Nature Conservancy, Biodiversity News Network 9(1):6-7.

Mehlhop, P. and C. C. Vaughn. 1994. Threats to and sustainability of ecosystems for freshwater mollusks. Pp. 68-77, In Sustainable Ecological Systems: Implementing an ecological approach to land management. U. S. Forest Service. General Technical Report RM-247.

New Mexico Department of Game and Fish. 1988. Handbook of species endangered in New Mexico. Account: A-302.

New Mexico Department of Game and Fish. 1996. Biennial review of threatened and endangered wildlifeof New Mexico.

Pennak, R. W. 1989. Fresh-water invertebrates of the United States: Protozoa to Mollusca. John Wiley & Sons, Inc.

Taylor, D. W. 1983. Endangered species: status investigation of mollusks of New Mexico. ProfessionalService Contract Nos. 519-69-01 and 519-69-01-A.

Taylor, D. W. 1987. Fresh-water mollusks from New Mexico and vicinity. New Mexico Bureau of Mines & Mineral Resources, Bulletin 116.

United States Fish and Wildlife Service. 1996. Endangered and threatened wildlife and plants; Review of plant and animal taxa that are candidates forlisting as endangered or threatened species. Federal Register 61(40):7596-7613.

B14 Wu, S-K., R. D. Oesch and M. E. Gordon. 1997. Missouri aquatic snails. Conservation Commission of the State of Missouri. Missouri Department of Conservation, Natural History Series, No. 5

B15 Gila pyrg, Pyrgulopsis gilae Taylor, 1987

Listing Status: New Mexico - Endangered (19 NMAC 33.1), listed 22 July 1983 (NMGF Reg. 624); Federal - Candidate (USFWS 1996).

Description: Pyrgulopsisgilae (Mollusca: Gastropoda) is a prosobranch snail of the freshwater family Hydrobiidae, which differ fromall but 1 aquatic snail family (Assimineidae) in New Mexico by the presence of internal gills for respiration and an operculum (lid-like structure) covering the aperture (shell opening). Hydrobiid snails are distinguished fromAssiminea pecos by the presence of eyes on long antennae and a globose to narrowly conical shell. The Hydrobiidae comprise a major faunal element of North American freshwaters, numbering approximately 28 genera and 148 species (Burch and Tottenham 1980). In such a large family, species recognition has been problematic since intra- and inter-generic affinities of taxa have been uncertain owing to significantoverlap and variation in shell characteristics. Most genera are distinguished by anatomical features, especially penial morphology and structure (Taylor 1987, Pennak 1989). Hershler and Thompson (1987) revised the Hydrobiidae in southwestern North America, and allocated the genus Fontelicella Gregg and Taylor, 1965 to Pyrgulopsis Call and Pilsbry, 1886.

The tan shells of P. neomexicana are elongately ovoid with a convex spire longer (i.e., :?: 4 mm l, 4¾ whorls) than most other Pyrgulopsis species of New Mexico. Whorls are regularly convex to slightly shouldered, separated by a distinct suture, peristome simply adnate Qoined) or free. The operculum is amber, more intensely hued in the callus. The bordered attachment scar lacks spiral trace. Penial morphology, unique to the genus, includes two glands on the free portion. The terminal "T" strip is unequally divided or reduced. Penial glands are present on right distal and left lateral lobules of the long strip (Taylor 1983, 1987).

Distribution: The Hydrobiidae of North America inhabit a great diversity of aquatic systems in the United States from epigean (surface)to hypogean (cave) habitats, small springruns to large rivers, and high energy rifflesto slack water pools (Wu et al. 1997). All 8 described hydrobiids of New Mexico are state endemics that typically occur in small geographically isolated point habitats consisting of eurythermal springs and springbrook wetland systems restricted to the southern half of the state (NMGF 1988). The endemic P. gilae is known from 10 disjunct populations associated with a series of spring-springbrook systems along the East and Middle forks Gila River and the mainstem, Gila Wilderness, Grant County (Landye 1981; Taylor 1983, 1987). Mehlhop (1993) reported 3 new P. gilae populations along Beaver and Taylor creeks and at Fall Spring, Catron County.

Biology: The biology of P. gilae is unknown. Most freshwatergastropods are 'herbivorous or detritivores that consume algae, bacteria, and decaying organic material, or that passively ingest small invertebrates while grazing periphyton. Respiration in hydrobiid snails is strictly aquatic via an internal gill with a small amount of oxygen absorption through the mantle (softbody) surface. Hydrobiid snails are sexually dimorphic, femalesare characteristically larger and live

B16 longer than males. Most prosobranch snails are annual species that reproduce several times (iteroparous) during the breeding period (spring-fall)with varying degrees ofreplacement of generations. Females lay adhesive egg masses (oviparous) attached to substrata. Most prosobranch snails live 9-15 months, and growth is indeterminate (Taylor 1987, Pennak 1989, Brown 1991).

Pyrgulopsis and Tryonia species ofNew Mexico occupy a narrow diversity ofhabitat types associated with freshto slightly saline spring and springbrook systems consisting ofeury- to stenothermic waters, slow to moderate velocities over substrates ranging fromdeep, organic silts to indurate rhyolitic talus or vertical rhyolitic facies (NMGF 1988). At the type locality, P. gilae inhabits cool waters (20°C)that issue from narrow watercress-lined rivulets ofa vertical rhyolitic cliffthat Taylor (1987) termed "hanging springs". A second, sparse P. gilae population exists in warmer waters (32-33 °C) ofa nearby spring, which is the type locality for P. thermalis (Landye 1981; Taylor 1983, 1987). Mehlhop (1993) reported new populations ofP. gilae occupying small (i.e., 10-25 m2), eurythermal (14-27 °C) point-habitats ofhighly degraded quality on private lands (Taylor and Beaver creeks and Fall Spring, Catron County) to relatively undisturbed thermal springs along the Gila River, Gila National Forest.

Status: While P. gilae populations in the Gila Wilderness and Gila National Forest appear stable, and are affordedsome measure ofhabitat protection (NMGF 1988, Mehlhop 1993), site occurrences on private lands are subject to uncontrolled recreational bathing and livestock grazing (Mehlhop 1993); thus rendering long-term, viability of the P. gilae "metapopulation" questionable (McCollough 1996). Natural stochastic events ( drought, forest fire, sedimentation, flooding), wetland habitat degradation by recreational bathing in thermal springs, and poor watershed management practices (e.g., overgrazing, silvicultural practices) represent primary threats to P. gilae populations on federal and private lands (Taylor 1983, 1987; NMGF 1988; Mehlhop 1993). Fire suppression and retardant chemicals have potentially deleterious effects on P. gilae populations (McDonald and Hamilton 1995).

Conservation: Genetic divergence between disjunct population may warrant taxonomic reevaluation ofthe species, which in turn could confer specific management recommendations particular to genetically distinct populations relative to current ownership and land-use practices.

Long-term persistence ofthis species is contingent upon protection of the riparian corridor immediately adjacent to springhead and springrun habitats, thereby ensuring the maintenance of perennial, oxygenated flowing water (Taylor 1983, Mehlhop and Vaughn 1994, Mehlhop 1996) within the species' required thermal range. Multi-interest conservation effortsare encouraged to develop comprehensive habitat conservation plans.

Literature Cited

Burch, J. B and J. L. Tottenham. 1980. North American freshwater snails: species, list, ranges and illustrations. Walkerana, Volume 1, Transaction of the POETS Society No.3.

B17 Brown, K.M. 1991. Mollusca: Gastropoda. Pp. 285-314, In Ecology and Classificationof North American Freshwater Invertebrates (J. H.Thorp and A.H. Covich, Eds.). Academic Press, Inc.

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

Landye, J. J. 1981. Current status of endangered, threatened, and/or rare mollusks of New Mexico and Arizona. Endangered Species Office, U.S. Fish and WildlifeService, Final Report 13.

McCollough, D.R. 1996. Metapopulations and wildlifeconservation. Island Press.429 pp.

McDonald and Hamilton. 1995. Fire retardant and foamsuppressant chemical may be toxic to aquatic invertebrates and algae. NBS Information Bulletin, No. 35.

Mehlhop, P. 1993. Establishment of a rare mollusc inventory and monitoring program for New Mexico. Year II Progress Report. NMGF Professional Services Contract No. 80-519-52-Amendment 1.

Mehlhop, P. 1996. Ecology and conservation needs of hydrobiid snails. The Nature Conservancy, Biodiversity News Network 9(1):6-7.

Mehlhop, P.and C.C. Vaughn. 1994. Threats to and sustainability of ecosystems for freshwatermollusks. Pp. 68-77, In Sustainable Ecological Systems: Implementing an ecological approach to land management. U.S. Forest Service. General Technical Report RM-247.

New Mexico Department of Game and Fish. 1988. Handbook of species endangered in New Mexico. Account: A-298.

Pennak, R. W. 1989. Fresh-water invertebrates of the United States: Protozoa to Mollusca. John Wiley & Sons, Inc.

Taylor, D. W. 1983. Endangered species: status investigation of mollusks of New Mexico. ProfessionalService Contract Nos. 519-69-01 and 519-69-01-A.

Taylor, D. W. 1987. Fresh-water mollusks fromNew Mexico and vicinity. New Mexico Bureau of Mines & Mineral Resources, Bulletin 116.

United States Fish and WildlifeService. 1996. Endangered and threatened wildlife and plants; Review of plant and animal taxa that are candidates for listing as endangered or

B18 threatened species. Federal Register 61(40):7596-7613.

Wu, S-K., R. D. Oesch and M. E. Gordon. 1997. Missouri aquatic snails. Conservation Commission of the State of Missouri. Missouri Department of Conservation, Natural History Series, No. 5.

B19 Pecos pyrg, Pyrgulopsis pecosensis Taylor, 1987

Listing Status: New Mexico - Endangered (19 NMAC 33.1), listed 22 July 1983 (NMGF Reg. 624); Federal - Species ofConcern (USFWS 1996a).

Description: Pyrgulopsis pecosensis (Mollusca: Gastropoda) is a prosobranch snail ofthe freshwater family Hydrobiidae, which differ fromall but 1 aquatic snail family (Assimineidae) in New Mexico by the presence ofinternal gills for respiration and an operculum (lid-like structure) covering the aperture (shell opening). Hydrobiid snails are distinguished fromAssiminea pecos by the presence ofeyes on long antennae and a globose to narrowly conical shell (Taylor 1987, Pennak 1989). The Hydrobiidae comprise a major faunal element ofNorth American freshwaters,numbering approximately 28 genera and 148 species (Burch and Tottenham 1980). In such a large family, species recognition has been problematic since intra- and inter-generic affinitiesof taxa have been uncertain owing to significantoverlap and variation in shell characteristics. Most genera are distinguished by soft anatomy (i.e., penial morphology and structure; Taylor 1987). Hershler and Thompson (1987) revised the Hydrobiidae in southwestern North America, and allocated the genus Fontelicella Gregg and Taylor, 1965 to Pyrgulopsis Call and Pilsbry, 1886.

The tan shells ofP. pecosensis are narrowly elongate with a relatively long conic spire, whorls are separated by a distinct suture, peristome is usually adnate Goined) or sometimes free. The operculum is amber, intensely hued in the callus. Distinctive penial morphology includes a terminal long strip, a long strip on the right side of the dorsal distal surfaceextending onto the freeportion of the penis, a dorsal distal lobule sometimes possessing small glands on or offthe lobule, and oftena small ventral glandular patch (Taylor 1987).

Biology: The biology ofP. pecosensis is unknown. Most freshwatergastropods are herbivorous or detritivores that consume algae, bacteria, and decaying organic material, or that passively ingest small invertebrates while grazing periphyton. Respiration in hydrobiid snails is strictly aquatic via an internalgill with limited oxygen absorption through the mantle (softbody) surface. Unlike many hydrobiid snails in which femalesare characteristically larger and longer-lived than males, sexes ofP. pecosensis do not differ substantially in size (Taylor 1987). Most prosobranch snails are annual species that reproduce several times (iteroparous) during the breeding period (spring-fall)with varying degrees ofreplacement ofgenerations. Females lay adhesive egg

B20 masses (oviparous) attached to substrata. Growth is indeterminate formost hydrobiids. While longevity is variable, prosobranch snails typically live 9-15 months (Pennak 1989, Brown 1991).

In New Mexico, Pyrgulopsis and Tryonia species occupy a diversity of habitat types associated with fresh to slightly saline spring and springbrook systems consisting of eury- to stenothermic waters, slow to moderate velocities over substrates ranging fromdeep, organic silts to indurate rhyolitic talus or vertical limestone facies(Taylor 1983, 1987). In Blue Spring, P. pecosensis occurs in moderate to high-velocity habitats fromthe artesian springhead downstream to the upper reaches of the shallow water marsh(NMGF files). Pyrgulopsis pecosensis of Blue Spring 2 was stable between 1968-1990, with densities estimated at 20,000 snails/m , whereas the Castle Spring population was less dense and fluctuated more drastically(� 20,000 individuals/m2). Population fluctuationsare attributable to differencesin habitat stability--Blue Spring being more stable than Castle Spring(see Landye 1981; Taylor 1983, 1987; NMGF 1988).

Status: Mehlhop(1992) documented the extirpation of P. pecosensis from Castle Spring. While reasons for this extirpation are speculative, it's demise is likely attributed to a combination of natural processes( e.g., arroyo entrenchment; Haynes 1968) exacerbated by human-related land use activities( e.g., springrun dewatering fora municipal water supply [Black River Village], habitat manipulation, upstream water quality degradation from agricultural drainage and dairy run-off)(Landye 1981, NMGF 1988, Mehlhop 1992). Natural stochastic events, such as prolonged drought, could adversely impact the Blue Spring population by reducing flow through the system, thus potentially increasing salinity, concentrating contaminants, and manifesting increased grazing pressure along the riparian corridor.

Temporary acquisition(i.e., state lease) of Blue Spring surfacewater rights (NMSA 1995) and the "lack of oil and gas reserves in the area" prompted reclassification of P. pecosensis froma federal Candidate for listing under the Endangered Species Act to a Species of Concern (USFWS 1996b). Contrary to this reclassification,the Black River Valley has experienced repeated problems of ground-water depletion and contamination. Water levels of domestic and agricultural/range wells in the Black River Valley have lowered and even dried-up (residents of Black River Village and environs,pers. com.). Richard(1988a, 1988b) and Richard and Boehm (1989a, 1989b) documented ground-water contamination of domestic and agricultural/range wells in the upper Black River Valley(i.e., Washington Ranch, Ballard Wells) by petroleum derived hydrocarbons and sulfides. Richard and Boehm (1989b) reported "severe" sulfide contamination of Blue Spring in 1988. These authors indicated that gas contamination originating up-gradient was likely transported about 20 miles down-gradient to Blue Spring. Such long distance transport of groundwater is common in karst, evaporite rock (White 1995, Martinez et al. 1998), and raises concerns forsurface-water quality of the Blue Spring wetland complex and the Black River, especially considering the concentration of petroleum industry operations throughout the Black River watershed.

Oil and gas extractive practices(e.g., exploration, storage, transfer, refining)are ongoing in the Black River sub-basin (BLM 1994), including the immediate watershed of Blue Spring(NMGF

B21 files). These activities are known to deplete groundwater aquifersand contaminate ground- and surface-waters (Hennighausen 1969; Jercinovic 1982, 1984; Longmire 1983; Quarles 1983; Boyer 1986; Rail 1989; Martinez et al 1998); which can adversely impact aquatic mollusks (Eisler 1987, Havlik and Marking 1987, Green and Trett 1989), and threaten the extantP. pecosensis population of Blue Spring.

Conservation: Long-term viability of this species is contingent upon protection of the riparian corridor contiguous to the Blue Spring wetland complex, and persistence of uncontaminated, perennial, oxygenated flowingwater (Taylor 1983, Mehlhop and Vaughn 1994, Mehlhop 1996) within the species' required thermal range.

Literature Cited

Boyer, D. G. 1986. Differences in produced water contaminants fromoil and gas operations in New Mexico - implications forregulatory action. Pp. 291-316, In Proceedings of the Conferenceon Southwestern Groundwater Issues (D. K. Kreamer, Moderator). National Well Water Association, Dublin, Ohio.

Brown, K. M. 1991. Mollusca: Gastropoda. Pp. 285-314, In Ecology and Classification of North American Freshwater Invertebrates (J. H. Thorp and A. H. Covich, Eds.). Academic Press, Inc.

Burch, J. B and J. L. Tottenham. 1980. North American freshwater snails: species, list, ranges and illustrations. Walkerana, Volume 1, Transaction of the POETS Society No.3.

Bureau of Land Management. 1994. Draftresource management plan/environmentalimpact statement forthe Roswell Resource Area, Roswell, New Mexico, and draftresource management plan amendment/environmental impact statement for the Carlsbad Resource Area, Carlsbad, New Mexico. Bureau of Land Management, Roswell, NM.

Eisler, R. 1987. Polycyclic aromatic hydrocarbon hazards to fish, wildlife, and invertebrates: a syntopic review. U.S. Fish and WildlifeService. Contaminant Hazard Reviews Report No. 11, Biological Report 85 (1.11).

Green, J. and M. W. Trett. 1989. The fateand effectsof oil in freshwater. Elsevier Science Publishing Co., Inc., New York.

Havlik, M. E. and L. L. Marking. 1987. Effectsof contaminants on naiad mollusks (Unionidae): a review. U.S. Fish and WildlifeService, Resource Publication 164.

Haynes, C. V. 1968. Geology of Late-Quaternary alluvium. Pp. 591-631, In Means of Correlation of QuaternarySuccessions (R. B. Morrison and H. E. Wright, Eds.). University of Utah Press, Salt Lake City.

B22 Hennighausen, F. H. 1969. Meters and their effects in the RoswellArtesian Basin in Chaves and Eddy counties, New Mexico. Pp. 29-33, In 14thAnnual New Mexico Water Conference (Water Resources Institute).

Hershler, R. and F. C. Thompson. 1987. NorthAmerican Hydrobiidae (Gastropoda: Rissoacea): redescription and systematic relationships of TryoniaStimpson, 1865 and Pyrgulopsis Call and Pilsbry, 1886. The Nautilus 101 :25-32.

Jercinovic, D. E. 1982. Assessment ofrefined petroleum-product contamination problems in surfaceand ground waters ofNew Mexico. Water Pollution Control Bureau, New Mexico Environmental Improvement Division, EID/WPC-82/5.

Jercinovic, D. E. 1984. Petroleum-product contamination ofsoil and water in New Mexico. New Mexico Environmental Improvement Division, EID/GWH84/2.

Jones, M.A. and W. P. Balleau. 1996. Interrelation of groundwater and surfacewater at Bitter Lake National Wildlife Refuge. Balleau Groundwater, Inc. Report to U.S. Department ofJustice, 16 pp.

Landye, J. J. 1981. Current status of endangered, threatened, and/or rare mollusks ofNew Mexico andArizona. EndangeredSpecies Office, U.S. Fish and WildlifeService, Final Report 13.

Longmire, P.A. 1983. Petroleum-product contamination of ground and surfacewater: a literature review. Ground WaterSection, Water Pollution Control Bureau, New Mexico Environmental Improvement Division. EID/WPC-83/7.

Martinez, J. D., K. S. Johnson, and J. T. Neal. 1998. Sinkholes in evaporite rocks. American Scientist 86:38-51.

Mehlhop, P. 1992. Establishment ofa rare mollusc inventory and monitoring program forNew Mexico. Progress Report. NMGF ProfessionalServices Contract 80-519-52.

Mehlhop, P. 1996. Ecology and conservation needs ofhydrobiid snails. The Nature Conservancy, Biodiversity News Network 9(1):6-7.

Mehlhop, P. and C. C. Vaughn. 1994. Threats to and sustainability ofecosystems for freshwater mollusks. Pp. 68-77 InSustainable Ecological Systems: Implementing an ecological approach to land management. U.S. ForestService. Gen. Tech. Rep. RM-247.

New Mexico Department of Game and Fish. 1988. Handbook ofspecies endangered in New Mexico.Account: A-299.

B23 New Mexico Statutes Annotated. 1995. Interstate Stream Commission Water Conservation Program: Pecos River Portion. NMSA Supplement 72-5-28.

Pennak, R. W. 1989. Fresh-water invertebrates of the United States: Protozoa to Mollusca. John Wiley & Sons, Inc.

Quarles, J. 1983. Groundwater contamination in the United States. University of Pennsylvania Press, Philadelphia.

Rail, C. D. 1989. Groundwater contamination: sources, control, and preventative measures. Techonomic Publishing Company, Inc. Lancaster, PA.

Richard, M. and A. Boehm. 1989a. Natural gas contamination at Rattlesnake Springs, Carlsbad CavernsNational Park: report of the second field investigation, March, 1988. Report 3. National Park Service Contract RFQ 7029-8-0025.

Richard, M. and A. Boehm. 1989b. Natural gas contamination at Rattlesnake Springs, Carlsbad CavernsNational Park: finalsummary of the investigation. Report 4. National Park Service Contract RFQ 7029-8-0025.

Taylor, D. W. 1983. Endangered species: status investigation of mollusks ofNew Mexico. Professional Service ContractNos. 519-69-01 and 519-69-01-A.

Taylor, D. W. 1987. Fresh-water mollusks fromNew Mexico and vicinity. New Mexico Bureau Mines & Mineral Resources, Bulletin 116.

United States Fish and Wildlife Service. 1996a. Endangered and threatened wildlifeand plants; Review of plant and animal taxa that are candidates forlisting as endangered or threatened species. Federal Register 61(40):7596-7613.

United States Fish and Wildlife Service. 1996b. Endangered and threatened species; Notice of reclassificationof 96 candidate taxa. Federal Register 61(40):7457-7463.

White, B. W., D. C. Culver, J. S. Herman, T. C. Kane, and J.E. Mylroie. 1995. Karst lands: the dissolution of carbonate rock produces unique landscapes and poses significant

B24 hydrological and environmental concerns. American Scientist 83:450-459.

Wu, S-K., R. D. Oesch and M. E. Gordon. 1997. Missouri aquatic snails. Conservation Commission of the State of Missouri. Missouri Department of Conservation, Natural History Series, No. 5.

B25 Roswell pyrg, Pyrgulopsisroswellensis Taylor, 1987

Listing Status: New Mexico - Endangered (19 NMAC 33.1), listed 22 July 1983 (NMGF Reg. 624); Federal - Species of Concern (USFWS 1996).

Description: Pyrgulopsis roswellensis (Mollusca: Gastropoda) is a prosobranch snail of the freshwater family Hydrobiidae, which differ from all but 1 aquatic snail family(Assimineidae) in New Mexico by the presence of internal gills for respiration and an operculum(lid-like structure) covering the aperture(shell opening). Hydrobiid snails are distinguished fromAssiminea pecos by the presence of eyes on long antennae and a globose to narrowly conical shell (Taylor 1987, Pennak 1989). The Hydrobiidae comprise a major faunal element of North American fresh waters, numbering about 28 genera and 148 species(Burch and Tottenham 1980). In such a large family, species recognition has been problematic since intra- and inter-generic affinitiesof taxa have been uncertain owing to significantoverlap and variation in shell characteristics. Most genera are distinguished by softanatomy (i.e., penial morphology and structure; Taylor 1987). Hershler and Thompson(1987) revised the Hydrobiidae in southwestern North America, and allocated the genus Fontelicella Gregg and Taylor, 1965 to Pyrgulopsis Call and Pilsbry, 1886.

Tan shells of P. roswellensis are elongately ovoid, spire is long(:< = 3.011 mm; n = 30) and slightly convex with up to 5 whorls that are regularly convex to shouldered and separated by a distinct suture, the peristome is usually adnate G oined) or sometimes free. The pale amber operculum is unique in the genus with an internal corneous callus and white calcareous material that appear as irregular white streaks. Distinctive penial morphology includes a long terminal strip on the terminal lobe, a y-shaped penial gland with two posterior limbs, a dorsal distal lobule oftenbearing a patch, and ventral lobule with a transverse strip(Taylor 1983, 1987).

Distribution: The Hydrobiidae of North America inhabit a great diversity of aquatic systems in the United States from epigean(surface) to hypogean(cave) habitats, small springruns to large rivers, and high energy rifflesto slack water pools(Wu et al. 1997). All 8 described hydrobiids of New Mexico are state endemics that typically occur in small geographically isolated point habitats consisting of eurythermal springs and springbrook wetland systems restricted to the southern half of the state (NMGF 1988). Taylor(1987) described P. roswellensis from a "seepage" along the western edge of an impoundment Unit 7 on the Bitter Lake National Wildlife Refuge(BLNWR), Chaves County; 2 additional populations inhabit springbrook wetland systems of Bitter Creek and Sago Springs. The North Spring population of the Roswell Country Club (RCC) represents the species' most western occurrence in the state. Pyrgulopsis roswellensis of Lander Springbrook, errantly referred to as Amniota neomexicana by Noel (1954), went extinct by the early 1960's(Cole 1981, 1985). Pleistocene fossils referred to this species have been found in the general vicinity of extant populations(i.e., Berrendo Creek and Pecos River northeast of Roswell)(Taylor 1987).

Biology: Most freshwater gastropods are herbivorous or detritivores that consume algae, bacteria, and decaying organic material, or that passively ingest small invertebrates while grazing

B26 periphyton. Respiration in hydrobiid snails is strictly aquatic via an internalgill with a small amount ofoxygen absorption through the mantle (soft body) surface. Hydrobiid snails are sexually dimorphic, femalesare characteristically larger and longer-lived than males. Most prosobranch snails are annual species that reproduce sevsal times (iteroparous) d4Iingthe '-¥ breeding period (spting-fall)with varying degrees ofreplacement ofgenerations. The females lay adhesive egg masses (oviparous) attached to substrata. Most prosobranch snails live9'-15 months, and growth is indeterminate (Taylor 1987, Pennak 1989, Brown 1991).

Pyrgulopsis and Tryonia species ofNew Mexico occupy a diversity ofhabitat types associated with freshto slightly saline spring and springbrook systems consisting of eury- to stenothermic waters, slow to moderate velocities over substrates ranging from deep, organic silts to indurate limestone cobble or rhyolitic talus or vertical facies (NMGF 1988). Seasonal lifehistory and population ecology of P. roswellensis were studied by Noel (1954). Snails were most abundant on limestone rubble in swiftwater of the Lander Springbrook springhead; population density decreased downstream of the rheocrene. While Taylor (1987) reported only Tryonia kosteri from "Lost River" (Bitter Creek), monthly spring snail censusses at the BLNWR (1995-1998) documented syntopic occurrences of P. roswellensis and T. kosteri in both Bitter Creek and Sago Springs. In 1995-1996, P. toswellensis was more abundant in the indurate gypsum substrates of Sago Springs (1125-27,924 snails/m2), compared to the less dense population (64-512 snails/m2) in the deep, organic substrates ofBitter Creek (NMGF 1998). Taylor (1983) reported similar patternsof distribution and abundance forP. roswellensis and T. kosteri at North Spring, RCC.

Status: While the date and cause ofextinction at the species' type locality (BLNWR) remain uncertain, the RCC population is small with reductions attributed to springhead modification (Landye 1981) and regional groundwater depletion (Taylor 1987, NMGF 1988). The trend in range reduction ofP. roswellensis by extirpation ofonce widely distributed, but localized, populations is supported by the Pleistocene fossilrecord and contemporaneous reinventory of known site occurrences (Noel 1954; Taylor 1987; Mehlhop 1992, 1993; NMGF files). Although BLNWR populations are stable under present refuge management practices, the RCC population has never been monitored routinely.

While P. roswellensis populations of the BLNWR are stable under present refugemanagement practices, habitat loss and alteration (e.g., artesian spring source diversion, dewatering,capping), groundwater depletion, and ground- and surface-watercontaminants are considered principal causes of decline in hydrobiid spring snails (Cole 1981, 1985; Pennak 1989; Brown 1991). Regional groundwater pumping and oil/gas industry operations ( exploration, transfer, storage, and refining) are ongoing in the Pecos River Valley (BLM 1994). Such extractive processes and industry operations are known to deplete groundwater aquifersand to contaminate ground- and surface-waters(Hennighausen 1969; Jercinovic 1982, 1984; Longmire 1983; Quarles 1983; Boyer 1986; Richard 1988a, 1988b; Rail 1989; Richard and Boehm 1989a, 1989b; Jones and Balleau 1996; Martinez et al. 1998); which can adversely impact aquatic snails (Eisler 1987, Havlik and Marking 1987, Green and Trett 1989), and threaten extant P. roswellensis ofthe BLNWR (USFWS 1997). Increase risk ofpotential water quality degradation due to domestic

B27 sewage contamination (i.e., septic discharge) is posed by encroachment ofresidential development within aquifer recharge-discharge areas along the western bounds of the BLNWR (Bitner and Graves 1992, McQuillan et al. 1989, White et al. 1995). Natural stochastic events, such as prolonged drought, could adversely impact extant populations by reducing discharge through refugesurface waters while concomitantly increasing salinity and concentrating contaminants.

Conservation: Federal surface and ground-water rights forthe BLNWR were secured in 1996 (USDJ 1996). Spring snail population and habitat monitoring is ongoing at the BLNWR. The NMGF initiated procedures for the development ofa conservation management plan fora suite of 4 state-listed Chaves County invertebrates, including P. roswellensis, under section 17-2-40.1 of the amended WildlifeConservation Act (1995). The North Spring population ofthe RCC remains vulnerable to habitat degradation and loss under current site management practices (Taylor 1983, NMGF 1988).

Literature Cited

Bitner, M. J. And T. Graves. 1992. Effectof lot sizes on potential ground-water contaminants fromconventional septic-tank systems: numerical modeling. Policy Coordinating Committee. 4 7 pp.

Boyer, D. G. 1986. Differencesin produced water contaminants from oil and gas operations in New Mexico - implications for regulatory action. Pp. 291-316, In Proceedings ofthe Conferenceon Southwestern Groundwater Issues (D. K. Kreamer, Moderator). National Well Water Association, Dublin, Ohio.

Burch, J. B and J. L. Tottenham. 1980. North American freshwatersnails: species, list, ranges and illustrations. Walkerana, Volume 1, Transaction ofthe POETS Society No. 3.

Bureau of Land Management. 1994. Draftresource management plan/environmental impact statement forthe Roswell Resource Area, Roswell, New Mexico, and draftresource management plan amendment/environmental impact statement for the Carlsbad Resource Area, Carlsbad, New Mexico. Bureau of Land Management, Roswell, NM.

Brown, K. M. 1991. Mollusca: Gastropoda. Pp. 285-314, In Ecology and Classificationof North American Freshwater Invertebrates (J. H. Thorp and A. H. Covich, Eds.). Academic Press, Inc.

Cole, G. A. 1981. Gammarus desperatus, a new species fromNew Mexico (Crustacea: Amphipoda). Hydrobiologia 76:27-32.

Cole, G. A. 1985. Analysis ofthe Gammarus-pecos complex (Crustacea: Amphipoda) in

B28 Texas and New Mexico, USA. Journal of the Arizona-Nevada Academy ofScience 20:93-103.

Eisler, R. 1987. Polycyclic aromatic hydrocarbon hazards to fish, wildlife, and invertebrates: a syntopic review. U. S. Fish and WildlifeService. Contaminant Hazard Reviews Report No. 11, Biological Report 85 (1.11).

Green, J.and M. W. Trett. 1989. The fateand effectsof oil in freshwater.Elsevier Science Publishing Co., Inc., New York.

Havlik, M. E. and L. L. Marking. 1987. Effects ofcontaminants on naiad mollusks (Unionidae): a review. U.S. Fish and WildlifeService, Resource Publication 164.

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

Jercinovic, D. E. 1982. Assessment ofrefinedpetroleum-product contamination problems in surface and ground waters ofNew Mexico. Water Pollution Control Bureau, New Mexico Environmental Improvement Division, EID/WPC-82/5.

Jercinovic, D. E. 1984. Petroleum-product contamination of soil and water in New Mexico. New Mexico Environmental Improvement Division, EID/GWH84/2.

Jones, M. A. and W.P. Balleau. 1996. Interrelation of groundwater and surface.water at Bitter Lake National Wildlife Refuge. Balleau Groundwater, Inc. Report to U.S.Department of Justice, 16 pp.

Landye, J. J. 1981. Current status ofendangered, threatened, and/or rare mollusks ofNew Mexico and Arizona. Endangered Species Office, U. S. Fish and WildlifeService, Final Report 13.

Longmire, P. A. 1983. Petroleum-product contamination of ground and surfacewater: a literature review. Ground Water Section, Water Pollution Control Bureau, New Mexico Environmental Improvement Division. EID/WPC-83/7.

Martinez, J. D., K. S.Johnson, and J. T.Neal. 1998. Sinkholes in evaporite rocks. American sScientist 86:38-51.

B29 Texas and New Mexico, USA . Journal ofthe Arizona-Nevada Academy ofScience 20:93-103.

Eisler, R. 1987. Polycyclic aromatic hydrocarbon hazards to fish, wildlife, and invertebrates: a syntopic review. U.S. Fish and WildlifeService. Contaminant Hazard Reviews Report No. 11, Biological Report 85 (1.11).

Green, J. and M. W. Trett. 1989. The fateand effects of oil in freshwater. ElsevierScience Publishing Co., Inc., New York.

Havlik, M. E. and L. L. Marking. 1987. Effectsof contaminants on naiad mollusks (Unionidae): a review. U.S. Fish and WildlifeService, Resource Publication 164.

Hennighausen, F. H. 1969. Meters and their effectsin the RoswellArtesian Basin in Chaves and Eddy counties, New Mexico. Pp. 29-33, In 14thAnnual New Mexico Water Conference(Water Resources Institute).

Hershler, R. and F. C. Thompson. 1987. NorthAmerican Hydrobiidae (Gastropoda: Rissoacea): redescription and systematic relationships of TryoniaStimpson, 1865 and Pyrgulopsis Call and Pilsbry, 1886. The Nautilus 101:25-32.

Jercinovic, D. E. 1982. Assessment ofrefinedpetroleum-product contamination problems in surfaceand ground waters ofNew Mexico. Water Pollution Control Bureau, New Mexico Environmental Improvement Division, EID/WPC-82/5.

Jercinovic, D. E. 1984. Petroleum-product contamination of soil and water in New Mexico. New Mexico Environmental Improvement Division, EID/GWH84/2.

Jones, M.A. and W. P. Balleau. 1996. Interrelation of groundwater and surfacewater at Bitter Lake National WildlifeRefuge. Balleau Groundwater, Inc. Report to U.S. Department ofJustice, 16 pp.

Landye, J. J. 1981. Current status of endangered, threatened, and/or rare mollusks of New Mexico and Arizona. Endangered Species Office, U.S. Fish and WildlifeService, Final Report 13.

Longmire, P.A. 1983. Petroleum-product contamination of ground and surface water: a literature review. Ground Water Section, Water Pollution Control Bureau, New Mexico Environmental Improvement Division. EID/WPC-83/7.

Martinez, J. D., K. S. Johnson, and J. T. Neal. Sinkholes in evaporite rocks. AmericanScientist 86:38-51.

B29 McQuillan, D. M., M. J. Jasper, and B. S. Swanson. 1989. Ground-water contamination by septic-tank use: a field study in the Albuquerque South Valley - West Mesa Region, BernalilloCounty, New Mexico. New Mexico Health & Environment Department, EID/GWB-89/2.

Mehlhop, P. 1992. Establishment of a rare mollusc inventory and monitoring program for New Mexico. Progress Report. NMGF Professional Services Contract 80-519-52.

Mehlhop, P. 1993. Establishment of a rare mollusc inventory and monitoring program for New Mexico. Year II Progress Report. NMGF Professional Services Contract No. 80-519-52-Amendment 1.

New Mexico Department of Game and Fish. 1988. Handbook of species endangered in New Mexico. Account: A-300.

New Mexico Department of Game and Fish. 1998. Status of aquatic mollusks of New Mexico. Annual PerformanceReport, E-20-6.

Noel, M. S. 1954. Animal ecology of a New Mexico springbrook. Hydrobiolgia 6:120-135.

Pennak, R. W. 1989. Fresh-water invertebrates of the United States: Protozoa to Mollusca. John Wiley & Sons, Inc.

Quarles, J. 1983. Groundwater contamination in the United States. University of Pennsylvania Press, Philadelphia.

Rail, C. D. 1989. Groundwater contamination: sources, control and preventive measures. Techonomic Publishing Company, Inc., Lancaster, PA.

Richard, M. 1988b. Natural gas contamination at Rattlesnake Springs, Carlsbad Caverns National Park: report of the first fieldinvestigation, August 1988. Report 2. National Park Service Contract RFQ 7029-8-0025.

Richard, M. and A. Boehm. 1989a. Natural gas contamination at Rattlesnake Springs, Carlsbad Caverns National Park: report of the second fieldinvestigation, March, 1988. Report 3. National Park Service Contract RFQ 7029-8-0025.

Richard, M. and A. Boehm. 1989b. Natural gas contamination at Rattlesnake Springs, Carlsbad Caverns National Park: final summary of the investigation. Report 4. National Park

B30 Service Contract RFQ 7029-8-0025.

Taylor, D. W. 1983. Endangered species: status investigation of mollusks of New Mexico. ProfessionalService Contract Nos. 519-69-01 and 519-69-01-A.

Taylor, D. W. 1987. Fresh-water mollusks fromNew Mexico and vicinity. New Mexico Bureau Mines & Mineral Resources, Bulletin 116.

United States Department of Justice. 1996. United States of America's statement of claim for reserved surfacewater and groundwater rights forBitter Lake National Wildlife Refuge. Roswell Basin Section, RAB 923 and 1793, Denver.

United States Fish and Wildlife Service. 1996. Endangered and threatened wildlife and plants; Review of plant and animal taxa that are candidates for listing as endangered or threatened species. Federal Register 61(40):7596-7613.

United States Fish and WildlifeService. 1997. Biological opinion on the Roswell Resource Area Resource Management Plans. Section 7 Consultation #2-22-96-102.

WildlifeConservation Act. 1995. Sections 17-2-37 through 17-2-46 NMSA 1978.

Wu, S-K., R. D. Oesch and M. E. Gordon. 1997. Missouri aquatic snails. Conservation Commission of the State of Missouri. Missouri Department of Conservation, Natural History Series, No. 5

B31 Gila pyrg, Pyrgulopsis thermalis Taylor, 1987

Listing Status: New Mexico - Threatened (19 NMAC 33.1), listed 22 July 1983 (NMGF Reg. 624); Federal - Candidate (USFWS 1996).

Description: Pyrgulopsis thermalis (Mollusca: Gastropoda) is a prosobranch snail of the freshwaterfamily Hydrobiidae, which differ fromall but 1 aquatic snail family(Assimineidae) in New Mexico by the presence of internalgills forrespiration and an operculum (lid-like structure) covering the aperture ( shell opening). Hydrodiid snails are distinguished fromAssiminea pecos by the presence of eyes on long antennae and a globose to narrowly conical shell (Taylor 1987, Pennak 1989). The Hydrobiidae comprise a major faunalelement of North American freshwaters,numbering approximately 28 genera and 148 species (Burch and Tottenham 1980). In such a large family, species recognition has been problematic since intra- and inter-generic affinitiesof taxa have been uncertain owing to significant overlap and variation in shell characteristics. Most genera are distinguished by softanatomy (i.e., penial morphology and structure; Taylor 1987). Hershler and Thompson (1987) revised the Hydrobiidae in southwestern North America, and allocated the genus Fontelicella Gregg and Taylor, 1965 to Pyrgulopsis Call and Pilsbry, 1886.

The tan shells of P. thermalis are globose and short spired (i.e., up to 1.68 mm, 3½ whorls). Whorls are strongly convex to weakly shouldered, separated by a distinct suture, forming a convex spire. The peristome is simply adnate Goined) with a broad, flat columellar margin and coarse traces of earlier peritreme edges. The operculum is pale orange-brown with a dark orange-brown internal callus; the border attachment scar leaves no conspicuous spiral trace. Distinctive penial morphology, unique to the genus, includes a horseshoe-shaped terminal gland. The terminal lobe is smaller relative to the freeportion, and lacks a lobed ventral gland situated more distad than in other congeners. The dorsal surface bears a long hook-shaped gland with several short glandular strips oblique to the long axis of the penis; the number and arrangement of these glands represent the principal variation in the penis (Taylor 1987).

Biology: The biology of P. thermalis is unknown. Most freshwater gastropods are herbivorous or detritivores that consume algae, bacteria, and decaying organic material, or that passively ingest small invertebrates while grazing periphyton. Respiration in hydrobiid snails is strictly

B32 aquatic via an internalgill with a small amount of oxygen absorption through the softbody (mantle) surface. Hydrobiid snails are sexually dimorphic, females are characteristically larger and longer-lived than males. Most prosobranch snails are annual species that reproduce several times (iteroparous) during the breeding period (spring-fall)with varying degrees of replacement of generations. Females lay adhesive egg masses (oviparous) attached to substrata. Growth is indeterminate formost hydrobiids. While longevity is variable, most prosobranch snails live 9- 15 months (Taylor 1987, Pennak 1989, Brown 1991).

Pyrgulopsis and Tryonia species of New Mexico occupy a diversity of habitat types associated with freshto slightly saline spring and springbrook systems consisting of eury-to stenothermic waters, slow to moderate velocities over substrates ranging fromdeep, organic silts to indurate rhyolitic talus or vertical rhyolitic facies(Taylor 1983, 1987). At the type locality, P. thermalis inhabits thermal waters (33-38 ° C) that issue from multiple sources along a vertical rhyolitic cliff adjacent to the Gila River; principal spring outflowsare too hot (>38 ° C) forthe snails (Taylor 1987). The East Fork Gila River population of P. thermalis also inhabits thermal waters of vertical rock facies(38-39 °C), but is more abundant in cooler, lower gradient lotic habitats with thermal conditions similar to the type locality (Landye 1981, Taylor 1987).

Status: Taylor (1983) reported that each P. thermalis population numbered several hundred thousand. Mehlhop (1993) documented the persistence of both P. thermalis populations. Seasonal floodingand high water discharge may result in annual population losses, and likely exert ecological constraints resulting in the unusual conchological characteristics atypical of the genus (Taylor 1987). Natural stochastic events ( drought, forestfire, sedimentation, flooding), wetland habitat degradation by recreational bathing in thermal springs, and poor watershed management practices (e.g., overgrazing, silvicultural practices) represent primary threats to P. thermalis populations (Taylor 1987, NMGF 1988). Fire suppression and retardant chemicals have potentially deleterious effectson P. gilae populations (McDonald and Hamilton 1995).

Conservation: Long-term persistence of this species is contingent upon protection of the riparian corridor immediately adjacent to springhead and springrun habitats, thereby ensuring maintenance of perennial, oxygenated flowingwater (Taylor 1983, Mehlhop and Vaughn 1994, Mehlhop 1996) within the species' required thermal range. Genetic divergence between geographically isolated, disjunct populations of P. thermalis may warrant taxonomic re evaluation of the species, which in turn could conferspecific management recommendations particular to genetically distinct populations relative to current ownership and land-use practices (Weins 1996). While the Gila Wilderness affordssome measure of habitat protection (NMGF 1988), multi-interest conservation effortsare encouraged to develop habitat management plans under the federal"candidate conservation agreement" program (USFWS 1997).

Literature Cited

Brown, K. M. 1991. Mollusca: Gastropoda. Pp. 285-314, In Ecology and Classificationof

B33 North American Freshwater Invertebrates (J. H.Thorp and A.H. Covich, Eds.). Academic Press, Inc.

Burch, J.B and J.L. Tottenham. 1980. North American freshwatersnails: species, list, ranges and illustrations. Walkerana, Volume 1, Transaction ofthe POETS Society No.3.

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

Landye, J.J. 1981. Current status ofendangered, threatened, and/or rare mollusks ofNew Mexico and Arizona. Endangered Species Office, U.S.Fish and WildlifeService, Final Report 13.

McDonald, S.F. and S. J. Hamilton. 1995. Fire retardant and foam suppressant chemicals may be toxic to aquatic invertebrates and algae. National Biological Service, NBS Information Bulletin 35.

Mehlhop, P. 1993. Establishment ofa rare mollusc inventory and monitoring program for New Mexico. Year II Progress Report.NMGF Professional Services Contract No. 80-519-52-Amendment 1.

Mehlhop, P. 1996. Ecology and conservation needs ofhydrobiid snails. The Nature Conservancy, Biodiversity News Network 9(1):6-7.

Mehlhop, P. and C.C. Vaughn. 1994. Threats to and sustainability of ecosystems for freshwater mollusks. Pp. 68-77, In Sustainable Ecological Systems: Implementing an ecological approach to land management. U.S.Forest Service. General Technical Report RM-247.

New Mexico Department ofGame and Fish. 1988. Handbook of species endangered in New Mexico. Account: A-301.

Pennak, R.W. 1989. Fresh-water invertebrates ofthe United States: Protozoa to Mollusca. John Wiley & Sons, Inc.

Taylor, D. W. 1983. Endangered species: status investigation ofmollusks ofNew Mexico. ProfessionalService Contract Nos. 519-69-01 and 519-69-01-A.

Taylor, D. W. 1987. Fresh-water mollusks fromNew Mexico and vicinity. New Mexico Bureau ofMines & Mineral Resources, Bulletin 116.

United States Fish and WildlifeService. 1996. Endangered and threatened wildlifeand plants;

B34 Review of plant and animal taxa that are candidates forlisting as endangered or threatened species. Federal Register 61(40):7596-7613.

United States Fish and Wildlife Service. 1997. Announcement of draftpolicy forcandidate conservation agreements. FederalRegister 62(113):32183-32188.

Weins, J. A. 1996. Wildlifein patchy environments: metapopulations, mosaics, and management. Pp 53-84, In Metapopulations and Wildlife Conservation (Ed. D.R. McCollough). Island Press.

Wu, S-K., R. D. Oesch and M. E. Gordon. 1997. Missouri aquatic snails. Conservation Commission of the State of Missouri. Missouri Department of Conservation, Natural History Series, No. 5.

B35

Pecos River (Taylor 1987).

Biology: The biology of T kosteri is unknown, and until recently was limited to observations by Taylor (1983, 1987) and Mehlhop (1992, 1993). Most freshwatergastropods are herbivorous or detritivores that consume algae, bacteria, and detritus, or that passively ingest small invertebrates while grazing periphyton. Respiration in hydrobiid snails is strictly aquatic via an internal gill with a small amount of oxygen absorption through the mantle (soft body) surface. Hydrobiid snails are sexually dimorphic with females typically larger and longer-lived than males. Growth in hydobiids is indeterminate. Tryonia kosteri is a seasonal breeder with reproduction occurring between March and September (NMGF files). Whereas most hydrobiid females lay adhesive egg masses (oviparous) attached to substrata, T kosteri is ovoviviparous, with a series of embryos in various stages of development; thus, population recruitment is continuous during the breeding period (Taylor 1987, Pennak 1989, Brown 1991).

Pyrgulopsisand Tryoniaspecies of New Mexico occupy a diversity of habitat types associated with freshto slightly saline spring and springbrook systems consisting of eury-to stenothermic waters, slow to moderate velocities over substrates ranging fromdeep, organic silts to coarse gravels or vertical bedrock (limestone, rhyolitic) facies(NMGF 1988). Taylor (1987) reported an abundance of ,T kosteriin Sago Spring (type locality), and throughout the mile long reach of Bitter Creek '("LostRiver"), BLNWR. In 1995-1996, T kosteri was more abundant (704-89 ,4 72 snails/m2) in the deep, organic substrates of Bitter Creek compared to the notably less dense population in the indurate gypsum substrates of Sago Springs (75-512 snails/m2) (NMGF files). Seepage areas along refugeunits ponds 3 and 6 supported relict populations of T kosteri. Landye (1981) and Taylor (1983, 1987) considered populations of T. kosteri marginal at the RCC, where it was taken fromshallow flowover limestone gravels and poured concrete of the modified rheocrene of North Spring.

Status: Mehlhop (1992, 1993) documented additional T kosteri populations on the BLNWR in Dragonfly Spring (Bitter Creek) and Sinkhole 32 near Sago Spring. Although the current status of the North Spring population is unknown, as site access has been denied repeatedly by the private land steward (NMGF files),the New Mexico Natural Heritage Program collected a few T kosteri from North Spring in 1995 (P. Mehlhop,pers. comm.). Populations at the BLNWR are stable under present refugemanagement practices.

Habitat loss and alteration (e.g., artesian spring source diversion, dewatering, capping), groundwater depletion, and ground- and surface-water contaminants are considered principal causes of decline in hydrobiid spring snails (Cole 1981, 1985; Pennak 1989; Brown 1991). Regional groundwater pumping and oil/gas industry operations (exploration, transfer,storage, and refining)are ongoing in the Pecos River Valley (BLM 1994). Such extractive processes and industry operations are known to deplete groundwater aquifers and to contaminate ground- and surface-waters (Hennighausen 1969; Jercinovic 1982, 1984; Longmire 1983; Quarles 1983; Boyer 1986; Richard 1988a, 1988b; Rail 1989; Richard and Boehm 1989a, 1989b; Jones and Balleau 1996; Martinez et al. 1998); which can adversely impact aquatic snails (Eisler 1987,

B37 Havlik and Marking 1987, Green and Trett 1989), and threaten extant T kosteri populations at the BLNWR (USFWS 1997a). Increase risk of potential water quality degradation due to domestic sewage contamination (i.e., septic discharge) is posed by encroachment of residential development within aquifer recharge-discharge areas along the western bounds of the BLNWR (Bitner and Graves 1992, McQuillan et al. 1989, White et al. 1995). Natural stochastic events, such as prolonged drought, could adversely impact extant populations by reducing discharge through refuge surfacewaters while concomitantly increasing salinity and concentrating contaminants.

Conservation: Federal surfacewater and ground-water rights forBLNWR were secured in 1996, thereby effectivelyensuring minimum surface water discharge of Bitter Creek (USDJ 1996). Under section 17-2-40.1 of the amended WildlifeConservation Act (1995), the NMGF initiated procedures forthe development of a conservation management plan for a suite of 4 state listed Chaves County invertebrates, including T kosteri. The RCC population remains vulnerable to habitat degradation and loss under current site management practices (Taylor 1983, NMGF 1988). The federal"candidate conservation agreement" program (USFWS 1997b) may provide a frameworkfor species and habitat conservation at the RCC.

Literature Cited

Bitner, M. J. And T. Graves. 1992. Effectof lot sizes on potential ground-water contaminants fromconventional septic-tank systems: numerical modeling. Policy Coordinating Committee. 47 pp.

Boyer, D. G. 1986. Differencesin produced water contaminants fromoil and gas operations in New Mexico - implications for regulatory action. Pp. 291-316, In Proceedings of the Conferenceon Southwestern Groundwater Issues (D. K. Kreamer, Moderator). National Well Water Association, Dublin, Ohio.

Brown, K. M. 1991. Mollusca: Gastropoda. Pp. 285-314, In Ecology and Classification of North American Freshwater Invertebrates (J. H. Thorp and A. H. Covich, Eds.). Academic Press, Inc.

Burch, J. B and J. L. Tottenham. 1980. North American freshwatersnails: species, list, ranges and illustrations. Walkerana, Volume 1, Transaction of the POETS Society No.3.

Bureau of Land Management. 1994. Draft resource management plan/environmental impact statement forthe Roswell Resource Area, Roswell, New Mexico, and draft resource management plan amendment/environmental impact statement forthe Carlsbad Resource Area, Carlsbad, New Mexico. Bureau of Land Management, Roswell, NM.

Cole, G. A. 1981. Gammarus desperatus,a new species fromNew Mexico (Crustacea: Amphipoda). Hydrobiologia 76:27-32.

B38 Cole, G. A. 1985. Analysis of the Gammarus-pecos complex (Crustacea: Amphipoda) in Texas and New Mexico, USA. Journalof the Arizona-Nevada Academy of Science 20:93-103.

Eisler, R. 1987. Polycyclic aromatic hydrocarbon hazards to fish, wildlife, and invertebrates: a syntopic review. U.S. Fish and WildlifeService. Contaminant Hazard Reviews Report No. 11, Biological Report 85 (1.11).

Green, J. and M. W. Trett. 1989. The fateand effects ofoil in freshwater. Elsevier Science Publishing Co., Inc., New York.

Havlik, M. E. and L. L. Marking. 1987. Effectsof contaminants on naiad mollusks (Unionidae): a review. U.S. Fish and WildlifeService, Resource Publication 164.

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

Jercinovic, D. E. 1982. Assessment ofrefinedpetroleum-product contamination problems in surface and ground waters ofNew Mexico. Water Pollution Control Bureau, New Mexico Environmental Improvement Division, EID/WPC-82/5.

Jercinovic, D. E. 1984. Petroleum-product contamination of soil and water in New Mexico. New Mexico Environmental Improvement Division, EID/GWH84/2.

Jones, M.A. and W. P. Balleau. 1996. Interrelation ofgroundwater and surfacewater at Bitter Lake National WildlifeRefuge. Balleau Groundwater, Inc. Report to U.S. Department of Justice, 16 pp.

Land ye, J. J. 1981. Current status of endangered, threatened, and/or rare mollusks ofNew Mexico and Arizona. EndangeredSpecies Office, U.S. Fish and WildlifeService, Final Report 13.

Longmire, P.A. 1983. Petroleum-product contamination of ground and surfacewater: a literature review. Ground WaterSection, Water Pollution Control Bureau, New Mexico Environmental Improvement Division. EID/WPC-83/7

Martinez, J. D., K. S. Johnson, and J. T. Neal. 1998. Sinkholes in evaporite rocks. American Scientist 86:3 8-51.

B39 McQuillan, D. M., M. J. Jasper, and B. S. Swanson. 1989. Ground-water contamination by septic-tank use: a field study in the AlbuquerqueSouth Valley - West Mesa Region, Bernalillo County,New Mexico. New Mexico Health & Environment Department, EID/GWB-89/2.

Mehlhop, P. 1992. Establishment of a rare mollusc inventory and monitoring program for New Mexico. Progress Report. NMGF ProfessionalServices Contract 80-519-52.

Mehlhop, P. 1993. Establishment of a rare mollusc inventory and monitoring program for New Mexico. Year II Progress Report. NMGF ProfessionalServices Contract No. 80-519-52-Amendment 1.

New Mexico Department of Game and Fish. 1988. Handbook of species endangered in New Mexico. Account: A-306

New Mexico Department of Game and Fish. 1996. Status of aquatic and terrestrial mollusks of New Mexico. Final Report submitted to U.S. Fish and WildlifeService.

Pennak, R. W. 1989. Fresh-water invertebrates of the UnitedStates: Protozoa to Mollusca. John Wiley & Sons, Inc.

Quarles, J. 1983. Groundwater contamination in the UnitedStates. University of Pennsylvania Press, Philadelphia.

Rail, C. D. 1989. Groundwater contamination: sources, control and preventive measures. Techonomic Publishing Company, Inc., Lancaster, PA.

Richard, M. 1988a. Natural gas contamination at RattlesnakeSprings, Carlsbad Caverns National Park: review of the geohydrology in the vicinity of RattlesnakeSprings and the contamination problem. Report 1. National ParkService Contract RFQ 7029-8-0025.

Richard, M. 1988b. Natural gas contamination at RattlesnakeSprings, Carlsbad Caverns National Park: report of the firstfield investigation, August 1988. Report 2. National ParkService Contract RFQ 7029-8-0025.

Richard, M. and A. Boehm. 1989a. Natural gas contamination at RattlesnakeSprings, Carlsbad CavernsNational Park: report of the second fieldinvestigation, March, 1988. Report 3. National ParkService Contract RFQ 7029-8-0025.

Richard, M. and A. Boehm. 1989b. Natural gas contamination at RattlesnakeSprings, Carlsbad Caverns National Park: finalsummary of the investigation. Report 4. National Park Service Contract RFQ 7029-8-0025.

B40 Taylor, D. W. 1983. Endangered species: status investigation of mollusks of New Mexico. Professional Service Contract Nos. 519-69-01 and 519-69-01-A.

Taylor, D. W. 1987. Fresh-water mollusks fromNew Mexico and vicinity. New Mexico Bureau of Mines & Mineral Resources, Bulletin 116.

United States Department of Justice. 1996. United States of America's statement of claim for reserved surfacewater and groundwater rights for Bitter Lake National Wildlife Refuge. Roswell Basin Section, RAB 923 and 1793, Denver.

United States Fish and WildlifeService. 1996. Endangered and threatened wildlifeand plants; Review of plant and animal taxa that are candidates forlisting as endangered or threatened species. Federal Register 61(40):7596-7613.

United States Fish and Wildlife Service. 1997a. Biological opinion on the Roswell Resource Area Resource Management Plans. Section 7 Consultation #2-22-96-102.

United States Fish and WildlifeService. 1997b. Announcement of draftpolicy forcandidate conservation agreements. Federal Register 62(113):32183-32188.

Wildlife ConservationAct. 1995. Sections 17-2-37 through 17-2-46 NMSA 1978.

Wu, S-K., R. D. Oesch, and M.E. Gordon. 1997. Missouri aquatic snails. Conservation Commission of the State of Missouri, Missouri Department of Conservation, Natural History Series, No. 5.

B41 Sangre de Cristo peaclam, Pisidium sanguinichristi Taylor, 1987

Listing Status: New Mexico - Threatened (19 NMAC 33.1), listed 22 July 1983 (NMGF Reg. 624); Federal - Species of Concern (USFWS 1996).

Characteristics: Pisidium sanguinichristi (Mollusca: Bivalvia) is a member of the freshwater clam familySphaeriidae, which are distinguished fromother bivalve families in the state (Unionidae and Corbiculidae) by soft anatomy, location and development of zygotes in specialized brood pouches (marsupia) of the inner gills (endobranchous brooders), release of fullyformed juveniles (ovoviviparous ), and small shell (adult size - 2-15 mm l) (Pennak 1989, MacMahon 1991). The North American sphaeriacean faunais represented by 4 genera (Eupera sp., Musculium sp., Sphaerium sp., and Pisidium sp.) and 37 species (Burch 1975). Heard (1965a) recognized generic-level differences between Sphaerium, Musculium, and Pisidium based on softanatomical differences. Pisidium species differ fromother sphaeriids by the presence of a well-developed anal siphon, the branchial siphon (if present) is rudimentary or represented as a slit in the partially-fused mantle (Heard 1966), absence of a byssal gland, anterior end of the shell longer than the posterior end, beaks (umbo) are posterior, or if subcentral, to the shell mid-length line (Herrington 1962, Burch 1975, Wu 1978).

Pisidium sanguinichristi is distinguished fromall other 24 North American pisidia (Herrington 1962) by a small (2.41 x 2.0h x 1.6w mm) rounded trapezoidal shell, highly inflated (H/L=0.83), broad umbos smooth and low, posterior end truncate, anterior end elongate, ventral margin broadly curved, hinge plate 70% of shell length, greatest shell length below horizontal midline, and shell sculpturing with smooth riblets (see Taylor 1987 forvalve dentition description).

Distribution: Pisidia bivalves are cosmopolitan inhabiting lakes, ponds (perennial and vernal), and streams. The endemic P. sanguinichristi can be considered the most narrowly restricted of all known North American pisidia (Taylor 1983), and perhaps even worldwide. The type locality is a shallow (- 25 ft. deep), 2.5-3.0 acre glacial cirque lake situated at the southeast base ofBull of-the-Woods Mountain, Sangre de Cristo Mountains, Taos County (Questa Ranger District, Carson National Forest [CNF]) (Taylor 1987).

Biology: The biology of P. sanguinichristi is unknown. In general, sphaeriid species are highly adaptable to a wide range of environmental conditions, and demonstrate notable variation in life history patterns (Pennak 1989). Sphaeriidae typically burrow below the substrate and feed by an interstitial suspension-feedingmechanism, whereby aqueously suspended food particles are filteredout prior to selective ingestion of organic fooditems (Pennak 1989), which may consist of bacteria, detritus, and phytoplankton, including diatoms, green and blue-green algae (Gale and Lowe 1971 ). Consequently, sphaeriids are reliable indicators of lacustrine chemical trophic conditions (Pennak 1989).

Sphaeriidae are common in water depths from 0.25 to 30 m below the surface (Pennak 1989). Sphaeriids can burrow into substrates during drought conditions; immatures are active burrowers

B42 and have been collected in softsubstrates at 0.25 cm (MacMahon 1991). TheSangre de Cristo peaclam colonizes muddy shallows along the lake perimeter and a narrow reach of the lake outflow,Middle Fork Creek (Taylor 1983, 1987; NMGF 1988). Taylor (1987) reported the syntopic occurrence of several pisidia (P. casertanum, P. contortum) in Middle Fork Lake. Several congeners (P. insigne, P. lillgeborgi, P. nitidum, P. variable, and P. ventricosum) occur in theSangre de Cristo Mountain of north-central New Mexico (Taylor 1983, 1987; NMGF 1988), including a morphologically similar species, P. milium, fromMiddle Fork Lake (NMGF 1996).

Sphaeriid clams are uniformlyhermaphrodit ic (both sexes in one) with self-fertilization occurring in the reproductive ducts (Pennak 1989). Embryos are brooded in water tubes of the inner gills (marsupia) where 1-60 young are maintained in various stages of development. Immature sphaeriids are bornfully developed commonly ¼ to 1/3 as long as the adult. Most pisidia live 12-18 months, although some may live as long as 13 years (i.e., P. conventus, Heard 1965b ). The breeding habits of pisidia are quite variable and may be classified as iteroparous (breeding more than once) or semelparous (breeding only once). Intraspecific and interspecific differencesof gonad activity and litter size are manifest by ecological influences (e.g., permanency of water) and genetic makeup (Heard 1965a, 1966). Consequently, lifehistory studies require detailed examination of clearly definedtaxa froma variety of habitat types in which a species might occur.

Geographically dispersed and narrowly localized sphaeriid bivalve populations are common, and largely the result of natural introductions by migratory shorebirds and waterfowl (Bequaert and Miller 1973). Avifauna,that frequentmargins of wetlands or forageon benthic substrata by dabbling or diving, commonly transport young clams from one body of water to another in mud that clings to their feetand/or feathers (Pennak 1989, MacMahon 1991). Founding populations of highly adaptable species, such as sphaeriid clams, commonly demonstrate short-term, rapid population success followedby diminution to some lower sustainable number, or extinction within a relatively short period (MacArthur 1972). Although local environmental factorsmay play a significant role influencing success of introductions by avian phoresy events, sphaeriid distribution patternsare also correlated with general climatic conditions. Habitat conditions (e.g., substrate type, physicochemical regime, permanency of water, flow) commonly affect development and growth of sphaeriid bivalves, and manifestmarked ecophenotypic variation of shell characteristics in sphaeriid populations of geographically disparate conspecifics(Herrington 1962). Consequently, endemicity ofSphaeriacean clams is uncommon, as only two taxa, P. sanguinichristi Taylor, 1987 and P. ultramontanum Prime, 1865, are considered endemic to North America (Taylor 1960, 1987).

Status: Until 1995, routine monitoring of the Middle Fork Lake population had not been conducted since Taylor's (1987) initial description. Potential occurrence of the species in other glacial cirque lakes of theSangre de Cristo Mountains was unexplored. The NMGF initiated annual population monitoring of P. sanguinichristi in July 1995 under a multi-agency conservation effortinitiated by the U.S. Forest Service (1996). A total of 6 sites (3 each in

B43 Middle Fork Lake and Middle Fork Creek) was sampled in 1995. Based on the absence of P. sanguinichristi fromthis survey, and the lack of discernable differencesin shell shape and hinge dentition between "paratype" P. sanguinichristi and the morphologically similar species, P. milium, in Middle Fork Lake, the NMGF requested expert assessment of the putative P. sanguinichristi as a valid taxon (NMGF 1996). Mitochondrial DNA analysis comparing shell proteins of the nominate species with the conchologically similar conger, P. milium, yielded inconclusive results since shell proteins fromP. sanguinichristi were not readily extracted (Wilson et al. 1998). Resolution of outstanding taxonomic questions via genetic studies appears intractable, unless a live population of P. sanguinichristi can be located.

Middle Fork Lake was re-sampled at 6 sites in July 1996, while expanding the survey area to include localities on Placer Creek (n = 5), Goose Lake (n = 1), and an unnamed glacial cirque and bog within the Goose Lake sub-basin (n = 4). Deep waters of Middle Fork and Goose lakes were re-sampled in September 1996 by skin diving. No P. sanguinichristi specimens were observed in these fieldcollections; most specimens were P. nitidum (NMGF 1996). No P. sanguinichristi were collected during 1997 inventory efforts,which included 10 sites in the Valle Vidal and Vermejo units of the CNF, and Latir Lakes 1-3 of the Rio Costilla Recreational Park. Pisidium sanguinichristi did not occur in glacial cirque lake collections in 1999 (see Appendix A, attached).

Conservation: The U.S. Forest Service (1996), working in collaboration with the U.S. Fish and WildlifeService, New Mexico Department of Game and Fish, and New Mexico Natural Heritage Program, formalizeda conservation assessment plan forthe P. sanguinichristi, which calls formulti-agency research and management effortsdirected at species protection. While remoteness and ownership of Middle Fork Lake affordsome measure of protection, this site experiences intense periods of active and passive recreational use. Research on population distribution and abundance is ongoing. Population and habitat threats include shoreline destabilization ( erosion and sedimentation due to foot/vehiculartraffic), chemical contamination from forest firesuppressants (McDonald and Hamilton 1995), placer mining runoff, and stochastic natural events (fire,drought) (Taylor 1983, NMGF 1988, USFS 1996).

Literature Cited

Bequaert, J.C. and W. B.Miller. 1973. The mollusks of the Arid Southwest with an Arizona checklist. University of Arizona Press, Tucson. 271 pp.

Burch, J. B. 1975. Freshwater sphaeriacean clams (Mollusca: Pelecypoda) of North America. U.S. Environmental Protection Agency. Biota of Freshwater Ecosystems, Identification Manual No. 3.

Gale, W. F. and R. L. Lowe. 1971. Phytoplankton ingestion by the fingernailclam, Sphaerium transversum (Say), in Pool 19, Mississippi River. Ecology 52:507-513.

B44 Heard, W. H. 1965a. Recent Eupera (Pelecypoda: Sphaeriidae) in the United States. American Midland Naturalist 74:309-317.

Heard, W. H. 1965b. Comparative lifehistories of North American pill clams (Sphaeriidae: Pisidium). Malacologia 2(3):381-411.

Heard, W. H. 1966. Subgeneric classificationof Pisidium in North America. The Nautilus 79:86- 89.

Herrington, H.B. 1962. A revision of the Sphaeriidae of North America (Mollusca: Pelecypoda). University of Michigan Museum of Zoology. Miscellaneous Publications No. 18.

MacArthur, R. M. 1972. Geographical Ecology. Harper & Row, New York.

MacMahon, R. F. 1991. Mollusca:Bivalvia. Pp. 315-399, In Ecology and Classificationof North American Freshwater Invertebrates (J. H. Thorp and A. P. Covich, Eds.). Academic Press, Inc.

New Mexico Department of Game and Fish. 1988. Handbook of species endangered in New Mexico. Species Account B-334.

New Mexico Department of Game and Fish. 1996. Status of aquatic and terrestrial mollusks of New Mexico, E-20 (1-4) . Final Report submitted to the USFWS.

Pennak, R. W. 1989. Fresh-water invertebrates of the United States: Protozoa to Mollusca. John Wiley & Sons, Inc.

Taylor, D. W. 1960. Distribution of the freshwaterclam Pisidium ultramontanum: a zoogeographic inquiry. American Journal of Science 258-A:325-334.

Taylor, D. W. 1983. Endangered species: status investigation of mollusks of New Mexico. ProfessionalService Contract Nos. 519-69-01 and 519-69-01-A.

Taylor, D. W. 1987. Fresh-water mollusks from New Mexico and vicinity. New Mexico Bureau of Mines & Mineral Resources Bulletin 116.

United States Fish and WildlifeService. 1996. Endangered and threatened wildlifeand plants; Review of plant and animal taxa that are candidates forlisting as endangered or threatened species. Federal Register 61(40):7596-7613.

United States Forest Service. 1996. Habitat conservation assessment forSangre de Cristo peaclam (Pisidium sanguinichristi).

B45 --

Wilson, A. B., W. T. Claxton, and G. L. Mackie. 1998. mtDNA COI sequencing of Pisidium milium and P. sanguinichristi: Does molecular data support species-level designations? Final Report under ProfessionalServices Contract, 5 pp.

Wu, S-K. 1978. The Bival via of Colorado. Part 1. The fingernailand pill clams (Family Sphaeriidae). University of Colorado Museum, Natural History Inventory of Colorado 2.

B46