ABSTRACT. The Desert Pupfish, Cyprinodon macularius, was listed as endangered in 1986 due to the well-known and extensively documented threats of habitat loss and the spread of exotic and nonnative fishes. Even though the Desert Pupfish was split into three species by Echelle et al. in 2000 (C. eremus) and Minckley et al. in 2002 (C. arcuatus), under the U.S. Endangered Species Act it is still considered one species.

The 1993 Recovery Plan was recently amended to add criteria for delisting the species, through drought, climate change, border activities, and increasing human populations still threaten streams and springs and nonnative and exotic species are still introduced and distributed across the landscape. The status of the species continues to improve in Arizona due to the actions of the Arizona Game and Fish Department and its partners. However, the natural population inhabiting the Salton Sink in California continues to experience declines. The populations in Mexico appear to be mostly static, except for Rio Sonoyta

ABSTRACT. The poecilid family is formed by a group of viviparous fishes, where the male’s anal fin is modified into a reproductive system called gonopodium. This modification makes rays 3 to 5 enlarged and formed segments in each ray that may present structures like spines, hooks, claws, serrated areas and more. The gonopodium has been proven useful to identify species like Xiphophorus or Gambusia and therefore it could be useful in the Poecilia genus. The present study will focus on the taxonomical differences within the species of the genus Poecilia mainly P. latipinna, P. velifera P. petenensis, P. mexicana (sulfur and non-sulfur), P. butleri and P. sphenops; its study may be used as an extra tool for the inexperienced on the taxonomy of Poecilia spp. Each gonopodium was cut and processed for a better description of it. Each species has their traits like the number of spines in the serrated area, the number of internal spines, the presence or absence of a membranous hook in ray 3. The number of spines in ray 4p, the spines in ray 5a and the shape of the claw in ray 5p may serve as an useful taxonomic complement. 

ABSTRACT. Tributary streams offer basal resources for aquatic food webs and unique habitats to taxa that differ from the main stem of the river. Because of this, many stream tributaries are known to be biological “hot spots” for species diversity, making them important for river conservation strategies. The Pecos River flows from New Mexico through Texas and offers an ideal study system to investigate diversity in stream tributary junctions across both natural and impacted conditions. In this study, we explored seasonal (summer 2016, fall 2016, and spring 2017) effects of tributary confluences in the Middle and Lower Pecos on the diversity of benthic macroinvertebrate assemblages across sites that encompass a range of habitat conditions. Longitudinally, specific conductivity, substrate, and discharge varied, and sites were significantly different when comparing macroinvertebrate density, Shannon- Weiner diversity, and species evenness. Post-hoc analyses revealed that the Middle Pecos confluence sites of Taiban Creek and Rio Hondo had lower benthic macroinvertebrate density than the Permian Basin site of Delaware River. Additionally, the Taiban Creek and Independence Creek, the most northern and southern sites, were significantly different when comparing Shannon-Weiner diversity. Seasonal differences also existed in the density of macroinvertebrates and the functional feeding groups present across sites. Nonmetric multidimensional scaling analysis revealed that confluences within the same region had similar community structure, and indicator species analysis showed that some taxa were strongly associated with particular regions (e.g., Psephenidae and Naucoridae in the Edwards Plateau). Taken together, these findings indicate that tributary confluences are important sites for benthic macroinvertebrate production in the highly altered Pecos River, and ecoregion-scale physiographic variation strongly influences local confluence community structure.

ABSTRACT. Mexico is considered a Megadiverse country because its geographical position into the Neotropical and Nearctic biogeographic regions, due to the variety of climates, the great orographic diversity, being surrounded by two different oceans, presenting different types of soil, inland waters and different types of vegetation, generating a high fauna richness. However, biodiversity has been diminished due to anthropogenic activities, as well as environmental changes that have affected populations. To mitigate the effects of these factors, it is necessary to be aware on how this diversity has changed over time, making biological and ecological comparisons at different time and geographic scales. The aquatic systems in Mexico are used for the disposal of wastewater, which generates ecological disturbances in the rivers and the surrounding ecosystem. La Silla river, in Nuevo León, Mexico, is considered one of the aquatic ecosystems with the highest ecological priority in North America, due to its biodiversity, as well as the different environmental services it offers as a system, in addition to the potential risk due the human settlements around. It is at this point that the importance of Biological Collections arises, considered as libraries of specimens that are stored in special conditions to guarantee their integrity over time, and providing biological information at historical, geographical, genetic, ecological, anatomical and morphological levels. Fish species lists of Nuevo León have demonstrated the presence of several national or international protected species, and some of these species are distributed in La Silla river. However, for many of them there is not enough information about their biology and ecology to assess their vulnerability to adverse ecosystem conditions. The current conditions of the La Silla river allow us to infer that the fish populations will present unfavorable conditions, both ecological, demographic and genetic, that will increase the need for their protection. At the Ichthyological Collection of the Biological Sciences Faculty from the Autonomous University of Nuevo León, specimens from almost all the States of Mexico and from other countries of the world are present. From La Silla River, there are records dating since 1966, with the Catostomidae, Centrarchidae, Cyprinidae, Characidae, Cichlidae, Poecilidae and Ictaluridae families being the oldest recorded for the area. In this way, for different locations of La Silla river, there are records from 1966, 1969, 1981, 1982, 1988, 1995, 1996, 1998 and 2011, where, in addition, the families Clupeidae, Percidae and Cyprinodontidae are included. During the second half of 2019, a weekly monitoring is carried out in different locations of La Silla river, to analyze the current diversity of species, with the main goal of temporary comparisons and assessing how diversity has changed, both in richness of species as functional, in order to understand how anthropogenic changes, affect the health of the freshwater ecosystem. So far, it a tendency in the decrease of the specific richness is observed, produced, possibly, by the contamination of the river, as well as the decrease of the tributaries and the quality of the water.

ABSTRACT. The prairie rivers of the Great Plains have been altered significantly over the past century and these changes have disproportionately impacted the pelagic broadcast spawning guild of minnows. We used genetic monitoring time series data from microsatellites and mtDNA for Arkansas River Shiner, Notropis girardi, (2009-2019), Peppered Chub, Macrhybopsis tetranema, (2015-2018) and Plains Minnow, Hybognathus placitus, (2013-2015) to evaluate genetic status and trajectory of genetic change in these taxa. Genetic data was considered with reference to stream flow data and metrics of species density. Results indicate that the Canadian River harbors genetically diverse populations of these species despite losses of populations elsewhere. Metrics of genetic diversity were also stable across the time series for all taxa. Despite clear differences in contemporary abundance, all species have high values of haplotype diversity, consistently low values of nucleotide diversity and an excess of rare haplotypes. These results are indicative of populations that have experienced bottlenecks in the past but that have subsequently expanded rapidly. Despite all taxa having considerable standing stocks of genetic diversity, their persistence is not guaranteed. Populations that experience large fluctuations in abundance and have a narrow geographical distribution, face higher extinction risks than larger and more broadly distributed species. The presence of genetically diverse populations of all species in the Canadian River does however present an opportunity to establish captive populations using the Canadian River as a source. Captive populations of Peppered Chub and Arkansas River Shiner could serve as both an insurance policy for these taxa when drought conditions return to the southwest, and as a source of individuals for future reintroduction efforts.

ABSTRACT. In the past 100 years, many rivers in the southwest USA have dried up, but some reaches in these rivers have remained perennial due to the continuous input of effluent discharged by wastewater treatment facilities. The re-establishment of perennial reaches has brought back habitat for numerous aquatic and riparian taxa. However, because these reaches are artificially supported by effluent, flow regimes and water quality gradients may differ from former natural conditions and water quality below effluent outfalls may be a limiting factor in supporting native fish populations. The objective of this study was to quantify spatial and temporal changes in basic physical and chemical water quality parameters below the outfalls of three effluent-dependent rivers in Arizona: Santa Cruz (Tucson), Salt (Phoenix) and Rio de Flag (Flagstaff). Six reaches were studied; three reaches were short (~3-5 km), one was intermediate (~9 km), and two were long (>24 km). In 2018, we measured dissolved oxygen, temperature, pH, specific conductance, and nutrients at 26 river sites. In the long reaches, dissolved oxygen increased with distance from effluent outfalls, whereas temperature and ammonia concentration decreased; most other water quality variables did not exhibit clear longitudinal trends. No trends were apparent in the short reaches studied. In all reaches, most variables exhibited at least some seasonal variation; for example, in summer, dissolved oxygen and pH tended to decrease, whereas temperature increased. In all seasons, water quality conditions in most reaches were within ranges tolerated by native desert fishes. These findings help us understand the potential for managing effluent to augment perennial river habitats in arid regions.

ABSTRACT. Gila Trout, Oncorhynchus gilae, is a federally protected species that inhabits headwater streams of the Gila and San Francisco rivers in New Mexico and Arizona. Gila Trout occupy habitats that test the limits of their physiological tolerances. Severe droughts, floods, and wildfires present risks of local extirpation. Gila Trout is actively managed and past focus has been on preserving ‘purity’ of individual lineages. Now, genetic rescue and restoration of metapopulation dynamics are planned. Therefore, it is imperative to understand sources of genetic variation available to effectively conserve genetic diversity and existing population structure within Gila Trout. Using a dataset of 961 high-quality single nucleotide polymorphisms (SNPs), we characterized genetic diversity among all known lineages of Gila Trout. Gila Trout lineages are highly structured. Individual lineages contain low, yet unique, genetic diversity and low effective population sizes. Spruce Creek lineage had the lowest diversity with an expected heterozygosity estimate of 0.02 and 75% of loci monomorphic. Iron Creek lineage had the highest observed heterozygosity (0.30). All lineages were significantly differentiated from one another, but Iron Creek, Main Diamond Creek, and South Diamond Creek lineages showed the least differentiation relative to other lineages. A set of SNPs associated with genes related to immunity, ion homeostasis, growth, and thermal tolerances were also characterized and analyzed. Our data indicate evidence for local adaptation despite low genetically effective population sizes. The data suggest a management strategy focused on increasing genetic diversity while retaining the unique diversity within each lineage.

ABSTRACT. The endangered Devils Hole Pupfish, Cyprinodon diabolis, has persisted as a single population in Devils Hole, Nevada for an estimated ≥10,000 years. Twice on the brink of extinction during the past 15 years, adaptive conservation strategies have proven essential to its survival. The first population decline to under 40 fish in 2006 prompted the reconvening of the Devils Hole Recovery Team, a task force comprised of managers, researchers, and subject matter experts. This paved the way for the subsequent formation of the Devils Hole Incident Command and Management Oversight Teams (ICT/MOT). The ICT structure facilitates biologists and managers from the US National Park Service, US Fish and Wildlife Service, and Nevada Department of Wildlife who work directly with the species to formulate and execute management efforts in real time, with the MOT ultimately providing higher-level oversight. ICT members regularly communicate to guide minimal impact recovery planning for research, monitoring, and habitat restoration projects; public outreach; and partnerships with outside researchers to investigate underlying factors in past population declines and current trends. Recent successes include the largest population estimates since 2003 (187, 136, and 170 during fall 2018, spring 2019, and fall 2019, respective), record larval pupfish estimates, and new milestones in captive propagation, offering renewed hope of a positive trajectory for this unique desert fish.

ABSTRACT. Rangeland restoration in Far West Texas is a risky venture; failure lurks around every corner. Practitioners can increase the likelihood of success 1) by establishing reasonable goals and expectations, 2) by choosing sites with potential to respond, 3) when appropriate, by selecting species adapted to the site, and 4) by adopting management practices that promote the germination, establishment, and reproduction of the selected species.

ABSTRACT. The Trans-Pecos region of Texas, is a region of extremes where mountain ranges interrupt the Chihuahuan Desert, which is recognized as both the largest desert in North America and the most biologically diverse in the Western Hemisphere. With an average annual rainfall of only twelve inches, perennial water is derived primarily from freshwater springs sourced in local and regional aquifers. Freshwater springs, such as San Solomon, San Felipe, Caroline, Dolan, Giffin, and East Sandia springs, contribute substantially to the region’s water quantity and quality. In addition, these springs are ecologically important as they provide habitat for numerous rare and federally listed endemic species and are a vital water source that keeps regional and migratory fish and wildlife species common. The loss and decline of springs in the region has been well-documented and concern exists regarding the potential impacts associated with recent oil and gas discoveries and related activities in the region. The many challenges facing West Texas Springs and groundwater management will be discussed along with efforts to protect and conserve these vital resources.

ABSTRACT. The Rio Grande Wild and Scenic River (RIGR) starts in Big Bend National Park (BBNP) and extends 315 km to the Terrell/Val Verde county line. This segment of the Rio Grande benefits from a base flow increase provided by the Edwards Trinity Plateau Aquifer (ETPA), which is part of a binational aquifer system. The base flow increases start in BBNP, and continue through the Lower Canyons and on to Amistad reservoir. We initiated monitoring of this system in 2005 and continue to conduct annual monitoring trips to assess water quality, flow, geomorphology and aquatic habitat. Comprehensive seepage runs completed in 2006 and 2011 suggest a flow increase of ~8 and ~9 m3/s for the entire segment. All of this can be attributed to ground water input as there are no perennial tributaries and the field work was completed during low flow conditions with no local atmospheric input to the river. We have also analyzed existing stream gage data between Johnson Ranch and Foster Ranch using only data from low flow conditions for a similar groundwater inflow assessment. This 1962 to 2011 estimate yielded an increase of 6.4 m3/s. This estimate is lower than the seepage run data because it includes a shorter segment and excluded some of the downstream springs.

For comparison, a 1944 water treaty between the US and Mexico stipulates 13.7 m3/s (350,000 ac-ft/yr) in the Rio Grande. The ETPA in the RIGR contributes an additional ~8.5 m3/s (217,000 ac-ft/yr; an average of the two seepage runs). The water quality in the segment improves as a result of the groundwater inflows. The specific conductivity (SC) of the springs varies from ~350 uS/cm up to a maximum of 1000 uS/cm while the SC of the Rio Grande above the segment is rarely lower than 1000 uS/cm. The groundwater inflows result in a dilution effect with an overall increase in water quality. This increase in flow and water quality support the conclusion made in the Upper Rio Grande Basin and Bay Expert Science Team report that the area represents a Sound Ecological Environment with a functioning aquatic habitat.

ABSTRACT. Spring ecosystems serve as ecotones (i.e., transition zones between adjacent ecosystem types) between surface and subterranean as well as terrestrial and aquatic habitats. As ecotones, spring ecosystems often contain complex assemblages from multiple habitat and ecosystem types including spring obligate (crenic) taxa, subterranean taxa (hypogean), and more widespread surface water associated (epigean) species. This study examines patterns of resource and habitat use in the invertebrate communities at spring ecosystems in semi-arid and arid areas of central and west Texas, USA. We examined invertebrate food web structure and function at Comal Springs (central Texas), Finegan Springs (Devils River in west Texas) using stable isotopes of carbon (d13C), nitrogen (d15N) in organisms and their potential food sources. In the Comal and Finegan spring systems, endemic crenic and hypogean invertebrate species generally relied upon inputs of terrestrial organic matter (leaves and woody material) as their primary organic matter source, but more cosmopolitan epigean taxa relied upon algal-derived resources. We also found that the ecological niche (as determined by stable isotope values) of endemic crenic and hypogean species were narrow and exhibited little overlap with other species. We conducted a comparable study in several spring systems in the Davis Mountains region of west Texas (i.e., San Solomon systems) and similarly found that endemic and endangered spring obligate snail and amphipod fauna exhibit narrow ecological niches with little overlap with non-native invertebrates. Overall, our results indicate that invertebrate food webs found in spring ecotones exhibit a substantial trophic complexity and endemic fauna are finely partitioning food resources and exhibit narrow feeding niches. Results also highlight the importance of lateral connections to riparian zones as a source of organic matter for the macroinvertebrate communities in spring systems.

ABSTRACT. Freshwater resources in arid and semi-arid regions are in extreme demand, which creates conflicts between needs of humans and aquatic ecosystems. The Rio Grande basin in the southwestern United States and northern Mexico exemplifies this issue, as much of its aquatic biodiversity is currently in peril as a result of human activities. Unionid mussels have been disproportionately impacted, though the specific factors responsible for their decline remain largely enigmatic. This is problematic because the Rio Grande basin harbors three unionid mussel species (Potamilus metnecktayi, Salina mucket; Popenaias popeii, Texas hornshell; and Truncilla cognata, Mexican fawnsfoot), which are being considered for listing under the U.S. Endangered Species Act. To date, surveys for these species have not corrected for variability in detection; thus, current range estimates may be inaccurate. Using single occupancy-modeling to estimate detection and occupancy at 115 sites along ~ 800 river kilometers of the Rio Grande in Texas, we found that detection probabilities were relatively high, indicating that our survey design was efficient. In contrast, the estimated occupancy was low, indicating that our focal species were likely rare within the Rio Grande drainage. In general, the predicted occupancy of our focal species was reduced throughout their respective ranges, indicating possible range declines. A comparison of currently occupied ranges to presumptive ranges underscores this point. The best-approximating models indicated that occupancy was influenced by habitat, water quantity, and quality and proximity to large-scale human activities, such as dams and major urban centers. Our study provides important empirical evidence on the ecological implications of hydrologic alterations and land use on rare endemic mussel species and highlights the need for better management of semi-arid rivers. We also provide recommendations on conservation activities that may not only improve the long-term prognosis of our focal species but also other aquatic taxa within this basin.

ABSTRACT. Popenaias popeii (Texas Hornshell), is endemic to the Rio Grande drainage, in Texas and New Mexico, and to Mexico in select coastal streams. Currently, only four populations persist in the United States and its status within Mexico remains unknown. In 2018, USFWS listed Texas Hornshell as Endangered under the ESA. A number of factors have been implicated in the decline of this species including degraded water quality due to changes in land use, river impoundment, and ground water pumping, but none of these stressors have been explicitly tested. In particular, salinization of the Rio Grande and its tributaries has long been a concern due to the underlying geology, the effects of which have been exacerbated by agricultural practices, natural gas extraction, and river impoundments. In general, unionid mussels are considered sensitive to even low levels of salinity so increased salinization could be a major contributing factor to the decline of Texas Hornshell in the Rio Grande. The objective of this study was to determine the effects of various concentrations of salinity on survival of adult mussels of Texas Hornshell. We performed acute and chronic toxicity tests at various salinity concentrations for up to 10 days. We found that mussels exposed to concentrations above 4 ppt showed significant mortality, while concentrations below this showed no mortality. Our results demonstrate that Texas Hornshell is tolerant of salinization compared to other unionid mussel species. However, large segments of the Pecos and parts of the Rio Grande are near or exceed 4 ppt, which indicates that these reaches are becoming unsuitable and populations within them at risk.

ABSTRACT. Freshwater mussels are among the most imperiled groups of aquatic organisms in North America largely due to anthropogenic impacts, such as altered temperature regimes. Detailed knowledge on lethal temperatures for freshwater mussels has been limited to only 22 species, which is less than 10% of the species known to occur in North America, and relatively little is known about the thermal tolerance of mussel species inhabiting arid or semi-arid river systems. This lack of information is problematic because climate change coupled with increasing human water demand is expected to increase the frequency and intensity of droughts in these regions, which may negatively impact threatened mussel populations. To determine the effects of elevated water temperature on vulnerable mussel populations, we tested the upper thermal tolerances of the larval (glochidia) and juvenile life stages of Popenaias popeii (Texas Hornshell) from the Devils River, a species recently listed as Endangered under the U.S. Endangered Species Act. Mussels were acclimated to 27°C across a range of experimental temperatures (30 – 38 °C) in standard acute laboratory tests. The median lethal temperature (LT50) among populations in 24-h tests with glochidia averaged 32.0 °C and ranged from 31.1 to 32.7 °C. The LT50 in 96-h juvenile trials was 32.7 °C. Ongoing thermal trials will test P. popeii throughout its range in the Rio Grande basin.

ABSTRACT. Flow alteration impacts native river biota through multiple stressors, including altered disturbance regimes, water quality, and physical habitat. To understand the relative impacts of these different stressors on native fish communities in the Rio Grande, we examined how native fish richness responded to variation in flow, water quality, physical habitat, and non-native fish relative abundance in two reaches of the Rio Grande that differed in their degree of flow alteration. Flows in the Forgotten Reach (FR) have been completely altered from historic conditions, the historic channel has narrowed by 90%, and water quality is severely degraded. In the Big Bend, flows from the Rio Conchos provide higher baseflows than in the Forgotten Reach and periodic channel reset floods that temporarily widen the channel. In each reach, we identified all available fish sampling records at several common sampling points, and for each fish sample compiled information on flow levels, specific conductivity, water temperature, channel width, and nonnative fish relative abundance. We then developed and parameterized a structural equation model for each reach relating fish richness to hydrology, water quality, habitat, and non-native abundance variables. Comparison of the models between the two reaches revealed that width variation is a major factor driving native fish richness in Big Bend, where channel-widening floods occur, and where water quality is less impaired. In the Forgotten Reach, where channel-widening floods do not occur, small flow spikes and water quality are equally as important as habitat changes for native richness. Though additional research is needed, results suggest flow management to maintain channel width in the Big Bend is warranted if water quality is protected, whereas in the Forgotten Reach, habitat management may be ineffective without improvements in water quality.

ABSTRACT. The Pecos River drainage hosts three endemic species within Cyprinodon. Although their biogeography is fundamentally understood [Echelle & Echelle 1978, Copeia 1978(4):569-582; Echelle et al. 2005, Copeia 2005(2):320-339], this study provides an updated synthesis of essential details. The three species ultimately descend from the same widespread coastal ancestor, but directly descend from two separate geographic lineages of Pliocene age: (1) C. elegans from a lower Rio Grande branch, (2) C. pecosensis-bovinus from a Red River branch. The Rio Grande taxa evolved in a karst-dominated watershed and C. elegans eventually colonized springs, similar to relatives elsewhere. In the ancestral Pecos River drainage, these occurred in Cretaceous limestones cropping out across the slope northeast of the Davis and Glass mountains. In contrast, the Red River taxa evolved in sediment-laden plains rivers, within a region with widespread salt dissolution and high rates of evaporation. There, saline habitats (backwaters, wetlands, springs) were widespread and are still occupied by members of the Red River clade. The most recent common ancestor of C. pecosensis and C. bovinus (sister species) colonized the incipient Pecos River via stream capture. Although secondary contact between pupfishes of Rio Grande and Red River descent resulted in mtDNA introgression, the lineages remained distinct [Echelle et al. 2005, op. cit.]. Based on recent secondary contact of C. elegans with C. variegatus (an invasive species), habitat segregation was likely an important isolating mechanism, restricting hybridization to ecotones [Stevenson & Buchanan 1973, Copeia 1973(4):682-692; Echelle & Echelle 1994, Copeia 1994(3):590-597]. Captive breeding experiments indicate mate selectivity and hybrid sterility/inviability could have also been involved [Tech 2006, J. Evol. Biol. 19:1830-1837]. In contrast, representatives of the Red River clade lack reproductive isolation from C. variegatus [Wilde & Echelle 1992, Trans. Amer. Fish. Soc. 121(3):277-286; Echelle & Echelle 1997, Conserv. Biol. 11(1):153-161], consistent with a heritage of similar habitat use. Both endemic species require strict protection from introgression with the nonnative invader. Speciation of C. bovinus versus C. pecosensis reflects isolation of Leon Creek on a horst where C. bovinus is endemic. The horst became elevated above an otherwise subsiding, surrounding landscape. Ephemeral stream reaches between the horst and the Pecos River, possible dispersal barriers (i.e. vertical drops) at the horst boundary, and spring adaptation presumably explain interspecific reproductive isolation. Today, only residual habitats remain available to each of the three endemic species. All require conservation management, are severely imperiled, and—history suggests—could quickly disappear.

ABSTRACT. Native fishes in the American southwest are threatened by anthropogenic landscape alterations involving habitat destruction and dewatering. Consequently, many species are in need of conservation and status assessments are necessary for conservation planning. However, many conservation assessments are based on expert opinions or data available only to the researchers that develop status assessments. There is a need for repeatable, empirically-driven assessment frameworks that can be applied by multiple conservation entities and repeated as new data become available. We present a status assessment framework based on publically available geospatial data and apply this framework to native stream fishes occupying the Chihuahuan Desert region of the United States. Criteria included in the assessing were: (1) area occupied based on open access digital data from the Global Biodiversity Information facility; (2) abundance inferred from probability of occurrence modeled using landscape data and environmental niche modelling (ENM); (3) dependence on humans for persistence based on the percent of occurrences that fall within freshwater protected areas; (4) tolerance to environmental alteration based on cumulative habitat alterations at locations where species occur; (5) genetic risk based on the percent of habitat that is co-occupied by an non-native congener; (6) vulnerability to climate change based on expected climatic shifts where species occur; and (7) anthropogenic causes of declined based on ENM and geospatial data. Scores ranging 1-5 for each of these criteria were averaged to give a quantitative conservation status (1 = endangered; 5 = least concern) for 55 native species occupying the Chihuahuan Desert region of the United States. We present species status ranks and the major factors contributing to current conservation status and hope that Desert Fishes Council members with expert knowledge can provide their opinions.

ABSTRACT. The Texas Conservation Action Plan's (TCAP) purpose is to provide a statewide "roadmap" for research, restoration, management, and recovery projects addressing Species of Greatest Conservation Need (SGCN) and important habitats (TPWD 2012). There are 6 herps, 27 freshwater fishes, 30 invertebrates, and 27 plants SGCN’s in the Chihuahuan Desert Ecoregion that are aquatic-obligate or associated and another 5 mammals, 11 birds, 1 herp, and 1 invertebrate that are riparian-associated. Many of these species are dependent on groundwater-fed springs along the Rio Grande or it’s tributaries. Significant cross-taxa conservation threats and opportunities exist where multiple SGCN species occupy overlapping aquatic habitats such as the Lower Canyons of the Rio Grande or Dolan Falls on the Devil’s River.

ABSTRACT. The hydrologic health of uplands directly affects the health of riparian systems. The predominate land use in most arid uplands is livestock ranching. Planned grazing can improve the ecological health of uplands watersheds and the downstream riparian areas.

ABSTRACT. The Nature Conservancy has a deep history in conservation of aquatic ecosystems in the Chihuahuan Desert. This began with investment as a landowner and/or stakeholder in Texas, New Mexico, and several states of Mexico. In Texas, the Conservancy manages six major desert preserves, which protect habitat for at least nine endemic and endangered fishes as well as numerous invertebrates and plants. Development of science has also been a major goal, from an initial focus on natural heritage inventory, to ecoregional and local conservation planning, to targeted studies at preserves and watershed projects. Recently, in Texas this has taken on a focus on understanding ecosystem needs and balancing human needs with those of nature. In the Chihuahuan Desert we are collaborating with partners to better understand the groundwater-surface water interactions sustaining desert aquatic ecosystems to enable sustainable water management, even as Texas grows. The Conservancy is using this science to inform several conservation efforts that move beyond land protection to groundwater and surface water protection and restoration at scale. Developing understanding of springflow needs and underlying hydrogeology is informing groundwater policy and management. We also hope to help encourage sustainable approaches to energy development, including water use for hydraulic fracturing. Instream flow needs are also serving as targets for development of environmental water transactions and irrigation efficiency strategies.

ABSTRACT. With 95% of the land in Texas privately owned, conservation of the aquatic resources is particularly daunting and is exemplified by the fact that 48% of the 191 native freshwater fishes in Texas are now of conservation concern. Partnerships with private landowners is not only sensible, but often the only way to achieve long-term conservation goals. In the Chihuahuan Desert region of Texas, 55% of the native fishes are of conservation concern or already lost to extirpation or extinction. Although there are numerous contributing factors, habitat degradation and loss are the primary culprits. For decades, research and restoration have focused on some of the more imperiled species and their habitats. From reestablishing ciénegas, to landowner partnerships, to Conservation Agreements, much has been accomplished. Unfortunately, the challenges increase faster than our accomplishments. Our latest, and most promising, approach has been to develop six Native Fish Conservation Areas in the Chihuahuan Desert. These NFCAs represent an ecologically-focused conservation prioritization of watershed segments that serve as native fish “strongholds” and they function as priority areas for conservation investments to promote integrated, holistic conservation strategies that enable the long-term persistence of freshwater biodiversity. Current and future conservation of aquatic resources in Texas emphasizes a landscape-scale approach, working primarily with private landowners to provide conservation best management practices and support on-the-ground projects to maintain or restore habitats to sustain functional ecosystems.