The lower Pecos River located in the southwest USA, is a naturally saline river system that has been significantly altered in relatively recent years. Climate change, coupled with anthropogenic disturbances such as dam construction have led to portions of the river becoming more susceptible to increased salinization and declines in water quality. These alterations have been documented to be detrimental to multiple freshwater communities; however, there is a lack of knowledge on how these alterations influence long-lived species in the river, such as freshwater turtles, where the effects can appear over dramatically different temporal scales. The Rio Grande Cooter (Pseudemys gorzugi) is a species of concern known to occur in the Pecos River. To understand the current distribution and habitat requirements for P. gorzugi in the Pecos River, we used a single-season, single-species occupancy modeling framework to estimate occurrence while accounting for the sampling process. Day of year, water surface area, and water visibility had the greatest influence on the ability to detect the species given a sampling unit is occupied. Conductivity (a measure of salinity) had the greatest influence on the occupancy probability for the species, where sites with higher conductivity coincided with lower occupancy probabilities. This study indicates that increased salinization on the lower Pecos River is a cause for concern regarding freshwater turtle populations within the Chihuahuan Desert.

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T exas, USA, harbors a rich amphibian fauna, including 44 anuran species and 27 caudate species from a total of 15 families (Tipton et al. 2012;Dixon 2013). This diversity can likely be attributed to the large size of the state (67,805,143 ha) and the variety of habitats it contains. Elevation and average annual precipitation differ dramatically across Texas, ranging from 0-2,667 m and 113-1,597 mm, respectively (Ghebreyesus and Sharif 2021). As a result, myriad habitat types occur throughout the state such as coniferous forests, deciduous forests, shrublands, plains, and desert. Aquatic habitats are likewise variable and include large reservoirs, rivers, creeks, ponds, swamps, aquifers, and springs -all of which harbor amphibians.Globally, amphibian populations are severely declining (Stuart et al. 2004) and extant populations are often impacted by multiple pressures including habitat loss (Gallant et al. 2007), fungal pathogens (Lips 2016; Stegen et al. 2017), climate change (Menéndez-Guerrero and Graham 2013), chemical pollution (Davidson et al. 2002; Zocche et al. 2013), and the introduction of non-native predators (Kats and Ferrer 2003). Texas contains several imperiled amphibian taxa including four federally endangered species, four federally threatened species, and an additional nine species that are not listed at the federal level, but are designated as either threatened or endangered by the Texas Parks and Wildlife Department. Federally endangered species include the Austin Blind Salamander (Eurycea waterlooensis), the Barton Springs Salamander (Eurycea sosorum), the Texas Blind Salamander (Eurycea rathbuni), and the Houston Toad (Anaxyrus houstonensis). Federally threatened species include the Georgetown Salamander (Eurycea naufragia), the Jollyville Plateau Salamander (Eurycea tonkawae), the Salado Salamander (Eurycea chisholmensis), and the San Marcos Salamander (Eurycea nana).Distributional data for amphibian species can be useful for informing research, management, and conservation. For example, presence-only data can be used to develop habitat suitability models (Préau et al. 2018), historical distribution records allow for quantitative measures of range contraction

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