New occurrence records for Eurycea sosorum Chippindale, Price &amp;amp; Hillis, 1993 (Caudata, Plethodontidae) in Travis and Hays counties, Texas, USA

Devitt, Thomas J.; Nissen, Bradley D.

doi:10.15560/14.2.297

Cited by 6 publications

(10 citation statements)

References 7 publications

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“…Population monitoring of the endangered Barton Springs Salamander ( Eurycea sosorum ; Figure ) has been ongoing for well over two decades, as the species was initially described from springs that feed a public swimming pool in Austin, Texas (Chippindale, Price, & Hillis, ). Eurycea sosorum is neotenic and is endemic to four main spring outlets of Barton Springs, as well as the contributing aquifer and springs within its watershed (Devitt & Nissen, ). The species is easily observed around spring outlets, but is rarely seen in abundance of more than a dozen individuals at most sites (with the exception of two spring outlets).…”

Section: Introductionmentioning

confidence: 99%

Density‐dependent and density‐independent drivers of population change in Barton Springs salamanders

Bendik¹,

Dries²

2018

Ecology and Evolution

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Understanding population change is essential for conservation of imperiled species, such as amphibians. Worldwide amphibian declines have provided an impetus for investigating their population dynamics, which can involve both extrinsic (density‐independent) and intrinsic (density‐dependent) drivers acting differentially across multiple life stages or age classes. In this study, we examined the population dynamics of the endangered Barton Springs Salamander (Eurycea sosorum) using data from a long‐term monitoring program. We were interested in understanding both the potential environmental drivers (density‐independent factors) and demographic factors (interactions among size classes, negative density dependence) to better inform conservation and management activities. We used data from three different monitoring regimes and multivariate autoregressive state‐space models to quantify environmental effects (seasonality, discharge, algae, and sediment cover), intraspecific interactions among three size classes, and intra‐class density dependence. Results from our primary data set revealed similar patterns among sites and size classes and were corroborated by our out‐of‐sample data. Cross‐correlation analysis showed juvenile abundance was most strongly correlated with a 9‐month lag in aquifer discharge, which we suspect is related to inputs of organic carbon into the aquifer. However, sedimentation limited juvenile abundance at the surface, emphasizing the importance of continued sediment management. Recruitment from juveniles to the sub‐adult size class was evident, but negative density‐dependent feedback ultimately regulated each size class. Negative density dependence may be an encouraging sign for the conservation of E. sosorum because populations that can reach carrying capacity are less likely to go extinct compared to unregulated populations far below their carrying capacity. However, periodic population declines coupled with apparent migration into the aquifer complicate assessments of species status. Although both density‐dependent and density‐independent drivers of population change are not always apparent in time series of animal populations, both have important implications for conservation and management of E. sosorum.

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Section: Introductionmentioning

confidence: 99%

Density‐dependent and density‐independent drivers of population change in Barton Springs salamanders

Bendik¹,

Dries²

2018

Ecology and Evolution

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“…However, the extent to which local population persistence contributes to the conservation status of the species as a whole is uncertain. Newly documented localities for Barton Springs salamanders ( Devitt & Nissen, 2018 ) expand the known range of this species by (potentially) hundreds of square km within the Barton Springs segment of the Edwards Aquifer and the adjacent Trinity Aquifer. One individual was captured deep within a well ( McDermid, Sprouse & Krejca, 2015 ), while others have been regularly observed within a cave stream that eventually flows to Barton Springs (Blowing Sink Cave; Bendik et al, 2013a ; City of Austin, 2018a ).…”

Section: Discussionmentioning

confidence: 99%

“…One individual was captured deep within a well ( McDermid, Sprouse & Krejca, 2015 ), while others have been regularly observed within a cave stream that eventually flows to Barton Springs (Blowing Sink Cave; Bendik et al, 2013a ; City of Austin, 2018a ). Data on abundance and density for populations outside of Barton Springs are scarce and difficult to obtain, but available evidence suggests that both population density and spatial density (number of sites/area) both appear to be lower outside of the Barton Springs complex ( Devitt & Nissen, 2018 ; Dries & Colucci, 2018 ; City of Austin, 2018a ). While this observation is partly biased by our inability to adequately explore subterranean habitats, it underscores the need to understand how populations at the endpoint of the Barton Springs system interact with other, lower density populations throughout their range.…”

Section: Discussionmentioning

confidence: 99%

“…Following its description, in 1997 this species was listed as endangered under the US Endangered Species Act of 1973 due to its exceptionally small range (at the time, known from only three springs in a city park) and presumed low abundances ( Chippindale, Price & Hillis, 1993 ; City of Austin, 1997 ; US Fish and Wildlife Service, 1997 ). Although additional occurrences of this species have subsequently been recorded outside of the type locality ( Bendik et al, 2013a ; McDermid, Sprouse & Krejca, 2015 ; Devitt & Nissen, 2018 ), abundances at those sites are lower and surface habitat is more limited in extent compared to Barton Springs. Abundances can be high at the type locality (e.g., >500 individuals) but may fluctuate by orders of magnitude and occasionally reach zero, or nearly so ( Bendik & Dries, 2018 ; Dries & Colucci, 2018 ).…”

Section: Introductionmentioning

confidence: 99%

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Subterranean movement inferred by temporary emigration in Barton Springs salamanders (Eurycea sosorum)

Bendik¹,

Chamberlain²,

Devitt

et al. 2021

PeerJ

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Movement behavior is an important aspect of animal ecology but is challenging to study in species that are unobservable for some portion of their lives, such as those inhabiting subterranean environments. Using four years of robust-design capture-recapture data, we examined the probability of movement into subterranean habitat by a population of endangered Barton Springs salamanders (Eurycea sosorum), a species that inhabits both surface and subterranean groundwater habitats. We tested the effects of environmental variables and body size on survival and temporary emigration, using the latter as a measure of subterranean habitat use. Based on 2,046 observations of 1,578 individuals, we found that temporary emigration was higher for larger salamanders, 79% of which temporarily emigrated into subterranean habitat between primary sampling intervals, on average. Body size was a better predictor of temporary emigration and survival compared to environmental covariates, although coefficients from lower ranked models suggested turbidity and dissolved oxygen may influence salamander movement between the surface and subsurface. Surface population dynamics are partly driven by movement below ground and therefore surface abundance estimates represent a fraction of the superpopulation. As such, while surface habitat management remains an important conservation strategy for this species, periodic declines in apparent surface abundance do not necessarily indicate declines of the superpopulation associated with the spring habitat.

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“…Although initially considered a primarily surface-dwelling species, the description of E. sosorum noted that the species is morphologically intermediate between surface-dwelling and subterranean salamander populations [17]. Recent research has confirmed that the species uses both surface and subterranean groundwater extensively [12,20,39,40]. Because our landmark configurations were the same for both E. sosorum and E. waterlooensis, separate PCAs were directly comparable, and we noted that variation is more complex for E. sosorum.…”

Section: Discussionmentioning

confidence: 99%

Phenotypic Variation in Endangered Texas Salamanders: Application of Model-Based Clustering for Identifying Species and Hybrids

et al. 2020

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The endangered Barton Springs and Austin blind salamanders (Eurycea sosorum and E. waterlooensis, respectively) are micro-endemics to the Barton Springs segment of the Edwards Aquifer and its contributing zone in Central Texas. Although vertically segregated within the aquifer system, both species are known from the same spring outflows and occasionally hybridize. We used geometric morphometrics and model-based clustering applied to a large sample of standardized salamander photographs to evaluate the potential for objective phenotypic assignment to either species, as well as putative hybrids. In addition to characterizing variation in head shape, our analyses inferred sets of clusters corresponding to ontogenetic series in both species but did not infer any distinct hybrid clusters. Eurycea sosorum and E. waterlooensis have distinctive head size to trunk length allometries, which contributed to the effective clustering of species, even at small body sizes. We also observed subtle, but significant, microgeographic variation in E. sosorum, suggesting the possibility of population substructuring, phenotypic plasticity, or undetected hybridization.

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New occurrence records for Eurycea sosorum Chippindale, Price & Hillis, 1993 (Caudata, Plethodontidae) in Travis and Hays counties, Texas, USA

Cited by 6 publications

References 7 publications

Density‐dependent and density‐independent drivers of population change in Barton Springs salamanders

Density‐dependent and density‐independent drivers of population change in Barton Springs salamanders

Subterranean movement inferred by temporary emigration in Barton Springs salamanders (Eurycea sosorum)

Phenotypic Variation in Endangered Texas Salamanders: Application of Model-Based Clustering for Identifying Species and Hybrids

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