Conservation of Texas Spring and Cave Salamanders (Eurycea)

Chippindale, Paul T.; Price, Andrew H.

doi:10.1525/california/9780520235922.003.0027

Cited by 13 publications

(11 citation statements)

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“…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). Threats to E. sosorum are exacerbated by its small range and include vulnerability to catastrophic spills over the karst aquifer, declining water quality from development, anthropogenically modified habitat, and declines in water quantity from pumping and climate change (Chippindale & Price, ; Chippindale et al., ; Stamm et al., ; U.S. Fish and Wildlife Service , ).…”

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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“…Within the Edwards Plateau of central Texas, thirteen salamander species (genus Eurycea , clade Paedomolge , sensu Hillis, Chamberlain, Wilcox, & Chippindale, ) inhabit a range of karst‐associated aquatic habitats, from hillside seeps to large springs and expansive stream networks both above and below ground (Chippindale, Price, Wiens, & Hillis, ; Sweet, ; Sweet, ). Seven species in this group are federally listed as threatened or endangered, and have small distributions within and around urbanized and rapidly developing areas (Chippindale & Price, ; US Fish and Wildlife Service , ). However, detailed information on reproductive phenology, population demographics, and life history for this group is limited (but see Bruce, ; Tupa & Davis, ; Pierce, McEntire, & Wall, ).…”

Section: Introductionmentioning

confidence: 99%

“…BENDIK areas (Chippindale & Price, 2005; Wildlife Service 2013, 2014a). However, detailed information on reproductive phenology, population demographics, and life history for this group is limited (but see Bruce, 1976;Tupa & Davis, 1976;Pierce, McEntire, & Wall, 2014).…”

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confidence: 99%

Demographics, reproduction, growth, and abundance of Jollyville Plateau salamanders (Eurycea tonkawae)

Bendik¹

2017

Ecology and Evolution

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Insights into the ecology and natural history of the neotenic salamander, Eurycea tonkawae, are provided from eight years of capture‐recapture data from 10,041 captures of 7,315 individuals at 16 sites. Eurycea tonkawae exhibits seasonal reproduction, with peak gravidity occurring in the fall and winter. Size frequency data indicated recruitment occurred in the spring and summer. Open‐population capture‐recapture models revealed a similar seasonal pattern at two of three sites, while recruitment was dependent on flow at the third site. Females can reach sexual maturity within one year, and oviposition likely takes place below ground. The asymptotic body length of 1,290 individuals was estimated as 31.73 mm (at ca. two years of age), although there was substantial heterogeneity among growth trajectories. Longevity was approximately eight years, and the median age for a recaptured adult was 2.3 years. Abundance estimated from closed‐population and robust‐design capture‐recapture models varied widely within and among sites (range 41–834), although, surprisingly, dramatic changes in abundance were not observed following prolonged dry periods. Seasonal migration patterns of second‐year and older adults may help explain lower ratios of large individuals and higher temporary emigration during the latter half of the year, but further study is required. Low numbers of captures and recaptures precluded the use of open‐population models to estimate demographic parameters at several sites; therefore, closed‐population (or robust‐design) methods are generally recommended. Based on observations of their life history and population demographics, E. tonkawae seems well adapted to conditions where spring flow is variable and surface habitat periodically goes dry.

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“…Karst fauna exemplify species that are both cryptic (in the evolutionary and ecological sense) and rare, and are often of conservation concern due to their high rates of endemicity and sensitivity to environmental perturbations ( Culver et al, 2000 ). Among the many dozens of endemic karst fauna inhabiting the Edwards Plateau of central Texas ( Reddell, 1994 ) is a unique group of aquatic salamanders (genus Eurycea ), several of which have been at the center of highly publicized, political conflicts over development and the Endangered Species Act ( Krausse, 1989 ; Haurwitz, 1993 ; Haurwitz, 1995 ; Chippindale & Price, 2005 ; Wermund, 2012 ). Many are federally listed with or without designated critical habitat ( E. tonkawae , E. nana , E. waterlooensis, E. sosorum , E. rathbuni ), are candidates for listing ( E. latitans , E. neotenes , E. sp.…”

Section: Introductionmentioning

confidence: 99%

Movement, demographics, and occupancy dynamics of a federally threatened salamander: evaluating the adequacy of critical habitat

Bendik¹,

McEntire

Sissel³

2016

PeerJ

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Critical habitat for many species is often limited to occupied localities. For rare and cryptic species, or those lacking sufficient data, occupied habitats may go unrecognized, potentially hindering species recovery. Proposed critical habitat for the aquatic Jollyville Plateau salamander (Eurycea tonkawae) and two sister species were delineated based on the assumption that surface habitat is restricted to springs and excludes intervening stream reaches. To test this assumption, we performed two studies to understand aspects of individual, population, and metapopulation ecology of E. tonkawae. First, we examined movement and population demographics using capture-recapture along a spring-influenced stream reach. We then extended our investigation of stream habitat use with a study of occupancy and habitat dynamics in multiple headwater streams. Indications of extensive stream channel use based on capture-recapture results included frequent movements of >15 m, and high juvenile abundance downstream of the spring. Initial occupancy of E. tonkawae was associated with shallow depths, maidenhair fern presence and low temperature variation (indicative of groundwater influence), although many occupied sites were far from known springs. Additionally, previously dry sites were three times more likely to be colonized than wet sites. Our results indicate extensive use of stream habitats, including intermittent ones, by E. tonkawae. These areas may be important for maintaining population connectivity or even as primary habitat patches. Restricting critical habitat to occupied sites will result in a mismatch with actual habitat use, particularly when assumptions of habitat use are untested, thus limiting the potential for recovery.

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Conservation of Texas Spring and Cave Salamanders (Eurycea)

Cited by 13 publications

References 0 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

Demographics, reproduction, growth, and abundance of Jollyville Plateau salamanders (Eurycea tonkawae)

Movement, demographics, and occupancy dynamics of a federally threatened salamander: evaluating the adequacy of critical habitat

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