Delineating Source Areas to Cave Drips and Cave Streams in Austin, Texas, USA

Groundwater-dependent species are among the least-known components of global biodiversity, as well as some of the most vulnerable because of rapid groundwater depletion at regional and global scales. The karstic Edwards–Trinity aquifer system of west-central Texas is one of the most species-rich groundwater systems in the world, represented by dozens of endemic groundwater-obligate species with narrow, naturally fragmented distributions. Here, we examine how geomorphological and hydrogeological processes have driven population divergence and speciation in a radiation of salamanders (Eurycea) endemic to the Edwards–Trinity system using phylogenetic and population genetic analysis of genome-wide DNA sequence data. Results revealed complex patterns of isolation and reconnection driven by surface and subsurface hydrology, resulting in both adaptive and nonadaptive population divergence and speciation. Our results uncover cryptic species diversity and refine the borders of several threatened and endangered species. The US Endangered Species Act has been used to bring state regulation to unrestricted groundwater withdrawals in the Edwards (Balcones Fault Zone) Aquifer, where listed species are found. However, the Trinity and Edwards–Trinity (Plateau) aquifers harbor additional species with similarly small ranges that currently receive no protection from regulatory programs designed to prevent groundwater depletion. Based on regional climate models that predict increased air temperature, together with hydrologic models that project decreased springflow, we conclude that Edwards–Trinity salamanders and other codistributed groundwater-dependent organisms are highly vulnerable to extinction within the next century.

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“…springs in the Cypress Creek watershed (103,104) that may allow for gene flow between these separate drainages.…”

Section: Discussionmentioning

confidence: 99%

Species delimitation in endangered groundwater salamanders: Implications for aquifer management and biodiversity conservation

Devitt

Wright

Cannatella

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

100

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“…Driprate was not measured continuously at MR-Waterfall as the discharge at that site greatly exceeds the capacity of the tipping buckets during rain events. To collect enough drip water Ranch Cave (BR) have been delineated (Hauwert and Cowan, 2013) and no discrete recharge features, such as sink holes or open apertures in the bedrock, are known to exist within their catchment areas. The majority of the delineated catchment areas are overlain by soils, and at Goat Cave and Maple Run Cave, by some impervious cover (roads and houses).…”

Section: Study Areamentioning

confidence: 99%

Use of Physical and Chemical Response in Cave Drips to Characterize Upland Recharge in the Barton Springs Segment of the Edwards Aquifer, Central Texas, USA

Cowan¹,

Hauwert²

2013

Full Proceedings of the Thirteenth Multidisciplinary Conference on Sinkholes and the Engineering and Environmental Impacts of K

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Cave drips are useful for characterizing recharge and transport through soils, particularly in upland karst settings. Estimation of upland recharge is important for the Barton Springs Segment (BSS) of the Edwards Aquifer, but discrepancies between previous and recent studies indicate how little is known about it in the BSS. We outline a methodology for using cave drips to characterize upland recharge and present initial findings from a study of drips in four BSS caves.

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Delineating Source Areas to Cave Drips and Cave Streams in Austin, Texas, USA

Cited by 2 publications

References 12 publications

Species delimitation in endangered groundwater salamanders: Implications for aquifer management and biodiversity conservation

Species delimitation in endangered groundwater salamanders: Implications for aquifer management and biodiversity conservation

Use of Physical and Chemical Response in Cave Drips to Characterize Upland Recharge in the Barton Springs Segment of the Edwards Aquifer, Central Texas, USA

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