THE EDWARDS AQUIFER and its Unique Ecosystem

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THE EDWARDS AQUIFER and its Unique Ecosystem
potential threats from Groundwater Management
Glenn Longley Director Edwards Aquifer Research
Data Center
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Outline

• Hydrologic Setting of Edwards (BFZ) Aquifer
• Unique Aquatic Ecosystem
• History of Management
• Current work
• Summary
• Contact information

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Edwards AquiferSan Antonio portion of FZ

• Elevation near 575 feet ?

SM spgs
Comal spgs
Elevation near 1400 feet ?
SA spgs
Watershed Recharge Zone Artesian Zone
Leona spgs
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San Marcos Springs
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Barton Springs Segment (BFZ) Aquifer
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Unique? How?

• 40 species of Invertebrates
• 4 species of Vertebrates

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Discoveries made in the last 20 years

• Diversity of Amphipods, snails overall
• Presence of marine relicts
• Monodella
• Some amphipod families
• Foraminiferans
• New species, deep aquifer system
• More detailed information about vertebrates

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Community diversity

• Greatest in Amphipods (12 species-5 families)
• Other Arthropods (13 species representing 8
  families)
• Next is Mollusca (10 species of Hydrobiid snail
  family)

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More about diversity

• Biological diversity is important - Ecological
  stability
• The species in this system may hold important
  genetic information

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Marine relicts

• Amphipods in the families Hadziidae,
  Bogidiellidae, Sebidae
• These families are primarily marine with few
  examples of freshwater sp.
• Hadziids are distributed today around the
  Caribbean and Mediterranean
• These areas are important as remnants of the
  Tethys Sea

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Marine relicts

• May assist in better understanding of how the
  aquifer formed and its relationship with
  paleomarine areas
• Additional studies of these species will shed
  light on paleogeography

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Other marine relicts in the Aquifer

• Monodella texana (Only N.A. Thermosbaenacean)
• M. texanas marine ancestors are represented by
  groups in the W. Indies
• A Foraminiferan from the Lagenidae (Probably
  Robulus sp) was found

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Other marine relicts continued

• Foraminiferans have only been found in fresh
  water from wells (Trans Caspian Province)
• Cirolanid isopods (predominantly marine) are also
  found

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New species

• 8 new snails, 2 others renamed
• 10 new amphipods, 1 new family (Artesiidae)
• 1 new aquatic beetle - Hadeoporus texanus (larvae
  adult described)
• 1 new vertebrate described - Typhlomolge robusta

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Flowing Edwards well with biomass being
discharged southwest of San Antonio, Texas
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Texas State University Artesian Well

• Drilled in 1895 to furnish water for Federal Fish
  Hatchery
• Five foot cavern at 195 feet
• Source of water is Edwards Aquifer
• Sampled continuously since early 70s

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64 micron mesh net on 12 discharge with
removable sample chamber
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Two day sample out of Texas State Artesian well
net
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Filamentous colonies of fungi and other organisms
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Placing a net on flowing well at San Antonio Zoo
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Invertebrate Fauna

• TURBELLARIA (Flatworms)
• Kenkiidae
• Sphalloplana mohri Hyman
• NEMATODA (Roundworms)
• Rhabdochonidae
• Rhabdochona longleyi Moravec Huffman

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Sphalloplana mohri
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Gastropods (Snails)

• Hydrobiidae
• Phreatodrobia conica Hershler Longley Hueco
  cavesnail
• P. coronae Hershler Longley
• P. imitata Hershler Longley mimic cavesnail
• P. micra (Pilsbry Ferris) flattened cavesnail
• P. nugax inclinata Hershler Longley
• P. nugax nugax (Pilsbry Ferris) domed
  cavesnail

• P. plana Hershler Longley disc cavesnail
• P. punctata Hershler Longley high-hat cavesnail
• P. rotunda Hershler Longley beaked cavesnail
• Phreatoceras taylori Hershler Longley nymph
  trumpet
• Balconorbis uvaldensis Hershler Longley
  Balcones ghostsnail
• Stygopyrgus bartonensis Hershler Longley Barton
  cavesnail
• Texapyrgus longleyi Thompson Hershler striated
  hydrobe

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HIRUDINEA(Leeches)

• Erpobdellidae
• Mooreobdella microstoma Pawlowski

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Crustaceans

• ISOPODA
• Cirolanidae
• Caecidotea reddelli (Steeves)
• Cirolanides texensis Benedict
• Asellidae
• Lirceolus pilus (Steeves)
• L. smithi (Ulrich) Texas troglobitic Water Slater
• Mexistenasellus sp.

• OSTRACODA Entocytheridae
• Sphaeromicola (Hobbsiella) moria
• Hart

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Asellid Isopod
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Mexistenasellus sp.
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AMPHIPODS

• Hadziidae
• Allotexiweckelia hirsuta Holsinger
• Holsingerius samacos (Holsinger)
• Texiweckelia texensis (Holsinger)
• Texiweckeliopsis insolita (Holsinger)

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Amphipods continued

• Stygobromus balconis (Hubricht)
• Crangonyctidae
• S. bifurcatus (Holsinger)
• S. flagellatus (Benedict)
• S. pecki (Holsinger)
• S. russelli (Holsinger)

• Sebidae
• Seborgia relicta Holsinger
• Bogidiellidae
• Artesia subterranea Holsinger
• Parabogidiella americana Holsinger

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Stygobromus sp.
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CRUSTACEANS continued

• THERMOSBAENACEA
• Monodellidae
• Monodella texana Maguire

• DECAPODA
• Palaemonidae
• Palaemonetes antrorum Benedict
• P. holthuisi Strength

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Monodella texana
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Paleomonetes antrorum
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COLEOPTERA(Insect beetles)

• Dryopidae
• Stygoparnus comalensis Barr Spangler
• Dytiscidae
• Comaldessus stygius Spangler Barr
• Haideoporus texanus Young Longley Edwards
  Aquifer water beetle

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Haideoporus texanus
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VERTEBRATESPISCES (Fish)

• Ictaluridae
• Satan eurystomus Hubbs Bailey Widemouth
  blindcat
• Trogloglanis pattersoni Eigenmann Toothless
  blindcat

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Satan eurystomus
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Trogloglanis pattersoni

• Toothless blindcat
• Found in same area of Widemouth Blindcat
• Shallowest collection 1350 below surface
• Deepest 2000
• Only below San Antonio TX area

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CAUDATATailed amphibians

• Plethodontidae
• Eurycea chisholmensis Chippindale, Price Hillis
  Salado salamander
• E. latitans Smith Potter
• Cascade Caverns salamander
• E. naufragia Chippindale, Price Hillis
• E. sp.nov. Comal
• E. nana Bishop
• San Marcos salamander
• E. neotenes Bishop Wright
• Texas salamander
• E. pterophila Burger, Smith Potter
• Fernbank salamander
• E. rathbuni (Stejneger)
• Texas Blind salamander

• E. robusta (Longley)
• Blanco Blind salamander
• E. sosorum Chippindale, Price Hillis
• Barton Springs salamander
• E. tonkawae Chippindale, Price HillisJollyville
  salamander
• E. tridentifera Mitchell Reddell
• Comal blind salamander
• E. troglodytes Baker
• Valdina Farms salamander
• E. sp.
• Comal Springs salamander

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Eurycea rathbuni Texas Blind Salamander
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• San Antonio portion of the Balcones Fault Zone
  Edwards Aquifer

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Bexar Co. Texas Catfish Well flows at gt 30 MGD
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History of Management

• 1983 - EUWD given authority to regulate transport
  of water out of district (5 counties)
• 1987 EUWD gains legislative approval for a
  drought management plan (DMP)
• 1988-90 DMP requirements set
• 1989 Two western Counties withdraw from
  District
• May 1991 SA defeats construction of Applewhite
  Reservoir (Alternate source)
• May 1991 Sierra Club files suit against USFWS

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History Continued

• Sierra Club suit asks that USFWS be required to
  insure min. springflow to protect endangered
  species.
• EUWD and SARA file suit against Living Waters
  (Catfish Well owners) for waste and water quality
  issues.
• 1992 TWC declares Edwards Aquifer to be an
  underground river, therefore regulated by the
  state
• Later that year State Court invalidates TWCs
  determination

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History continued

• Nov 16, 1992 Trial begins in U.S. District Court
  for Sierra Club lawsuit.
• Jan 30, 1993 U.S. Dist. Judge Bunton rule for
  the Sierra Club and orders
• Springflow must be maintained
• TWC must submit plan to court by March 1993 to
  assure Comal San Marcos Springs do not drop
  below Jeopardy levels
• USFWS must develop springflow thresholds for take
  jeopardy
• Tx Legislature must develop regulations to limit
  withdrawals by May 31, 1993.

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History continued

• May 30, 1993 Texas Legislature adopts SB 1477
  that creates the Edwards Aquifer Authority (EAA)
  with a 9 member appointed board
• Aug. 30, 1993 U. S. Justice Dept. ruled
  legislation may have violated the Voting Rights
  Act, in November they determined it did
• Feb. 1994 Fed. Court Appointed monitor to
  gather information for the court.

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Hydrologic

• Less storage in aquifer (1ft of head approx.
  35,000 acre feet).
• Low flows of San Marcos Springs occur sooner
  during critical dry periods.
• Greater potential for saline water intrusion
  during critical periods.

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Ecological

• Lower flows would possibly jeopardize listed
  species sooner.

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Threats to the system

• Historic lows vs. recent time (recharge
  discharge)
• Increasing water use
• Aquifer Storage recovery
• Proposed policy to raise pumping caps
• Proposed policy to limit minimal pumping required
  during drought

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Summary
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Detailed studies (Past Continuing)

• Texas Blind Salamander - Typhlomolge rathbuni
• Two blindcatfish from San Antonio area Satan
  eurystomus Trogloglanis pattersoni
  (Ictaluridae)
• Distribution of species throughout the aquifer,
  important in showing hydrologic relationships

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Studies currently underway

• Water Quality - investigating freshwater/saline
  water interface
• Modeling of groundwater hydrology and the effect
  of pumping

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This system is a microcosm of problems in our
world

• Population growth and human demands threaten the
  system and the surface ecosystems (springs) it
  supports
• We should educate the users of water from the
  aquifer about its dynamics
• Its importance as the habitat for a community of
  organisms

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Additional studies needed

• Biomagnification of contaminants up the aquifer
  food chain
• Toxicity studies of specific members of the
  aquifer community
• Additional studies of rarer species
• Energy flow and sources in the deep confined
  aquifer

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Acknowledgements

• The work on the aquifer through the years has
  been supported by USFWS, TPWD, USDA, USEPA and
  numerous other sources too numerous to mention.
• Staff of the Research Center, Graduate Students,
  Collaborators and numerous others have assisted
  in developing the information about the Aquifer
  community.
• Texas State University has been very supportive
  of this work.

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Thank you!

• I can be reached at the following
• email GL01_at_txstate.edu
• EARDC homepage http//www.eardc.txstate.edu
• Phone [phone]
• Fax [phone]
• Feel free to contact me with questions.