What We Do

The mission of the San Marcos Aquatic Resources Center is to support conservation efforts through applied research on species that are endangered, threatened, and at risk. The center is a refugium – or safe harbor – for endangered species. Major consideration is placed on assessment of biological issues related to the springs of the Edwards Aquifer and other west Texas spring systems.

Management and Conservation

Our activities include 

  1. collection, maintenance, and propagation of rare, threatened, or endangered fishes, amphibians, plants, and invertebrates;   2.
  2. research on life history, ecological requirements, genetics, and culture of Edwards Aquifer organisms;  
  3. research on restoration of refugium species;  
  4. collection of biological information on the region’s aquatic biological resources;  5.
  5. research related to invasive species invasive species
    An invasive species is any plant or animal that has spread or been introduced into a new area where they are, or could, cause harm to the environment, economy, or human, animal, or plant health. Their unwelcome presence can destroy ecosystems and cost millions of dollars.

    Learn more about invasive species     in aquatic ecosystems, especially involving listed species;  
  6. critical habitat restoration;  
  7. research on life history and culture of listed aquatic west Texas species;  8.
  8. troubleshooting problems at other hatcheries; and 
  9. training hatchery personnel. 

Our Projects and Research

We use science and innovative technology to drive our management and conservation of aquatic resources. And we work collaboratively with partners to effectively meet today’s complex conservation challenges 

Our Aquatic Ecology and Conservation Program studies multiple species that are not the primary focus of traditional fisheries programs, including insects, crustaceans, mollusks, salamanders, and toads.  

Our Edwards Aquifer Species Conservation program supports species endemic to the Edwards Aquifer and associated springs, providing populations supported in captivity as insurance against catastrophic events. 

Our Plant Ecology and Restoration Program conducts research on Texas wild rice to improve its management in the wild and its captive propagation. We also assist with habitat restoration within and along the San Marcos River.  

Selected Bibliography


Alvear, D, PH Diaz, JR Gibson, M Jones, and KE Perez. 2020. “An Unusually Sculptured New Species of Phreatodrobia Hershler & Longley (Mollusca: Caenogastropoda: Cochliopidae) from Central Texas.” ZOOTAXA 4810 (1): 143–52. https://doi.org/10.11646/zootaxa.4810.1.8.

Barnes, MA, CL Jerde, D Keller, WL Chadderton, JG Howeth, and DM Lodge. 2013. “Viability of Aquatic Plant Fragments Following Desiccation.” INVASIVE PLANT SCIENCE AND MANAGEMENT 6 (2): 320–25. https://doi.org/10.1614/IPSM-D-12-00060.1.

Barr, CB, JR Gibson, and PH Diaz. 2015. “Typhloelmis barr (Coleoptera: Elmidae: Elminae), A New Stygobiontic Riffle Beetle Genus with Three New Species from Texas, USA.” COLEOPTERISTS BULLETIN 69 (4): 531–58. https://doi.org/10.1649/0010-065X-69.4.531.

Brewer, SK, R Mollenhauer, J Alexander, and D Moore. 2022. “Critical Thermal Maximum Values for Stream Fishes, Including Distinct Populations of Smallmouth Bass.” NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT 42 (2): 352–60. https://doi.org/10.1002/nafm.10749.

Britton, DK, and S Dingman. 2011. “Use of Quaternary Ammonium to Control the Spread of Aquatic Invasive Species by Wildland Fire Equipment.” AQUATIC INVASIONS 6 (2): 169–73. https://doi.org/10.3391/ai.2011.6.2.06.

Britton, DK, and RF McMahon. 2004a. “Environmentally and Genetically Induced Shell-Shape Variation in the Freshwater Pond Snail Physa (Physella) virgata (Gould, 1855).” AMERICAN MALACOLOGICAL BULLETIN 19 (1–2): 93–100.

Britton, DK, and RF McMahon. 2004b. “Seasonal and Artificially Elevated Temperatures Influence Bioenergetic Allocation Patterns in the Common Pond Snail, Physella virgata.” PHYSIOLOGICAL AND BIOCHEMICAL ZOOLOGY 77 (2): 187–96. https://doi.org/10.1086/381469.

Britton, DK, and RF McMahon. 2005. “Analysis of Trailered Boat Traffic and the Potential Westward Spread of Zebra Mussels across the 100th Meridian.” AMERICAN MALACOLOGICAL BULLETIN 20 (1–2): 147–59.

Brodersen, J, JG Howeth, and DM Post. 2015. “Emergence of a Novel Prey Life History Promotes Contemporary Sympatric Diversification in a Top Predator.” NATURE COMMUNICATIONS 6 (September). https://doi.org/10.1038/ncomms9115.

Crow, JC, MRJ Forstner, KG Ostrand, and JR Tomasso. 2016. “The Role of Temperature on Survival and Growth of the Barton Springs Salamander (Euryceasosorum).” HERPETOLOGICAL CONSERVATION AND BIOLOGY 11 (2): 328–34.

Crow, JC, KG Ostrand, MRJ Forstner, M Catalano, and JR Tomasso. 2017. “Effects of Nitrogenous Wastes on Survival of the Barton Springs Salamander (Euryceasosorum).” ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 36 (11): 3003–7. https://doi.org/10.1002/etc.3865.

DeColo, SL, AS Aspbury, KG Ostrand, and CR Gabor. 2016. “Male-Male Interactions and Their Influence on the Mating Behavior and Success in the Fountain Darter, Etheostomafonticola.” ACTA ETHOLOGICA 19 (1): 15–20. https://doi.org/10.1007/s10211-015-0216-x.

Diaz, Peter, Justin Crow, Jennifer Bronson-Warren, Stephanie Wong, and Joe Yelderman. 2023. “Eurycea chisholmensis (Salado Salamander). Seasonal Breeding.” HERPETOLOGICAL REVIEW 54 (2): 257.

Ethridge, JZ, JR Gibson, and CC Nice. 2013. “Cryptic Diversity within and amongst Spring-Associated Stygobromus Amphipods (Amphipoda: Crangonyctidae).” ZOOLOGICAL JOURNAL OF THE LINNEAN SOCIETY 167 (2): 227–42. https://doi.org/10.1111/j.1096-3642.2012.00877.x.

Howeth, JG, JD Lozier, CT Olinger, ML Dedmon, JM Matthews, and SJ Cardoza. 2024. “Crayfish Communities Converge over Succession in Beaver Pond Metacommunities.” FRESHWATER BIOLOGY 69 (6): 843–58. https://doi.org/10.1111/fwb.14250.

Huston, DC, D Araujo, JR Gibson, and JT Hutchinson. 2014. “Epicautapolingi (Coleoptera: Meloidae) Feeding on Mountain Laurel (Sophorasecundiflora) and Guajillo (Acaciaberlandieri) in West Texas.” SOUTHWESTERN ENTOMOLOGIST 39 (4): 887–89. https://doi.org/10.3958/059.039.0412.

Huston, DC, and JR Gibson. 2015. “Underwater Pupation by the Comal Springs Riffle Beetle, Heterelmis comalensis Bosse, Tuff, and Brown, 1988 (Coleoptera: Elmidae), with an Update on Culture Techniques.” COLEOPTERISTS BULLETIN 69 (3): 521–24. https://doi.org/10.1649/0010-065X-69.3.521.

Huston, DC, and JR Gibson. 2018. “New Record of an Isolated Spring Population of Huleechius marroni Brown, 1981 in West Texas.” SOUTHWESTERN ENTOMOLOGIST 43 (3): 803–6. https://doi.org/10.3958/059.043.0328.

Huston, DC, JR Gibson, KG Ostrand, CW Norris, and PH Diaz. 2015. “Monitoring and Marking Techniques for the Endangered Comal Springs Riffle Beetle, Heterelmiscomalensis Bosse, Tuff, and Brown, 1988 (Coleoptera: Elmidae).” COLEOPTERISTS BULLETIN 69 (4): 793–98. https://doi.org/10.1649/0010-065X-69.4.793.

Huston, DC, MD Worsham, DG Huffman, and KG Ostrand. 2014. “Infection of Fishes, Including Threatened and Endangered Species by the Trematode Parasite Haplorchis pumilio (Looss, 1896) (Trematoda: Heterophyidae).” BIOINVASIONS RECORDS 3 (3): 189–94. https://doi.org/10.3391/bir.2014.3.3.09.

Hutchins, BT, JR Gibson, PH Diaz, and BF Schwartz. 2021. “Stygobiont Diversity in the San Marcos Artesian Well and Edwards Aquifer Groundwater Ecosystem, Texas, USA.” DIVERSITY-BASEL 13 (6). https://doi.org/10.3390/d13060234.

Hutchinson, JT, DC Huston, and JR Gibson. 2015. “Defoliation of Cultured Creeping Primrose Willow (Ludwigia Repens) and Other Aquatic Plants by Parapoynx obscuralis (Lepidoptera: Crambidae).” SOUTHWESTERN ENTOMOLOGIST 40 (1): 227–31. https://doi.org/10.3958/059.040.0122.

Hutchinson, JT, and KG Ostrand. 2017. “Evaluation of Copper on Texas Wild Rice, Creeping Primrose-Willow and Waterstargrass.” JOURNAL OF AQUATIC PLANT MANAGEMENT 55 (July):113–15.

Jean, A, ND Telles, JR Gibson, D Foley, and KB Miller. 2012. “Description of a New Genus and Species of Stygobiontic Diving Beetle, Psychopomporusfelipi Jean, Telles, and Miller (Coleoptera: Dytiscidae: Hydroporinae), From the Edwards-Trinity Aquifer System of Texas, USA.” COLEOPTERISTS BULLETIN 66 (2): 105–10. https://doi.org/10.1649/072.066.0202.

Kosnicki, E, EP Julius, and JR Gibson. 2019. “Variation in the Number of Lateral Telson Spines of Stygobromus flagellatus (Benedict, 1896) (Amphipoda: Crangonyctidae), a Subterranean Species from Texas, USA.” JOURNAL OF CRUSTACEAN BIOLOGY 39 (2): 186–88. https://doi.org/10.1093/jcbiol/ruy106.

Lieurance, D, S Canavan, DC Behringer, AE Kendig, CR Minteer, LS Reisinger, CM Romagosa, et al. 2023. “Identifying Invasive Species Threats, Pathways, and Impacts to Improve Biosecurity.” ECOSPHERE 14 (12). https://doi.org/10.1002/ecs2.4711.

Lovejoy, RT, AN Kandow, and JG Howeth. 2023. “Zebra Mussels (Dreissena polymorpha) Influence Reservoir Ecosystem Attributes along Southern Invasion Front Metaecosystems in North America.” HYDROBIOLOGIA, January. https://doi.org/10.1007/s10750-022-05112-3.

Lucas, LK, Z Gompert, JR Gibson, KL Bell, CA Buerkle, and CC Nice. 2016. “Pervasive Gene Flow across Critical Habitat for Four Narrowly Endemic, Sympatric Taxa.” FRESHWATER BIOLOGY 61 (6): 933–46. https://doi.org/10.1111/fwb.12758.

McDermott, KS, TL Arsuffi, TM Brandt, DC Huston, and KG Ostrand. 2014. “Distribution and Occurrence of the Exotic Digenetic Trematode (Centrocestusformosanus), Its Exotic Snail Intermediate Host (Melanoidestuberculatus), and Rates of Infection of Fish in Springs Systems in Western Texas.” SOUTHWESTERN NATURALIST 59 (2): 212–20. https://doi.org/10.1894/F08-FRG-06.1.

Moore, DM, and SK Brewer. 2021. “Evaluation of Visual Implant Elastomer, PIT, and p-Chip Tagging Methods in a Small-Bodied Minnow Species.” NORTH AMERICAN JOURNAL OF FISHERIES MANAGEMENT 41 (4): 1066–78. https://doi.org/10.1002/nafm.10607.

Moore, DM, MS Gillis, and TS Funk. 2024. “Evaluation of P-Chip Microtransponder Tags on Small-Bodied Salamanders (Eurycea Spp.).” AMPHIBIAN & REPTILE CONSERVATION 18 (1–2): 10–19.

Nair, P, AH Hunter, MLD Worsham, M Stehle, JR Gibson, and WH Nowlin. 2019. “Sexual Dimorphism in Three Species of Heterelmis Sharp (Coleoptera: Elmidae).” COLEOPTERISTS BULLETIN 73 (4): 1075–83. https://doi.org/10.1649/0010-065X-73.4.1075.

Olsen, JB, AP Kinziger, JK Wenburg, CJ Lewis, CT Phillips, and KG Ostrand. 2016. “Genetic Diversity and Divergence in the Fountain Darter (Etheostoma fonticola): Implications for Conservation of an Endangered Species.” CONSERVATION GENETICS 17 (6): 1393–1404. https://doi.org/10.1007/s10592-016-0869-7.

Phillips, CT, JR Gibson, and JN Fries. 2011. “Spawning Behavior and Nest Association by Diondadiaboli in the Devils River, Texas.” SOUTHWESTERN NATURALIST 56 (1): 108–12. https://doi.org/10.1894/RJE-07.1.

Schmidt, H, KK Heinrich, J Reynolds, and JG Howeth. 2022. “An Ecological Succession Lesson from a Beaver’s Point of View.” AMERICAN BIOLOGY TEACHER 84 (4): 229–35. https://doi.org/10.1525/abt.2022.84.4.229.

Wilson, WD, JT Hutchinson, and KG Ostrand. 2017. “Genetic Diversity Assessment of in Situ and Ex Situ Texas Wild Rice (Zizaniatexana) Populations, an Endangered Plant.” AQUATIC BOTANY 136 (January):212–19. https://doi.org/10.1016/j.aquabot.2015.12.005.

Worsham, MLD, DG Huffman, F Moravec, and JR Gibson. 2016. “The Life Cycle of Huffmanela huffmani Moravec, 1987 (Nematoda: Trichosomoididae), an Endemic Marine-Relict Parasite of Centrarchidae from a Central Texas Spring.” FOLIA PARASITOLOGICA 63 (June). https://doi.org/10.14411/fp.2016.020.

Worsham, MLD, P Nair, JR Gibson, D Rodriguez, BF Schwartz, and WH Nowlin. 2023. “Phylogenetically Independent Behavior Mediating Geographic Distributions Suggests Habitat Is a Strong Driver of Phenotype in Crangonyctid Amphipods.” FRONTIERS IN ECOLOGY AND EVOLUTION 11 (September). https://doi.org/10.3389/fevo.2023.1234244.