Applied Research

1. Applied Research (HCP Sections 6.3.4.2 & 6.3.4.3) Nathan Pence Bob Hall

2. Categories Tier A primarily focus on habitat requirements and responses. Tier B primarily focus on low-flow impacts directly on the fountain darter and Comal Springs riffle beetle. Tier C primarily focuses on the implications of timing, frequency, and duration of multiple events and varying sequences to assess ecological model predictions (model validation). Additional Studies are primarily in situ studies conducted as part of the implementation of minimization and mitigation measures. Recommended Studies are not listed in the HCP, rather they are proposed by the Committees, Modelers or Contractors as necessary studies to further the other studies in order to benefit the species.

3. Applied Research 2013 – Projects Completed

4. 2013 Applied ResearchField – vs – Laboratory StudyRecommended StudyDoes laboratory and field aquatic vegetation studies produce comparable data?

5. 2013 Applied Research pH Drift StudyRecommended StudyEvaluate HCO3 utilization by select aquatic vegetation types in the Comal and San Marcos springs systems.

6. 2013 Applied Research Vegetation Tolerance StudyTier ALow-flow threshold evaluation of aquatic vegetation.

7. 2013 Applied Research Food Source StudyTier AEvaluation of fountain darter food source low-flow threshold.

8. 2013 Applied Research Results for Calibration and Validation of the Ecological Model • Field data provides best “numbers” for analysis. • Lab data works well for “trends” or “magnitudes” of change. • Cabomba, Vallisneria and Riccia have a high temperature tolerance <35° C. • Ludwigia has a high temperature tolerance of 37° - 40° C. • All of the plants tested had a low CO2 tolerance of <5 mg/l. • Preliminary data on algal growth in varying temperature and CO2 conditions. • High temperature threshold for fountain darter food source Hyalella azteca and the benefit of Riccia to the food chain was sampled. • Water temperature and dissolved oxygen data collected in pond studies may be applicable for water quality refinement or validation under low to no flow conditions.

9. Applied Research 2014 – Projects Underway

10. 2014 Applied Research Extended Low-Flow Period Effects on Comal Springs Riffle Beetles • Tier A • How does the CSRB survive in low-to-no spring flow? • Evaluate CSRB movement as related to flow. • Lab study.

11. 2014 Applied Research Effects of Vegetation Decay and Water Quality Deterioration on Fountain Darter Movement • Tier B • Low-flow and summer conditions favor algae, which shades and kills off the bryophytes, resulting in the collection of fewer darters in the Upper Spring Run reach. • At what point in time are the bryophytes rendered unsuitable habitat? • How far will darters move to find usable habitat? • Lab and field study. • Variance to continue during low-flow requested.

12. 2014 Applied Research Effects of Low-Flow on Fountain Darter Fecundity • Tier B • Reproductive success of fountain darters is reduced under low flow conditions • Attributed to greater variability in physical habitats and to increases in organic substrates. • Lab and field study. • Variance requested to continue during low-flow.

13. 2014 Applied Research Effects of Predation on Fountain Darter Population Size at Various Flow Rates • Tier B • Flow conditions may cause different relationships to predator & prey and habitat utilization. • Laboratory and field study. • Variance requested to continue during low-flow.

14. 2014 Applied Research Determination of Limitations of Comal Springs Riffle Beetle Plastron Use During Low-Flow • Recommended Study • Adult riffle beetles have fine hairs (plastron) that trap air next to their body, acting as a gill to breath underwater. • Plastrons require clean, cool water to function.

15. 2014 Applied Research Estimate Comal Springs Riffle Beetle Population in Comal Springs/Landa Lake • Recommended Study • Sample a random distribution of previously sampled and unsampled springs for CSRB within Comal Springs/Landa Lake to estimate the CSRB population. • Currently “on hold” due to low-flow conditions.

16. Applied Research 2015 – Studies Proposed Projects Prioritized by the EAHCP Science Committee

17. 2015 Applied Research Ludwigia repens Interference Plant Competition • Recommended study. • Evaluate the ability of Ludwigia to compete with Hygrophilla and Hydrilla. • In-situ study. Hydrilla will not be used in Comal system. • Necessary for the EcoModel.

18. 2015 Applied Research Suspended Sediment Impacts on TX Wild-Rice (and Other Aquatic Plant) Growth Characteristics and Aquatic Macroinvertebrates • Recommended study. • Evaluate timing and duration of suspended sediments. • Evaluate suspended sediment impact on aquatic plant communities. • Evaluate suspended sediment impact on the aquatic macroinvertebrate community. • Possible inclusion in EcoModel.

19. 2015 Applied Research Algae Dynamics • Recommended study. • Every summer filamentous algae bloom in the Upper Spring Run overwhelms the bryophytes and aquatic macrophytes. • Necessary for the EcoModel.

20. 2015 Applied Research Effects of Shear Stress on Submerged Aquatic Vegetation • Recommended study • Evaluate the effects of shear stress based on aquatic substrate and vegetation types. • Evaluate aquatic vegetation growth patterns after high-flow event. • Necessary for the EcoModel.

21. 2015 Applied Research Comal Springs Riffle Beetle Habitat Connectivity (Surface, Riparian, Submerged) • Tier A • Evaluate the importance of the surface, riparian and submerged food sources to the ecology of the CSRB at the springs. • Lab study. • May not be an integral part of the EcoModel at this time.

22. 2015 Applied Research Food Source Temperature Refinement and Response to Plant Species. • Recommended study. • Evaluate the food-type’s preference of aquatic vegetation (Ludwigia, Valesneria & Riccia) • Evaluate the impact of increasing temperature on the food-type. • Necessary for the EcoModel.

23. 2015 Applied Research When Does Fountain Darter Compensatory Reproduction Get Triggered, and If So, When and What Causes It? • Tier B • Evaluate fountain darter reproduction success to dietary restrictions. • Evaluate reproduction success to determine if compensatory reproduction is taking place. • Possible inclusion in the EcoModel.

24. 2015 Applied Research What Are the Behavioral Impacts of the Fountain Darter Under Different Turbidity Levels in Relation to Feeding Success • Tier B • Evaluate the behavior of the fountain darter toward prey under varying turbidity levels. • Evaluate the behavior of the prey under varying turbidity levels. • Evaluate consumption and composition of food items under varying turbidity levels. • Possible inclusion in EcoModel.

25. 2015 Applied Research Studies Not Considered at This Time Tier C – The timing is not suitable for these studies. Other work needs to be done first. - System memory - EcoModel evaluation Additional Studies in HCP – The timing is not suitable for these studies. - Non-native plant removal and control, and native plant restoration. - Old Channel environmental and protection area (ERPA)