Management Strategies for the Rincon Bayou Pipeline
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Management Strategies for the Rincon Bayou Pipeline Final Report CBBEP Publication – 128 Project Number -1817 January 2019 Prepared by: Dr. Paul A. Montagna, Principal Investigator Harte Research Institute for Gulf of Mexico Studies Texas A&M University-Corpus Christi 6300 Ocean Dr., Unit 5869 Corpus Christi, Texas 78412 Phone: 361-825-2040 Email: [email protected] Submitted to: Coastal Bend Bays & Estuaries Program 615 N. Upper Broadway, Suite 1200 Corpus Christi, TX 78401 The views expressed herein are those of the authors and do not necessarily reflect the views of CBBEP or other organizations that may have provided funding for this project. Management Strategies for the Rincon Bayou Pipeline Principal Investigator: Dr. Paul A. Montagna Harte Research Institute for Gulf of Mexico Studies Texas A&M University - Corpus Christi 6300 Ocean Drive, Unit 5869 Corpus Christi, Texas 78412 Phone: 361-825-2040 Email: [email protected] Final report submitted to: Coastal Bend Bays & Estuaries Program, Inc. 615 N. Upper Broadway, Suite 1200 Corpus Christi, TX 78401 CBBEP Project Number 1817 January 2019 Cite as: Montagna, P.A. 2019. Management Strategies for the Rincon Bayou Pipeline. Final Report to the Coastal Bend Bays & Estuaries Program for Project # 1817, CBBEP Publication – 128. Harte Research Institute, Texas A&M University- Corpus Christi, Corpus Christi, Texas, 45 pp. Left Blank for 2-sided printing Acknowledgements This project was funded in part by U.S. Environmental Protection Agency (EPA) Cooperative Agreement Numbers: C6-480000-54, EPA Q-TRAK# - 18-387. We thank Sharon R. Coleman, Texas Commission on Environmental Quality (TCEQ); Terry Mendiola, EPA; Cory Horan, TCEQ; Curry Jones, EPA; and Kerry Niemann, TCEQ for reviewing and approving the Quality Assurance Project Plan. The work was overseen at the Coastal Bend Bays & Estuaries Program by Leo Trevino and Rae Mooney, who provided helpful guidance and oversight to complete the project. i Abstract Decreased inflow due to damming of the Nueces and Frio rivers has resulted in increasing salinity in Nueces Bay and caused Rincon Bayou to become a reverse estuary disturbing the overall hydrology of the adjacent Corpus Christi Bay. Adaptive management to perform hydrological restoration began in 1994 and continues today. The objective of the present study is to develop a set of recommendations and implementation strategy for management of environmental flows delivered to upper Rincon Bayou by the Rincon Bayou Pipeline. This information is needed to improve the environmental effectiveness of pumped flow deliveries to Rincon Bayou and the Nueces marsh. Change in water quality and benthic community structure were used as indicators of ecological effects. High inflow reduces salinity and introduces nutrients. Large and haphazard salinity fluctuations result in an often disturbed system populated by pioneer species, such as chironomid larvae and the polychaete Streblospio benedicti, during especially low and high salinity periods. Epifaunal organisms are mobile and capable of escaping unsuitable conditions, so the more immediate results of fluctuations in water quality is the lack of higher trophic marine organisms following pumping events. Results of time lags indicated that variance in diversity variables in response to changes in salinities occurred within the first few weeks after pumping. Immediate responses to salinity were not identified in abundance and biomass. Positive relationships between abundance and biomass, in response to salinity fluctuations, were evident after 6 to 8 weeks. A little bit of water pumped during dry times can have positive environmental benefits, and too much water pumped during wet times can have a negative influence and act as an ecological disturbance. The results of the infaunal and epifaunal analyses indicate that further changes need to be made to the Rincon Bayou restoration and management programs in order to reestablish a reasonably undisturbed ecosystem. ii Table of Contents Acknowledgements .......................................................................................................................... i Abstract ........................................................................................................................................... ii List of Figures ................................................................................................................................ iv List of Tables ................................................................................................................................. vi Introduction ..................................................................................................................................... 1 Literature Review and Analysis of Long-Term Data ..................................................................... 2 Literature Review ........................................................................................................................ 2 Data Analysis .............................................................................................................................. 4 Spatial Sampling ...................................................................................................................... 4 Temporal Sampling ................................................................................................................. 6 Measurement Methods ............................................................................................................ 7 Statistical Methods .................................................................................................................. 8 Hydrography Response ............................................................................................................... 9 Macroinfauna Response ............................................................................................................ 16 Science-Based Recommendation .................................................................................................. 30 Epifauna Response to Salinity ................................................................................................... 33 Mechanistic Modeling of Benthic Response.............................................................................. 35 Empirical Modeling of Benthic Response ................................................................................. 35 Consensus Recommendation ..................................................................................................... 37 Stakeholder Team ......................................................................................................................... 39 Management or Regulatory Options ............................................................................................. 40 Literature Cited ............................................................................................................................. 42 iii List of Figures Figure 1. Map of study area. a) State of Texas with the Nueces Basin highlighted. b) Location of Choke Canyon Reservoir, Lake Corpus Christi and Nueces Estuary (Nueces Bay) within the Nueces Basin. c) Location of the Nueces Delta marsh containing Rincon Bayou. .......................................................................................................................... 5 Figure 2. Rincon Bayou salinity (PSU) observations from October 28, 1994 to February 28, 2017 for stations C, F, and G. .................................................................................... 11 Figure 3. Rincon Bayou mean sonde temperature (°C) observations from October 28, 1994 to February 28, 2017 for stations C, F, and G. .............................................................. 12 Figure 4. Rincon Bayou water depth (m) observations from October 28, 1994 to February 28, 2017 for stations C, F, and G. .................................................................................... 13 Figure 5. Rincon Bayou dissolved oxygen (DO) sonde observations from October 28, 1994 to February 28, 2017 for stations C, F, and G. .............................................................. 14 Figure 6. Rincon Bayou pH sonde observations from October 28, 1994 to February 28, 2017 for stations C, F, and G.................................................................................................... 15 Figure 7: Mean benthic infaunal abundance over time for Rincon Bayou Stations C, F, and G from October 28, 1994 to February 28, 2017. ........................................................... 18 Figure 8: Mean benthic infaunal dry weight biomass over time for Rincon Bayou Stations C, F, and G from October 28, 1994 to February 28, 2017. ................................................ 19 Figure 9: Mean benthic infaunal diversity over time for Rincon Bayou Stations C, F, and G from October 28, 1994 to February 28, 2017. .................................................................... 20 Figure 10: Mean benthic infaunal Shannon diversity index over time for Rincon Bayou Stations C, F, and G from October 28, 1994 to February 28, 2017. ........................................ 21 Figure 11: Mean benthic infaunal richness over time for Rincon Bayou Stations C, F, and G from October 28, 1994 to February 28, 2017. .................................................................... 22 Figure 12: Mean benthic infaunal abundance and salinity at all stations from October 28, 1994 to February 28,