Aquatic Geochemistry

, Volume 18, Issue 2, pp 159–181 | Cite as

Texas Coastal Hypoxia Linked to Brazos River Discharge as Revealed by Oxygen Isotopes

  • Steven F. DiMarco
  • Josiah Strauss
  • Nelson May
  • Ruth L. Mullins-Perry
  • Ethan L. Grossman
  • David Shormann
Original Paper


Hypoxic conditions in the coastal waters off Texas (USA) were observed since the late 1970s, but little is known about the causes of stratification that contribute to hypoxia formation. Typically, this hypoxia is attributed to downcoast (southwestward) advection of waters from the Mississippi–Atchafalaya River system. Here, we present evidence for a hypoxic event on the inner shelf of Texas coincident with the presence of freshwater linked to high flow of the Brazos River in Texas. These conclusions are based on hydrographic observations and isotopic measurements of waters on the inner shelf near the Brazos River mouth. These data characterize the development, breakdown, and dispersal of a hypoxic event lasting from June through September 2007 off the Texas coast. Oxygen isotope compositions of shelf water indicate that (1) discharge from the Brazos River was the principal source of freshwater and water column stratification during the 2007 event, and (2) during low Brazos River discharge in 2008, freshwater on the Texas shelf was derived mainly from the Mississippi–Atchafalaya River System. Based on these findings, we conclude that the Mississippi–Atchafalaya River System is not the sole cause of hypoxia in the northern Gulf of Mexico; however, more data are needed to determine the relative influence of the Texas versus Mississippi rivers during normal and low flow conditions of Texas rivers.


Coastal hypoxia Stratification Oxygen isotopes Continental shelf processes Gulf of Mexico Texas 


  1. Belabbassi L (2006) Examination of the relationship of river water to occurrences of bottom water with reduced oxygen concentration in the northern Gulf of Mexico. Ph.D. dissertation, Texas A&M University, College StationGoogle Scholar
  2. Bianchi TS, DiMarco SF, Cowan JH Jr, Hetland RD, Chapman P, Day JW, Allison MA (2010) The science of hypoxia in the northern Gulf of Mexico: a review. Sci Total Environ 408(7):1471–1484CrossRefGoogle Scholar
  3. Boesch DF (2002) Challenges and opportunities for science in reducing nutrient over-enrichment of coastal ecosystems. Estuaries 25(4B):886–900CrossRefGoogle Scholar
  4. Cho K, Reid RO, Nowlin WD Jr (1998) Objectively mapped stream function fields on the Texas-Louisiana shelf based on 32 months of moored current meter data. J Geophys Res 103(C5):10377–10390CrossRefGoogle Scholar
  5. Conley DL, Paerl HW, Howarth RW, Boesch DF, Seitzinger SP, Havens KE, Lancelot C, Likens GE (2009) Controlling eutrophication: nitrogen and phosphorus. Science 323(5917):1014–1015CrossRefGoogle Scholar
  6. Cooper LW, Benner R, McClelland JW, Peterson BJ, Holmes RM, Raymond PA, Hansell DA, Grebmeier JM, Grebmeier JM, Codispoti LA (2005) Linkages among runoff, dissolved organic carbon, and the stable oxygen isotope composition of seawater and other water mass indicators in the Arctic Ocean. J Geophys Res 110(G2):GO2013. doi:10.1029/2005JG000031 CrossRefGoogle Scholar
  7. Coplen TB, Kendall C (2000) Stable hydrogen and oxygen isotope ratios for selected sites of the U.S. Geological Survey’s NASQAN and benchmark surface-water networks. Open-file report, USGSGoogle Scholar
  8. Craig H (1961) Isotopic variations in precipitation. Science 133:1702–1703CrossRefGoogle Scholar
  9. Dale VH et al (2010) Hypoxia in the Northern Gulf of Mexico. Springer series on environmental management. Springer, New YorkCrossRefGoogle Scholar
  10. Dansgaard W (1964) Stable isotopes in precipitation. Tellus 16(436):468Google Scholar
  11. Diaz RJ, Rosenberg R (1995) Marine benthic hypoxia: a review of its ecological effects and the behavioral responses of benthic macrofauna. Ocean Mar Biol Ann Rev 33:245–303Google Scholar
  12. Diaz RJ, Rosenberg R (2008) Spreading dead zones and consequences for marine ecosystems. Science 321:926–929CrossRefGoogle Scholar
  13. DiMarco SF, Howard MK, Reid RO (2000) Seasonal variation of wind-driven diurnal cycling on the Texas-Louisiana continental shelf. Geophys Res Lett 21(7):1017–1020CrossRefGoogle Scholar
  14. DiMarco SF, Chapman P, Hetland RD, Walker ND (2010) Does local topography control hypoxia on the Louisiana shelf? J Mar Sci 80(1–2):25–35Google Scholar
  15. Dinnel SP, Wiseman WJ Jr (1986) Fresh water on the Louisiana and Texas Shelf. Cont Shelf Res 6(6):765–784CrossRefGoogle Scholar
  16. Etter PC, Howard MK, Cochrane JD (2004) Heat and freshwater budgets of the Texas-Louisiana Shelf. J Geophys Res. doi:10.1029/2003JC001820 Google Scholar
  17. Harper DE Jr, McKinney LD, Nance JM, Salzer RR (1991) Recovery responses of two benthic assemblages following an acute hypoxic event on the Texas continental shelf, northwestern Gulf of Mexico. From Tyson RV, Pearson TH (eds) Modern and ancient continental shelf anoxia. Geological Society, London, Special Publication no. 58, pp 49–64Google Scholar
  18. Harper DE, Guillen GJ (1989) Occurrence of a dinoflagellate bloom associated with low salinity water off Galveston, Texas and coincident mortalities of demersal fish and benthic invertebrates. Contrib Mar Sci 31:147–161Google Scholar
  19. Harper DE Jr, Salzer RR, Case RJ (1981) The occurrence of hypoxic bottom water off the upper Texas coast and its effect on the benthic biota. Contrib Mar Sci 24:53–79Google Scholar
  20. Hetland RD, DiMarco SF (2008) The effects of bottom oxygen demand in controlling the structure of hypoxia on the Texas-Louisiana continental shelf. J Mar Syst 70:49–62CrossRefGoogle Scholar
  21. Hyeong K, Lawrence JR (2003) Hydrology of the Gulf intra-coastal waterway in the San Bernard-BR estuaries, Texas, USA: Oxygen isotopic ratio and salinity. Geosci J 7(1):27–35CrossRefGoogle Scholar
  22. Kendall C, Coplen TB (2001) Distribution of 18O and deuterium in river waters across the United States. Hydrol Process 15:1363–1393CrossRefGoogle Scholar
  23. Kiselkova V (2008) Effects of instabilities in the buoyancy-driven flow on the bottom oxygen: applications to the Louisiana Shelf. Ph.D., dissertation. Texas A&M University, College StationGoogle Scholar
  24. Lee DH, Veizer J (2003) Water and carbon cycles in the Mississippi River basin: potential implications for the Northern Hemisphere residual terrestrial sink. Glob Biogeochem Cycle 17(2):1037CrossRefGoogle Scholar
  25. Mackenzie FT, Mucci A, Luther III, GW (2011) Preface to John W. Morse special issue of aquatic geochemistry. Aquat Geochem 17:307–310 Google Scholar
  26. McInnes A, Quigg AS (2011) Near-annual fish kills in small embayments: casual vs. causal factors. Journal of Coastal Research (in press)Google Scholar
  27. Mullins, RL, DiMarco SF, Guinasso NL Jr (2010) Innovative environmental sampling during the summer of 2010 in the western Gulf of Mexico. OCEANS 2010, Washington State Conference and Trade Center (WSCTC), 20–23 Sept 2010, Seattle. OCEANS-IEEE, 2010Google Scholar
  28. Mullins RL, DiMarco SF, Walpert J, Guinasso NL Jr (Sept 2009) Real-time environmental monitoring from a wind farm platform in the Texas hypoxia zone. In: Proceedings of oceans 2009 marine technology society. 11 ppGoogle Scholar
  29. Mullins RL, DiMarco SF, Walpert J, Guinasso NL Jr (2011) Interdisciplinary ocean observing on the Texas Coast. Marine Tech Soc J 45(1):98–111CrossRefGoogle Scholar
  30. Nowlin WD Jr, Jochens AE, DiMarco SF, Reid RO, Howard MK (2005) Low-frequency circulation over the Texas-Louisiana continental shelf. In: Sturges W, Lugo-Fernandez A (ed) Circulation in the Gulf of Mexico: Observations and Models. American Geophysical Union, Washington, DC, pp 219–240Google Scholar
  31. Osterman LE (2003) Benthic foraminifers from the continental shelf and slope of the Gulf of Mexico: an indicator of shelf hypoxia. Estuar Coastal Shelf Sci 58:17–35CrossRefGoogle Scholar
  32. Pokryfki L, Randall RE (1987) Nearshore hypoxia in the bottom water of the northwestern Gulf of Mexico from 1981 to 1984. Mar Environ Res 22(1):75–90CrossRefGoogle Scholar
  33. Rabalais NN, Turner RE, Scavia D (2002) Beyond science into policy: Gulf of Mexico hypoxia and the Mississippi River. Bioscience 52:129–142CrossRefGoogle Scholar
  34. Rabalais NN, Turner RE, Sen Gupta BK, Boesch DF, Chapman P, Murrell MC (2007) Characterization and long-term trends of hypoxia in the northern Gulf of Mexico: does the science support the action plan? Estuar Coasts 30:753–772Google Scholar
  35. Rabalais NN, Turner RE, Wiseman WJ Jr (2001) Hypoxia in the Gulf of Mexico. J Environ Qual 30(320):329Google Scholar
  36. Strauss J (2010) Stable isotope geochemistry of Gulf of Mexico hypoxia: modern processes and paleontological proxies. Ph.D. dissertation, Texas A&M University, College Station, Texas, 119 ppGoogle Scholar
  37. Thronson A, Quigg AS (2008) Fifty-five years of fish kills in Coastal Texas. Estuar Coasts 31:802–813CrossRefGoogle Scholar
  38. Torgersen T (1979) Isotopic composition of river runoff on the US East Coast: evaluation of stable isotope versus salinity plots for coastal water mass identification. J Geophys Res 84:3773–3775CrossRefGoogle Scholar
  39. Wagner AJ, Slowey NC (2011) Oxygen isotopes in seawater from the Texas-Louisiana shelf. Bull Mar Sci 87. doi:10.5343/bms.2010.1004
  40. Wiseman WJ, Rabalais NN, Turner RE, Dinnel SP, MacNaughton A (1997) Seasonal and interannual variability within the Louisiana coastal current: stratification and hypoxia. J Mar Sys 12:237–248CrossRefGoogle Scholar
  41. Yankovsky AE, Chapman DC (1997) A simple theory for the fate of buoyant coastal discharge. J Phys Oceanogr 27(7):1386–1401CrossRefGoogle Scholar
  42. Zerai B (2001) Spatial and temperature variability in the stable isotope compositions of waters of the Gulf of Mexico: Louisiana-Texas Shelf and upper slope. M.S. thesis, University of Akron, Akron. 160 ppGoogle Scholar
  43. Zhang X, DiMarco SF, Smith DC, Howard MK, Jochens AE, Hetland RD (2009) Near-resonant ocean response to sea breeze on a stratified continental shelf. J Phys Oceanogr 39:2137–2155. doi:10.1175/2009JPO4054.1 CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Steven F. DiMarco
    • 1
  • Josiah Strauss
    • 2
  • Nelson May
    • 3
  • Ruth L. Mullins-Perry
    • 1
  • Ethan L. Grossman
    • 4
  • David Shormann
    • 5
  1. 1.Department of OceanographyTexas A&M UniversityCollege StationUSA
  2. 2.Water Research Centre, School of Civil and Environmental EngineeringUniversity of New South WalesSydneyAustralia
  3. 3.Southeast Fisheries Science CenterNational Marine Fisheries Service, NOAAStennis Space CenterUSA
  4. 4.Department of Geology and GeophysicsTexas A&M UniversityCollege StationUSA
  5. 5.DIVE, LLC MagnoliaUSA

Personalised recommendations