Estuaries and Coasts

, Volume 41, Issue 3, pp 855–865 | Cite as

Hypersalinity During Regional Drought Drives Mass Mortality of the Seagrass Syringodium filiforme in a Subtropical Lagoon

  • Sara S. WilsonEmail author
  • Kenneth H. Dunton


Seagrasses are sensitive to local environmental conditions such as salinity, the underwater light environment, and nutrient availability. To characterize seagrass coverage and condition, as well as to relate changes in community structure to local environmental and hydrologic conditions, we monitored seagrass communities in the Upper Laguna Madre (ULM), Texas annually from 2011 to 2015. In 2011 and 2012, the lagoon was dominated primarily by Halodule wrightii, with mixed meadows of H. wrightii and Syringodium filiforme located in the northwest of our study area. By 2013, the expansive S. filiforme meadows had disappeared and the species was restricted to the northernmost reaches of the lagoon. The S. filiforme mortality occurred following an extended period of extremely high salinity (salinities 50–70) during a regional drought. Continuous measurements of underwater photosynthetically active radiation and stable carbon isotopic signatures of seagrass blade tissues did not suggest light limitation, and H. wrightii N/P molar ratios near 30:1 were not indicative of nutrient limitation. Based on the absence of strong evidence for light or nutrient limitation, along with the known tolerance of H. wrightii for higher salinities, we conclude that hypersalinity driven by regional drought was likely the major driver behind the observed S. filiforme mortality. With a substantial portion of the global seagrass distribution threatened by drought in the next 50 years, the increased frequency of hypersaline conditions is likely to exacerbate stress in seagrass systems already vulnerable to the effects of rising water temperatures, eutrophication, and sea level rise.


Seagrass Syringodium Hypersalinity Laguna Madre Monitoring 



We thank K. Jackson, K. Darnell, V. Congdon, and many others for assistance with the Texas Seagrass Statewide Monitoring Program. We are appreciative to J. Meiman for field assistance within Padre Island National Seashore (PINS) and for providing salinity data from Bird Island and Baffin Bay. We thank J. Tunnell for field assistance in ULM and continued support of our monitoring efforts. We thank T. Whiteaker and S. Schonberg for assistance with GIS mapping.

Funding Information

Funding for ULM seagrass monitoring was provided by the Coastal Bend Bays & Estuaries Program (#1201 and 1336), and monitoring within PINS was funded by the National Park Service (#P11AT51021). This is contribution #68 of the Marine Education and Research Center in the Institute for Water and Environment at Florida International University.


  1. Atkinson, M.J., and S.V. Smith. 1983. C:N:P ratios of benthic marine plants. Limnology and Oceanography 28 (3): 568–574.CrossRefGoogle Scholar
  2. Ball, D., M. Soto-Berelov, and P. Young. 2014. Historical seagrass mapping in Port Phillip Bay, Australia. Journal of Coastal Conservation 18: 257–282.CrossRefGoogle Scholar
  3. Borum, J., O. Pedersen, T.M. Greve, T.A. Frankovich, J.C. Zieman, J.W. Fourqurean, and C.J. Madden. 2005. The potential role of plant oxygen and sulphide dynamics in die-off events of the tropical seagrass, Thalassia testudinum. Journal of Ecology 93 (1): 148–158.CrossRefGoogle Scholar
  4. Burkholder, J.M., D.A. Tomasko, and B.W. Touchette. 2007. Seagrasses and eutrophication. Journal of Experimental Marine Biology and Ecology 350: 46–72.CrossRefGoogle Scholar
  5. Cambridge, M.L., M.W. Fraser, M. Holmer, J. Kuo, and G.A. Kendrick. 2012. Hydrogen sulfide intrusion in seagrasses from Shark Bay, Western Australia. Marine and Freshwater Research 63: 1027–1038.CrossRefGoogle Scholar
  6. Campbell, J.E., and J.W. Fourqurean. 2009. Interspecific variation in the elemental and stable isotope content of seagrasses in South Florida. Marine Ecology Progress Series 387: 109–123.CrossRefGoogle Scholar
  7. Cayan, D., T. Das, D. Pierce, T. Barnett, M. Tyree, and A. Gershunov. 2010. Future dryness in the southwest United States and the hydrology of the early 21st century drought. Proceedings of the National Academy of Sciences 107: 21271–21276.CrossRefGoogle Scholar
  8. Chapman, H.D., and P.F. Pratt. 1961. Methods of analysis for soils, plants and waters. Riverside: University of California.Google Scholar
  9. Collier, C.J., and M. Waycott. 2014. Temperature extremes reduce seagrass growth and induce mortality. Marine Pollution Bulletin 83 (2): 483–490.CrossRefGoogle Scholar
  10. Cullen-Unsworth, L., and R. Unsworth. 2013. Seagrass meadows, ecosystem services, and sustainability. Environment: Science and Policy for Sustainable Development 55 (3): 14–28.Google Scholar
  11. deFouw, J., L.L. Govers, J. van de Koppel, J. van Belzen, W. Dorigo, M.A. Sidi Cheikh, M.J.A. Christianen, K.J. van der Reijden, M. van der Geest, T. Piersma, A.J.P. Smolders, H. Olff, L.P.M. Lamers, J.A. van Gils, and T. van der Heide. 2016. Drought, mutualism breakdown, and landscape-scale degradation of seagrass beds. Current Biology 26: 1051–1056.CrossRefGoogle Scholar
  12. Duarte, C.M. 1990. Seagrass nutrient content. Marine Ecology Progress Series 67: 201–207.CrossRefGoogle Scholar
  13. Dunton, K., W. Pulich, and T. Mutchler. 2011. A seagrass monitoring program for Texas coastal waters: Multiscale integration of landscape features with plant and water quality indicators. Final Report to Coastal Bend Bays & Estuaries Program, 39 pp. Corpus Christi.Google Scholar
  14. Dunton, K.H. 1994. Seasonal growth and biomass of the subtropical seagrass Halodule wrightii in relation to continuous measurements of underwater irradiance. Marine Biology 120: 479–489.CrossRefGoogle Scholar
  15. Fernández-Torquemada, Y., and J.L. Sánchez-Lizaso. 2011. Responses of two Mediterranean seagrasses to experimental changes in salinity. Hydrobiologia 669: 21–33.CrossRefGoogle Scholar
  16. Ferreira, C., C. Simioni, E.C. Schmidt, F. Ramlov, M. Maraschin, and Z.L. Bouzon. 2017. The influence of salinity on growth, morphology, leaf ultrastructure, and cell viability of the seagrass Halodule wrightii Ascherson. Protoplasma 254: 1529–1537.CrossRefGoogle Scholar
  17. Fourqurean, J.W., C.M. Duarte, H. Kennedy, N. Marbà, M. Holmer, M.A. Mateo, E.T. Apostolaki, G.A. Kendrick, D. Krause-Jensen, K.J. McGlathery, and O. Serrano. 2012. Seagrass ecosystems as a globally significant carbon stock. Nature Geoscience 5: 505–509.CrossRefGoogle Scholar
  18. Fourqurean, J.W., and L.M. Rutten. 2003. Competing goals of spatial and temporal resolution: Monitoring seagrass communities on a regional scale. In Monitoring Ecosystems, ed. D.E. Busch and J.C. Trexler, 257–288. Washington D.C.: Island Press.Google Scholar
  19. Fourqurean, J.W., and J.C. Zieman. 2002. Nutrient content of the seagrass Thalassia testudinum reveals regional patterns of relative availability of nitrogen and phosphorus in the Florida Keys USA. Biogeochemistry 61: 229–245.CrossRefGoogle Scholar
  20. Gallegos, M.E., M. Merino, A. Rodriguez, N. Marbà, and C.M. Duarte. 1994. Growth patterns and demography of pioneer Caribbean seagrasses Halodule wrightii and Syringodium filiforme. Marine Ecology Progress Series 109: 99–104.CrossRefGoogle Scholar
  21. Green, E.P., and F.T. Short. 2003. World Atlas of Seagrasses. Riverside: University of California.Google Scholar
  22. Grice, A.M., N.R. Loneragan, and W.C. Dennsion. 1996. Light intensity and the interactions between physiology, morphology and stable isotope ratios in five species of seagrass. Journal of Experimental Marine Biology and Ecology 195: 91–110.CrossRefGoogle Scholar
  23. Griffin, N.E., and M.J. Durako. 2012. The effect of pulsed versus gradual salinity reduction on the physiology and survival of Halophila johnsonii Eiseman. Marine Biology 159: 1439–1447.CrossRefGoogle Scholar
  24. Hall, M.O., B.T. Furman, M. Merello, and M.J. Durako. 2016. Recurrence of Thalassia testudinum seagrass die-off in Florida Bay, USA: initial observations. Marine Ecology Progress Series 560: 243–249.CrossRefGoogle Scholar
  25. Heck, K.L., Jr., T.J.B. Carruthers, C.M. Duarte, A.R. Hughes, G.A. Kendrick, R.J. Orth, and S.W. Williams. 2008. Trophic transfers from seagrass meadows subsidize diverse marine and terrestrial consumers. Ecosystems 11: 1198–1210.CrossRefGoogle Scholar
  26. Hemminga, M.A., and M.A. Mateo. 1996. Stable carbon isotopes in seagrasses: variability in ratios and use in ecological studies. Marine Ecology Progress Series 140: 285–298.CrossRefGoogle Scholar
  27. Hernandez, E.A., and V. Uddameri. 2014. Standardized precipitation evaporation index (SPEI)-based drought assessment in semi-arid south Texas. Environmental Earth Sciences 71: 2491–2501.CrossRefGoogle Scholar
  28. Hirst, A.J., and G.P. Jenkins. 2017. Experimental test of N-limitation for Zostera nigricaulis seagrass at three sites reliant upon very different sources of N. Journal of Experimental Marine Biology and Ecology 486: 204–213.CrossRefGoogle Scholar
  29. Hirst, A.J., A.R. Longmore, D. Ball, P.L.M. Cook, and G.P. Jenkins. 2016. Linking nitrogen sources utilised by seagrass in a temperate marine embayment to patterns of seagrass change during drought. Marine Ecology Progress Series 549: 79–88.CrossRefGoogle Scholar
  30. Holmer, M., O. Pedersen, D. Krause-Jensen, B. Olesen, M. Hedegård Petersen, S. Schopmeyer, M. Koch, B.A. Lomstein, and H.S. Jensen. 2009. Sulfide intrusion in the tropical seagrasses Thalassia testudinum and Syringodium filiforme. Estuarine, Coastal and Shelf Science 85: 319–326.CrossRefGoogle Scholar
  31. Hu, X., D.J. Burdige, and R.C. Zimmerman. 2012. δ13C is a signature of light availability and photosynthesis in seagrass. Limnology and Oceanography 57 (2): 441–448.CrossRefGoogle Scholar
  32. IPCC. 2014. Climate change 2014: Synthesis report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, Pachauri, RK and LA Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp.Google Scholar
  33. IPCC, 2013. Summary for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. In: Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.Google Scholar
  34. Kenworthy, J.W., and M.S. Fonseca. 1996. Light requirements of seagrasses Halodule wrightii and Syringodium filiforme derived from the relationship between diffuse light attenuation and maximum depth distribution. Estuaries 19 (3): 740–750.CrossRefGoogle Scholar
  35. Koch, M.S., and J.M. Erskine. 2001. Sulfide as a phytotoxin to the tropical seagrass Thalassia testudinum: interactions with light, salinity and temperature. Journal of Experimental Marine Biology and Ecology 266: 81–95.CrossRefGoogle Scholar
  36. Koch, M.S., S.A. Schopmeyer, M. Holmer, C.J. Madden, and C. Kyhn-Hansen. 2007a. Thalassia testudinum response to the interactive stressors hypersalinity, sulfide and hypoxia. Aquatic Botany 87 (2): 104–110.CrossRefGoogle Scholar
  37. Koch, M.S., S.A. Schopmeyer, C. Kyhn-Hansen, C.J. Madden, and J.S. Peters. 2007b. Tropical seagrass species tolerance to hypersalinity stress. Aquatic Botany 86: 14–24.CrossRefGoogle Scholar
  38. Koch, M.S., S.A. Schopmeyer, O.I. Nielsen, C. Kyhn-Hansen, and C.J. Madden. 2007c. Conceptual model of seagrass die-off in Florida Bay: Links to biogeochemical processes. Journal of Experimental Marine Biology and Ecology 350 (1–2): 73–88.CrossRefGoogle Scholar
  39. Lee, T.N., E. Johns, N. Melo, R.H. Smith, P. Ortner, and D. Smith. 2006. On Florida Bay hypersalinity and water exchange. Bulletin of Marine Science 79 (2): 301–327.Google Scholar
  40. Lirman, D., and W.P. Cropper Jr. 2003. The influence of salinity on seagrass growth, survivorship, and distribution within Biscayne Bay, Florida: Field, experimental and modeling studies. Estuaries 26 (1): 131–141.CrossRefGoogle Scholar
  41. Manuel, S.A., K.A. Coates, W.J. Kenworthy, and J.W. Fourqurean. 2013. Tropical species at the northern limit of their range: Composition and distribution in Bermuda’s benthic habitats in relation to depth and light availability. Marine Environmental Research 89: 63–75.CrossRefGoogle Scholar
  42. Marbà, N., M. Holmer, E. Gacia, and C. Barrón. 2007. Seagrass beds and coastal biogeochemistry. In Seagrasses: Biology, Ecology and Conservation, ed. A.W.D. Larkum, R.J. Orth, and C.M. Duarte, 135–157. Dordrecht: Springer.Google Scholar
  43. Martin, S.R., C.P. Onuf, and K.H. Dunton. 2008. Assessment of propeller and off-road vehicle scarring in seagrass beds and wind-tidal flats of the southwestern Gulf of Mexico. Botanica Marina 51: 79–91.CrossRefGoogle Scholar
  44. McMahan, C.A. 1968. Biomass and salinity tolerance of shoalgrass and manateegrass in Lower Laguna Madre, Texas. The Journal of Wildlife Management 32 (3): 501–506.CrossRefGoogle Scholar
  45. McMahan, C.A. 1970. Food habits of ducks wintering on Laguna Madre, Texas. The Journal of Wildlife Management 34 (4): 946–949.CrossRefGoogle Scholar
  46. McMillan, C., and F.N. Moseley. 1967. Salinity tolerances of five marine spermatophytes of Redfish Bay, Texas. Ecology 48 (3): 503–506.CrossRefGoogle Scholar
  47. McMillan, C. 1981. Seed reserves and seed germination for two seagrasses, Halodule wrightii and Syringodium filiforme, from the Western Atlantic. Aquatic Botany 11: 279–296.CrossRefGoogle Scholar
  48. Merkord, GW. 1978. The distribution and abundance of seagrasses in Laguna Madre of Texas. M.S. Thesis, Texas A&I University, Kingsville, Texas, USA.Google Scholar
  49. Mitchell, C.A., T.W. Custer, and P.J. Zwank. 1994. Herbivory on shoalgrass by wintering redheads in Texas. The Journal of Wildlife Management 58: 131–141.CrossRefGoogle Scholar
  50. Montagna, P.A., T.A. Palmer, and J. Beseres Pollack. 2013. Hydrological changes and estuarine dynamics, 94 pp. New York: SpringerBriefs in Environmental Sciences. Scholar
  51. Neckles, H.A., B.S. Kopp, B.J. Peterson, and P.S. Pooler. 2012. Integrating scales of seagrass monitoring to meet conservation needs. Estuaries and Coasts 35: 23–46.CrossRefGoogle Scholar
  52. Onuf, C.P. 1994. Seagrasses, dredging and light in Laguna Madre, Texas, USA. Estuarine, Coastal and Shelf Science 39: 75–91.CrossRefGoogle Scholar
  53. Onuf, CP. 2007. Laguna Madre. In: Handley, L, D Altsman and R DeMay (eds.). Seagrass status and trends in the northern Gulf of Mexico: 1940–2002. U.S. Geological Survey Scientific Investigations Report 2006–5287 and US Environmental Protection Agency 855-R-04-003. 29 pp.Google Scholar
  54. Orth, R.J., T.J.B. Carruthers, W.C. Dennison, C.M. Duarte, J.W. Fourqurean, K.L. Heck Jr., A.R. Hughes, G.A. Kendrick, W.J. Kenworth, S. Olyarnik, F.T. Short, M. Waycott, and S.L. Williams. 2006. A global crisis for seagrass ecosystems. Bioscience 56 (12): 987–996.CrossRefGoogle Scholar
  55. Palmer, T.A., and P.A. Montagna. 2015. Impacts of droughts and low flows on estuarine water quality and benthic fauna. Hydrobiologia 753: 111–129. Scholar
  56. Quammen, M.L., and C.P. Onuf. 1993. Laguna Madre: Seagrass changes continue decades after salinity reduction. Estuaries 16 (2): 302–310.CrossRefGoogle Scholar
  57. Romero-Lankao, P, JB Smith, DJ Davidson, NS Diffenbaugh, PL Kinney, P Kirshen, P Kovacs and L Villers Ruiz. (2014). North America. In: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part B: Regional Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. In: Barros, VR, CB Field, DJ Dokken, MD Mastrandrea, KJ Mach, TE Billir, M Chatterjee, KL Ebi, YO Estrada, RC Genova, R Girma, ES Kissel, AN Levy, S MacCracken, PR Mastrandrea and LL White (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. 1439–1498 pp.Google Scholar
  58. Rooker, J.R., and S.A. Holt. 1997. Utilization of subtropical seagrass meadows by newly settled red drum Sciaenops ocellatus: patterns of distribution and growth. Marine Ecology Progress Series 158: 139–149.CrossRefGoogle Scholar
  59. Ruíz, J.M., L. Marín-Guirao, and J.M. Sandoval-Gil. 2009. Responses of the Mediterranean seagrass Posidonia oceanica to in situ simulated salinity increase. Botanica Marina 52: 459–470.Google Scholar
  60. Schoenbaechler, C and CG Guthrie. 2011. Coastal hydrology for the Laguna Madre estuary, with emphasis on the Lower Laguna Madre. Report by Texas Water Development Board Bays & Estuaries Program. 29 pp.Google Scholar
  61. Shepard, D. 1968. A two-dimensional interpolation function for irregularly-spaced data. Proceedings of the 1968 23rd ACM National Conference.
  62. Short, F.T., and H.A. Neckles. 1999. The effects of global climate change on seagrasses. Aquatic Botany 63: 169–196.CrossRefGoogle Scholar
  63. Short, F.T., B. Polidoro, S.R. Livingstone, K.E. Carpenter, S. Bandeira, J. Sidik Bujang, H.P. Calumpong, T.J.B. Carruthers, R.G. Coles, W.C. Dennison, P.L.A. Erftemeijer, M.D. Fortes, A.S. Freeman, T.F. Jagtap, A.H.M. Kamal, G.A. Kendrick, W.J. Kenworthy, Y.A. La Nafie, I.M. Nasution, R.J. Orth, A. Prathep, J.C. Sanciangco, B. van Tussenbroek, S.G. Vergara, M. Waycott, and J.C. Zieman. 2011. Extinction risk assessment of the world’s seagrass species. Biological Conservation 144 (7): 1961–1971.CrossRefGoogle Scholar
  64. Short, F.T., and S. Wyllie-Echeverria. 1996. Natural and human-induced disturbance of seagrasses. Environmental Conservation 23 (1): 17–27.CrossRefGoogle Scholar
  65. Solis, R.S., and G.L. Powell. 1999. Hydrography, mixing characteristics, and residence times of Gulf of Mexico estuaries. In Biogeochemistry of Gulf of Mexico Estuaries, ed. T.S. Bianchi, J.R. Pennock, and R.Y. Twilley, 29–62. New York: John Wiley & Sons, Inc.Google Scholar
  66. Tolan, J.M., S.A. Holt, and C.P. Onuf. 1997. Distribution and community structure of ichthyoplankton in Laguna Madre seagrass meadows: Potential impacts of seagrass species change. Estuaries 20: 450–464.CrossRefGoogle Scholar
  67. Touchette, B.W. 2007. Seagrass-salinity interactions: Physiological mechanisms used by submersed marine angiosperms for a life at sea. Journal of Experimental Marine Biology and Ecology 350: 194–215.CrossRefGoogle Scholar
  68. Tunnell, J.W., Jr., and F.W. Judd. 2002. The Laguna Madre of Texas and Tamaulipas. College Station: Texas A&M University Press.Google Scholar
  69. Waycott, M., C.M. Duarte, T.J.B. Carruthers, R.J. Orth, W.C. Dennison, S. Olyarnik, A. Calladine, J.W. Fourqurean, K.L. Heck Jr., A.R. Hughes, G.A. Kendrick, W.J. Kenworthy, F.T. Short, and S.L. Williams. 2009. Accelerating loss of seagrasses across the globe threatens coastal ecosystems. Proceedings of the National Academy of Sciences 106 (30): 12377–12381.CrossRefGoogle Scholar
  70. Zieman, J.C., J.W. Fourqurean, and T.A. Frankovich. 1999. Seagrass die-off in Florida Bay: Long-term trends in abundance and growth of turtle grass, Thalassia testudinum. Estuaries 22 (2): 460–470.CrossRefGoogle Scholar

Copyright information

© Coastal and Estuarine Research Federation 2017

Authors and Affiliations

  1. 1.University of Texas Marine Science InstitutePort AransasUSA
  2. 2.Marine Education and Research Center, Institute for Water and EnvironmentFlorida International UniversityMiamiUSA

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