Declines in Plant Productivity Drive Carbon Loss from Brackish Coastal Wetland Mesocosms Exposed to Saltwater Intrusion
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Coastal wetlands, among the most productive ecosystems, are important global reservoirs of carbon (C). Accelerated sea level rise (SLR) and saltwater intrusion in coastal wetlands increase salinity and inundation depth, causing uncertain effects on plant and soil processes that drive C storage. We exposed peat-soil monoliths with sawgrass (Cladium jamaicense) plants from a brackish marsh to continuous treatments of salinity (elevated (~ 20 ppt) vs. ambient (~ 10 ppt)) and inundation levels (submerged (water above soil surface) vs. exposed (water level 4 cm below soil surface)) for 18 months. We quantified changes in soil biogeochemistry, plant productivity, and whole-ecosystem C flux (gross ecosystem productivity, GEP; ecosystem respiration, ER). Elevated salinity had no effect on soil CO2 and CH4 efflux, but it reduced ER and GEP by 42 and 72%, respectively. Control monoliths exposed to ambient salinity had greater net ecosystem productivity (NEP), storing up to nine times more C than plants and soils exposed to elevated salinity. Submersion suppressed soil CO2 efflux but had no effect on NEP. Decreased plant productivity and soil organic C inputs with saltwater intrusion are likely mechanisms of net declines in soil C storage, which may affect the ability of coastal peat marshes to adapt to rising seas.
KeywordsCladium jamaicense Florida Everglades Biogeochemistry Salinity Marsh Peat collapse
We thank Shawn Abrahams, Laura Bauman, Kristina Morales, and Ryan Stolee for help in the field. Viviana Mazzei, Steven Oberbauer, and Fred Sklar provided valuable feedback on early drafts of this manuscript. This is contribution number 16 of the Sea Level Solutions Center and 877 of the Southeast Environmental Research Center in the Institute of Water & Environment at Florida International University.
Funding for research was supported by the Florida Sea Grant R/C-S-56, including cooperative agreements with the South Florida Water Management District (SFWMD), the Everglades Foundation, and Everglades National Park (ENP). Additional funding was provided through the National Science Foundation’s Florida Coastal Everglades Long Term Ecological Research Program (DEB-1237517). ENP and the Everglades section of the SFWMD provided in-kind support for the mesocosm facilities. Benjamin Wilson was supported by a Florida International University Teaching Assistantship, Florida Sea Grant, FCE LTER, and FIU Dissertation Year Fellowship
- Andronov, E.E., S.N. Petrova, A.G. Pinaev, E.V. Pershina, S.Z. Rakhimgalieva, K.M. Akhmedenov, A.V. Gorobets, and N.K. Sergaliev. 2012. Analysis of the structure of microbial community in soils with different degrees of salinization using T-RFLP and real-time PCR techniques. Eurasian Soil Science 45: 147–156. https://doi.org/10.1134/s1064229312020044.CrossRefGoogle Scholar
- Beard, D.B., Zimmer, E.S., and Tobin, D.J. 1952. Soil & Moisture Conservation Plan [map]. Scale not given. Everglades National Park: United States Department of Interior.Google Scholar
- Bouillon, S., A.V. Borges, E. Castaneda-Moya, K. Diele, T. Dittmar, N.C. Duke, E. Kristensen, S.Y. Lee, C. Marchand, J.J. Middelburg, V.H. Rivera-Monroy, T.J. Smith, and R.R. Twilley. 2008. Mangrove production and carbon sinks: a revision of global budget estimates. Global Biogeochemical Cycles 22. https://doi.org/10.1029/2007gb003052.CrossRefGoogle Scholar
- Capone, D.G., and R.P. Kiene. 1988. Comparison of microbial dynamics in marine and fresh water sediments—contrasts in anaerobic carbon catabolism. Limnology and Oceanography 33: 725–749.Google Scholar
- Chambers, L.G., S.E. Davis, T.T. Troxler, J.N. Boyer, A. Downey-Wall, and L.J. Scinto. 2013. Biogeochemical effects of simulated sea level rise on carbon loss in an Everglades mangrove peat soil. Hydrobiologia. https://doi.org/10.1007/s10750-10013-11764-10756.
- Delaune, R.D., J.A. Nyman, and W.H. Patrick. 1994. Peat collapse, ponding and wetland loss in a rapidly submerging coastal marsh. Journal of Coastal Research 10: 1021–1030.Google Scholar
- Dessu SB, Price RM, Troxler TG, Kominoski JS (2018) Effects of sea-level rise and freshwater management on long-term water levels and water quality in the Florida Coastal Everglades. Journal of Environmental Management In Press.Google Scholar
- Eaton, A.D., L.S. Clesceri, E.W. Rice, and A.E. Greenberg. 2005. Standard methods for the examination of water and wastewater: centennial edition. Washington, D.C.: American Public Health Association.Google Scholar
- Green, A.J., P. Alcorlo, E. Peeters, E.P. Morris, J.L. Espinar, M.A. Bravo-Utrera, J. Bustamante, R. Diaz-Delgado, A.A. Koelmans, R. Mateo, W.M. Mooij, M. Rodriguez-Rodriguez, E.H. van Nes, and M. Scheffer. 2017. Creating a safe operating space for wetlands in a changing climate. Frontiers in Ecology and the Environment 15: 99–107. https://doi.org/10.1002/fee.1459.CrossRefGoogle Scholar
- Herbert, E.R., P. Boon, A.J. Burgin, S.C. Neubauer, R.B. Franklin, M. Ardon, K.N. Hopfensperger, L.P.M. Lamers, and P. Gell. 2015. A global perspective on wetland salinization: ecological consequences of a growing threat to freshwater wetlands. Ecosphere 6. https://doi.org/10.1890/es14-00534.1.CrossRefGoogle Scholar
- Hu, J., C.M. VanZomeren, K.S. Inglett, A.L. Wright, M.W. Clark, and K.R. Reddy. 2017. Greenhouse gas emissions under different drainage and flooding regimes of cultivated peatlands. Journal of Geophysical Research-Biogeosciences 122: 3047–3062. https://doi.org/10.1002/2017jg004010.CrossRefGoogle Scholar
- Lenth, R.V. 2017. Using lsmeans. https://cran.rproject.org/web/packages/lsmeans/vignettes/using-lsmeans.pdf
- Light, S.S., and J.W. Dineen. 1994. Water control in the Everglades: a historical perspective. In Everglades: the ecosystem and its restoration, ed. S.M. Davis and J.C. Ogden, 47–84. Delray Beach: St. Lucie Press.Google Scholar
- McLeod, E., G.L. Chmura, S. Bouillon, R. Salm, M. Bjork, C.M. Duarte, C.E. Lovelock, W.H. Schlesinger, and B.R. Silliman. 2011. A blueprint for blue carbon: toward an improved understanding of the role of vegetated coastal habitats in sequestering CO2. Frontiers in Ecology and the Environment 9: 552–560. https://doi.org/10.1890/110004.CrossRefGoogle Scholar
- McVoy, C.W., W.P. Said, J. Obeysekera, J. Van Arman, and T.W. Dreschel. 2011. Landscapes and hydrology of the predrainage everglades. Gainesville, FL: University of Florida Press.Google Scholar
- Munns, R., and M. Tester. 2008. Mechanisms of salinity tolerance. Annual Review of Plant Biology 59: 651–681. https://doi.org/10.1146/annurev.arplant.59.032607.092911.CrossRefGoogle Scholar
- R Core Team. 2017. R: a language and environment for statistical computing. Vienna: R Foundation for Statistical Computing. http://www.R-project.org/. Accessed 5 August 2015.
- Richardson, C.J., A. Dickson, and M. Ho. 2008. The effects of disturbance, phosphorus, and water level on plant succession in the Everglades experiments, 531–544. New York: Springer.Google Scholar
- Sippo, J.Z., D.T. Maher, D.R. Tait, C. Holloway, and I.R. Santos. 2016. Are mangroves drivers or buffers of coastal acidification? Insights from alkalinity and dissolved inorganic carbon export estimates across a latitudinal transect. Global Biogeochemical Cycles 30: 753–766. https://doi.org/10.1002/2015gb005324.CrossRefGoogle Scholar
- Smith, K.A., T. Ball, F. Conen, K.E. Dobbie, J. Massheder, and A. Rey. 2003. Exchange of greenhouse gases between soil and atmosphere: interactions of soil physical factors and biological processes. European Journal of Soil Science 54: 779–791. https://doi.org/10.1046/j.1351-0754.2003.0567.x.CrossRefGoogle Scholar
- Sylvia, D.M., J.J. Fuhrmann, P.G. Hartel, and D.A. Zuberer. 2004. Principles and applications of soil microbiology. Prentice Hall.Google Scholar
- Wanless, H.R., and B.M. Vlaswinkel. 2005. Coastal landscape and channel evolution affecting critical habitats at Cape Sable. Florida: Everglades National Park.Google Scholar
- Weston, N.B., R.E. Dixon, and S.B. Joye. 2006. Ramifications of increased salinity in tidal freshwater sediments: geochemistry and microbial pathways of organic matter mineralization. Journal of Geophysical Research-Biogeosciences 111. https://doi.org/10.1029/2005JG000071 doi 10.1029/2005jg000071.
- Whittle, A., and A.V. Gallego-Sala. 2016. Vulnerability of the peatland carbon sink to sea-level rise. Scientific Reports 6. https://doi.org/10.1038/srep28758.
- Wilson, B.J., B. Mortazavi, and R.P. Kiene. 2015. Spatial and temporal variability in carbon dioxide and methane exchange at three coastal marshes along a salinity gradient in a northern Gulf of Mexico estuary. Biogeochemistry 123: 329–347. https://doi.org/10.1007/s10533-015-0085-4.CrossRefGoogle Scholar