Ecosystem metabolism in salt marsh tidal creeks and ponds : applying triple oxygen isotopes and other gas tracers to novel environments
Author(s)Howard, Evan M. (Evan Michael)
Woods Hole Oceanographic Institution.
RacheI H. R. Stanley and Scott D. Wankel.
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Salt marshes are physically, chemically, and biologically dynamic environments found globally at temperate latitudes. Tidal creeks and marshtop ponds may expand at the expense of productive grass-covered marsh platform. It is therefore important to understand the present magnitude and drivers of production and respiration in these submerged environments in order to evaluate the future role of salt marshes as a carbon sink. This thesis describes new methods to apply the triple oxygen isotope tracer of photosynthetic production in a salt marsh. Additionally, noble gases are applied to constrain air-water exchange processes which affect metabolism tracers. These stable, natural abundance tracers complement traditional techniques for measuring metabolism. In particular, they highlight the potential importance of daytime oxygen sinks besides aerobic respiration, such as rising bubbles. In tidal creeks, increasing nutrients may increase both production and respiration, without any apparent change in the net metabolism. In ponds, daytime production and respiration are also tightly coupled, but there is high background respiration regardless of changes in daytime production. Both tidal creeks and ponds have higher respiration rates and lower production rates than the marsh platform, suggesting that expansion of these submerged environments could limit the ability of salt marshes to sequester carbon.
Thesis: Ph. D., Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2017.Cataloged from PDF version of thesis. Page 216 blank.Includes bibliographical references (pages 179-215).
DepartmentJoint Program in Oceanography/Applied Ocean Science and Engineering.; Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences.; Woods Hole Oceanographic Institution.
Massachusetts Institute of Technology
Joint Program in Oceanography/Applied Ocean Science and Engineering., Earth, Atmospheric, and Planetary Sciences., Woods Hole Oceanographic Institution.