Publication Date:
2022-05-26
Description:
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy
at the
Massachusetts Institute of Technology
and the
Woods Hole Oceanographic Institution February 2017
Description:
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.
Description:
Financial support for my doctoral research was provided by the United States Department of Defense
through the National Defense Science and Engineering Graduate Fellowship Program, the National
Science Foundation under grant OCE-1233678, and the Woods Hole Oceanographic Institution (WHOI)
under grants from the WHOI Coastal Ocean Institute, Ocean and Climate Change Institute, and Ocean
Life Institute. WHOI Academic Programs Office also provided funding support for research, through the
Ocean Ventures Fund, and for my stipend, as graduate research assistantships including an assistantship
from the United States Geological Survey administered by WHOI.
Keywords:
Marshes
;
Chemistry
;
Metabolism
;
Knorr (Ship : 1970-) Cruise KN210-04
Repository Name:
Woods Hole Open Access Server
Type:
Thesis
