High Marsh Experiment Dr. Steven C. Pennings University of Houston

Department of Biology and Biochemistry University of Houston Houston Texas 77204-5513 USA

scpennin@central.uh.edu https://uh.edu/nsm/biology-biochemistry/people/profiles/steven-pennings/ https://orcid.org/0000-0003-4757-7125 Georgia Coastal Ecosystems LTER Project

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

gcelter@uga.edu https://gce-lter.marsci.uga.edu/ Dr. Steven C. Pennings University of Houston

Department of Biology and Biochemistry University of Houston Houston Texas 77204-5513 USA

scpennin@central.uh.edu https://uh.edu/nsm/biology-biochemistry/people/profiles/steven-pennings/ https://orcid.org/0000-0003-4757-7125 Principal investigator Dr. Alicia M. Wilson University of South Carolina

Department of Geological Sciences University of South Carolina Columbia South Carolina 29208 USA

awilson@geol.sc.edu https://sc.edu/study/colleges_schools/artsandsciences/earth_ocean_and_environment/our_people/directory/wilson_alicia.php https://orcid.org/0000-0002-1113-6267 Co-investigator Dr. Christine Angelini University of Florida

Department of Environmental Engineering Sciences University of Florida Gainesville Florida 32611 USA

christine.angelini@essie.ufl.edu http://www.angeliniecologylab.com/the-lab.html https://orcid.org/0000-0002-6669-5269 Co-investigator Dr. Christopher B. Craft Indiana University at Bloomington

Indiana University - School of Public and Environmental Affairs Room 408. MSB II. 702 N. Walnut Grove Ave. Bloomington Indiana 47405 USA

ccraft@indiana.edu https://orcid.org/0000-0002-6225-786X Co-investigator Dr. Christof Meile University of Georgia

Dept. of Marine Sciences University of Georgia Athens Georgia 30602-3636 USA

cmeile@uga.edu http://www.marsci.uga.edu/directory/christof-meile https://orcid.org/0000-0002-0825-4596 Co-investigator Dr. James Byers University of Georgia

Room 194B, Ecology Bldg. Odum School of Ecology University of Georgia Athens Georgia 30602 USA

jebyers@uga.edu http://www.ecology.uga.edu/directory/james-jeb-byers/ https://orcid.org/0000-0001-9240-0287 Co-investigator Dr. Richard N. Peterson Coastal Carolina University

Center for Marine and Wetland Studies 1270 Atlantic Avenue, Room 111 Coastal Carolina University Conway South Carolina 29526 USA

rpeters2@coastal.edu Co-investigator Dr. Richard F. Viso Coastal Carolina University

Center for Marine and Wetland Studies 1270 Atlantic Avenue Coastal Carolina University Conway South Carolina 29526 USA

rviso@coastal.edu http://ww2.coastal.edu/rviso/ Co-investigator Jacob Shalack University of Georgia Marine Institute

University of Georgia Marine Institute Sapelo Island Georgia 31327 USA

shalack@uga.edu Research coordinator Fan Li University of Houston

Department of Biology and Biochemistry 369 Science and Research Bldg 2 University of Houston Houston Texas 77204-5001 USA

lifan.uh@gmail.com Graduate research assistant 2026

We propose to experimentally test the hypothesis that water flow from the upland to high marsh directly affects high marsh function. We will work in high marsh areas adjacent to Sapelo Island where the vegetation is a mixture of Juncus and Borrichia.

Area 3: Responses to Salinity and Inundation (more information)

marsh terrestrial high marsh upland biomass GPS photosynthesis plant composition LTER NSF Sapelo Island GCE Borrichia Juncus plants experiment groundwater plots runoff vegetation Overall geographic extent of the research project -81.307978 -81.176185 31.536369 31.380150 2015-11-01 2018-11-30

National Science Foundation grant number OCE-1237140.

estuary marsh complex Sapelo Island - Sapelo Island on the Southeast Georgia Coast -81.307978 -81.176185 31.536369 31.380150

Our experiment will have 3 treatments: 1) upland water reduction (to assess how upland connections, as opposed to elevation, mediate high marsh community composition); 2) impervious surface addition (to assess how increased runoff and decreased groundwater alter high marsh community composition); and 3) controls. Plots (n=8/treatment) will each extend 10 m along the upland/high marsh border and be separated by at least 10 m, with treatments fully interspersed. The water reduction treatments will have vertical plastic barriers (sheeting that extends from 60 cm deep to 30 cm above the soil surface) that will divert shallow groundwater and runoff away from the plots. The impervious surface treatment will use corrugated plastic roofing just above the soil surface to cover the upland immediately adjacent to the marsh plot (with gaskets around tree trunks to intercept stemflow). A ditch will be dug and then filled back in in the control and impervious surface treatments to control for the disturbance of installing the barrier in the water reduction treatment. The experiment will be set up in year 4 and will last a minimum of 3 y.

We will use DGPS to delineate the edge of the high marsh, and establish permanent sub-plots in each plot located 2, 4 and 8 m from the upland edge, which we will survey with an RTK GPS along with the elevation of the high marsh edge. We will use standard GCE protocols to monitor pore water salinity, plant photosynthetic rates, plant biomass and composition, and benthic invertebrate density and composition in each sub-plot. Measurements will be weekly for the first 8 weeks to capture the short-term response, monthly for the next year, and quarterly thereafter.