Effects of Sesarma reticulatum on tidal creek growth. 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 Huy Vu University of Houston

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

hdvu4@central.uh.edu Co-investigator 2026

The goal of this proposal is to develop an understanding of creek development under the conditions of RSLR that integrates both physical and biological processes. We will test the hypothesis that crabs facilitate growth of creeks by bioturbating sediment and removing stabilizing vegetation. Three pairs of creeks, each of which bifurcates into two similar heads will be selected. We will remove Sesarma crabs from one head of each bifurcating creek using a combination of pitfall traps and direct removal by hand. A fence on the “watershed” between the two heads of each creek will be installed to restrict migration of crabs from the reference to the removal head. Four boardwalk stations will be deployed at each creek head using permanent boardwalk legs and portable aluminum platforms, with two permanent 0.5 x 0.5 m plots in three zones along each boardwalk for a total of 24 plots per creek head. Within each plot, we will monitor visible crabs (by species), burrow densities and diameters, stem densities and heights, and sediment deposition on a monthly basis. Adjacent to these plots, we will measure belowground biomass and shear strength on a quarterly basis. Periodic measurement of water flow and suspended sediment flux over spring-neap tide cycles will be taken with acoustic flow meters with optical backscatter sensors placed at the two branches of each creek.

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

creek marsh biomass oxygen population density population diversity sedimentology turbidity water flow LTER NSF GCE crustaceans Eurytium other Panopeus plants Spartina Uca geology invertebrate ecology movement of inorganic matter population ecology population studies pore-water chemistry Overall geographic extent of the research project -81.301987 -81.263124 31.486493 31.371003 2012-03-15 2017-08-15

$105,854

estuary marsh complex Duplin River - Duplin River transect used for GCE quarterly hydrographic monitoring surveys. Nominal profiling stations are defined at various locations along the Duplin River west of Sapelo Island, Georgia. -81.301987 -81.263124 31.486493 31.410854 Dean Creek - Doboy Sound/salt marsh site at the southern end of Sapelo Island near Dean Creek and the Sapelo lighthouse. A few small creeks are present, but a large creek (Dean Creek) is easily accessed. Upland is composed of small hammocks and some constructed causeways, with sand dune complexes east of Dean Creek and extending to the beach. Upper end of the watershed is affected by a culvert at Beach Road and heavy student use of marsh immediately adjacent to culvert. A hydrographic sonde is deployed in Doboy Sound near Commodore Island approximately 1.5km from this site. GCE6 is also the focus of Sapelo Island Microbial Observatory research on microbial diversity and genomics (http://simo.marsci.uga.edu) -81.299522 -81.264378 31.394072 31.371003

Southeastern corner of Little Sapelo Island (preferred), mouth of the Duplin River, or Dean Creek.

Boardwalk legs (5yrs), plastic fencing (3'x10'; 5 yrs). All experimental infrastructure will be removed at the end of the experiment.

Common marsh crab species will be collected (Uca, Panopeus, Eurytium, and Sesarma).Crabs will be measured, sexed, and released back to the marsh. Spartina alterniflora stems will be harvested in a 0.5mx0.5m plots at the end of the experiment. We will be using the general UGAMI collection permits.