DUPLEX experiment Dr. Daniela Di Iorio University of Georgia

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

daniela@uga.edu http://www.marsci.uga.edu/directory/daniela-di-iorio 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. Daniela Di Iorio University of Georgia

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

daniela@uga.edu http://www.marsci.uga.edu/directory/daniela-di-iorio Principal investigator 2026

Seven GCE-LTER Pis participated in a directed study of the exchange processes between a large tidal creek and its adjacent intertidal areas during the time period of 12-21 August 2003 - a time when metabolic activity in the study area was at its annual maximum. High-resolution sampling of geochemical variables was undertaken to see if changes can be detected between water that goes onto the marsh and that which comes off. Attention focused on sampling small peripheral creeks which drain the marsh and on measuring spatial changes of tidal currents and other properties. Part of the study was designed to place the detailed work in the Duplin into a larger context by measuring and comparing metabolic rates in the marsh-estuarine-shelf continuum. Long-term moorings (Figure 1, Study Area) were in place for more than a month to place the data from the various components into perspective. Each mooring contained instruments to measure vertical profiles of currents, near-bottom measurements of water pressure (depth), salinity and temperature. The data at these fixed locations were complimented by axial and lateral surveys of the tidal river from a fast, instrumented boat conducted at spring and neap tide. Surveys for pCO2, DO and water column parameters were conducted at high water (HW) and low water (LW) along the Duplin (Fig. 2). Suspended particulate matter, PC/PN/PP, chlorophyll, DIC and alkalinity were also measured. Surface samples were taken at all seven stations while bottom samples were taken at Stations 1,2,3 and 4. Piezometers with temperature sensors were deployed throughout the intertidal area - mostly in the upper end of the Duplin River (Fig. 2). Samples were taken at depths of +10 cm, -50 cm, -100 cm and -200 cm (negative values denote distance below the sediment surface). The temperature data were used to track groundwater, which is expected to be colder than surface water during August. Water samples were collected from the piezometers at different times during the tidal cycle.

Question 2: How do the spatial and temporal patterns of biogeochemical processes, primary production, community dynamics, decomposition, and disturbance vary across the estuarine landscape, and how do they relate to environmental gradients? (more information)

LTER NSF Duplin River Georgia GCE Overall geographic extent of the research project -81.301987 -81.263124 31.486493 31.410854 2003-08-01 2006-08-30

National Science Foundation grant numbers OCE-9982133 and OCE-0620959

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 Figure 1. Map of Duplin River study area showing locations of in situ measurements of currents, temperature, salinity, bottom pressure and water-column sampling. Inset is of biogeochemical sampling stations in the upper Duplin River. Black dotted line represents intertidal limit. https://gce-lter.marsci.uga.edu/public/resources/projects/DuplexMapQ2.png