I. Data Set Descriptors A. Title: Steven C. Pennings. 2025. Elevation and soil salinity transects at Airport Marsh and Old Beach Road on Sapelo Island, Georgia in 2001. Georgia Coastal Ecosystems LTER Data Catalog (data set MSH-GCED-2510; /data/MSH-GCED-2510) B. Accession Number: MSH-GCED-2510 C. Description 1. Originator(s): Name: Steven C. Pennings Address: Department of Biology and Biochemistry University of Houston Houston, Texas 77204-5513 Country: USA Email: scpennin@central.uh.edu 2. Abstract: To examine the relationship between elevation and soil characteristics, I sampled two sites on Sapelo Island (Old Beach Road and Airport Marsh) in July of 2001. At each site, I collected 160 soil samples across a transect from the high to the low marsh, and surveyed the relative elevation of each sample location with a theodolite. I determined soil water content gravimetrically, soil organic content by ashing samples, and soil salinity by rehydrating dried soils, adding deionized water, measuring the salinity of the supernatant, and back calculating to the original soil water content. 3. Study Type: Directed Study 4. Study Themes: Marsh Ecology, Pore-water Chemistry 5. LTER Core Areas: Organic Matter 6. Georeferences: none 7. Submission Date: Oct 31, 2025 D. Keywords: elevation, GCE, Georgia, Georgia Coastal Ecosystems, LTER, marshes, organic content, Organic Matter, salinity, Sapelo Island, Sediment Monitoring, soil water content, soils, USA II. Research Origin Descriptors A. Overall Project Description 1. Project Title: Georgia Coastal Ecosystems LTER - V 2. Principal Investigators: Name: Merryl Alber Address: Dept. of Marine Sciences University of Georgia Athens, Georgia 30602-3636 Country: USA Email: malber@uga.edu 3. Funding Period: Jul 01, 2025 to Jun 30, 2031 4. Objectives: The GCE-V project has 5 objectives. Obj. 1 Characterize spatial and temporal patterns in mean and variability of drivers and responses. This will be done by measuring external drivers (e.g., sea level), marsh and estuarine conditions, the wetland biophysical template, and modeling. Obj. 2 Evaluate linkages between external drivers and ecological responses, and determine whether assessing the variability of abiotic drivers improves explanatory power for predicting ecological responses. This will be done by analyzing long-term data and conducting field campaigns in areas with different salinity standard deviations and time-varying inundation, and complementary mechanistic experiments exploring effects of driver variability (e.g., salinity). Obj. 3 Assess disturbances and their effects on patterns of variability in ecological responses. This will be done by tracking response and recovery to natural disturbances in the field and in ongoing experimental manipulations. Obj. 4 Evaluate how ecological properties change across abiotic gradients, and determine whether variability increases near habitat transitions. This will be done using remote sensing, sampling across gradients of salinity and inundation, and establishing new long-term monitoring sites in forested areas to track upland marsh migration. Obj. 5 Determine the mechanisms by which coastal wetlands respond to changing drivers and assess whether variability informs this understanding. This will be done by conducting univariate and multivariate analyses relating key ecosystem variables (e.g., net ecosystem exchange, plant biomass) to drivers (salinity, inundation, temperature), using remote sensing to investigate spatial and temporal patterns in the mean and variability of marsh productivity and their relationship to variability in climate drivers, and synthesizing results to describe net daytime production and above- and below-ground C stocks and how they might change in response to future conditions. 5. Abstract: The Georgia Coastal Ecosystems (GCE) Long Term Ecological Research (LTER) program, which was established in 2000 to understand estuaries (places where salt water from the ocean mixes with fresh water from the land) and their adjacent coastal wetlands (i.e., marshes and tidal forests) and how they respond to long-term change. The GCE LTER researchers evaluate how environmental conditions (e.g., sea level, temperature, storms and hurricanes) and human activities (e.g., land use) affect the properties of estuaries (e.g., salinity, flooding patterns), and how that in turn affects wetlands and their ability to provide food and refuge for fish, shellfish and birds, to protect the shoreline from storms, to help to keep the water clean, and to store carbon, all of which have significant implications for the US economy. Many of the changes that are occurring are affecting not just average conditions, but also their fluctuations and extremes (e.g., variability). For example, not only has the average high tide level increased over the past decade, but the number of extreme flooding events has also increased, both of which have the potential to lead to wetland loss through drowning. During this award, the research team will conduct studies to systematically evaluate 1) whether we can improve our predictions of ecological responses by considering variability in environmental conditions, and 2) the use of variability as an early indicator of underlying environmental stress. The findings from this research will be important for predicting the long-term survival of coastal wetlands in a time of global change. In addition to research, the GCE program works with teachers and students, coastal managers, citizen scientists, and the general public to enhance scientific literacy and improve our understanding of coastal ecosystems. 6. Funding Source: NSF OCE 2425396 B. Sub-project Description 1. Site Description a. Geographic Location: Sapelo -- Sapelo Island, Sapelo Island, Georgia Airport_marsh -- Airport_marsh Old_Beach -- Old_Beach Coordinates: Sapelo -- NW: 081 18 28.72 W, 31 32 10.93 N NE: 081 10 34.26 W, 31 32 10.93 N SE: 081 10 34.26 W, 31 22 48.54 N SW: 081 18 28.72 W, 31 22 48.54 N Airport_marsh -- 81 17 22.8 W, 31 25 07.8 N Old_Beach -- 81 15 43.2 W, 31 24 31.2 N b. Physiographic Region: Sapelo -- unspecified Airport_marsh -- unspecified Old_Beach -- unspecified c. Landform Components: Sapelo -- Barrier island Airport_marsh -- unspecified Old_Beach -- unspecified d. Hydrographic Characteristics: Sapelo -- unspecified Airport_marsh -- unspecified Old_Beach -- unspecified e. Topographic Attributes: Sapelo -- unspecified Airport_marsh -- unspecified Old_Beach -- unspecified f. Geology, Lithology and Soils: Sapelo -- unspecified Airport_marsh -- unspecified Old_Beach -- unspecified g. Vegetation Communities: Sapelo -- Salt marsh vegetation on the island exterior (dominated by Spartina alterniflora), transitioning to marsh meadow and maritime forest on the island interior Airport_marsh -- unspecified Old_Beach -- unspecified h. History of Land Use and Disturbance: none recorded i. Climate: Climate summary for Sapelo Island, Georgia, based on NWS data from 1980-2010: Daily-aggregated Values: Mean (sample standard deviation) mean air temperature: 20.09°C (7.28°C) minimum air temperature: 15.02°C (7.96°C) maximum air temperature: 24.82°C (6.98°C) total precipitation: 3.26mm (10.3mm) Yearly-aggregated Daily Values: Mean (sample standard deviation) total precipitation (1980-2010): 1124mm (266mm) 2. Experimental or Sampling Design a. Design Characteristics: At each site (Airport Marsh and Old Beach Road), I collected 160 soil samples across a transect from the high to the low marsh. b. Permanent Plots: not specified c. Data Collection Duration and Frequency: not specified Beginning of Observations: Jul 01, 2001 End of Observations: Jul 30, 2001 3. Research Methods a. Field and Laboratory Methods: Method 1: Soils -- Soil cores were collected within each plot to measure salinity and organic matter. Cores were collected at Old Beach on 19 July 2001, and Airport Marsh on 20 July 2001. Separate cores (approximately 5 cm deep) were taken for salinity and organic matter analysis. Salinity cores were immediately weighed after collection for a wet weight and then dried at 60 degrees C for three days after which they were reweighed to obtain a dry weight. Samples were then rehydrated with 40 mL of deionized water for three days. A sample of the supernatant was then taken from each hydrated core and salinity was read in parts per thousand using a refractometer. Organic matter was determined using loss on ignition. Soil cores were dried for three days at 60 degrees C and ashed at 500 degrees C. Method 2: Elevations -- Elevation data were recorded for each plot using surveying equipment (a theodolite). At each site the plot with the lowest elevation was set to zero and all other plots at that particular site were recalculated to correspond with the lowest point at this arbitrary zero elevation. Due to the lack of a common point for the two sites, elevation between sites should not be compared. b. Protocols: Method 1: none Method 2: none c. Instrumentation: Method 1: none Method 2: none d. Taxonomy and Systematics: Method 1: not applicable Method 2: not applicable e. Speclies List: f. Permit History: Method 1: not applicable Method 2: not applicable 4. Project Personnel a. Personnel: Steven C. Pennings b. Affiliations: University of Houston, Houston, Texas III. Data Set Status and Accessibility A. Status 1. Latest Update: 13-Nov-2025 2. Latest Archive Date: 13-Nov-2025 3. Latest Metadata Update: 13-Nov-2025 4. Data Verification Status: Reviewed by IM B. Accessibility 1. Storage Location and Medium: Stored at GCE-LTER Data Management Office Dept. of Marine Sciences Univ. of Georgia Athens, GA 30602-3636 USA on media: electronic data download (WWW) or compact disk 2. Contact Person: Name: Adam Sapp Address: Department of Marine Sciences University of Georgia Athens, Georgia 30602 Country: USA Email: asapp@uga.edu 3. Copyright Restrictions: not copyrighted 4. Restrictions: This information is licensed under a Creative Commons Attribution 4.0 International License (see: https://creativecommons.org/licenses/by/4.0/). The consumer of these data ("Data User" herein) has an ethical obligation to cite it appropriately in any publication that results from its use. The Data User should realize that these data may be actively used by others for ongoing research and that coordination may be necessary to prevent duplicate publication. The Data User is urged to contact the authors of these data if any questions about methodology or results occur. Where appropriate, the Data User is encouraged to consider collaboration or co-authorship with the authors. The Data User should realize that misinterpretation of data may occur if used out of context of the original study. While substantial efforts are made to ensure the accuracy of data and associated documentation, complete accuracy of data sets cannot be guaranteed. All data are made available "as is." The Data User should be aware, however, that data are updated periodically and it is the responsibility of the Data User to check for new versions of the data. The data authors and the repository where these data were obtained shall not be liable for damages resulting from any use or misinterpretation of the data. a. Release Date: Affiliates: Oct 31, 2025, Public: Oct 31, 2025 b. Citation: Data provided by the Georgia Coastal Ecosystems Long Term Ecological Research Project, supported by funds from NSF OCE 2425396 (data set MSH-GCED-2510) c. Disclaimer: The user assumes all responsibility for errors in judgement based on interpretation of data and analyses presented in this data set. 5. Costs: free electronic data download via WWW, distribution on CD may be subject to nominal processing and handling fee IV. Data Structural Descriptors A. Data Set File 1. File Name: MSH-GCED-2510_1_0.CSV 2. Size: 320 records 3. File Format: ASCII text (comma-separated value format) 3a. Delimiters: single comma 4. Header Information: 5 lines of ASCII text 5. Alphanumeric Attributes: 6. Quality Control Flag Codes: Q = questionable value, I = invalid value, E = estimated value 7. Authentication Procedures: 8. Calculations: Soil_water_proportion: (Mass of water)/(mass of wet soil) Soil_salinity_PSU: (Salinity of supernatant) x (ml of DI water added)/(ml of water present in soil before drying) Soil_organic_percent: 100 x (mass of organic matter)/(mass of dry soil) 9. Processing History: Software version: GCE Data Toolbox Version 3.9.10 (23-May-2022) Data structure version: GCE Data Structure 1.1 (29-Mar-2001) Original data file processed: MSH-GCED-2510.txt (320 records) Data processing history: 11-Nov-2025: new GCE Data Structure 1.1 created ('newstruct') 11-Nov-2025: 320 rows imported from ASCII data file 'MSH-GCED-2510.txt' ('imp_ascii') 11-Nov-2025: 13 metadata fields in file header parsed ('parse_header') 11-Nov-2025: data structure validated ('gce_valid') 11-Nov-2025: Q/C flagging criteria applied, 'flags' field updated ('dataflag') 11-Nov-2025: automatically assigned study date metadata descriptors based on the range of date values in date/time columns (add_studydates) 11-Nov-2025: updated 1 metadata fields in the Dataset section(s) ('addmeta') 11-Nov-2025: imported Dataset, Project, Site, Study, Status, Supplement metadata descriptors from the GCE Metabase ('imp_gcemetadata') 11-Nov-2025: updated 57 metadata fields in the Dataset, Project, Site, Status, Study, Supplement section(s) ('addmeta') 11-Nov-2025: updated 1 metadata fields in the Dataset section(s) ('addmeta') 11-Nov-2025: imported Dataset, Project, Site, Study, Status, Supplement metadata descriptors from the GCE Metabase ('imp_gcemetadata') 11-Nov-2025: updated 57 metadata fields in the Dataset, Project, Site, Status, Study, Supplement section(s) ('addmeta') 13-Nov-2025: Q/C Criteria of column Soil_salinity_PSU changed from 'x<0='I';x>300='I';x<0='Q';x>300='Q'' to 'x<0='I';x>305='I';x<0='Q';x>305='Q''; Q/C Criteria of column Soil_organic_percent changed from 'x<0='I';x>25='I';x<0='Q';x>25='Q'' to 'x<0='I';x>26='I';x<0='Q';x>26='Q' ('ui_editor') 13-Nov-2025: Q/C flagging criteria applied for column(s) Soil_salinity_PSU and Soil_organic_percent, 'flags' field updated ('dataflag') 13-Nov-2025: updated 1 metadata fields in the Dataset section(s) ('addmeta') 13-Nov-2025: imported Dataset, Project, Site, Study, Status, Supplement metadata descriptors from the GCE Metabase ('imp_gcemetadata') 13-Nov-2025: updated 57 metadata fields in the Dataset, Project, Site, Status, Study, Supplement section(s) ('addmeta') 13-Nov-2025: updated 6 metadata fields in the Data section(s) ('addmeta') 13-Nov-2025: updated 15 metadata fields in the Status, Data sections to reflect attribute metadata ('updatecols') 13-Nov-2025: parsed and formatted metadata ('listmeta') B. Variable Information 1. Variable Name: column 1. Month column 2. Year column 3. Site column 4. Elevation_m column 5. Soil_water_proportion column 6. Soil_salinity_PSU column 7. Soil_organic_percent 2. Variable Definition: column 1. Month in which sampling was done column 2. Year in which sampling was done column 3. Site name column 4. Relative elevation of plots column 5. Soil water content column 6. Porewater salinity column 7. Soil organic content 3. Units of Measurement: column 1. None column 2. None column 3. None column 4. m column 5. proportion column 6. PSU column 7. percent 4. Data Type a. Storage Type: column 1. integer column 2. integer column 3. string column 4. floating-point column 5. floating-point column 6. floating-point column 7. floating-point b. Variable Codes: c. Numeric Range: column 1. 7 to 7 column 2. 2001 to 2001 column 3. (none) column 4. 0 to 1.1498 column 5. 0.11718 to 0.72061 column 6. 9.4563 to 300.5367 column 7. 1.1287 to 25.3392 d. Missing Value Code: 5. Data Format a. Column Type: column 1. numerical column 2. numerical column 3. text column 4. numerical column 5. numerical column 6. numerical column 7. numerical b. Number of Columns: 7 c. Decimal Places: column 1. 0 column 2. 0 column 3. 0 column 4. 3 column 5. 2 column 6. 1 column 7. 1 6. Logical Variable Type: column 1. datetime (discrete) column 2. datetime (discrete) column 3. nominal (none) column 4. data (continuous) column 5. calculation (continuous) column 6. calculation (continuous) column 7. calculation (continuous) 7. Flagging Criteria: column 1. x<7="I";x>8="I";x<7="Q";x>8="Q" column 2. x<2001="I";x>2001="I";x<2001="Q";x>2001="Q" column 3. none column 4. x<0="I";x>2="I";x<0="Q";x>2="Q" column 5. x<0="I";x>1="I";x<0="Q";x>1="Q" column 6. x<0="I";x>305="I";x<0="Q";x>305="Q" column 7. x<0="I";x>26="I";x<0="Q";x>26="Q" C. Data Anomalies: V. Supplemental Descriptors A. Data Acquisition 1. Data Forms: 2. Form Location: 3. Data Entry Validation: B. Quality Assurance/Quality Control Procedures: C. Supplemental Materials: D. Computer Programs: E. Archival Practices: F. Publications: not specified G. History of Data Set Usage 1. Data Request History: not specified 2. Data Set Update History: none 3. Review History: none 4. Questions and Comments from Users: none