I. Data Set Descriptors A. Title: Brian R. Silliman. 2009. Rates of consumption of marsh periwinkles (Littoraria irrorata) by mud crabs (Eurytium limosum and Panopeus obesus) between August and December in a Georgia salt marsh. Georgia Coastal Ecosystems LTER Data Catalog (data set INV-GCES-0912; http://gce-lter.marsci.uga.edu/public/app/dataset_details.asp?accession=INV-GCES-0912) B. Accession Number: INV-GCES-0912 C. Description 1. Originator(s): Name: Brian R. Silliman Address: 135 Duke Marine Lab Rd. Duke University Marine Lab Beaufort, North Carolina 28516-9721 Country: USA Email: brian.silliman@duke.edu 2. Abstract: Predatory mud crabs (Panopeus obesus and Eurytium limosum) are two of the main resident infaunal predators in southeastern US salt marshes.The relative importance of the two species in the trophic control of marsh periwinkles (snails; Littoraria irrorata) is likley to change across seasons. We therefore manipulated the these predator species (Panopeus obesus and Eurytium limosum) in experimental cages in the field (at Dean Creek, Sapelo Island, GA) and assessed monthly predation rates over four months, between 15th August to 15th December. We included 3 treatments, consisting of two treatments containing each species alone, and one containing both species together; all treatments had the same density. Specifically, 1) 4 x Panopeus individuals; 2) 4 x Eurytium individuals; 3) 2 x Panopeus individuals + 2 Eurytium individuals. Only adult crabs (33-40mm carapace diameter) were used. We maintained the treatments over 4 months (15th Aug - 15th Dec 2009), replacing any missing crabs every two weeks and counting the number of snails killed by predators each month. 3. Study Type: Directed Study 4. Study Themes: Aquatic Invertebrate Ecology 5. LTER Core Areas: Other Site Research 6. Georeferences: none 7. Submission Date: Dec 15, 2009 D. Keywords: Eurytium, GCE, Georgia, Georgia Coastal Ecosystems, Littoraria, LTER, Panopeus, predation, salt marshes, Sapelo Island, speciation, USA II. Research Origin Descriptors A. Overall Project Description 1. Project Title: Georgia Coastal Ecosystems LTER Project II 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: May 01, 2006 to Jan 01, 2013 4. Objectives: To understand the mechanisms by which variation in the quality, source and amount of both fresh and salt water create temporal and spatial variability in estuarine habitats and processes, in order to predict directional changes that will occur in response to long-term shifts in estuarine salinity patterns 5. Abstract: The Georgia Coastal Ecosystems (GCE) LTER program, located on the central Georgia coast, was established in 2000. The study domain encompasses three adjacent sounds (Altamaha, Doboy, Sapelo) and includes upland (mainland, barrier islands, marsh hammocks), intertidal (fresh, brackish and salt marsh) and submerged (river, estuary, continental shelf) habitats. Patterns and processes in this complex landscape vary spatially within and between sites, and temporally on multiple scales (tidal, diurnal, seasonal, and interannual). Overlain on this spatial and temporal variation are long-term trends caused by climate change, sea level rise, and human alterations of the landscape. These long-term trends are likely to manifest in many ways, including changes in water quality, river discharge, runoff and tidal inundation patterns throughout the estuarine landscape. The overarching goal of the GCE program is to understand the mechanisms by which variation in the quality, source and amount of both fresh and salt water create temporal and spatial variability in estuarine habitats and processes, in order to predict directional changes that will occur in response to long-term shifts in estuarine salinity patterns. The objectives of the current funding cycle are 1) to continue to document long-term patterns of environmental forcing to the coastal zone, 2) to link environmental forcing to observed spatial and temporal patterns of biogeochemical processes, primary production, community dynamics, decomposition and disturbance, 3) to investigate the underlying mechanisms by which environmental gradients along the longitudinal (freshwater-saltwater) and 4) lateral (upland-subtidal) axes of estuaries drive ecosystem change, and 5) to explore the relative importance of larval transport and the conditions of the adult environment in determining community and genetic structure across both the longitudinal and vertical gradients of the estuary. To meet these objectives, we utilize a suite of approaches including long-term monitoring of abiotic drivers and ecosystem responses; manipulative and natural experiments designed to enable us to examine the importance of key ecosystem drivers; and modeling. 6. Funding Source: NSF OCE 0620959 B. Sub-project Description 1. Site Description a. Geographic Location: Coordinates: b. Physiographic Region: c. Landform Components: d. Hydrographic Characteristics: e. Topographic Attributes: f. Geology, Lithology and Soils: g. Vegetation Communities: 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: We manipulated the identity of two species of predatory mud crabs (Panopeus obesus or Eurytium limosum) using experimental cages in the field (at Dean Creek, Sapelo Island, GA). We included 3 treatments, two containing a single species of mud crab: 4 x Panopeus individuals; 4 x Eurytium individuals; and a third treatment containing a mix of both species at the same overall density, i.e., 2 x Panopeus + 2 x Eurytium. Only adult crabs (33-40mm carapace diameter) were used. We maintained the treatments over 4 months (15th August - 15th Dec 2009), counting the number of crushed shells within each cage as a measure of the number of snails killed by the predatory crabs. Note that all empty or crushed shells were removed from plots at the beginning of the experiment (and each time they were counted thereafter) to avoid spurious counts. Each experimental treatment had 7 replicates, all maintained within 100cm x 100cm x 100cm (l x w x h) galvanized wire mesh cages (with 8mm mesh size). Dead or missing crabs were replaced after checking every two weeks. Initial density of Littoraria set to 300 adults. b. Permanent Plots: Experimental cages were 100cm x 100cm x 100cm (l x w x h). They consisted of 4 pine stakes (one at each corner) to which galvanised welded wire mesh (8mm hole size) was stapled. These cages were open topped, although escape of snails was likely to be minimal due to the zinc coating on the mesh, which they find toxic and thus do not tend to climb on. c. Data Collection Duration and Frequency: The response variable of interest in this study was the rate of predation over each month. This was estaimated by exhaustively searching each plot (and crab burrow) by hand after each month and counting (and removing) crushed shells of Littoraria irrorata. Beginning of Observations: Sep 01, 2009 End of Observations: Dec 01, 2009 3. Research Methods a. Field and Laboratory Methods: Method 1: Collection of mud crabs -- crabs were colleted by hand from burrows at the field site prior to set-up of the experiment and ad hoc as needed when found to be missing from cages. Crabs were meaured with vernier callipers (only crabs 33-40mm were used), collected in a bucket and added to appropriate enclosures. Crabs were checked every two weeks and replaced where neccessary. Collection of snails -- Adult snails were collected by hand from the short Spartina zone of Dean creek, before the start of the experiment, and added to experimental enclosures (that had first been cleared of living and crushed snails). Predated snails were not replaced during the expeirment, thus the number of snails in each plot was deplted over the course of the experiment. Snails were added one day before predatory crabs. Method 2: Measurement of predation rate -- the number of snails that had been consumed by the mud crabs over each month was assessed by counting middens of crushed Littoraria shells (which were then removed to avoid recounting). This was done within a single day by thoroughly searching all plots by hand and feeling for shells with finger tips. Lab trial showed that apices of the snail shells remained intact when crabs crushed the rest of the shell; moreover there is only one apex per shell -- this allowed an accurate assessment of predation rate each month. Method 3: Set-up of enclosures -- experimental cages (see 'plots') were sunk 15cm into the mud to deter crab escape or entry. They were installed along approximately 200m of Dean Creek in intermediate-height Spartina zone. They were placed haphazardly at locations with approximately equal Spartina height and density (judged by eye - data on initial canopy height not taken). Tretament replicates were randomly assigned to cages. b. Instrumentation: Method 1: none Method 2: none Method 3: none c. Taxonomy and Systematics: Method 1: not applicable Method 2: not applicable Method 3: not applicable d. Speclies List: e. Permit History: Method 1: not applicable Method 2: not applicable Method 3: not applicable 4. Project Personnel a. Personnel: 1: Brian R. Silliman 2: John Griffin b. Affiliations: 1: Duke University, Beaufort, North Carolina 2: University of Swansea, Swansea III. Data Set Status and Accessibility A. Status 1. Latest Update: 06-Feb-2015 2. Latest Archive Date: 02-Feb-2015 3. Latest Metadata Update: 06-Feb-2015 4. Data Verification Status: Awaiting Revisions 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: Wade M. Sheldon, Jr. Address: Dept. of Marine Sciences University of Georgia Athens, Georgia 30602-3636 Country: USA Email: sheldon@uga.edu 3. Copyright Restrictions: not copyrighted 4. Restrictions: All publications based on this data set must cite the contributor and Georgia Coastal Ecosystems LTER project, and two copies of the manuscript must be submitted to the GCE-LTER Information Management Office. a. Release Date: Affiliates: Dec 15, 2009, Public: Dec 15, 2011 b. Citation: Data provided by the Georgia Coastal Ecosystems Long Term Ecological Research Project, supported by funds from NSF OCE 0620959 (data set INV-GCES-0912) 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: INV-GCES-0912_1_0.CSV 2. Size: 84 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: 7. Authentication Procedures: not specified 8. Calculations: 9. Processing History: Software version: GCE Data Toolbox Version 3.9.2 (01-Dec-2014) Data structure version: GCE Data Structure 1.1 (29-Mar-2001) Original data file processed: INV-GCES-0912.txt (84 records) Data processing history: 02-Feb-2015: new GCE Data Structure 1.1 created ('newstruct') 02-Feb-2015: 84 rows imported from ASCII data file 'INV-GCES-0912.txt' ('imp_ascii') 02-Feb-2015: 82 metadata fields in file header parsed ('parse_header') 02-Feb-2015: data structure validated ('gce_valid') 02-Feb-2015: Q/C flagging criteria applied, 'flags' field updated ('dataflag') 02-Feb-2015: automatically assigned study date metadata descriptors based on the range of date values in date/time columns (add_studydates) 02-Feb-2015: imported Dataset, Project, Site, Study, Status, Supplement metadata descriptors from the GCE Metabase ('imp_gcemetadata') 02-Feb-2015: updated 48 metadata fields in the Dataset, Project, Site, Status, Study, Supplement sections ('addmeta') 02-Feb-2015: imported Data, Dataset, Project, Site, Study, Status, Supplement metadata descriptors from the GCE Metabase ('imp_gcemetadata') 02-Feb-2015: Q/C flagging criteria applied, 'flags' field updated ('dataflag') 06-Feb-2015: manually edited data set metadata ('ui_editmetadata') 06-Feb-2015: Variable Type of column Treatment changed from 'text' to 'code ('ui_editor') 06-Feb-2015: updated 6 metadata fields in the Data sections ('addmeta') 06-Feb-2015: updated 15 metadata fields in the Status, Data sections to reflect attribute metadata ('updatecols') 06-Feb-2015: parsed and formatted metadata ('listmeta') B. Variable Information 1. Variable Name: column 1. Plot column 2. Treatment column 3. Snails_Consumed column 4. Months_Elapsed column 5. Sampling_Date 2. Variable Definition: column 1. Unique idetifyer for each experimental plot column 2. Crab composition (Panopeus/Eurytium = only specified species; 'combination' = both species) column 3. Based on middens. Initial density of 300 live Littoraria. column 4. Month after beginning of experiment column 5. Actual date on which the plots were sampled 3. Units of Measurement: column 1. none column 2. none column 3. count column 4. nominalMonth column 5. MM/DD/YYYY 4. Data Type a. Storage Type: column 1. integer column 2. string column 3. integer column 4. integer column 5. string b. Variable Codes: none Treatment: Combination = combination of Panopeus and Eurytium, Euytium = Eurytium only, Panopeus = Panopeus only c. Numeric Range: column 1. 3 to 54 column 2. (none) column 3. 7 to 71 column 4. 1 to 4 column 5. (none) d. Missing Value Code: 5. Data Format a. Column Type: column 1. numerical column 2. text column 3. numerical column 4. numerical column 5. text b. Number of Columns: 5 c. Decimal Places: column 1. 0 column 2. 0 column 3. 0 column 4. 0 column 5. 0 6. Logical Variable Type: column 1. nominal (discrete) column 2. coded value (none) column 3. data (discrete) column 4. datetime (discrete) column 5. datetime (none) 7. Flagging Criteria: column 1. none column 2. none column 3. x<0="I";x>300="I" column 4. none column 5. none 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