I. Data Set Descriptors A. Title: Brian R. Silliman. 2010. Experimental manipulation of predatory crab species identity (Panopeus obesus vs. Eurytium limosum) and size-structure and assessment of effects on invertebrate densities, sediment properties and plant biomass.. Georgia Coastal Ecosystems LTER Data Catalog (data set INV-GCES-1010; http://gce-lter.marsci.uga.edu/public/app/dataset_details.asp?accession=INV-GCES-1010) B. Accession Number: INV-GCES-1010 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. Little is known, however, about their effects on important prey species, or their influences on sediment or plant properties. These influences are likely to be dependent on the identity of species and the size-stucture of the population. We therefore manipulated the species identity (Panopeus or Eurtium) and size-structure. The size-structure treatrment had four levels: small [9 individuals, each 18-22mm carapace diameter], medium [6 ind. 24 -28mm], large [3 ind. 32-36mm], mixed (3 small, 2 medium, 1 large, all within same cage). The numbers of crabs in each size-structure treatment were chosen to capture natural size-abundance relationships. The treatments were maintained in experimental cages (70 x 70 x 100 cm, length, width, height) in the mid-Spartina zone at Dean Creek, Sapelo Island, GA. We maintained the treatments over 4 months (July - October 2010), before assessing impacts on prey densitities (mud fiddler crabs, ribbed mussels and marsh periwinkles), and ecosystem properties (aboveground plant biomass, sediment redox potential, sediment water content). 3. Study Type: Directed Study 4. Study Themes: Aquatic Invertebrate Ecology 5. LTER Core Areas: Populations 6. Georeferences: none 7. Submission Date: Oct 15, 2010 D. Keywords: Eurytium, GCE, Georgia, Georgia Coastal Ecosystems, Littoraria, LTER, organic, Panopeus, Populations, primary production, salt marshes, Sapelo Island, Spartina, 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: To examine the effects of predatory mud crabs (and their species identity and size-structure) we conducted a manipulative experiment over 4 months in the field (July – October 2010). Specifically, we crossed species identity (2 levels: Panopeus obesus vs. Eurytium limosum) with size structure (4 levels: small [9 individuals, each 18-22mm carapace diameter], medium [6 ind. 24 -28mm], large [3 ind. 32-36mm], mixed [3 small, 2 medium, 1 large, all within same cage]), and also included a control with no predators. The numbers of crabs in each size-structure treatment were chosen to approximately equalize the ‘metabolic biomass’ (essentially how much energy all crabs combined would require based on ecological theory; i.e., mass of each individual raised to the 0.75 power and summed). Crab densities were also within the natural range observed. A pre-survey found that densities of adult marsh periwinkles varied across the experimental plots. We therefore equalized initial density to a naturally-occurring intermediate density of 175 individuals per plot. Ribbed mussels and mud fiddlers occurred at ambient densities. b. Permanent Plots: Each experimental treatment (and the control) had 8 replicates, all maintained within 70cm x 70cm x 100cm (l x w x h) galvanized wire mesh cages. The cages had a mesh size of 8mm, which prevented manipulated mud crabs from moving in or out of cages, but allowed passage of small mud fiddler crabs and marsh periwinkles). Treatments were maintained (dead, missing and crabs grown out of size class replaced) during the experiment. c. Data Collection Duration and Frequency: We sampled all response variables at the end of the experiment. See Methods Steps for more details. Beginning of Observations: Jul 01, 2010 End of Observations: Oct 01, 2010 3. Research Methods a. Field and Laboratory Methods: Method 1: Collection of predatory crabs -- Crabs were collected and aded to cages over a one week period at the start of the experiment and added ad hoc as needed to replace any missing (presumed dead) crabs during the experiment. All crabs used in the experiment were collected by hand from throughout (all zones) Dean Creek marsh. The widest point of each crab's carapace was measured using vernier callipers to assess whether they fitted within a size bin. A total of 384 crabs were added to cages to establish the treatments. Method 2: Measurement of plant responses -- At the end of the experiment, linear wounds caused by snail grazing (radulations) were measured on all leaves of ten plants per plot using a standard 15cm ruler and a per leaf estimate calculated, before an average radualtion lenegth per leaf per plot was calculated; Aboveground plant biomass was measured by cutting with shears at base and drying in oven at 60 degrees Celsius until constant weight, and then weighed. Method 3: Measurement of prey densities -- At the end of the experiment, mud fiddler crab (Uca pugnax) density was estimated based on a careful viual count of burrows within each plot; Ribbed mussels (Geukensia demissa) were excavated from below the ground and fully counted; Marsh periwinkles (Littoraria irrorata) were removed and counted. Method 4: Measurement of sediment responses -- At the end of the experiment, sediment redox potential measured using a standard Hach multi-metric probe. The probe head (~3cm in diamter) was inserted ~6cm into the sediment until redox reading had stabilised. 6 replicate redox measurements were taken per plot, with particular spots selected haphazardly; this was then averaged to produce a measure of average redox per plot. Also at the end of the expeirment, sediment % mass of core (from 1 core per plot, located haphazardly on on-mussel area in each plot; core was 10cm diameter x 15cm depth). Core was immediately placed in a sealed plastic bag in the field following collection to ensure that none of the contained water was lost prior to taking initial mass. Each core was then dried in an oven at 60 degrees Celcius until reaching constant mass. % water mass was then calculated for each core as: ((initial wet mass - final dry mass)/initial mass)) x 100. b. Instrumentation: Method 1: none Method 2: none Method 3: none Method 4: none c. Taxonomy and Systematics: Method 1: not applicable Method 2: not applicable Method 3: not applicable Method 4: not applicable d. Speclies List: e. Permit History: Method 1: not applicable Method 2: not applicable Method 3: not applicable Method 4: not applicable 4. Project Personnel a. Personnel: 1: Brian R. Silliman 2: John Griffin 3: Nicole Soomsdat 4: Zachary Chejanovski 5: Kamala Earl 6: Jack Butler b. Affiliations: 1: Duke University, Beaufort, North Carolina 2: University of Swansea, Swansea 3: University of Florida 4: University of Florida 5: University of Florida 6: University of Florida III. Data Set Status and Accessibility A. Status 1. Latest Update: 02-Feb-2015 2. Latest Archive Date: 02-Feb-2015 3. Latest Metadata Update: 02-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: Oct 15, 2010, Public: Oct 15, 2012 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-1010) 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-1010_1_0.CSV 2. Size: 79 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: 8. Calculations: Sediment_satuaration: ((initial wet mass - final dry mass)/initial mass)) x 100 9. Processing History: Software version: GCE Data Toolbox Version 3.8.0 (09-Nov-2013) Data structure version: GCE Data Structure 1.1 (29-Mar-2001) Original data file processed: INV-GCES-1010.txt (79 records) Data processing history: 02-Feb-2015: new GCE Data Structure 1.1 created ('newstruct') 02-Feb-2015: 79 rows imported from ASCII data file 'INV-GCES-1010.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: 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: manually edited data set metadata ('ui_editmetadata') 02-Feb-2015: flags for columns Snails, Fiddlers, Mussels, Sediment_satuaration, Sediment_redox_potential, Leaf_scars_(radulations) and Abveground_biomass_of_Spartina converted to data columns, flag codes updated in metadata ('flags2cols') 02-Feb-2015: updated 6 metadata fields in the Data sections ('addmeta') 02-Feb-2015: updated 15 metadata fields in the Status, Data sections to reflect attribute metadata ('updatecols') 02-Feb-2015: parsed and formatted metadata ('listmeta') B. Variable Information 1. Variable Name: column 1. Species column 2. Size column 3. Snails column 4. Flag_Snails column 5. Fiddlers column 6. Flag_Fiddlers column 7. Mussels column 8. Flag_Mussels column 9. Sediment_satuaration column 10. Flag_Sediment_satuaration column 11. Sediment_redox_potential column 12. Flag_Sediment_redox_potential column 13. Leaf_scars_(radulations) column 14. Flag_Leaf_scars_(radulations) column 15. Abveground_biomass_of_Spartina column 16. Flag_Abveground_biomass_of_Spartina 2. Variable Definition: column 1. Species of mud crab column 2. Size Structure of mud crabs within experimental plot (also includes two control treatments) column 3. Final density of snails (Littoraria irrorata) column 4. QA/QC flags for Final density of snails (Littoraria irrorata) (flagging criteria, where "x" is Snails: x<0="I", x>175="Q") column 5. Final density of fiddler crabs (Uca pugnax) column 6. QA/QC flags for Final density of fiddler crabs (Uca pugnax) (flagging criteria, where "x" is Fiddlers: x<0="I", x>200="Q") column 7. Final density of mussels (Geukensia demissa) column 8. QA/QC flags for Final density of mussels (Geukensia demissa) (flagging criteria, where "x" is Mussels: x<0="I", x>100="Q") column 9. Percent water mass of sediment core column 10. QA/QC flags for Percent water mass of sediment core (flagging criteria, where "x" is Sediment_satuaration: x<0="I", x>100="I") column 11. Redox of sediment (mean of 6 random samples/plot) column 12. QA/QC flags for Redox of sediment (mean of 6 random samples/plot) (flagging criteria, where "x" is Sediment_redox_potential: x<-100="Q", x>100="Q") column 13. Mean of all leaves of 10 plants column 14. QA/QC flags for Mean of all leaves of 10 plants (flagging criteria, where "x" is Leaf_scars_(radulations): x<0="I", x>10="Q") column 15. Total dried Spartina biomass per plot column 16. QA/QC flags for Total dried Spartina biomass per plot (flagging criteria, where "x" is Abveground_biomass_of_Spartina: x<0="I", x>300="Q") 3. Units of Measurement: column 1. none column 2. none column 3. count column 4. none column 5. count column 6. none column 7. count column 8. none column 9. percent column 10. none column 11. mV column 12. none column 13. cm column 14. none column 15. grams column 16. none 4. Data Type a. Storage Type: column 1. string column 2. string column 3. integer column 4. string column 5. integer column 6. string column 7. integer column 8. string column 9. floating-point column 10. string column 11. floating-point column 12. string column 13. floating-point column 14. string column 15. floating-point column 16. string b. Variable Codes: Flag_Abveground_biomass_of_Spartina: Q = questionable value c. Numeric Range: column 1. (none) column 2. (none) column 3. 0 to 147 column 4. (none) column 5. 46 to 175 column 6. (none) column 7. 6 to 71 column 8. (none) column 9. 37.4574 to 64.6458 column 10. (none) column 11. -64.6458 to -37.4574 column 12. (none) column 13. 0 to 3.7749 column 14. (none) column 15. 68.25 to 346.75 column 16. (none) d. Missing Value Code: 5. Data Format a. Column Type: column 1. text column 2. text column 3. numerical column 4. text column 5. numerical column 6. text column 7. numerical column 8. text column 9. numerical column 10. text column 11. numerical column 12. text column 13. numerical column 14. text column 15. numerical column 16. text b. Number of Columns: 16 c. Decimal Places: column 1. 0 column 2. 0 column 3. 0 column 4. 0 column 5. 0 column 6. 0 column 7. 0 column 8. 0 column 9. 2 column 10. 0 column 11. 2 column 12. 0 column 13. 2 column 14. 0 column 15. 2 column 16. 0 6. Logical Variable Type: column 1. free text (none) column 2. free text (none) column 3. data (discrete) column 4. coded value (none) column 5. data (discrete) column 6. coded value (none) column 7. data (discrete) column 8. coded value (none) column 9. calculation (continuous) column 10. coded value (none) column 11. calculation (continuous) column 12. coded value (none) column 13. calculation (continuous) column 14. coded value (none) column 15. calculation (continuous) column 16. coded value (none) 7. Flagging Criteria: column 1. none column 2. none column 3. x<0="I";x>175="Q" column 4. none column 5. x<0="I";x>200="Q" column 6. none column 7. x<0="I";x>100="Q" column 8. none column 9. x<0="I";x>100="I" column 10. none column 11. x<-100="Q";x>100="Q" column 12. none column 13. x<0="I";x>10="Q" column 14. none column 15. x<0="I";x>300="Q" column 16. none C. Data Anomalies: V. Supplemental Descriptors A. Data Acquisition 1. Data Forms: Field Notebooks 2. Form Location: Silliman/Angelini Office, Sapelo Island, Georgia. 3. Data Entry Validation: NA B. Quality Assurance/Quality Control Procedures: C. Supplemental Materials: NA D. Computer Programs: Microsoft Exel 2007 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