Spatial distribution and risk analysis data for diamond-backed terrapins relative to crab trapping, Savannah Coastal Refuge Complex, USA
Data for journal manuscript: Spatial distribution of estuarine diamond-backed terrapins (Malaclemys terrapin) and risk analysis from commercial blue crab (Callinectes sapidus) trapping at the Savannah Coastal Refuges Complex, USA
Dates
Publication Date
2018-09-14
Start Date
2015
End Date
2018
Citation
Thomas, M., Puffer, S.R., Lovich, J.E., Ironside, K.E., and Yackulic, C.B., 2018, Spatial distribution and risk analysis data for diamond-backed terrapins relative to crab trapping, Savannah Coastal Refuge Complex, USA: U.S. Geological Survey data release, https://doi.org/10.5066/F7PN94W3.
Summary
There were five objects for compiling these data: 1) to conduct a systematic inventory of diamond-backed terrapins (Malaclemys terrapin) using headcount surveys on four National Wildlife Refuges (Harris Neck, Blackbeard Island, Wassaw, and Wolf Island) that are a part of the greater Savannah Coastal Refuges Complex in southeast Georgia, USA; 2) to use occupancy modeling to determine detection probability and distribution of diamondback terrapins; 3) to perform risk assessments of these terrapin populations in relation to crabbing pressure; 4) to generate maps with associated GIS files of terrapin relative densities related to crabbing pressure; and 5) to provide scientific information that will allow for effective management of diamond-backed [...]
Summary
There were five objects for compiling these data: 1) to conduct a systematic inventory of diamond-backed terrapins (Malaclemys terrapin) using headcount surveys on four National Wildlife Refuges (Harris Neck, Blackbeard Island, Wassaw, and Wolf Island) that are a part of the greater Savannah Coastal Refuges Complex in southeast Georgia, USA; 2) to use occupancy modeling to determine detection probability and distribution of diamondback terrapins; 3) to perform risk assessments of these terrapin populations in relation to crabbing pressure; 4) to generate maps with associated GIS files of terrapin relative densities related to crabbing pressure; and 5) to provide scientific information that will allow for effective management of diamond-backed terrapins on these National Wildlife Refuges. The data collected during the course of the systematic inventory of diamond-backed terrapins includes information on terrapin detection in tidal creeks on refuges, crab pot numbers and locations, and a variety of environmental-, location-, and observer-related variables to examine the effects of both environmental conditions and observer bias on terrapin detection. Data were collected on crabbing pressure, terrapin detections, and other variables related to date, time, location, environment, observer, and transect length and IDs. Data was collected simultaneously. For example, while performing headcounts, we were also noting crab trap locations, environmental, and observer variables. Data resulting from occupancy modeling is contained in the data.csv file and was used to test hypotheses about the scale at which terrapin head counts respond to crab trapping. Three covariates were considered for generalized linear mixed effects models, including the average observed crab pot density at either the creek scale (creek_cpot) or the refuge/island scale (island_cpot), and the cloud metric (environmental variable as cloud cover can have an influence on terrapin detectability). The risk assessment used data from terrapin head counts and crab pot locations to assess the risk of terrapin mortality due to the presence, density, and distribution of crab trapping activities. Risk was defined as spatial overlap in observations of crab trapping activities and observations of terrapins along head count survey transects in creeks over the entire length of the study. No adjustments for detection probabilities were made, so the risk is based solely on the survey results. Each of the four National Wildlife Refuges sampled were analyzed separately. Maps were generated to show crabbing pressure in relation to terrapin hotspots, thus highlighting areas in need of protection to assure the persistence of terrapin populations and helping to meet the goal of providing information for effective management of diamond-backed terrapins on these refuges.
Click on title to download individual files attached to this item.
Data_Metadata.zip
198.62 KB
application/zip
USGS_2018_JLovich_Terrapin_Metadata.xml Original FGDC Metadata
View
14.8 KB
application/fgdc+xml
Related External Resources
Type: Related Primary Publication
Spatial distribution of estuarine diamond-backed terrapins (Malaclemys terrapin) and risk analysis from commercial blue crab (Callinectes sapidus) trapping at the Savannah Coastal Refuges Complex, USA
The purpose of this project was to examine crabbing pressure in relation to terrapin occupancy on Georgia National Wildlife Refuges. In 2015 we conducted headcount surveys of tidal creeks along four different National Wildlife Refuges (Blackbear, Wassaw, Wolf, and Harris Neck) during which we documented the numbers of crab traps seen during these surveys, as well as whether or not we detected any terrapins within the tidal creeks. The data related to crabbing pressure is compiled under the Crab_Pot_Data sheet, and the data related to terrapin detections on refuges is found under the Terrapin_Data sheet. Additionally, we measured a variety of different enviornmental and observer related variables to examine the effects of both enviornmental conditions and observer bias on terrapin detection. These data can all be found under the Head_Count_Data sheet. Data was collected simultaneously for each sheet but that is it. For example while doing headcounts we were also noting crab trap locations.
Rights
The authors of these data request that data users contact them regarding intended use and to assist with understanding limitations and interpretation. Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty.
