Comparison of Invasive and Non-Invasive Techniques for Measuring Fiddler Crab Density in a Salt Marsh

Quantifying the density of burrowing crabs is challenging, and several techniques have been developed to accomplish it, including burrow counting, visual surveys of surface-active crabs, and substrate excavation. These techniques have been compared in mangrove forests but not in a salt marsh, nor has anyone attempted to excavate traps repeatedly for multiple days. Previous comparisons have not examined these techniques over the course of several months, nor considered the cost and precision associated with each technique. Therefore, from May of 2007 to April 2008, I conducted burrow, visual, single excavation, and repeated excavation surveys to estimate Uca pugnax density in a salt marsh on Tybee Island, Georgia and estimated the cost and precision associated with each technique. Only single and repeated excavation accurately measured juvenile density, but these methods were more costly and caused temporary habitat damage. Burrow surveys yielded reliable adult density but visual surveys underestimated adult and juvenile density, likely due to the difficulty of spotting small crabs in thick vegetation. This information may be useful to management officials monitoring fiddler crab populations and their predators in salt marsh ecosystems.

Name thesis:degree_name

Master of Science in Biology (M.S.)

Level thesis:degree_level

Thesis (open access)

Discipline thesis:degree_discipline

Department of Biology

Year dc:date.available

2008

Author dc:creator

• Hubbard, Charles Robert

Contributors dc:contributor

• C. Ray Chandler
• Bruce Schulte
• Sophie S. George

• ETD
• Fiddler crabs
• Population density
• Salt marsh
• Survey techniques

Repository record dc:identifier

https://digitalcommons.georgiasouthern.edu/etd/737

OAI identifier oai:identifier

oai:digitalcommons.georgiasouthern.edu:etd-1737