Evaluating Effects of Everglades Restoration on American Crocodile Populations in South Florida Using a Spatially-Explicit, Stage-Based Population Model

Authors

Timothy W. Green, US Geological Survey, Southeast Ecological Science Center
Daniel H. Slone, US Geological Survey, Southeast Ecological Science Center
Eric D. Swain, US Geological Survey, Florida Water Science CenterFollow
Michael S. Cherkiss, US Geological Survey, Southeast Ecological Science CenterFollow
Melinda Lohman, US Geological Survey, Florida Water Science Center
Frank J. Mazzotti, Department of Wildlife Ecology and Conservation, University of FloridaFollow
Kenneth G. Rice, US Geological Survey, Southeast Ecological Science CenterFollow

Abstract

The distribution and abundance of the American crocodile (Crocodylus acutus) in the Florida Everglades is dependent on the timing, amount, and location of freshwater flow. One of the goals of the Comprehensive Everglades Restoration Plan (CERP) is to restore historic freshwater flows to American crocodile habitat throughout the Everglades. To predict the impacts on the crocodile population from planned restoration activities, we created a stage-based spatially explicit crocodile population model that incorporated regional hydrology models and American crocodile research and monitoring data. Growth and survival were influenced by salinity, water depth, and density-dependent interactions. A stage-structured spatial model was used with discrete spatial convolution to direct crocodiles toward attractive sources where conditions were favorable. The model predicted that CERP would have both positive and negative impacts on American crocodile growth, survival, and distribution. Overall, crocodile populations across south Florida were predicted to decrease approximately 3 % with the implementation of CERP compared to future conditions without restoration, but local increases up to 30 % occurred in the Joe Bay area near Taylor Slough, and local decreases up to 30 % occurred in the vicinity of Buttonwood Canal due to changes in salinity and freshwater flows.

Comments

The definitive publisher-authenticated version is available online at http://dx.doi.org/10.1007/s13157-012-0370-0

This material is based upon work supported by the National Science Foundation through the Florida Coastal Everglades Long-Term Ecological Research program under Cooperative Agreements #DBI-0620409 and #DEB-9910514. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

Recommended Citation

Green, T.W., D.H. Slone, E. Swain, M.S. Cherkiss, M. Lohmann, F.J. Mazzotti, K.G. Rice. 2013. Evaluating effects of Everglades restoration on American Crocodile populations in South Florida using a spatially-explicit, stage-based population model. Wetlands DOI: 10.1007/s13157-012-0370-0