TY - JOUR
T1 - Evaluating the effect of salinity on a simulated American crocodile (Crocodylus acutus) population with applications to conservation and Everglades restoration
AU - Richards, Paul M.
AU - Mooij, Wolf M.
AU - Deangelis, Donald L.
N1 - Funding Information:
We thank Frank Mazzotti, George Dalrymple, Carol Horvitz, Rachel King, and Ted Fleming for comments and critical review. We also thank Rachel King for listening to endless hours of model algorithm development and debugging. This research was supported in substantial part by DOI’s Critical Ecosystems Studies Initiative, a special funding initiative for Everglades restoration, administered by the National Park Service and the US Geological Survey, under Cooperative Agreement 1445-CA09-95-0111 with the University of Miami.
PY - 2004/12/25
Y1 - 2004/12/25
N2 - Everglades restoration will alter the hydrology of South Florida, affecting both water depth and salinity levels in the southern fringes of the Everglades, the habitat of the endangered American crocodile (Crocodylus acutus). A key question is what the effects of these hydrologic changes will be on the crocodile population. Reliable predictions of the viability of endangered species under a variety of management scenarios are of vital importance in conservation ecology. Juvenile American crocodiles are thought to be sensitive to high salinity levels, suffering reduced mass, and potentially reduced survivorship and recruitment. This could negatively impact the population recovery. We addressed the management issue of how the crocodile population will respond to alterations in hydrology with a spatially explicit individual-based model. The model is designed to relate water levels, salinities, and dominant vegetation to crocodile distribution, abundance, population growth, individual growth, survival, nesting effort, and nesting success. Our analysis shows that Everglades restoration, through its effects on water flow to estuaries, may benefit crocodile populations if increased freshwater flow reduces the chance that regional salinity levels exceed levels where small individuals lose mass. In addition, we conclude that conservation priority should be placed on reducing anthropogenic sources of mortality on large individuals, such as road mortality. Finally, research should focus on estimates of annual survivorship for large individuals.
AB - Everglades restoration will alter the hydrology of South Florida, affecting both water depth and salinity levels in the southern fringes of the Everglades, the habitat of the endangered American crocodile (Crocodylus acutus). A key question is what the effects of these hydrologic changes will be on the crocodile population. Reliable predictions of the viability of endangered species under a variety of management scenarios are of vital importance in conservation ecology. Juvenile American crocodiles are thought to be sensitive to high salinity levels, suffering reduced mass, and potentially reduced survivorship and recruitment. This could negatively impact the population recovery. We addressed the management issue of how the crocodile population will respond to alterations in hydrology with a spatially explicit individual-based model. The model is designed to relate water levels, salinities, and dominant vegetation to crocodile distribution, abundance, population growth, individual growth, survival, nesting effort, and nesting success. Our analysis shows that Everglades restoration, through its effects on water flow to estuaries, may benefit crocodile populations if increased freshwater flow reduces the chance that regional salinity levels exceed levels where small individuals lose mass. In addition, we conclude that conservation priority should be placed on reducing anthropogenic sources of mortality on large individuals, such as road mortality. Finally, research should focus on estimates of annual survivorship for large individuals.
KW - American crocodile
KW - Everglades restoration
KW - Individual-based model
KW - Simulation model
KW - Uncertainty analysis
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U2 - 10.1016/j.ecolmodel.2004.04.038
DO - 10.1016/j.ecolmodel.2004.04.038
M3 - Article
AN - SCOPUS:4744356431
VL - 180
SP - 371
EP - 394
JO - Ecological Modelling
JF - Ecological Modelling
SN - 0304-3800
IS - 2-3
ER -