Modeling the effects of nutria (Myocastor coypus) on wetland loss
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Authors: J. Carter, A. L. Foote, and L. A. Johnson-Randall
Date: 1999
Journal: Wetlands
Volume: 19
Number: 1
Pages: 209-219
Summary of Methods: A model was created to study the process in which nutria (Myocastor coypus) feeding activities lead to erosion and loss of marsh area. The nutria-biomass-model consists of three linked modes: a nutria population dynamics model (nutria model), a marsh biomass model for Spartina patens and Scirpus americanus (biomass model), and a marsh area loss model (area model). Four grazing spans (0-52 weeks, 52-104 weeks, 104-156 weeks, 156-208 weeks) were tested.
Article Summary / Main Points: The simulated model when used with standard parameters showed nutria numbers increasing from 40 to 92 followed by a population collapse. High population densities and low survivorship rates as reported in the literature are incompatible. The nutria model is most sensitive to adult and juvenile survivorship and, to a lesser degree, young born per female. It is least sensitive to time based parameters; gestation periods, impregnation rates, or time to maturity. The marsh area model is not sensitive to the marsh loss equation nor to the density at which loss of marsh area begins but is sensitive to the amount of biomass destroyed per nutria. Nutria numbers do not significantly decrease in the nutria-biomass-area model until the total marsh area approaches zero because marsh loss occurs only during the winter when marsh biomass is at its annual low.
Vegetation Types: Riparian and Wetlands
MLRA Ecoregions: 131A Southern Mississippi River Alluvium
Agrovoc Control Words: Riparian zones Grazing Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: nutria, myocastor coypus, scirpus americanus, spartina patens, eat-out, brackish marsh, marsh loss, population dynamics, coastal louisiana
Annotation: Applicability of this study to the western US is very limited.
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