A trophic cascade triggers collapse of a salt-marsh ecosystem with intensive recreational fishing

Authors

  • Andrew H. Altieri,

    1. Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island 02912 USA
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    • Present address: Smithsonian Tropical Research Institute, Apartado 0843-03092, Balboa, Ancon, Republic of Panama. E-mail: AltieriA@si.edu

  • Mark D. Bertness,

    1. Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island 02912 USA
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  • Tyler C. Coverdale,

    1. Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island 02912 USA
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  • Nicholas C. Herrmann,

    1. Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island 02912 USA
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  • Christine Angelini

    1. Department of Ecology and Evolutionary Biology, Brown University, Providence, Rhode Island 02912 USA
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    • Present address: Department of Biology, University of Florida, Box 118525, Gainesville, Florida 32601 USA.


Abstract

Overexploitation of predators has been linked to the collapse of a growing number of shallow-water marine ecosystems. However, salt-marsh ecosystems are often viewed and managed as systems controlled by physical processes, despite recent evidence for herbivore-driven die-off of marsh vegetation. Here we use field observations, experiments, and historical records at 14 sites to examine whether the recently reported die-off of northwestern Atlantic salt marshes is associated with the cascading effects of predator dynamics and intensive recreational fishing activity. We found that the localized depletion of top predators at sites accessible to recreational anglers has triggered the proliferation of herbivorous crabs, which in turn results in runaway consumption of marsh vegetation. This suggests that overfishing may be a general mechanism underlying the consumer-driven die-off of salt marshes spreading throughout the western Atlantic. Our findings support the emerging realization that consumers play a dominant role in regulating marine plant communities and can lead to ecosystem collapse when their impacts are amplified by human activities, including recreational fishing.

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