Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 16 December 2005:
Vol. 310. no. 5755, pp. 1803 - 1806
DOI: 10.1126/science.1118229
Prev | Table of Contents | Next

Reports

Drought, Snails, and Large-Scale Die-Off of Southern U.S. Salt Marshes

Brian R. Silliman,1* Johan van de Koppel,2 Mark D. Bertness,3 Lee E. Stanton,4 Irving A. Mendelssohn4

Salt marshes in the southeastern United States have recently experienced massive die-off, one of many examples of widespread degradation in marine and coastal ecosystems. Although intense drought is thought to be the primary cause of this die-off, we found snail grazing to be a major contributing factor. Survey of marsh die-off areas in three states revealed high-density fronts of snails on die-off edges at 11 of 12 sites. Exclusion experiments demonstrated that snails actively converted marshes to exposed mudflats. Salt addition and comparative field studies suggest that drought-induced stress and grazers acted synergistically and to varying degrees to cause initial plant death. After these disturbances, snail fronts formed on die-off edges and subsequently propagated through healthy marsh, leading to cascading vegetation loss. These results, combined with model analyses, reveal strong interactions between increasing climatic stress and grazer pressure, both potentially related to human environmental impacts, which amplify the likelihood and intensity of runaway collapse in these coastal systems.

1 Department of Zoology, University of Florida, Gainesville, FL 32611, USA.
2 Centre for Estuarine and Marine Ecology, Netherlands Institute of Ecology (NIOO-KNAW), NL 4401 NT7 Yerseke, Netherlands.
3 Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.
4 Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.

* To whom correspondence should be addressed. E-mail: brs{at}ufl.edu

Read the Full Text


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Herbivory: effects on plant abundance, distribution and population growth.
J. L Maron and E. Crone (2006)
Proc R Soc B 273, 2575-2584
   Abstract »    Full Text »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)