Predation restricts black mangrove (Avicennia germinans) colonization at its northern range limit along Florida’s Gulf Coast
- 533 Downloads
Climate change-driven range expansion of black mangroves (Avicennia germinans) is predicted along the northern Gulf of Mexico, where sea level rise is also driving conversion of freshwater forest islands to salt marsh. While climate-driven A. germinans range expansion has garnered considerable scientific attention, the role of top-down controls on colonization is largely overlooked. We investigated the effects of abiotic (flooding frequency, soil depth, soil salinity) and biotic (predation, herbivory) controls on A. germinans establishment at its northern range limit along Florida’s Gulf Coast by comparing fates of caged and non-caged propagules across four landscape positions (from creek edge to forest island interior) and at three sites along a tidal flooding frequency gradient. Within 12 days, grapsid crab, Sesarma reticulatum, consumed 99% of non-caged propagules. Among caged propagules, establishment increased with increasing flooding frequency; however, cages did not entirely prevent predation, which remained a primary cause of mortality, except in the rarely flooded island. Propagules that survived to seedlings experienced mild to fatal herbivory across landscape positions and sites. This study revealed that while relict forest islands and surrounding marshes can support A. germinans, predation and herbivory strongly suppress colonization, suggesting that mangrove expansion models should incorporate biotic controls.
KeywordsBottom-up Community reassembly Herbivory Predation Sea level rise Sesarma reticulatum Top-down
We thank Waccasassa Bay Preserve State Park for permission to conduct research at Turtle Creek. We also thank University of Florida Seahorse Key Marine Lab for providing transportation support, especially Captain Kenny and Rose McCain. We acknowledge Shawn Taylor and Nathan Reaver for much appreciated field assistance. AL acknowledges funding from the University of Florida Graduate School Fellowship and H. T. Odum Graduate Fellowship. CA acknowledges funding from National Science Foundation Department of Environmental Biology (Award 1546638).
Supplementary material 1 (M4 V 17755 kb)
- Castaneda, H. & F. Putz, 2007. Predicting sea-level rise effects on a nature preserve on the Gulf Coast of Florida: a landscape perspective. Florida Scientist 70: 166–175.Google Scholar
- Cavanaugh, K. C., J. R. Kellner, A. J. Forde, D. S. Gruner, J. D. Parker, W. Rodriguez & I. C. Feller, 2014. Poleward expansion of mangroves is a threshold response to decreased frequency of extreme cold events. Proceedings of the National Academy of Sciences of USA 111: 723–727.CrossRefGoogle Scholar
- FNAI, 2015. Florida Land Cover Classification System Definitions for the Cooperative Land Cover Map v3.1.Google Scholar
- Lewis, R. & F. Dunstan, 1975. The possible role of Spartina alterniflora Loisel in establishment of mangroves in Florida. Proceedings for Second Annual Conference on the Restoration of Coastal Vegetation in Florida May 17, 1975. Hillsborough Community College, Tampa: 82–100.Google Scholar
- Lugo, A. E. & C. Patterson-Zucca, 1977. The impact of low temperature stress on mangrove structure and growth. Tropical Ecology 18: 149–161.Google Scholar
- Patterson, C. S., I. A. Mendelssohn & E. M. Swenson, 1993. Growth and survival of Avicennia germinans seedlings in a mangal/salt marsh community in Louisiana, USA. Journal of Coastal Research 9: 801–810.Google Scholar
- R Core Team, 2016. R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna. www.R-project.org.
- Reddy, K. R., M. W. Clark, R. D. DeLaune & M. Kongchum, 2013. Physicochemical characterization of wetland soils. In Delaune, R. D., K. R. Reddy, C. J. Richardson & J. P. Megonigal (eds), Methods in Biogeochemistry of Wetlands. Soil Science Society of America, Madison: 41–53.Google Scholar
- Rhoades, J., 1996. Salinity: electrical conductivity and total dissolved solids. Methods of Soil Analysis, Part 3: Chemical Methods. Soil Science Society of America and American Society of Agronomy, Madison: 417–435.Google Scholar
- Vince, S. W., S. R. Humphrey & R. W. Simons, 1989. The Ecology of Hydric Hammocks: A Community Profile. U.S. Department of the Interior, Fish and Wildlife Service, Research and Development.Google Scholar
- Williams, K., M. MacDonald, K. McPherson & T. H. Mirti, 2007. Ecology of the coastal edge of hydric hammocks on the Gulf Coast of Florida. In: Ecology of Tidal Freshwater Forested Wetlands of the Southeastern United States. Springer, Dordrecht: 255–289.Google Scholar