PARENT SESSION
Oral Session # 15: Wetland Ecology I: The Everglades and Southern Wetlands.
Presiding: J Chick
Tuesday, August 5. 8:00 AM to 11:30 AM, SITCC Meeting Room 101.
Paleoecological determination of effects of salt-water encroachment on community migration in coastal South Florida wetlands.
Gaiser, Evelyn*,1, Ruiz, Pablo1, Wachnicka, Anna1, Zafiris, Angelikie1, Ross, Michael1, 1 Southeast Environmental Research Center, Miami, FL
ABSTRACT- Coastal communities in South Florida are migrating landward due to the combined effects of freshwater diversion and sea-level rise. We examined the current distribution of plants, periphyton and mollusks among 112 sites in a 4 km2 area of coastline in the southeast saline Everglades, and compared it to past distributions determined from soil cores taken along transects in the same wetland band. Soil profies show an upper mangrove-derived peat layer that thickens toward the coast, overlying a marl layer on top of the limestone bedrock. Because marl-producing periphyton communities are associated with freshwater gramminoid and mixed gramminoid-mangrove communities, this transition likely represents an expansion of the peat-producing fringing mangrove forest into areas previously occupied by Everglades marl prairie. The mollusk record confirmed this hypothesis, as sites located between the drainage canal and the coast showed significant upcore increases in the ratio of marine to freshwater taxa, while sites to the interior of the canal show the opposite trend. Terrestrial taxa have also increased in the interior sites, indicating encroachment of remaining shallow gramminoid marsh by a shrub-forest community. Maps showing the distribution of ecotones (including, in order from coast to interior, fringing mangrove, dwarf mangrove, brackish gramminoid, freshwater gramminoid, and interior shrub-forest) in surface (modern) and subsurface layers have been used to calculate spatially explicit rates of ecotonal migration in this hydrologically complex band of wetland basins.
Key words: Paleoecology, Everglades, Salt-water encroachment, Sea-level rise