243 



Thomas J. Smith III and W. M. Kitchens 



Florida Cooperative Fish and Wildlife Research 



Department of Wildlife and Range Science 



117 Newins-Ziegler 



University of Florida 



Gainesville, PL 32611 



SECT. 10.4 WETLAND RESPONSE and SECT. 11. COASTAL ECOSYSTEMS 



Two important coastal ecosystems were excluded from consideration in 

 Sect. 11. These are coral reefs and tropical hardwood hammocks. Sea level 

 rise would affect both of these systems. Some 7000 years before the 

 present, an extensive barrier reef system was located offshore of Fort 

 Lauderdale. With the small rise in sea level since then, this reef system 

 has been extirpated and the present Florida reef track has developed 

 (Lighty et al., 1978; Jaap, 1984). Although tropical hardwood hammocks are 

 usually found inland from the coast (Olmstead et al . , 1980) they occur at 

 elevations of 1-5 m above MSL. Thus a rise in sea level would have an 

 influence on these systems as well. 



Most conventional wisdom states that as sea level rises, affected 

 coastal ecosystems will simply shift inland. This may not be the case. A 

 man-made alteration of tidal regimes, water height, and salinity gradients 

 along the Savannah River mimics potential sea level rise and provides data 

 that can be used in evaluating ecological responses to sea level rise. 

 Briefly, salt-tolerant marsh grass species (e.g., Spartina cynosuroides . 

 Scirpus robustus) found in the lower portions of the Savannah River quickly 

 invaded affected upstream areas of the river that had been dominated by 

 tidal freshwater species (primarily Zizaniopsis miliaceae) . These tidal 

 freshwater species, however, did not shift their own ranges farther 

 upriver. They exist now within their former range but in greatly reduced 

 abundances. Thus the tidal freshwater marsh community was reduced in areal 

 extent within the overall system (Latham et al., 1988). Interesting 

 questions concerning ecological effects of sea level rise emerge: Did the 

 response of the vegetative communities along the Savannah arise because the 

 natural environmental gradients were steepened rather than just shifted 



