100 yr' 1 ). Prior to that time, relative sea level was rising at a rate of 23 - 50 cm 100 
yr 1 , too fast for coastal swamp, marl, or sand environments to stabilize along south 
Florida's coastlines. The establishment of a broad, coastal wetland during the past 3200 
yrs has provided a natural barrier to marine waters and permitted freshwater 
environments of the Everglades to expand. Tide gauges throughout the US record a 
dramatic increase in the rate of relative sea level rise beginning about 1930. During the 
following 60 yrs, the relative rise in sea level for south Florida has averaged 3-4 mm 
yr* 1 (equivalent to 20 - 40 cm 100 yr' 1 ). This rate is 6 - 10 times that of the past 
3200 yrs and is triggering dramatic changes in the coastal wetland communities, 
including accelerated erosion of shore margins, landward encroachment of marine 
wetlands, and saltwater encroachment of surficial and ground waters. Continuation at 
these rates or acceleration, as expected due to global warming, will cause dramatic to 
catastrophic modifications of both the coastal and freshwater wetlands of south Florida. 
Major hurricanes will cause dramatic steps of erosion as well as overstepping of 
coastal wetland margins. 
1913 - 1984 
Stephens, J. C. (1984) Subsidence of organic soils in the Florida Everglades - a review and 
update. Environments of Sout h F l o rid a ; Pre sent and Pa st II. P. J. Gleason (ed.). Miami 
Geological Society, Coral Gables, FL. 22-7. 
The Everglades contains the largest single tract of organic soils in the world, over 
3,100 square miles. Formed under marshy conditions, they subsided when drained by 
compaction, biochemical oxidation, or burning. The first elevations of surface 
subsidence profiles were started in 1913, and in the early 1930s, lines were added at 
the Everglades Experiment Station where land use and treatment could be controlled. 
Altogether 15 lines were established, and 11 were still surveyed by 1984. Those 
abandoned have been negated by construction or subsided until the organic cover 
disappeared and underlying mineral deposits were exposed. Biochemical oxidation has 
accounted for approximately two-thirds of the total loss of the arable soils in the 
Everglades. Subsidence has had serious environmental effects on agriculture, water 
supplies, and wildlife. Flooding the land in Conservation Areas will halt subsidence, and 
losses on arable lands can be ameliorated by maintaining water tables as high as 
feasible, making productive use of drained lands as soon as possible, and increasing 
research. 
1919 - 1989 
Meeder, J. F., and L. B. Meeder (1989) Hurricanes in Florida Bay: a dominant physical 
process. Symp. on Florida Bay: A Subtropical Lagoon. Miami, FL. June, 1987. Bull. Mar. 
Sci. . 44( 1):518. 
[ABSTRACT ONLY.] Hurricanes produce major ecological perturbations important to 
long term maintenance of the Florida Bay ecosystem. The effects of hurricanes on the 
Bay ecosystem are described and contrasted to the effects of fire in south Florida 
terrestrial ecosystems. Just as the importance of fires has been recognized in the 
management of terrestrial ecosystems, the role of hurricanes on coastal and shallow 
bay communities must also be recognized. Many perturbations produced by hurricanes 
are uncontrollable and, therefore their impact on the Florida Bay ecosystem has 
remained unaltered by man's activities. Alteration of hurricane runoff quantity and 
timing, quality of runoff water and tidal exchange rates are major exceptions. Intense 
periods of rapid runoff appear to be very significant in maintaining the Florida Bay 
ecosystem. Physical processes associated with hurricanes are: rainfall, storm tides, 
extreme wind and waves, and outwash. Although predicting the precise effects of any 
hurricane is difficult, several observations are made after analysis of storm data since 
1971: (1) a total of 95 tropical storms have affected the Florida Bay ecosystem (20 
120 
