SUMMARY 



A conceptual model of the study area identifies four major ecological 

 zones; 1) terrestrial and freshwater wetlands, 2) estuarine and saltwater 

 wetlands, 3) Florida Bay and mangrove islands and 4) the Florida Keys. 

 These are geographically delineated from one another by a combination of 

 elevation gradient and positioning relative to one another and to major 

 outside influences such as upstream watersheds, the continental shelf and 

 major ocean current systems. These zones are delineated by differences in 

 basic physical-chemical background factors such as substrate, climate, 

 hydrology and water chemistry which in turn promote characteristic ecologi- 

 cal communities. Many of these communities are similar between zones but 

 localized differences do exist, as do significant shifts in relative 

 abundance of community types. The terrestrial and freshwater wetlands 

 support pinelands, sawgrass marshes, wet prairies, sloughs and occasional 

 tree islands on freshwater peat, marl and limestone soils. The estuarine 

 and saltwater wetlands support mangrove forests, salt marshes and oscillat- 

 ing salinity systems on mangrove peat, marine marl, sand or "liver mud" 

 substrates. Florida Bay exhibits oscillating meso-to hypersaline waters 

 over grassbeds on marine lime mud sediments. These mud banks form an 

 anastomosing pattern surrounding deeper "lake" areas having only a thin 

 veneer of sediment. The exposed tips of the mud banks frequently support 

 mangrove or salt prairie vegetation. The Florida Keys support almost all 

 of the above communities to some small degree but are more prominently 

 characterized by extensive offshore coral reefs. The upper keys are them- 

 selves a relict reef exposed by global lowering of sea level. The lower 

 keys are composed of rock hardened Miami oolite, a limestone formed via 

 chemical precipitation rather than biological deposition. The productivity 

 of these communities with regard to fish and wildlife reflects 1) the 

 diversity and type of habitats available to species that are potentially 

 capable of exploiting them, 2) the degree of alteration of these habitats 

 by man and natural forces, and 3) historical, biogeographic and random 

 factors that restrict organisms to specific environments or prohibit them 

 from exploiting a potential habitat. 



