megascleres and microscleres and ranged in size from 1.5 $ (350 nm) to 8.0 4> (4 jim) 
long. Radiolaria were present in minor amounts and ranged in size from approximately 
3.0 to 6.0 4>. Quartz is transported from, the north, along the Gulf of Mexico nearshore 
zone and Cape Sable beaches, into northwest Florida Bay by longshore and flood tidal 
currents. Transport of quartz and other acid insoluble residue within the study area is 
primarily by tidal currents of which ebb tidal currents are more dominant. Sponge 
spicules and radiolaria are derived primarily from within the study area. However, 
some spicules and radiolaria could be derived from outside the study area and 
transported into the area by flood tidal currents from the west and ebb tidal currents 
from the east and southeast. A minor source of quartz, sponge spicules and radiolaria 
may be the Miami Oolite which forms the bedrock of Florida Bay. Sampling from 
Flamingo to East Cape Sable took place in 1976. 
1976 0 
McPherson, B. F., G. Y. Hendrix, H. Klein, and H. M. Tyus (1976) The environment of south 
Florida, a summary report. Geol. Surv. Prof. Pap. 1011. 81 pp. 
[DATE OF SAMPLING UNKNOWN OR NOT APPLICABLE.] After 1900 men came in 
increasing numbers to south Florida and began extensive modification of the vast 
wilderness of swamps, forests, marshes, prairies, and bays. The original south Florida 
ecosystem that evolved over thousands of years gave way to a new three-part 
ecosystem which incorporated an agricultural component, an urban component, and a 
component of the original ecosystem that is largely undeveloped but still has been 
affected by man. These components are interrelated through the flow of energy and 
resources. The remaining natural component of the south Florida ecosystem includes 
freshwater and terrestrial systems such as ponds and sloughs, sawgrass marshes, wet 
prairies, hammock forests, bay heads, cypress forests, pine forests, mixed swamp 
forests, and dry prairies; and coastal systems such as bays, coral reefs, mangroves 
and saline marshes, and beaches and dunes. Fire, tropical storms, frost and cold 
weather, saltwater intrusion, and man also affect systems. Freshwater is a key 
environmental factor in that it not only affects a system directly but that it also 
affects other controlling environmental factors such as fire, soil, temperature, and 
saltwater intrusion. The coastal systems of south Florida are dependent on currents, 
tides, waves, and in most cases freshwater runoff to circulate and transport salts, 
nutrients, and other essential products. Freshwater runoff also dilutes seawater. 
Mangrove forests usually grow where freshwater runoff is greatest and salinity is 
seasonally reduced, whereas coral reefs occur in areas of little or no runoff and normal 
seawater salinity. In estuaries and bays, salinity varies during the year depending on 
the amount of runoff and evaporation, and is a major controlling factor on the 
distribution of organisms. The coastal systems are also affected by other 
environmental factors such as cold weather, water turbidity, and tropical storms. 
Tropical storms often alter coastal systems and are the major natural force that 
changes the distribution of mangrove forests. Juveniles of many marine species derive 
food and protection in estuaries and bays and thus require these habitats to complete 
their life cycles. Man has been altering the ecosystem of south Florida extensively for 
70 yrs. Wetlands originally occupied about 75% of south Florida, but through the years 
much of this land has been drained. In southeast Florida, drainage has lowered water 
levels as much as 1.5 to 1.8 m (5 to 6 ft) below the 1900 level and has disrupted the 
natural systems. Drainage reduces productive wetlands, promotes organic soil 
oxidation and damaging fires, and has permitted seawater intrusion in some areas of 
excessive water-table lowering. 
222 
