period tidal response appears to be similar to that of the wind response. To begin 
addressing issues relating to how much freshwater is reaching the Bay, and to 
investigate the usefulness of freshness as a tracer, some simple analysis of salinity is 
presented. Rainfall within the catchment is not sufficient to produce the observed 
salinity variations. Freshwater releases from canal structures at the catchment 
boundaries are therefore important and appear to have been similar in magnitude to the 
direct runoff volume over the last 10 yrs. For an idealized l-day approximation of 
Northeast Florida Bay, a net evaporation rate (evaporation minus groundwater seepage) 
of approximately 0.5 cm/day is found from observed salinity variations in the Bay. The 
makeup water for this evaporation causes transports that vary linearly from the south 
to the north and attain a value of approximately 100 m 2 /day at a distance of 20 km 
from the edge of the Everglades. With an average depth of 1.5 m, this corresponds to a 
net speed of 67 m/day or 2000 m/month. The rate of salinity increase HdS/dt under 
evaporative conditions, i.e. when rainfall and runoff are zero, is approximately 0.16 
pptm/day. 
994 0 
Wanless, H. R., L. P. Tedesco, D. Cottrell, and M. G. Tagett (1994) Holocene environmental 
history of carbonate banks in Florida Bay and Biscayne Bay, south Florida. Bull. Mar. Sci. . 
54(3): 1 087. 
[ABSTRACT ONLY. DATE OF SAMPLING UNKNOWN OR NOT APPLICABLE.] Florida Bay is 
underlain by a gently westward sloping limestone surface which rising sea level 
transgressed between 4,500 and 3,000 yrs ago. Subtle irregularities in the limestone 
topography defined landward-penetrating peat-filled sloughs and temporary shore 
buildups (coastal levees). These peat and levee deposits, though now transgressed and 
dissected, served as a defining control on the patterns of subsequent growth of 
carbonate sand and mud banks. Portions of many islands are remnants. Skeletal sand 
and mud banks in Biscayne Bay either extend from gaps in the seaward limestone ridge 
(Featherbed Banks and Caesar's Creek Bank) or are positioned bayward of the 
protection of a shallowly submerged limestone ridge (Safety Valve). The carbonate mud 
banks in central Florida Bay and Biscayne Bay are either transgressed coastal deposits 
or marine carbonate banks built by the physical bank growth, extension and migration. 
The internal stratigraphy of the marine carbonate banks record pulses of physical 
growth followed by seagrass recolonization. Each physical growth pulse contains a 
basal erosion or smothering surface, covered by 1 - 10 cm of coarse skeletal sand and 
gravel (if available) and mud clasts. This is overlain by 1 - 10 cm of layered skeletal to 
peloidal sand which normally fines upwards. A 10 - 120 cm unit of layered mud (to fine 
sand in more exposed settings) forms the bulk of each physical growth pulse. Banks are 
extending/migrating southward and westward by repetitive pulses of physical banks 
growth. Banks tend not to form in the lee of emergent islands. We interpret these 
physical pulses of sedimentation to record a hurricane-level storm initiation (scour, 
smothering, gravel and layered sand) followed by years of layered mud sedimentation 
by winter storms. Gradual seagrass recolonization helps to stabilize the banks but 
appears to play little role in bank growth. The broad carbonate banks in western Florida 
Bay have resulted from the coalescence of smaller banks as interbank bays filled with 
sediment. Bay infillings are commonly associated with persistent seagrass cover and 
community. Both the narrow and broad banks tend to build towards and into the 
intertidal zone. This is accompanied by a coarsening of the substrate and elimination of 
the stabilizing seagrass and algal communities. Carbonate banks are dynamic features 
that are highly responsive to sea level changes, storm processes and sediment supply. 
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