Bay reflecting different environments. In addition to the grain-size analysis, the 
sediments were analyzed for weight percent of Ca, Mg, Ti, Si, Al, Sr, Fe, and K using 
x-ray fluorescent spectrometry. Water samples were analyzed in situ for pH, 
temperature, dissolved oxygen, dissolved carbon dioxide, salinity, and turbidity by a 
portable chemical analysis kit. Populations of benthonic organisms were estimated at all 
45 sampling stations spread through the three basins. X-ray diffractometry determined 
mineralogical content of each sediment sample. Means, standard deviations, and 
correlation coefficients were calculated to elucidate the relationships between the 
different components. Interpretation of the results obtained from the measured 
parameters indicate that physical processes control the grain-size distribution in Shell 
Key and Crab Key Basins, but biological processes control the grain-size distribution in 
the northernmost basin, Madeira Bay. The average strontium concentration of the 
sediments in all three basins inferred molluscan origin, instead of the expected algal 
origin. Chemical conditions above the sediment-water interface were not favorable for 
inorganic physiochemical precipitation of calcium carbonate at the time the 
measurements were taken. The expected significant negative correlation between 
Thalassia testudinum density and the percentage of coarse grains was recognized in 
only one basin. [This may be based on the same data used in Sorensen (1985).] 
1 985 
Swart, P. K., D. Berler, D. McNeill, M. Guzikowski, S. A. Harrison, and E. Dedick (1989) 
Interstitial water geochemistry and carbonate diagenesis in the sub-surface of a Holocene 
mud island in Florida Bay. Symp. on Florida Bay: A Subtropical Lagoon. Miami, FL. June, 
1987. Bull. Mar. ScL 44(1 ):490-514. 
Diagenetic reactions occurring in the sub-surface of an exposed Holocene island in 
Florida Bay were investigated in a core taken on Crane Key. Interstitial waters 
squeezed from the sediments at 10-cm intervals were filtered and analyzed for Ca, 
Mg, Cl, Sr, S and stable isotopic (C and O) compositions. Alkalinity, pH, salinity and 
sulfate concentrations were also determined. Mineralogy of the bulk sediments was also 
determined. These data were compared with the mineralogy, Sr concentration and 
carbon and oxygen isotopes of the bulk sample and isolated dolomite. Salinities 
throughout the core were in excess of 80 g kg* 1 . To eliminate effects of evaporation 
pore water data were normalized to the concentration of chloride. These data indicate 
that while Ca 2+ /CI\ Mg 2+ / Cl* and Sr 2+ /CI* ratios all increase downcore, Mg 2+ /Ca 2 + 
and Sr 2+ /Ca 2+ ratios exhibit a decrease in certain intervals which we believe is 
attributable to the dissolution of high magnesium calcite and perhaps the precipitation of 
dolomite. These findings are supported by the discovery of dolomite with a 14 C age 
some 2,000 yrs younger than the host sediment. The flux of magnesium, calculated 
from the present day gradient, indicates that more than enough Mg 2+ has been available 
from the dissolution of high magnesium calcite to account for the observed dolomite. 
The dolomites which were analyzed in this investigation did not form 
contemporaneously with deposition, but rather at some time between 2,600 BP and the 
present day. These conclusions are supported by stable carbon and oxygen isotopic data 
and calculation of the saturation state of relevant carbonate minerals. 
1985 0 
Thayer, G. W., W. F. Hettler, and D. W. Peters (1985) Utilization of the red mangrove prop 
root habitat by fishes in South Florida. Estuaries , 8(2B):104A. 
[ABSTRACT ONLY. DATE OF SAMPLING UNKNOWN OR NOT APPLICABLE.] Mangroves 
dominate the shorelines of South Florida, constituting about 4 x 10 5 acres of estuarine 
and coastal habitat. Studies have described the composition of fishes utilizing 
mangrove-fringed bays and lagoons, but, to our knowledge, none have evaluated the use 
of the fringing red mangrove prop root habitat by juvenile and adult fish. We sampled 
299 
