other F-bearing phases. The purpose of this dissertation was to examine the behavior of 
F during other mineral reactions in the sea. The involvement of F in carbonate and 
alumino-silicate mineral reactions during sediment early diagenesis are examined as is 
the effect of MgF + ion pair formation on F* adsorption. The approach was to combine 
field sampling, manipulative laboratory experiments, and diagenetic modeling. Models 
of pore water solute distributions, direct solute flux measurements, and reaction rate 
estimates from carbonate sediment of Florida Bay predict net F\ Sr 2+ , and Ca 2+ fluxes 
out of the sediment. The net flux ratio of F/Sr is consistent with dissolution of 
aragonite or high-Mg calcite, but F/Ca and Sr/Ca are 3-10 times that of biogenic 
carbonate sources. Concurrent dissolution and reprecipitation of phases with different F 
and Sr contents accounts for this discrepancy. These fluxes could cause significant 
mineralogical and chemical changes on rapid time scales in carbonate sediment. The 
speciation of F' in seawater is dominated by the free ion (51%) and the MgF + ion pair 
(47%). Experiments with hydrous oxides demonstrate that F* adsorption in seawater is 
predominantly reversible and directly linked to the formation of MgF + in solution and 
co-adsorption of Mg 2+ and F* at particle surfaces. MgF + formation in seawater and its 
influence on F* adsorption has important implications for the mobility and distribution of 
F* in the sea. Tremendous dissolved F* uptake by Amazon continental shelf sediment 
during early diagenesis occurs. The majority of this uptake (~7% of the previously 
defined global ocean sinks) is due to alteration of detrital alumino-silicates or 
authigenic alumino-silicate formation. If Amazon sediment is representative of all 
tropical river sediment, then F uptake by such reactions would equal -40% of the 
previously defined global F sinks and be the most important mechanism of fluoride 
removal in the sea. 
1991 - 1992 
Butler, M. J., W. F. Herrnkind, and J. H. Hunt (1994) Sponge mass mortality and Hurricane 
Andrew: catastrophe for juvenile spiny lobsters in south Florida?. Bull. Mar. Sci. . 
54(3): 1073. 
[ABSTRACT ONLY.] The hardbottom communities of Florida Bay and Biscayne Bay are 
dominated by sponges, macroalgae, and octocorals, and are prime settlement and 
juvenile nursery habitat for south Florida's spiny lobster (Panulirus argus) population. 
We have been studying spiny lobster recruitment in south Florida for nearly a decade 
and, in 1991—1992, our ongoing field investigations provided us the opportunity to 
quantitatively assess the impact of two large-scale disturbances on hardbottom 
community structure and, consequently, juvenile spiny lobster population dynamics. 
From November 1991 - January 1992, a massive sponge die-off occurred in south- 
central Florida Bay following an episodic phytoplankton bloom thought to have resulted 
from the nutrient flux emanating from a seagrass die-off event. Nearly every species 
of sponge was impacted and over 90% of the sponges were dead or damaged in many 
areas. Sponges are the primary shelter for juvenile spiny lobsters and their loss 
precipitated dramatic shifts in lobster shelter use and abundance. Hurricane Andrew 
slammed into south Florida the following September and passed directly over Biscayne 
Bay, where we had completed surveys of juvenile spiny lobster abundance and 
hardbottom habitat structure only a month before. We are resurveying those sites to 
determine the effect of the storm on hardbottom community structure and the juvenile 
spiny lobster abundance and distribution. These two massive, but dissimilar 
disturbances have potentially important consequences for south Florida's hardbottom 
habitat and the juvenile spiny lobsters that reside there. 
1991 - 1992 
Childress, M. J., and W. F. Herrnkind (1994) The behavior of juvenile Caribbean spiny 
lobster in Florida Bay: seasonality, ontogeny and sociality. Bull. Mar. Sci. . 54(3):819-27. 
346 
