behavior, feeding or predation. Laboratory experiments with Lucania and Cyprinodon (a 
congener of Floridichthys) indicated that single species distributions may be altered 
when schools of different species interact. Infaunal communities were altered as well. 
Predatory Opsanus consumed more Lucania in disturbed habitats than in healthy 
Thalassia. 
1991 0 
Andrews, J. E. (1991) Geochemical indicators of depositional and early diagenetic facies in 
Holocene carbonate muds, and their preservation potential during stabilization. Chem. Geol. . 
93(3-4):267-89. 
[DATE OF SAMPLING UNKNOWN OR NOT APPLICABLE.) Holocene carbonate muds (<63- 
pm fraction) and macro-organic matter were collected from marine subtidal mudbanks 
and supralittoral mud islands of Florida Bay, and freshwater marshes of the 
Everglades. Geochemistry, sedimentology and mineralogy were used to determine 
whether carbonate mud formation in specific marine and freshwater environments was 
geochemically distinct and to assess the importance of early diagenetic reactions on 
mud chemistry and mineralogy. Significant variations were found in the relative 
amounts of carbonate minerals, not just between the marine and freshwater 
environments, but also within Florida Bay. In particular, Mg-calcite is enriched in 
Crane Key muds by -10% relative to nearby Cross Bank. The Mg-calcite appears to 
precipitate in the surface-living cyanobacterial mats of the key and seems to be linked 
to Mg chelation by the cyanobacterial organic matter. This Mg-calcite has a distinct 
5 13 C around -4 %o, 6 %o lighter than Mg-calcite derived from Thalassia epibionts in 
the Cross Bank muds. Dolomite was found just below the cyanobacterial mats forming in 
the only part of the core where reactive organic carbon has been completely removed 
by sulfate-reducing bacteria. The § 13 C values of this dolomite (at least -4 %o) are 
consistent with previously published 8 13 C values of dissolved inorganic carbon in pore 
waters at this horizon which support dolomite formation in situ. Mg supply for dolomite 
formation may be from dissolution of the overlying cyanobacterial mat Mg-calcite. The 
various types of organic matter have distinctive 8 13 C-values ranging from - -25 %o 
(mangrove and sawgrass) to - -10 %o (cyanobacterial mats) and -8 %o ( Thalassia 
seagrass). Values intermediate between these end-members record mixing of the 
organic matter types which shows particularly the time when the bank muds became 
dominated by Thalassia organic matter, i.e. were relatively removed from mangrove 
vegetation. Five Holocene mud suites (bank, key, cyanobacterial mats, mangrove 
swamp, and freshwater Everglades swamp) show distinct chemical signatures in their 
mean 5 13 C, 5 18 0, MgC0 3 and Sr values. Sodium distinguishes between seawater and 
non-seawater influenced environments but Fe, Mn and P are mainly controlled by non¬ 
carbonate materials. Comparison with published stable isotope and elemental data for 
Pleistocene limestones in the South Florida area suggests that only the facies diagnostic 
signatures of 5 13 C and Mg will be resolvable once the muds have been stabilized to 
micrite. Alteration of the 5 ie O and Sr values during stabilization will probably be more 
severe to the extent that original facies variations are destroyed. 
1991 0 
Fourqurean, J. W., and J. C. Zieman (1991) Photosynthesis, respiration and whole plant 
carbon budget of the seagrass Thalassia testudinum. Mar. Ecol. Prog. Ser. . 69:161-70. 
[DATE OF SAMPLING UNKNOWN OR NOT APPLICABLE.) The photosynthesis versus 
irradiance (P/I) response of the seagrass Thalassia testudinum from Florida Bay was 
measured using the oxygen evolution of intact short shoots enclosed in sealed 
chambers, and found to have a light-saturated P/I behavior. All plants for this study 
were collected near Crane and Panhandle Keys and shipped to Charleston, VA. All four 
of the commonly used mathematical formulations of the P/I curve were of equal utility 
344 
