decline in turnover rate or specific plant productivity during the dieoff. External stress 
in the form of hypersaline conditions (maximum salinities > 70, max. yearly station 
averages > 50 °/oo), which are partly anthropogenically derived, were prevalent 
during much of the dieoff. Climatic stresses are (1) excessively warm waters in the 
late summer and fall of 1986 - 1988, and 90, and (2) a reduction of historic tropical 
storm frequency and intensity. Increased temperatures and decreased day length in the 
fall negatively impact seagrass P/R. Historical and anecdotal evidence suggests a 
continuing shift over the past decades from a mixed habitat to an increasingly 
monospecific Thalassia community. While recolonization processes are establishing a 
more diverse mixture of habitats with the potential of enhanced secondary productivity 
in some areas, in 1992, major dieoff expansion has occurred in western Florida Bay. 
1993 0 
Barber, T. R., and P. R. Carlson (1993) Effects of seagrass die-off on benthic fluxes and 
porewater concentrations of XC0 2 , XH 2 S, and CH 4 in Florida Bay sediments. Proc., 10th 
Annual Meeting, Internatl. Society of Environmental Biogeochemistry. R. S. Oremland (ed.). 
530-50. 
[NO COPY OF PAPER AVAILABLE.] 
1 993 
Barkay, T., P. Vaithiyanatahn, R. Kavanaugh, E. Saouter, and C. J. Richardson (1994) Is 
there a role for eutrophication in methylmercury accumulation in the Florida Everglades? 
Abs., ASLO/PSA Joint Mtg., Miami, FL. a-4. 
[ABSTRACT ONLY.] One possible mechanism for the recently reported accumulation of 
Hg in fish in the Florida Everglades is the increased production of methylmercury in 
eutrophied wetlands. To test this hypothesis we collected peat samples along a 
phosphorus/hydrology gradient, created by the input of agricultural run-off, in Water 
Conservation Area 2A during the summer of 1993. Samples were analyzed for total Hg, 
P, N, C and H and for the potential rates of biological Hg(ll) methylation and CH 3 Hg(l) 
degradation. Preliminary results showed an inverse correlation between total P and Hg 
in the soils (r 2 = 0.95; P = 0.052; N = 4) and a positive relationship between soil total 
P and the ratio of potential methylation to demethylation rates (r 2 = 0.92; P < 0.05; N 
= 5). These results may suggest that (1) Hg accumulation is reduced in eutrophied soils, 
possibly as a result of enhanced rates of Hg mobilization and/or increased rates of peat 
accretion and hydrologic conditions, and (2) eutrophication increases net 
methylmercury production. These trends are currently being investigated by a more 
rigorous sampling regime. 
1993 0 
Hallock, P., and M. W. Peebles (1993) Foraminifera with chlorophyte endosymbionts: 
habitats of six species in the Florida Keys. Mar. Micropaleontoloqv . 20:277-92. 
[DATE OF SAMPLING UNKNOWN OR NOT APPLICABLE.] Three species, Androsina lucasi, 
Archaias angulatus, and Cyclorbiculina compressa, all members of the subfamily 
Araiasinae, are among the largest and most abundant benthic foraminifera in the Florida 
Keys. Each species harbors a different chlorophyte endosymbiont, and each species 
thrives in a different habitat. Androsina lucasi is the most euryhaline species. It is 
found in exceptional abundance in open, dwarfed-mangrove flats in water commonly 
less than 0.2 m in depth, growing on mangrove roots and propagules, and algae such as 
Batophora oerstedii. Archaias angulatus is moderately eurohaline, thriving at sites in 
Florida Bay and Largo Sound at depths less than 2 m, where temperatures range from 
14°C in winter to 33°C in summer and salinities range from 29 to 39 %o,. Substratum 
includes rubble, seagrass ( Thalassia testudinum), Halimeda and a variety of other 
macroalgae, especially when overgrown by epiphytes. Archaias is also common open 
356 
