dissolved organic matter in the <500 molecular weight fraction. If dissolved methyl Hg 
exists measurements indicate that its concentration is less than 1 ng L* 1 . Between 60- 
80% of methyl Hg in water is associated with the particulate phase, the highest 
association occurring in the Mississippi River and the lowest in the Everglades. This 
relatively constant phase separation indicates that suspended particulate matter is 
very important in determining the low dissolved Hg concentrations. If any adsorption- 
desorption effects of Hg exist at the zone of salt water mixing they are effectively 
masked by dilution phenomena. Alkyl Hg concentrations in sediments constitute only 
about 0.04% of the total Hg present. The observed organic matter-mercury 
associations are rather of the humic and fulvic type. The chelating ability of these 
organic materials are mainly due to their carboxyl content, which increases with 
decreasing molecular weight. Laboratory experiments show in addition that the fulvic 
acid-mercury association is only partially reversible as higher salinity water is 
reached, indicating that a very strong complex is formed. Measurements of Hg in 
interstitial waters presumably of anoxic character show that this element does not 
become immobilized by the formation of insoluble sulfides. Theoretical considerations 
show that this observation can be explained by the formation of soluble polysulfide 
species as well as by organic matter-mercury complexes. 
1973 
Brook, I. M. (1978) Comparative macrofaunal abundance in turtlegrass (Thalassia 
testudinum) communities in South Florida characterized by high blade density. Bull. Mar. 
Sci. . 28(1 ):212-17. 
Five Thalassia communities with high blade density (-3,000 blades rrf 2 ) were sampled 
by suction dredge in April 1973. Four sites were in south Biscayne Bay, and one was at 
Murray Key in the Everglades National Park on the southwest coast of Florida. 
Macrofaunal abundance ranged from 292 to 10,728 individuals nr 2 . It is postulated that 
a high standing crop of seagrass may not be the primary determining factor in faunal 
abundance. 
1973 0 
Caldwell, D. K., and M. C. Caldwell (1973) Marine mammals of the eastern Gulf of Mexico. 
A Summary of Knowledge of the Eastern Gulf of Mexico: 1973. J. I. Jones, M. E. Ring, M. O. 
Rinkel, and R. E. Smith (eds.). State University System of Florida, Florida Institute of 
Technoloy, Melbourne, FL. III-I-1 - 23. 
[DATE OF SAMPLING UNKNOWN OR NOT APPLICABLE.] Positive records of marine 
mammals from the eastern Gulf of Mexico are listed with annotations, and maps are 
included to show the location of the records. The species listed in Florida Bay and 
Florida Keys are Balaenoptera acutorostrata (Minke whale), Globicephala macrorhyncha 
(short-finned pilot whale), Physeter catadon (sperm whale), Trichechus manatus 
latirostris (manatee), Tursiops truncatus (bottlenose dolphin), and Ziphius cavirostris 
(Cuvier's beaked whale). It is not possible to determine in the maps whether records 
for the Florida Keys are for the Bay or ocean side of the reef track. 
1973 0 
Carballo, J. D. (1985) Holocene dolomitization of supratidal sediments, Sugarloaf Key, 
Florida. M. S. Thesis. University of Texas, Austin, TX. 130 pp. 
[NO COPY OF PAPER AVAILABLE.] 
1973 0 
Chase, T. L. (1973) The variation in growth habits and ecology of the stony corals from Don 
Quixote Bank, Florida Bay. M. S. Thesis, University of Michigan, 
[NO COPY OF PAPER AVAILABLE.] 
206 
