The impact of food on reproduction in great white herons was measured by comparing 
timing of nesting, clutch size, and fledging success of naturally foraging herons with 
herons that received supplemental food during the 1981 breeding season. The timing of 
nest initiation was not significantly different between food-supplemented and 
unsupplemented herons. Supplemented herons laid larger clutches and raised more 
young than did unsupplemented birds. Clutch sizes of supplemented herons were not 
significantly different from clutches laid by herons in Florida Bay in the 1923 when the 
habitat was relatively pristine. These results provide evidence that food availability 
can influence clutch size and fledging success in great white herons However, the 
similarity in size of clutches produced by supplemented herons and 1923 herons also 
suggests that unsupplemented herons had depressed clutches. The response to food 
supplementation is therefore interpreted as evidence that herons decrease clutch size 
when food is scarce. It was not possible to determine from this study whether food 
abundance could be increased sufficiently to trigger herons to increase clutch size 
above levels considered typical for the species. 
1981 0 
Raymond, R., and T. D. Davies (1981) Mangrove root intrusion; a means for enriching 
sulfur in underlying peats. Scanning Electron Microscopy . 1981(1):651 -56 
[NO COPY OF PAPER AVAILABLE. ABSTRACT FROM SCHMIDT (1991).] Electron probe 
microanalysis has shown that Lower Kittanning coal samples (a seam in Western 
Pennsylvania) with freshwater overburden contain the least organic S, while those 
with marine overburden contain the most organic S. The organic S contents of 
freshwater coals are greater than those of marine coals conformably overlying them. 
Chemical analyses performed on Florida Bay peats deposited in freshwater 
environments and later affected by marine waters permeate a previously deposited low 
S peat, the organic S content will be increased. A mechanism must be present that 
increases permeability of the underlying peats and provides avenues along which 
marine waters travel downward. From scanning electron microscopy and petrographic 
data root intrusion by R. mangle L. (red mangrove) trees that grow in a marine 
environment appear to be a mechanism for emplacement of fin-grained pyrite in 
underlying freshwater peats. Root intrusion may provide a means for enriching organic 
S in freshwater peats overlain by marine conditions. 
1981 0 
Tyson, R. (1981) Sediments of a Florida Bay basin. M. S. Thesis. University of South 
Florida, Tampa, FL. 
In a southeastern Florida Bay basin, 44 surface sediment samples exhibited variations 
in texture, mineralogy, and molluscan assemblages. Sediment grain size analysis 
separated the samples into three major groups. Aragonite averaged approximately 51% 
in the silt and clay sized fractions. Bivalves were shown to prefer small grain sized 
sediments. A direct correlation between bivalve and Thalassia distribution was 
associated with the trapping of fine grained sediments by seagrass beds. Epifaunal 
gastropods exhibited uniform distribution. Correlations among sand, depth, rock 
fragments, foraminifera, Cerithium, Halimeda, and calcite content are identified for 
sand environments; correlations among other variables are also cited for silt 
environments. 
1981 0 
Walker, N. D. (1981) January water temperatures kill Florida fauna. Coast. Oceanoqr. 
Climatol. News . 3(3):30. 
[NO COPY OF PAPER AVAILABLE. ABSTRACT FROM SCHMIDT (1991).] Seven cold fronts 
reached southern Florida during January 1981, depressing air and water temperatures 
263 
