supplemented by fish or fish and crabs. Isotopic results reveal that the food webs are 
isotopically similar to the dominant vegetation. Estimates of trophic level fractionation 
were 3.2 and 1.3% for nitrogen and carbon respectively. Both qualitative and 
quantitative results suggest that nutritional support to food web members is derived 
from seagrass in the seagrass dominated location and from mangrove, Rhizophora 
mangle, and benthic vegetation, Ruppia maritima, in the mangrove dominated area. 
Despite the isotopic distinction between areas, within each food web carbon and 
nitrogen are transferred through a detrital food web by similar mechanisms. 
1983 - 1984 
Lapointe, B. E. (1989) Macroalgal production and nutrient relations in oligotrophic areas of 
Florida Bay. Symp. on Florida Bay: A Subtropical Lagoon. Miami, FL. June, 1987. Bull. Mar. 
Sci. . 44(1 ):312-23. 
Abundant macroalgae of southern Florida Bay were assayed during 1983 and 1984 for 
nitrogen (N) and phosphorus (P) limitation of productivity by enrichment effects on in 
situ growth rate, tissue C: N: P molar ratios, and capacity of alkaline phosphatase. 
Growth of two frondose rhodophytes, Cracilaria tikvahiae and Laurencia poitei was 
stimulated primarily by P (although N was also limiting during winter) as was growth 
of two frondose phaeophytes, Sargassum polyceratium and Sargassum pteropleuron. 
Tissue C:P and N:P ratios of the unenriched rhodophytes were elevated, ranging from 
1,080 to 1,939 and 75 to 147, respectively; C:P and N: P ratios of the unenriched 
phaeophytes were lower, ranging from 550 to 1,307 and 23 to 25, respectively. These 
tissue ratios support the primary P limitation suggested by the growth assays and 
suggest that phylogenetic differences may exist in storage and utilization of N and P 
compounds relative to C. Levels of dissolved inorganic nutrients (NH 4 + , N0 3 ', and 
P0 4 ‘ 3 ) in seawater during these studies also suggest that P, relative to N, was most 
limiting during summer months when N0 3 ' and NH 4 + were seasonally elevated and 
seawater N:P ratios were >30:1. Assays for alkaline phosphatase activity in 
phylogenetically diverse forms of Florida Bay macroalgae indicated broadly different 
capacities of this exoenzyme, with the highest rates observed for Dictyota divaricata 
and L. poitei and the lowest rates for G. tikvahiae. Considering that D. divaricata and L. 
poitei had the greatest observed capacity for this enzyme and that these and related 
species are particularly abundant in southern Florida Bay, utilization of dissolved 
organic phosphate pools appears to be ecologically important to sustaining productivity 
of indigenous frondose macroalgae in P-limited Florida Bay. The study sites were at Big 
Pine Key in the Florida Keys and at Content Key in the Bay. 
1983 - 1984 
Larson, D. K., and A. P. Ramus (1984) Distribution of caridean shrimp (Decapoda: 
Natantia:Caridea) in the shallow waters of western Florida Bay. Fla. Sci. . 47(suppl. 1):20. 
In conjunction with ongoing research on the settlement behavior of penaeid shrimp in 
Florida Bay, data has been collected for caridean shrimp. Species richness, distribution 
and abundance of caridean shrimp in shallow seagrass habitat bordering mangrove 
islands of Johnson Key Basin were studied from November 1983 to the present. A 
series of transects, 20 m long, were located perpendicular to the shoreline of the 
islands. Shrimp were collected from square meter plots located at regular intervals 
along the transects. Of six caridean shrimp species recorded, dominants included Thor 
floridanus, Hippolyte pleuracanthus, and Palaemonetes intermedius. Also, numbers of 
Tozeuma carolinense were observed to increase at offshore sites dominated by 
Thalassia testudinum. Total numbers of caridean shrimp were as high as 322 shrimp 
m' 2 . Preliminary results indicate that greatest species richness and peak abundance of 
caridean shrimp occur at the Haladule wrightii and Thallassia transition zone. 
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