are recommended research priorities. However, severe ecotonal differences between 
Bay and ocean waters, coupled with limited circulation and significant predation may 
inhibit recruitment and survival of postlarval fishes from offshore. An unbroken 
continuum of good habitat from outer to upper reaches may be necessary if 
northeastern Florida Bay is to function as a prime nursery area for estuarine transient 
fishes. 
1992 
Machusak, D. D., and L. R. Kump (1994) Geochemistry of near-shore groundwaters, Fiesta 
Key, FL. Bull. Mar. Sci. . 54(3):1079. 
In June 1992 five piezometers were installed along a 75 m shallow water transect 
offshore of a mangrove patch on Fiesta Key. At each well site a 5 cm dia. core was 
extracted using a rotary hydraulic drill, and a 2.5 cm dia. A PVC piezometer was 
installed. Four wells were cased to bedrock depths ranging from 75 cm to 140 cm with 
50 cm of screened interval. One shallow well was cased to 20 cm with 2.5 cm of 
screen. Wells were developed and sampled 24 hr after installation; well recovery was 
instantaneous. It is important to emphasize that the following results are preliminary 
and associated with initial well development. The majority of sampling will take place in 
mid-August 1992. Temperatures of sampled ground waters were consistently 27.0 ± 
0.2°C (1 - 3°C cooler than Florida Bay waters) with salinity values of 35 - 36 °/oo 
(38 °/oo for Bay water). All ground water samples contained a strong sulfidic odor. 
Ground water samples were also analyzed for alkalinity, pH, and Soluble Reactive 
Phosphate (SRP). Ground water alkalinity increased from 4.0 ± 0.1 meq L' 1 at 13 m 
away from the mangroves to 5.1 ±0.1 meq L' 1 at 72 m out. pH also increased from 7.3 
± 0.1 to 7.5 ± 0.1 at 13 and 72 m respectively. SRP followed a decreasing trend 
outward from the mangrove patch. At 13 m SRP measured 0.75 ^iM and decreased to 
0.45 ± 0.12 at 72 m out. The highest value for SRP, 0.88 ^M, was measured in the 
shallow well located at 20 m out. Ground water samples collected in August will also be 
analyzed for sulfide, N-species, F\ Cl*, S0 4 * 2 , Ca +2 , Mg +2 , and Na + . Cored materials 
represent Pleistocene patch reef deposits of coral and cemented shell hash and 
carbonate mud. In each of the four longer cores there are 1 - 5 cm thick highly porous 
zones (presumably of secondary origin) that contain light-colored coatings of carbonate 
precipitates. Other high porosity zones appear 'grungy' with coatings of darker 
material that may be associated with organic/inorganic processes. Cores will be 
examined using SEM, XRF and Microprobe techniques for comparison with aqueous 
determinations. At present there are insufficient data to suggest any definite 
conclusions, but it does appear that ground waters closest to the mangroves differ in 
measured alkalinity, pH, and SRP from those ground waters located at greater 
distances offshore. Continued study will elucidate these preliminary findings and it is 
hoped that inferences can be made about potential anthropogenic and/or natural ground 
water effects. 
1992 0 
McClanahan, T. R. (1992) Epibenthic gastropods of the Middle Florida Keys: the role of 
habitat and environmental stress on assemblage composition. J. Esd. Mar. Biol. EcoL 
160:169-90. 
[DATE OF SAMPLING UNKNOWN OR NOT APPLICABLE.] A survey of epibenthic 
prosobranch gastropods was undertaken in both seagrass and hard substratum (coral or 
old reef rock) habitats on opposite sides of the Florida Keys (Florida Bay and Hawk 
Channel) to compare faunal differences attributable to differences in the above two 
habitats and environments. Additionally, two data sets (26 continuous months) of 
daytime dissolved oxygen, surface salinity and water temperature from Florida Bay 
(Long Key) and Hawk Channel (Key Largo) environments were compared to determine 
differences that might constitute environmental stresses likely to affect the fauna. The 
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