Jennifer
Garte - NOAA/AOML
Objective: This program is a combined research effort of
scientists at AOML and three academic institutions that is designed to carry
out a retrospective analysis of sediments from the South Florida Everglades/Florida
Bay region in order to identify natural and anthropogenic changes recorded in
this ecosystem over time.
Rationale: Until the building of the water diversion canals
and roads, in the early 1900s, freshwater runoff across the South Florida peninsula,
and into the lower Everglades/Florida Bay ecosystem, was at volumes considerably
in excess (+59%) of today's levels. Perturbations such as these tend to stress
natural environments and their ecosystems. Current documented ecological problems,
within Florida Bay, may be the result of such perturbations.
Method: The proposed program combines a large variety of
physical, chemical, and biological measurements including stratigraphy, mineralogy,
geochronology, biostratigraphy, selected heavy-metals, isotopes, and pollen
analyses.
Accomplishment: Despite the fact that this program has
been funded just one year, our initial studies have documented anthropogenic
influences within the portion of the coastal zone that forms the transition
between the Everglades and Florida Bay. Specifically, preliminary results of
a three core sequence from the Everglades' freshwater zone coastward revealed
a elevated landward Hg burden within these sediments (>150 ppb) that declined
seaward (~10 ppb). Moverover, age dating of strata via geochronoloy shows an
increase above the 1940 time horizon. Ongoing work helps to resolve the causes
for this increase (figure). Changes in biocommunity
structure are also being evaluated for both anthropogenic and natural causes
as seen in the following (figure).
Key reference:
Wanless, H., T. Nelsen, L. Tedesco, J. Trefry, P. Blackwelder, and J.
Risi, (1995), Documenting the styles of sedimentation and contained historical
sedimentary record in shallow marine environments in and adjacent to Florida
Bay, South Florida. Abstract for Florida Bay Science Conference: A Report by
Principal Investigators.
Zetwo, M. editor, (1996), The Sediment Record as a Monitor of Natural
and Anthropogenic Changes in the Lower Everglades/Florida Bay Ecosystem,
NOAA/AOML/OCD, Progress Report.
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