geology and ecological history
of the "buttonwood ridge" region >
Program: FRAGILE ENVIRONMENTS
Program: FRAGILE ENVIRONMENTS
Project Summary: The understanding of the timing and the causes of terrestrial and estuarine ecological changes at the southern tip of Florida is paramount to establish a management scenario for restoring the Everglade Ecology. This project examines the floral, faunal and physical records to determine whether the changes can be related to anthropogenic or natural causes. The project has focus' on three areas, the terrestrial region north of the Bay, the "Buttonwood Ridge" and Florida Bay immediately adjacent to the peninsula. Each of these region have had a different ecological history imprinted in their sediments either by anthropogenic alteration or by natural causes such as sealevel changes.
Project Justification: The changes that have occurred in the transition zone between the Florida Peninsula and Florida Bay have change the biologic productivity of the region. Where there once were large flocks of wading birds, they are extremely rare at the present time. It is thought that this demise is a signal of a great environmental change that has been brought on by anthropogenic changes in the hydrologic regime. This project addresses the geologic history of the region seeking the causes and the timing of these changes. It is assumed that once the causes and timing are understood, a management scheme can be put in place that will correct these changes and revert this important ecologic region back to a sustainable biologic resource.
Project Objectives: The objectives of this study are to determine the origin of the "topographic feature" known as the Buttonwood Ridge and define its role ecologic history of the area. It is a feature which is an enigma, it that it is constructed of fine carbonate mud with no perceptual storm derived features. This program will examine the details geologic structure of the feature and determine how relates to the development of features on both the upland and bays sides. As this is a region of once high biologic productivity were "fed" the resource of Florida Bay, it is imperative that this information be ascertained.
Overall: The feature known as the Buttonwood Ridge appears to be unique among shoreline features. It contains information of the effect of a sealevel rise and it divided the study into the marine and non-marine component, The data collected thus far suggests it has played an important role recording the ecological changes within the region. It proposed to continue the investigation to define the extent of which these changes have occurred and to define the relative importance of sealevel change to changes in hydrology created by the anthropogenic engineering of the South Florida drainage system over the past eight of so decades.
FY98 Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sept Prepare for field ------- Second four Traverses ----- Reconnaissance of other areas ------- Compilation cross sections ------------------------------- Participation in NPS Ecology Workshop ---- Office Compilations: Analysis of sample material ------------------------------- Report Prep -----------------
Planned Reports: A semi-annual report will be prepared and present at the Proposed Ecology Workshop in Sept/Oct 1997. The first year report will be completed and present at the information transfer meeting in March 1998. In addition, the information of this study will be merged with other associated programs and the information will present in informal and formal meetings with the interested governmental agencies of south Florida. In addition the results will present in peer review publications to insure scientifically acceptably.
Planned Outreach Activities: The data from this project will be given to other in the Program element and present at the Annual meeting in August, a meeting with the manager in the South Florida Region.
Accomplishments and Outcomes, Including Outreach: FY 1997 Four cores in the marsh, landward of the "Buttonwood Ridge" were analyzed. Three of these sites are on marine to "non-marine" traverse up Taylor Creek into the saw grass plain. The 210Pb profiles demonstrate the presence of two episodes of sediment accumulation. The sediment in the lower sections of cores one and two is dominated by saw grass pollen, whereas the sediment in the upper part of these cores is dominated by mangrove pollen. The "dated" change at both sites indicates a transition from saw grass to mangrove began around 1950. Comparison of areal photographs of the area, 1940 versus 1990, shows that the site nearest the bay, has changed from a lake to a mangrove marsh. Offshore, the continued "dating"of cores situated at the mouths of Little Madeira Bay, Joe Bay and on Pass Key bank all indicates a very rapid sediment accumulation over the past few decades. At Pass key, it appears that banks have closed up, which could have an effect on circulation in this portion of the Bay. Also, the rapid accumulation at the mouth of the "fringing" bays must be the result of decreased circulation or outfall from the region to the north. Two virbacore traverses across the "Buttonwood Ridge" have provided much information on the nature of this feature. The sedimentology of this feature suggests its formation is related to sealevel changes and thus deciphering its history will provide information on the most recent fluctuations in sealevel. Completion of this part of the study coupled with the analysis of cores from the marsh and bay, will provide information on the relative importance of a sealevel rise versus the flux of fresh water in causing the changes in the ecological changes.
Deliverables, Products Completed: A fact sheet is being prepared that details the development of the central portion of the "Buttonwood Ridge " and data is being incorporated in the ecologic history studies of the area.
Required Expertise: The Geochemist/Sedimentologist and a Technician/compiler( Physical Scientist.
Names of Key Project Staff:
Approximate FTE: 1.5