Sedimentation, Sea-Level Rise, and Circulation in Florida BayEntry ID: USGS_SOFIA_RHsedsal
Abstract: The goal of this project was to document decade- to century- scale processes associated with sediment transport in Florida Bay. The results will quantify the influence of bottom topography on water quality in the Bay so that sea level and bathymetric change can be integrated with numerical modeling efforts conducted by cooperating agencies.
Recent algal blooms and seagrass mortality have raised ... concerns about the water quality of Florida Bay, particularly its nutrient content (nitrogen and phosphorous), hypersalinity, and turbidity. Water quality is closely tied to sediment transport processes because resuspension of sediments increases turbidity, releases stored nutrients, and facilitates sediment export to the reef tract. The objective of this research is to provide a better understanding of how and when sediments within Florida Bay are resuspended and deposited, to define the spatial distribution of the potential for resuspension, to delineate patterns of potential bathymetric change, and to predict the impacts of storms or seagrass die-off on bathymetry and circulation within the bay. By combining these results with the findings of other research being conducted in Florida Bay, we hope to quantify sediment export from the bay, better define the nutrient input during resuspension events, and assist in modeling circulation and water quality. Results will enable long-term sediment deposition and erosion in various regions of the bay to be integrated with data on the anticipated sea-level rise to predict future water depths and volumes. Results from this project, together with established sediment production rates, will provide the basis for a sediment budget for Florida Bay.
Data Set Citation
Dataset Originator/Creator: Robert Halley (retired) Ellen Prager (no longer with USGS)
Dataset Title: Sedimentation, Sea-Level Rise, and Circulation in Florida Bay
Dataset Release Date: 2002
Data Presentation Form: maps, images, and text filesOnline Resource: http://sofia.usgs.gov/projects/index.php?project_url=circulation/
Start Date: 1994-11-01Stop Date: 2002-12-31
Latitude Resolution: 0.0001
Longitude Resolution: 0.0001
Quality Six interrelated activities were undertaken for this project: 1) core analyses; 2) local sediment elevation surveys; 3) mudbank profiling and surveys; 4) integration of sedimentary analyses with circulation patterns and sea-level history; 5) salinity surveys to document effects of mudbanks on circulation; and 6)measurement of short-term productivity and carbonate precipitation. This project ... integrated results from several other projects in the USGS Place Based Studies and other programs. In particular, the bathymetry, turbidity, sediment transport, lead-2 10 dating, and ecosystem history projects in the bay both used results from this project and provided information to the project. Additional complimentary information was provided by the Marine and Coastal Program project "Sedimentation and water quality in Florida Bay" that provided funding for determining past salinity from geochemical analyses of fossil mollusks as part of a cooperative with the South Florida Water Management District.
Five of the six activities were designed to provide measures of sedimentation or erosion on mudbanks, the sixth activity documents the influence of mudbanks on water salinity. 1) Coring: Cores taken for this and other projects were x-rayed and some provided measurable sections of sediment above known (dated) horizons. These provided an average sedimentation rate based on the age of the horizon. 2) Pb-210 dating: A few cores were suitable for lead-210 dating from which an average sedimentation rate was calculated. The lead-210 method has the advantage of providing a continuous record of sedimentation rates during the last century with a resolution of a few years. However, there are only a few sites in the Bay that are suitable for analyses. 3) Sedimentation site monitoring: Fifteen local sediment survey stations were established in the bay. These were driven to bedrock and provided platforms for seasonal sediment elevation measurements accurate to a few millimeters. Five are in the eastern bay, five in the central bay, and five in the western bay. 4) Bank profiles: Each group of five survey stations is arranged in a transact across a mudbank. Repeated precision profiling across each mudbank will provide a multi-year record of sediment erosion or accretion on the bank and allow the data from individual survey stations, cores, and marker horizon sites to be placed in context of bank-wide patterns. Sedimentation rates provide basic data for determining long-term accumulation/erosion patterns and subsequent volume changes in the bay as a result of sea- level rise. 5) Salinity surveys: Salinity maps, produced semi monthly, illustrate the influence of mudbanks on circulation. The contours of salinity, constructed from bay-wide surveys, show conformity with the banks and often coincide with the banks. Turbid and algal bloom regions, monitored by other agencies, are also confined by shallow banks. 6) Productivity and calcification measurements: The measurements of the short-trem productivity and carbonate precipitaiton provided the data necessary for a comparison of current sedimentation rates with long-term sediment accumulation measured by lead-210 dating and elevation surveys from the project. Three measures of water quality (salinity, turbidity and chlorophyll) indicate that the mudbanks are a dominant control on circulation. Understanding mudbank dynamics is critical to predicting future water quality of the Bay.
Productivity measurements in Florida Bay, including calcification and net photosynthesis, were performed using geochemical techniques that have proven successful for measuring production in carbonate reef and seagrass bed ecosystems (Smith 1973, Barnes 1983, Barnes and Devereux 1984, Frankignoulle and Disteche 1984, Gattuso et al. 1993). These measurements were used to provide insight into the discrepancy between long-term sediment accumulation rates (Stockman et. al,. 1967) and short-term production measurements (Bosence, 1989). Total alkalinity, pH, calcium concentrations, salinity, irradiance, temperature, wind and current speed, and air-sea CO2 and O2 fluxes were measured along transects across carbonate mud banks in Florida Bay. Transects were located parallel to unidirectional current flow across a given bank. Sample stations along each transect were positioned at the upstream, middle, and downstream ends of each transect. Geochemical and physical parameters were measured at each station along a transect at different times (and irradiances) during the day.
Total alkalinity and pH were used to calculate calcification and net photosynthesis using the alkalinity anomaly technique of Smith and Key (1975) such that calcification (C) = half the change in total alkalinity, and net photosynthesis (P) = total carbon-calcification. Total carbon was calculated using carbonate system equations from Millero (1979). Calcium measurements provided an independent measure of calcification for comparison. Air-sea CO2 fluxes were measured directly at each station inside of a floating bell (Sugiura et al. 1963, Frankignoulle and Disteche 1984, Frankignoulle 1988, Gattuso et al. 1993, Kayanne et al. 1995) using the procedure and calculations of Frankignoulle (1988). Air-sea O2 fluxes wree determined by measuring atmospheric and water pO2 and calculating fluxes as described in Wanninkhof (1992). Differences in oxygen and carbon metabolism between upstream and downstream stations will be corrected for O2 and CO2 exchange with the atmosphere as described in (Gattuso et al., 1993).
Productivity and metabolic rates per unit area were calculated using the difference in concentration between upstream and downstream stations, the volume of water transported along a transect, and the transect area such that the change in concentration of a parameter (dC/m2/s) = C/m3 x m3/hr)/m2 (Barnes and Devereux, 1984). Productivity data from multiple transects in Florida Bay were used to estimate daily production rates for Florida Bay. Comparison of these data with previous productivity estimates and sediment accumulation rates will indicate whether discrepancies between production and accumulation rates are due to measurement and calculation techniques or to some real change in the productivity of the Bay.
Access Constraints None
Use Constraints None
Data Set Progress
Distribution Size: 0.2
Distribution Format: JPEG
Role: TECHNICAL CONTACT
Phone: 561 682-6561
Email: drudnic at sfwmd.gov
3301 Gun Club Road
City: West Palm Beach
Province or State: Fl
Postal Code: 33407
Role: DIF AUTHOR
Email: alicia.m.aleman at nasa.gov
Goddard Space Flight Center Code 610.2
Province or State: MD
Postal Code: 20771
Boscence, D. 1989, Biogenic carbonate production in Florida Bay, Bulletin of Marine Science, 44(1): 419-433, Coral Gables, FL, University of Florida Press
Frankignoulle, M. 1988, Field Measurements of air-sea CO2 exchange, Limnology and Oceanography, 33(3):313-322, Washington, D.C., American Society of Limnology and Oceanography
Millero, F.J. 1979, The thermodynamics of the carbonate system in seawater, Geochimica et Cosmochimica Acta, 43:1651-1661, Oxon, United Kingdom, Geochemical Society (Elsevier Science Ltd.)
Smith, S.V., Key, G.S. 1975, 1975 Carbon dioxide and metabolism in marine environments, Limnology and Oceanography, 20:493-495, Washington, DC, American Society of Limnology and Oceanography
Stockman, K.W., Ginsburg, R.N.; Shinn, E.A. 1967, The production of lime mud by algae in South Florida, Journal of Sedimentary Petrology, 37(2):633-648, Tulsa, OK, SEPM Society for Sedimentary Geology
Sugiura, Y., Ibert, E.R.; Hood, D.W. 1963, Mass transfer of carbon dioxide across sea surfaces, Journal of Marine Research, 21(1):11-24, New Haven, CT, Sears Foundation for Marine Research
Wanninkhof, R. 1992, Relationship between wind speed and gas exchange over the ocean, Journal of Geophysical Research, 97:7373-7382, Washington, DC, American Geophysical Union
Barnes, D.J. 1983, Profiling coral reef productivity and calcification using pH and oxygen electrodes, Journal of Experimental Marine Biology and Ecology, 66:149-161, Amsterdam, Netherlands, Elsevier Science BV
Barnes, D. J., Devereux, M. J. 1984, Productivity and calcification on a coral reef: a survey using pH and oxygen electrode techniques, Journal of Experimental Marine Biology and Ecology, 79:213-231, Amsterdam, Netherlands, Elsevier Science BV
Frankignoulle, M., Disteche, A. 1984, CO2 chemistry in the water column above a Posidonia seagrass bed and related air-sea exchanges, Oceanologica Acta, 7(2):209-219, Paris, France, Institute Franceis de Recherche pour l'apos; Exploitation de la Mer
Gattuso, J.P., Pichon, M.; Delesalle, B.; Frankignoulle, M. 1993, Community metabolism and air-sea CO2 fluxes in a coral reef ecosystem (Moorea, French Polynesia), Marine Ecology Progress Series, 96:259-267, Oldendorf, Germany, Inter-Research
Kayanne, H., Suzuki, A.; Saito, H. 1995, Diurnal changes in the partial pressure of carbon dioxide in coral reef water, Science, 269:214-216, Washington, DC, American Association for the Advancement of Science
Smith, S.V. 1973, Carbon dioxide dynamics: a record of organic carbon production, respiration, and calcification in the Eniwetok reef flat community, Limnology and Oceanography, 18(1):106-120, Washington, DC, American Society of Limnology and Oceanography
Prager, E.J., Halley, R.B. 1999, The influence of seagrass on shell layers and Florida Bay mudbanks, Journal of Coastal Research, v. 15, 1151-1162, Fort Lauderdale, FL, Coastal Education and Research Foundation (CERF)
Creation and Review Dates
DIF Creation Date: 2008-10-31
Last DIF Revision Date: 2009-01-07