Florida Bay has undergone dramatic changes in recent years. Following seagrass die-offs in the late 1980's, both algal blooms and high turbidity (from resuspended sediments) have become common in the Bay. Monitoring programs are documenting the system to describe current conditions and changes that may occur because of alteration to the Everglades and Florida Keys. We are monitoring the Bay using satellite imagery, in particular imagery from the AVHRR (advanced very high resolution radiometer), in order to provide details on sea surface temperature and water reflectance (the latter indicating light attenuation or sediment loads during turbid conditions). During the summer, when this extremely shallow bay is relatively clear, the reflectance information also provides bottom albedo information that may correspond to patterns in bottom habitat. In addition, daily processing of AVHRR data provides imagery suitable for the planning of monitoring cruises. Using AVHRR data starting July 1985, we have developed a time series consisting of over 700 usable scenes, and we anticipate extending the time series back to 1982. Comparisons with field data have provided relationships with light attenuation, Secchi depth, total suspended solids, and nephelometric turbidity. The time series data set provides monthly and seasonal mean conditions, showing the seasonal change in turbidity resulting from high winds associated with winter cold fronts. Over the 11 years studied, Florida Bay has shown a complex pattern of changes in water clarity, with spatial variations in the Bay being identified by looking at mean winter (December to March) conditions. Areas of high turbidity appear consistently in the northeast and western bay. Areas of clear water may have expanded in the southwest bay, and contracted in the central bay. The integration of AVHRR data with Landsat data may provide additional insights into the Bay in the 1970's and early 1980's.

REFERENCES

Stumpf, R.P., and M.L. Frayer, 1997, Temporal and spatial change in coastal ecosystems using remote sensing: Example with Florida Bay, USA, emphasizing AVHRR Imagery, in Proceedings of the 4th International Conference on Remote Sensing for Marine and Coastal Environments: Environmental Research Institute of Michigan, Ann Arbor, v.1, p. 65-73.

Stumpf, R.P., and M.L. Frayer, in press, Use of AVHRR Imagery to examine long-term trends in water clarity in coastal estuaries: Example in Florida Bay, in Kahru, M., and Brown, C., eds., Monitoring Algal Blooms: New Techniques for Detecting Large-Scale Environmental Change: Landes Bioscience, p. 1-23.

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