Diatom assemblages found in two sediment cores from northeastern Florida Bay indicated fluctuations in both salinity and subaquatic vegetation cover during the past 100 years. Diatoms from Russell Bank core 19A indicate that salinity was high prior to the 20th century. Between 1890 and 1920, assemblages dominated by Mastogloia species prevailed. After 1920, there was a dramatic shift to assemblages dominated by an epipelic (bottom-dwelling) taxon, Nitzschia granulata. About 1950, this taxon declined and the epiphytic species increased. Epiphytic species remained common until about 1972. After 1972, epiphytic diatoms decreased and diatoms indicative of higher salinity increased. Similar trends were seen in the Pass Key core 37 (which only spanned about 35 years, between 1960-96). Epiphytic diatoms were common between about 1967-77, and there was a general trend toward increasing salinity upcore. These findings are in general agreement with other studies of fossil indicators related to salinity and seagrass cover found in Florida Bay sediment cores.

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(This abstract was taken from the Greater Everglades Ecosystem Restoration (GEER) Open File Report (PDF, 8.7 MB))

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