Scientists studying the south Florida ecosystem have learned that invading cattail plants increased in number and are slowly displacing the native sawgrass communities along the margins of the canals. This may be due to increased nutrients entering the system through the canals. Also, scientists have learned that the amount of sawgrass present has fluctuated naturally over time.

In Florida Bay, the studies have shown that salinity and seagrass distribution have fluctuated a great deal over the last 100-200 years. Before 1940, these fluctuations seem to match natural cycles. After 1940, the fluctuations are much greater, and they no longer match natural cycles. The timing of this change coincides with a large part of the canal construction in the Everglades, so it seems that this human activity has had a big influence on Florida Bay. The studies also have shown that seagrass and macro-benthic algae were much less abundant in the 1800's and early 1900's, than in the last half of this century.

Our data provide strong evidence for region-wide ecosystem disturbance in the late 20th century that was accelerated by human activities. Research is continuing to find additional evidence, and to develop a better understanding of the relationships between salinity, seagrass, fresh-water input, and the plants and animals of the region.

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