Analyzing historical patterns of change in molluscan assemblages is a very powerful tool in reconstructing the history of an ecosystem. Molluscs possess a number of characteristics that make them excellent indicators:

• Components of micro-, meio-, and macro-fauna
• Present in terrestrial, freshwater, estuarine and marine environments
• Some move from plankton to benthos as pass through life stages
• Occupy a number of trophic levels
• Relatively tolerant of short-term environmental fluctuations
• Individuals relatively limited in movement in post larval stages
• Populations respond to seasonal variations (Dame, 1996; Lyons 1996, 1998)
• Most secrete a hard calcareous shell that is well preserved
• Shell chemistry records the details of short-term change
  

We believe changes in molluscan assemblages identify significant perturbations of an environment and filter out "noise" caused by short-term fluctuations, such as those caused by tropical storms. By understanding the factors controlling modern distributions of molluscs, we can interpret patterns of change in the past, and in turn, predict future responses to human-induced or natural environmental change.

Modern field data were compiled from 26 sites visited biannually between February 1995 and July 1999. Modern data consist of 1) a presence/absence data set, 2) vegetation sample counts, and 3) push core sample counts. Modern data were compared to percent abundance data from four cores using UPGM cluster analyses, with cosine theta distance measurement. Note: Whipray Core was not included in statistical analyses.

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Related information:

SOFIA Project: Ecosystem History: Florida Bay and the Southwest Coast

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