Tree islands are ecologically important features within the Everglades with high biodiversity, unique habitats, and ability to sequester nutrients.  Tree islands have decreased both in size and in number since the 1950s because the hydrology of the Florida Everglades was altered by management practices implemented to control water entering the Everglades.  A predictive model is needed that describes how the islands have developed in the past and how they respond to changing hydroperiods, describing duration, depth, and timing of inundation.  Evidence of response can be found by examining fossilized invertebrates within sediments.  As a pilot study, four sediment cores were taken from the head, tail, and sides of a tree island in the Florida Everglades and then sorted, with fossilized remains being identified to best taxonomic level, and placed as a proxy indicator of wet or dry hydroperiods (determined by ²¹⁰Pb dating).  The presence of fossilized terrestrial and aquatic organisms in the cores suggests that tree island environments were changing throughout the last century.  Although we are unable to construct a model from data from a single tree island, the information indicates the island has shifted position and hydroperiod during the period of alteration and management of flows in the Everglades.