Scope of Presentation Fossil pollen, macrophytes, and diatoms, along with dated sediment cores collected from the Chesapeake Bay, are used to study the history of the estuary. Change in the estuarine system from benthic (bottom-dwelling) to pelagic (open water) as the result of the transformation of the watershed from forest to agricultural fields beginning with European colonization. Large organisms that contributed to a highly productive economy, such as the oyster, shad, and striped bass have been replaced by smaller organisms with shorter life cycles such as microorganisms, small unicellular algae,...