U.S. Geological Survey Open-File Report 2006-1381

Geophysical Mapping of Oyster Habitats in a Shallow Estuary; Apalachicola Bay, Florida

Section 3: Preliminary Geologic Interpretation

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Section 3-
Geologic Interpretation


Apalachicola Bay is the largest oyster fishery in Florida, and an updated map of oyster bed distribution was needed for the continued management of this resource. Because of the large size of the study area (35 km long by 8 km wide), and high turbidity of the bay waters, acoustic mapping tools were employed. Sidescan sonar, interferometric bathymetry, single-beam bathymetry, and chirp seismic-reflection systems allowed detailed mapping of oyster bed locations and extents as well as defining their relationship to the morphology of the bay floor and underlying geologic features. Analysis of the resulting datasets has revealed strong relations between the stratigraphic and morphologic evolution of the estuary and the locations and extents of the oyster beds. Integration of the sidescan-sonar imagery and the bathymetric data shows that all oyster beds occur on shoals that stand in relief relative to the surrounding bay floor, but not all shoals are colonized by oyster beds. Seismic-reflection data show that many oyster beds developed on older deltaic deposits underlying the bay. While a variety of conditions influence oyster distribution in the bay, this study demonstrates that the underlying geology, particularly what appear to be Late Holocene delta systems, has significant control over oyster distribution by providing appropriate habitat for their growth.

Skip past bottom index informationTitle | Figures | 1-Introduction | 2-Data Collection and Processing | 3- Geologic Interpretation | 4-References | 5-Maps | Spatial Data | Acknowledgments