Oakley, B.A.; Alvarez, J.D., and Boothroyd, J.C., 2012. Benthic geologic habitats of shallow estuarine environments: Greenwich Bay and Wickford Harbor, Narragansett Bay, Rhode Island, U.S.A.

An integrated mapping approach using high-resolution side-scan sonar, surface sediment grab samples, digital aerial and orthophotography, and underwater video imagery was used to map Holocene sediment cover and Late Wisconsinan glacial outcrop in two shallow embayments in Narragansett Bay, Rhode Island, U.S.A. The use of side-scan sonar to characterize the seafloor has become common in a variety of different marine environments. Challenges remain in classifying side-scan or other acoustic data into a naming convention that is useful to scientists and managers. We characterize the benthic geologic habitats of these areas utilizing a flexible naming convention that combines information about geologic processes, morphologic form, particle size, biota, and anthropogenic impacts. Benthic geologic habitats were separated into three habitat groups (depositional environments) (estuarine bayfloor, estuarine cove, and estuarine marginal habitats), and further divided on the basis of morphologic form, surface sediment texture, geologic features, biologic characteristics, and anthropogenic impacts. There is a general trend of decreasing grain size with increasing distance from the open water of Narragansett Bay; however, the types and distribution of facies is complicated, and this work adds to the developing sedimentary models of estuaries. The methods outlined in this paper have been successfully applied in other estuarine, lagoon, and shoreface environments, providing a concise method of imaging and characterizing benthic geologic habitats on the seabed.

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