Eric S. Collins

The study of surface samples was used to characterize the marsh foraminiferal distributions for the first time in South Carolina in three marsh areas: Murrells Inlet, North Inlet and Santee Delta. Vertical zonations of foraminifera with respect to mean sea level are not as well defined as at more temperate localities to the north. The clearest marsh foraminiferal zonations were recognized at North Inlet which is also the least altered by human influence of the areas examined. Zonations in the other two areas were affected either by development (Murrells Inlet) or high river discharge (Santee Delta). Although some of the species are different from those in other marsh zonations from further north, comparable zonations do still exist but provide less absolute accuracy than found in, for example, Nova Scotian marshes. Marsh foraminifera are living infaunally in the shallow subsurface (to 20 cm) but appear to have little affect on the total assemblage (which is the ultimate fossil assemblage). Preservation of agglutinated foraminifera was generally poor in subsurface sediments, especially from Murrells Inlet, possibly as a result of bioturbation. Grab samples from the Intracoastal Waterway/Winyah Bay and nearshore localities show the effects of combined high organic matter loadings, pollution and high riverine discharge. Typical estuarine assemblages appear to be displaced offshore as a result of these effects. Using marsh foraminiferal assemblages in vibracores, a sea-level oscillation was identified in sediments from Murrells Inlet with a 2 m rise in sea-level between 5000 yBP and 4300 yBP followed by a 2 m fall between 4300 yBP and 3600 yBP which corresponds to the end of the mid Holocene warming. Limited data from North Inlet fit well on the Murrells Inlet sea-level curve although the highstand was not identified.

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Supervisor: David Scott