8 Beaches, Barriers, and Marshes of the Southeast Coast: Dynamic Systems in a Changing Climate

Thursday, 30 March 2017
1:00 PM - 5:00 PM
Potomac G

A REGIONAL SCALE FORAMINIFERAL DISTRIBUTION STUDY ENCOMPASSING A MAINLAND MARSH, CHINCOTEAGUE BAY, ASSATEAGUE ISLAND, AND THE INNER SHELF, MD AND VA

Paper number: 8-5
Program: Theme Sessions
Time: 2:20 PM – 2:40 PM

Authors

Abstract

Surface samples were collected from Chincoteague Bay, Assateague Island, and the marshes of mainland Maryland twice during 2014 and were examined for distributional patterns of stained, unstained, and total foraminifera. For contrast, three samples were collected offshore of Assateague Island on the inner shelf. A cluster analysis on the total assemblage of all the samples collected during the spring and offshore resulted in 8 groups which are geographically characterized as offshore, southern Chincoteague Bay, central and northern Chincoteague Bay, Johnson Bay, the marsh, and three samples which clustered alone for various reasons. In conjunction with foraminiferal samples, samples were also analyzed for sediment texture and organic matter content (e.g., LOI and stable and percent carbon and nitrogen).

The dominant stained and unstained species in the bay were similar during both sampling trips with the exception of A. salsum, which rarely occurred stained but dominated the unstained assemblage of the bay. Other dominant estuarine species included A. parkinsoniana which was found at every site, and E. excavatum which occurred in abundance at the sites closest to the inlets during both sampling trips, similar to B. frigida. The great abundance of E. excavatum distinguished the offshore samples from the estuarine samples closest to the inlets. Stained C. poeyanum dominated in Johnson Bay and near the marsh islands of Chincoteague Bay though these specimens appear to have low preservation potential when compared with the unstained assemblage. Haynesina germanica was dominant in two different sub-environments, the inner shelf samples along with E. excavatum, and those of Newport Bay, indicating that it is responding similarly to two different stimuli which may promote the idea that H. germanica is an opportunistic species.

Marsh samples were dominated by T. inflata, T. comprimata, J. macrescens, and M. fusca during both sampling trips with higher total densities in the spring. The fall exhibited an increased number of stained specimens, calcareous species and specimens at sites closest to Fox Hill Point and Great Egging Island on Assateague Island. All samples with an elevation < 0.090 meters and below MTL contained > 20% calcareous specimens though not all sites below MTL contained > 20% calcareous specimens.

Geological Society of America Abstracts with Programs. Vol. 49, No. 3

doi: 10.1130/abs/2017SE-291017

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