Foraminifera of Relict Salt Marsh Deposits, St. Catherines Island, Georgia: Taphonomic Implications

Abstract

Relict salt marsh sediments exposed along the eastern coast of St. Catherines Island, Georgia (about 200 to 1500 + years in age), contain fairly diverse and abundant foraminifera in addition to diatoms, ostracodes, fecal pellets, and particulate organic matter. Shallow subsurface sediment samples were collected from several relict low marsh habitats or subenvironments: ponded water marsh, streamside marsh, levee marsh, and creek banklchannel areas. Relict foraminiferal assemblages are overwhelmingly dominated by Arenoparrella mexicana, which accountedfor 43% of all specimens identified. Other common and widely distributed species include: Siphotrochammina lobata, Trochammina inflata, Trochammina macrescens, Textularia palustris, and Miliammina fusca. In addition, Ammotium salsum and Reophax nana are abundant locally. Patterns of species abundance in relict marsh sediments differ from those in surface sediments of modern marshes of neighboring Sapelo Island, reflecting the infaunal occurrence of Arenoparrella mexicana in marshes of coastal Georgia, and perhaps the selective preservation of agglutinated species. Broad foraminiferal associations are also recognized, but they do not correspond to specific salt marsh habitats or subenvironments as closely as do their modern counterparts. Although all samples were collected from relict low marsh habitats, foraminiferal assemblages contain several typical high marsh representatives which may reflect an unusually high extension of low marsh halophytes into the intertidal zone in this area.