Modern intertidal foraminifera of the outer banks, North Carolina, U.S.A., and their applicability for sea-level studies

We collected modern foraminiferal and environmental data from three back-barrier intertidal sites (Currituck Barrier Island, Oregon Inlet, and Pea Island) of the Outer Banks, North Carolina, United States, which have different salinity settings and a wind-driven tidal regime. The foraminiferal assemblages indicate that a vertical zonation of foraminifera occurs, with several significant site-specific variations of assemblages. The intertidal zone can be divided into two elements: first, an agglutinated assemblage that is restricted to the vegetated marsh and is dominated by Ammobaculites crassus, Ammobaculites subcatenulatus, Arenoparrella mexicana, Jadammina macrescens, Miliammina fusca, and Trochammina inflata and, second, a calcareous assemblage that dominates the mudflats and sandflats of the intertidal zone, characterized by Ammonia parkinsoniana, Elphidium excavatum, and Haynesina germanica. We used canonical correspondence analysis and partial canonical correspondence analyses of the foraminiferal and environmental data from the Outer Banks to support the hypothesis that the distribution of foraminifera in the intertidal zone is a direct function of elevation, with the duration and frequency of inundation as the most important factors. Partial canonical correspondence analyses and Monte Carlo permutation tests suggest that all available environmental variables except pH play a significant role in understanding the variations in foraminiferal data.