INFLUENCE OF PATCHINESS ON MODERN SALT-MARSH FORAMINIFERA USED IN SEA-LEVEL STUDIES (NORTH CAROLINA, USA)

Abstract

We collected replicate samples at stations placed systematically along a transect at Oregon Inlet (North Carolina, USA) to investigate spatial homogeneity of dead assemblages of salt-marsh foraminifera. Analysis of variance (ANOVA) was used to investigate the differences in mean proportions for six species ( Miliammina fusca, Trochammina inflata, Arenoparrella mexicana, Tiphotrocha comprimata, Haplophragmoides wilberti and Jadammina macrescens ) selected because of their importance in distinguishing assemblages across salt marshes in the study region. As expected, ANOVA’s on all species indicated significant differences among low-, middle-, and high-marsh zones defined by their flora. No significant differences were found between stations in the low- and high-marsh indicating homogeneity in these zones. In contrast, for all six species in the middle-marsh zone, significant outcomes for ANOVA, cluster analysis and post-hoc comparisons suggested that the middle-marsh should be divided into two zones. In addition, two species exhibited a patchy (inhomogeneous) distribution among all stations in the middle marsh. If confirmed by additional studies, our results indicate that sampling of modern salt-marshes to document the distribution of foraminifera for use in sea-level reconstructions should recognize the spatial variability associated with the middle-marsh floral zone.