Using Benthic Foraminiferal Distributions to Model Changes In the Western Bay Marshes of the South Shore Estuary, Long Island

The introduction of solid stabilization structures (such as bulk heads) in the marsh system of southern Long Island has had an impact on the marsh areas near the development, the effects of which is yet to be determined. Aerial photographs are available starting from 1920; however, the high and low marshes are indistinguishable from one another in these low resolution photographs. Since benthic foraminifera have known preferences for high and low marsh environments, analyzing the assemblages found downcore permits reconstruction of the marsh through time. We hypothesize that the excess fine sediments are expanding the low marsh, contrary to its anticipated pattern of reduction in the low to high marsh ratio with time.

This study focuses on the distribution of marsh benthic foraminifera, while utilizing cores from the Town of Hempstead's portion of the South Shore Estuary Reserve. Locations were cored throughout the Hempstead Bay area using a soil borer and a vibracore system. The cores were sampled at the surface and at depth, stained with Rose Bengal, and analyzed for foraminiferal assemblages. Rose Bengal Stain was used to distinguish living specimens from non-living specimens, allowing us to establish a baseline of living and dead foraminiferal assemblages. The foraminifera were extracted by removing them from sediments washed through a 63 micrometer sieve. Populations of Trochammina inflata, Trochammina macrescens, Tiphotroca comprimata, and agglutinated species are consistent with previous studies of marsh distributions observed in Nova Scotia and Southern California. Lead-210 and Cesium-137 radioisotopes provide age control.