INFAUNAL SALT-MARSH FORAMINIFERA AND BIOTURBATION IN TUCKERTON, NEW JERSEY AND IMPLICATIONS FOR SEA-LEVEL RECONSTRUCTIONS

Anthropogenic climate change and accelerating rates of sea-level rise have increased the need for accurate records of past sea-level records. Paleo sea level has been successfully studied in coastal salt marshes for the past few decades. Past relative sea level can be reconstructed through the use of proxies such as foraminiferal assemblages, under the assumption that salt marsh foraminifera primarily live epifaunally and do not move vertically after death. If foraminifera species live infaunally (below the upper cm of the marsh surface), those species and their depth habitat must be quantified when including them in paleo sea-level reconstructions. Additionally, if there is bioturbation in the salt-marsh environment, this effect must also be accounted for in sea-level reconstructions, as bioturbation could transport foraminifera vertically from the marsh surface. Inclusion of these site specific factors allows for more precise sea-level reconstructions, which are needed to forecast the coastal impacts of climate change. This study uses salt-marsh sediment cores (50 cm long) from four field sites in Tuckerton, New Jersey to quantify the occurrence of infaunal salt marsh foraminifera assemblages and to examine the extent of bioturbation. Foraminifera in the sediment cores were stained with Rose Bengal to distinguish live and dead tests, which were counted under binocular microscope. The resulting foraminifera assemblage and bioturbation data will be compared against other site variables, including vegetation type, marsh surface elevation, salinity, and organic carbon content, in order to evaluate the effect on paleo sea level reconstructions. The effects of bioturbation were measured using foraminifera-sized beads that were distributed on the marsh surface and then sampled with shallow sediment cores through time. Further results and interpretations will be presented at the meeting.