| A record of late Holocene sediment, foraminiferal, compound specific carbon isotope, and organic geochemical stratigraphy is presented for a series of radiocarbon-dated cores from four Maine, USA salt marsh sites. We also sampled 10 plant species common to Maine salt marshes including Spartina alterniflora, Spartina patens, Juncus Gerardi, Solidago sempervirens, Salicornia europa, Potentilla anserina, Atriplex patula, Plantago maritima, Suaeda maritima , and Limonium nashii. Isolation of two n-alkanes (C27 and C29) present in marsh plant samples allows for the reconstruction of past plant communities present in the core deposits. Salicornia europa has a similar n-alkane distribution to many of the salt marsh sediments, and we suggest that it is either an important source to the biomass of the marsh through time, or that another unidentified higher plant source is contributing heavily to the sediment pool. Compound specific carbon isotopic analyses of the C27 alkane are on average 7.2%o depleted relative to bulk values, but the two records are strongly correlated (R2 = 0.87), suggesting that marsh plants are "swamping" the bulk carbon isotopic signal. Though we present some evidence for correspondence between foraminiferal records, that indicate mean high water, and carbon isotope values, that record plant community fluctuations (p<0.05), there are also significant excursions in isotope values within specific foraminiferal zones. These excursions are not predictable, do not correspond between field sites, and cannot be related with any confidence to environmental variables. Separately, average fractal dimensions (D) are calculated for Maine's four coastal compartments using a GIS approach and digitized USGS 7.5 minute series topographic quadrangle maps. Statistical tests show that all of the geologically-different coastal compartments can be discriminated in terms of D at the 95% confidence level, while the geologically similar compartments (south-central compartment and Cobscook Bay sub-compartment) cannot be statistically distinguished. |
