FINDING A FINGERPRINT FOR SALT POOL DEPOSITS IN MAINE SALT MARSHES

Salt pools are shallow, continuously flooded depressions common to many north-temperate salt marshes. Previous work has shown that salt pool size and frequency may be increasing in Maine's salt marshes and that some marshes may be drowning from the inside out. It is therefore important to determine if salt pools in Maine's marshes are natural features that have been abundant throughout history or if pools are disturbance features that represent anthropogenic degradation of Maine's marshes. It is essential to discover a fingerprint for salt pool sediments in order to determine their life cycles and in order to identify their presence in ancient marsh deposits. In this study, we show that C/N ratios, percent organic carbon, n-alkane distributions and macrofossils can be used to identify salt pool sediments relative to other types of marsh deposits. Salt pool sediments have a lower C/N ratio and a lower percentage of organic carbon than low marsh, high marsh, or higher-high marsh deposits. Salt pool sediments have a similar C/N ratio to tidal flat sediments but a higher percentage of organic carbon. We also show that mid chain-length n-alkanes have the potential to be used as a biomarker for salt pool sediments. We have also found that macrofossils of Hydrobia totteni and seeds of Ruppia maritima are consistent markers of salt pool sediment. C/N ratios, n-alkane distributions and macrofossils can be used in future core work to determine salt pool development and past abundance.