TESTING OF A PALYNOMORPHIC FINGERPRINT FOR JUNCUS ROEMERIANUS MARSHES AS A METHOD FOR TRACKING SEA LEVEL CHANGES IN THE SOUTHEASTERN UNITED STATES

In the southeastern United States, Juncus roemerianus is the salt marsh plant that occurs at the highest level of saltwater influence. In Marsh and Cohen (2008), it was shown that in South Carolina marshes it is possible to distinguish surface sediments derived from these Juncus-dominated marshes from surface sediments derived from lower-level salt marshes using a new diagnostic palynomorphic fingerprint. This fingerprint was defined primarily by the presence of a host-specific fungal spore (Atrotorquata lineata). This palynomorphic fingerprint was also recently found by us in cores dating back to as much as 3000 years, which suggests its potential usefulness in tracking sea level rise and fall throughout at least the late Holocene.

One question that was not tested in Marsh and Cohen (2008) was whether this fingerprint was present throughout the entire modern range of Juncus roemerianus (from Delaware to Texas). To answer that question, surface samples from Juncus sites in many other parts of its range were collected and analyzed. The diagnostic fingerprint was present in all samples regardless of geographic location. A second question was whether this fingerprint was present regardless of sample position within any one Juncus stand. To answer this question, samples were collected at 50-foot intervals along a 600-foot transect across a Juncus stand. The diagnostic fingerprint was found in all samples within the transect regardless of position, thus providing additional support to those wishing to use this new technique to verify the position of high level salt marshes anywhere within the past or present range of Juncus roemerianus.