The low organic matter content upland soils give rise to high organic matter content high marsh sediments which in turn give rise to low organic matter content low marsh sediments. These changes in sediment organic matter content may be directly attributed to altered patterns of tidal flooding frequency or may be related to differences in the susceptibility of each zone's characteristic vegetation to decay. Therefore, the quantity and quality of DOC in sediment pore water may be an indicator of the rate of the susceptibility of sediment organic matter to mineralization or burial. For example, low concentrations of labile DOC would suggest rapid turnover of DOC and organic material mineralization, while high concentrations of refractory DOC would indicate slow turnover, long residence times, and the potential for organic material accumulation. During the summer of 1995, experiments will be conducted to determine if the differences in DOC concentration and conversion of DOC to bacterial cells is a result of differences in tidal inundation frequency, the type of plant materials characteristic of the four marsh zones, or a combination of both inundation frequency and type of organic material.
Concentrations are the mean of replicate samples collected from three lysimeters.
Error bars represent one standard deviation from the mean. Click here for Picture Figure 2. Bacteriovores were removed from the creek water by filtration through an 8 um pore diameter filter. DOC was filter-sterilized. Acridine orange direct counts of bacterial were done at the beginning and end of the 12-hour incubation.