Microbiological and physical properties of salt marsh and microecosystem sediments

Sediments from natural marsh and four microecosystem (MES) tanks were compared with reference to ATP, carbon content, and physical properties. Mean values for bacterial numbers and ATP were about twice as high in the MES, carbon content was slightly higher in the artificial systems, and the sediment of the MES was enriched for larger grain sizes and depleted of silt and clay. In the natural marsh sediment, ATP was strongly related (Pearson's correlation coefficient) to granulometric (or physical) factors, whereas ATP was related to biological factors in the MES. Approximately 61% of the variation in ATP concentrations in the marsh sediments could be accounted for by the parameters measured. Only half that amount could be explained on the basis of those same variables in the MES. Furthermore, one of the four tanks was significantly different from the other three in terms of ATP concentration, and an anomaly in respect to silt-clay content was demonstrated in another. Careful control and some type of equilibrating procedure will be necessary before the MES can be employed as replicate units.