|Dual-gradient concept of detritus transport and processing in estuaries|
Odum, W.E. (1984). Dual-gradient concept of detritus transport and processing in estuaries. Bull. Mar. Sci. 35(3): 510-521
In: Bulletin of Marine Science. University of Miami Press: Coral Gables. ISSN 0007-4977, more
Detritus; Estuaries; Gradient currents; Marshes; Organic carbon; Rivers; Salinity gradients; Marine
The concept is presented that organic detritus is not uniformly distributed in estuaries, but occurs principally along two gradients, the salinity axis gradient and the marsh stream order gradient. Preliminary evidence is reviewed suggesting that DOC and POC are distributed along these gradients in generally decreasing concentrations from the sources, river carbon in the first case and tidal marsh carbon in the second. Processing of detritus along the salinity axis gradient is proposed to be due principally to physical processes such as floculation while biological processes play a more important role along the marsh stream order gradient. Finally, the potential carbon sources for primary consumers along the marsh stream order gradient should demonstrate a shift from predominantly vascular plant detritus, benthic microalgae, and, possibly, carbon from terrestrial sources in the low order streams to phytoplankton and phytoplankton detritus in the larger streams and embayments. Large beds of submerged macrophytes such as seagrasses can introduce considerable variation in these trends in DOC and POC concentrations. All of these phenomenon are important in considerations of the relative importance of organic detritus as an energy source for estuarine consumers.