184 
migrate, for example, is limited to a distance of a few microns per 
day, which could easily be exceeded by fairly rapid accretion. When- 
ever the deposition rate exceeds the ability of the microflora to mi- 
erate upwards, the population at the surface will be a function of 
how rapidly the microflora can recolonize the mud surface, since new 
populations must be continuously established to replace those buried. 
The periodic nature of accretion could be important in this respect if, 
for example, colonization takes place sufficiently rapidly for a large 
population to become established and do considerable growth during 
those seasons when accretion is relatively slow. There is not enough 
data yet to indicate whether or not rapid accretion is severely limiting 
to the benthic microflora. 
The process of erosion presents similar problems. There is ample 
evidence indicating that rooted vegetation affects the rate of erosion 
in tidal and supertidal ranges. There is an additional suggestion’ 
that the benthic microflora may stabilize the mud surface, even where 
rooted plants are absent. Again, the converse of these relations have 
not been sufficiently analyzed. We know that marsh and estuarine 
plants have a considerable ability to resist erosion, but there is no 
way to predict the point at which this ability will be exceeded and 
erosion will become dominant. Yet we do know that this situation is 
possible; indeed it can be observed along much of the coast of Louisiana. 
As with deposition, erosion has a potentially important but virtually 
unstudied impact upon the process of primary production. 
The phytoplankton, too, is influenced by the processes of sedimenta- 
tion, and the detritus which has been shown above to constitute a 
vital link in the energy flow is also affected by these processes, but 
here again there is insufficient data to draw significant conclusions. 
Weiss,’® has shown that when silts are centrifuged from river waters, 
as much as 50 percent of the population of #. coli may be removed. 
Fox and others ™ have demonstrated the potential significance of the 
sorption of organic dissolved substances to clays in the estuarine 
environment. Macroscopic organic-inorganic complexes occur mainly 
in the form of loosely aggregated, flaky, sometimes frothy mixtures 
of organic molecules, including vitamins, organic colloids, and organic 
fragments intermixed with various proportions of clay, silt, fine sand, 
and living microbiota. These detrital aggregates typically have a 
specific gravity approaching that of sea water, and settle out very 
slowly. There have been no studies dealing with the direct interaction 
of sedimentary processes and energy flow through the agent of detritus. 
These results imply that there are processes taking place in the 
local environment of suspended particles which could have important 
implications for the energy-flow system. In the estuary where both 
dissolved organic matter and inorganic sediment are abundant in 
the water, the concentration of organic matter by sorption onto clay 
particles may provide an important food source for estuarine filter 
feeders. Likewise, the process of adsorption of bacteria upon inorganic 
grains, and the composition and distribution of detritus are closely 
related to processes involving suspended sediment. The exact nature 
and importance of these processes remain uninvestigated, but these 
results indicate potential interactions of inorganic suspended sedi- 
ment with biological processes related to primary production sufficient 
to warrant further research. At present we cannot speculate with 
Footnotes at end of article. 
