18 YLCliri^ lyr. These figures are shown added together in the diagram. 



2 



The author's data provide an estimate for the mud crabs of Zl KC/"^ /yr 



for respiration and 5. 3 KC/m^/yr for production. For the Clapper Rail, infor- 

 mation from a study by Oney (1954) was used to calculate the respiration of 

 1.4 KC/m^/yr and production of 0.2 KC/m'^/yr. In the absence of data for 

 racoons, they were assumed to be about as important as the rails and the rail 

 figures were used. The spiders, wrens and other insect predators were assum- 

 ed to be as effective as the predators on the crabs, snails, nematodes and 

 mussels and the ratios of assimilation, respiration and production for the latter 

 group were used for the former as well. 



The activity of mud bacteria was calculated from the figures of Burkholder 

 for the dry weight of bacteria per gram of mud, assuming the bacterial popula- 

 tion to be self -liquidating. 



The primary producers are fixing an unknown part of the incident solar 

 radiation, and 0. 5 percent of it shows up as primary production. The primary 

 consumers as a whole assinnilate 48 percent of the primary production and trans- 

 form 76 percent of that 48 percent into heat. By groups, the insects assiinilate 

 7 percent of the standing crop of Spartina and transform 73 percent to heat. The 

 detritus -algae feeders assimilate 10 percent of the food available to them, i.e., 

 the algae, bacteria and Spartina left after the insects and bacteria have taken 

 their portion, and transform 82 percent of their food energy into heat. Of the 

 production of primary consumers, the secondary consumers assimilate 40 per- 

 cent and transform 80 percent of that to heat. 



The marsh consumers as a whole transform less than half, 46 percent 

 of the total primary production of the marsh. This means the salt marsh is 

 producing and exporting enough energy to support a larger community than that 

 living on the marsh. (Much of the bacterial action upon Spartina considered a 

 part of the marsh system actually takes place in the water.) There is plenty 

 of energy fixed in the salt marsh to support a large population of shrimp, fish 

 and bottom organisms in the tidal creeks and estuaries occurring in the Georgia 

 salt marsh region. Data of Ragotzkie show that production of the local estuarine 

 plankton community as measured by oxygen changes is negative, indicating that 

 most aquatic organisms must obtain their energy from some outside source, in 

 the author's opinion the marsh. 



It is not suggested that the marsh is adapted to use less than half of the 

 energy fixed there so that the aquatic organisms will have a source of food. 

 The aquatic forms, because of the flushing of the marsh surface with every 

 tide, have a large part of the marsh production brought to them before the 

 marsh consumers have a chance to eat it. A similar relationship between 

 marsh and associated waters would not necessarildy be expected in a region 

 where the great extent of the marsh was not regularly flooded. 



103 



