these are usually considered grazing food 

 chains from phytopl ankters to herbaceous 

 zooplankton to larger consumers. 



Terrestrial grasslands are another. In 

 these, the grazers are large mammals, 

 ruminants that are able to digest the 

 rather refractory cellulose that is the 

 major structural material in plants 

 because their digestive tracts harbor 

 bacteria and protozoa that can break it 

 down to simpler compounds. 



Marshes are often called wet 

 grasslands, but they differ from their 



terrestrial counterparts in that large 

 mammals are not common. The microbial 

 equivalents to the digestive microflora of 

 the ruminants are bound up in the 

 decomposing grass and sediment on and in 

 the marsh. Much research has been devoted 

 to elucidation of this pathway of energy 

 flow in marshes, and I will try to 

 sui'iinarize the major current ideas about 

 how it works . 



Before considering decomposition, 

 however, let us pause to consider whether 

 herbivory is really as insignificant as it 



Table 19. Submerged aquatic plant species composition of ponds and 

 lakes by marsh zone along the Louisiana coast (August 1968, Chabreck 

 1971a). 



No vegetation in salt marsh zone. 



56 



