getting, assimilate food efficiently, and consequently have a low 

 production rate. (A. A.) 



Keywords: invertebrates, energy flow, saltmarsh ecosystem, Spartina , 

 productivity, Georgia 



V-D-n 



Odum, E.P., and A.E. Smalley. 1959. Comparison of population energy 

 flow of a herbivorous and a deposit-feeding invertebrate in a salt 

 marsh ecosystem. Proceedings of the National Academy of Science 

 45:617-622. 



Frequently the autotrophic and heterotrophic components of an ecosystem 

 are partially separated in space in that they are stratified one above 

 the other (vegetation - soil on land; phytoplankton - sediments in 

 water). The basic functions are also usually partially separated in 

 time in that there may be a considerable delay in the heterotrophic 

 utilization of a large portion of the net production of autotrophic 

 organisms. Consequently, between the first and second trophic levels, 

 the energy flow of the community is often divided into two broad streams 

 resulting in two types of primary consumption: 1) direct and immediate 

 utilization of living plant tissues by herbivores and plant parasites; 

 and 2) delayed utilization of dead tissues and stored food by other 

 consumers. This paper presents a comparison of the annual pattern 

 of population energy flow of two invertebrate species, a grasshopper 

 and a snail, which represent the two basic types of primary consumers 

 described above. The grasshopper, Orchelimum fidicinium , is a strict 

 herbivore, which feeds exclusively on Spartina alterniflora . The snail, 

 Littorina irrorata , lives on the surface of the sediments and on the 

 stems of marsh grass. 



The annual cycles of numbers, biomass, and energy flow for both 

 invertebrates are presented, as are measurements of net production of 

 the low marsh Spartina and the authors' preliminary estimate of the 

 rate of formation of Spartina detritus. The total annual energy flow 

 of the grasshopper population was estimated to be 28 kcal/m^/yr, and the 

 annual energy flow of the snail population was estimated to be about 

 290 kcal/mVyr. 



The authors point out that while different populations cannot be 

 compared on the basis of numbers and biomass, valid comparisons can 

 be made through the common denominator of energy flow. (B.W.) 



Keywords: energy flow, invertebrates, annual cycles, biomass, salt marsh 

 ecosystem 



261 



