spring of 1969 a daily average of 7 fish, weighing a total of 1081 

 grams, were caught moving upstream, and 17 fish, weighing a total of 

 472 grams, were caught moving downstream. Although more moved downstream 

 than up, the larger average size of the fish moving upstream resulted 

 in a larger transfer of fish mass upstream. 



Diurnal oxygen series were run to measure the metabolism of the 

 aquatic community. Area values of metabolism were similar for different 

 parts of the stream, but both production per volume and respiration 

 per volume were much larger near the headwaters than farther downstream. 

 This was apparently due to the diluting effect of the deeper water 

 downstream. Migration may allow populations to take advantage of such 

 differences in productivity by maintaining young fish in areas of high 

 productivity. 



An energy diagram was drawn comparing energies of insolation, currents, 

 photosynthesis, respiration, fish populations, and migrations. Parts 

 of this model were simulated on an analog computer. Input energies 

 from insolation and streamflow were similar. About 0.14 percent of 

 the total respiration of the stream was from fish populations, and 

 over one year about 0.01 percent of the total energy used by the ecosystem 

 was used for the process of migration. If it is assumed that upstream 

 migration is necessary to maintain upstream stocks, which may be peri- 

 odically decimated by droughts, the migration energy has an amplifying 

 value of 14. (A. A.) 



Keywords: stream ecosystem, fish migration, energy flow. North Carolina 



IV-D-17 



Daiber, F.C. 1974. Tidal marshes of Delaware. Pages 99-149 iji H.T. Odum, 

 B.J. Copeland, and E.A. McMahan, ed':.. Coastal ecosystems of the United 

 States, Vol. 2. Conservation Foundation, Washington, D.C. 



The Broadkill River Estuary of Delaware is an example of a salt 

 marsh system showing tidal creek interactions. The estuary was studied 

 by class teams of the University of Delaware, and information is 

 provided on hydrography, biogeochemical cycles, fractionation of 

 inorganic phosphorus, hydrogen sulfide production, distribution of 

 nitrite and nitrate, production and release of nutrients, angiosperm 

 plant material, and caloric studies of Spartina and Sesarma reticulatum 

 (Say). 



High salinity penetrated approximately the full length of the small 

 creeks and about half the length of the larger creeks in the study area. 

 The important role of marshes as nurseries in providing food for fishes 



171 



