Gross primary production of algae in the intertidal marshes on the 

 coast of Georgia was measured at various seasons. Measurements were 

 also made of light, temperature, pH, depth of flooding at high tide, 

 and sedimentary chlorophyll. Migration of the algae in the sediments 

 was observed along creek borders. 



2 2 



Production during low tide is 150 mg C/m /hr in winter and 20-30 mg C/m /hr 



in summer. Production under water during high tide is 200 mg C/m^/hr 

 in August and drops to 50 mg in winter. A relation between the changes 

 in production and the regime of light, temperature, and tides is 

 postulated. Changes in production during high and low tide alternate 

 so as to result in a nearly constant daily production throughout the ^ 

 year. The annual gross algal production is estimated to be 200 g C/m . 

 Net production is not less than 90 percent of gross production. 

 Photosynthetic efficiency varied from 3 percent to less than 0.1 percent. 



Because marshes make up about 75 percent of the area of the estuaries 

 of the coast of Georgia, the production of marsh plants is important in 

 its contribution to the energy flow of estuarine populations. The 

 rate of algal production in Georgia salt marshes was found in this 

 study to be similar to the production of phytoplankton in many aquatic 

 ecosystems. When the total production of the marshes is estimated, 

 including Spartina and phytoplankton as well as the algae of sediments, 

 it will probably be comparable to the most productive aquatic and 

 terrestrial ecosystems. Certainly the production of algae in salt 

 marshes is a significant contribution to the energy flow of the 

 ecosystem of marshy estuaries. (J.B.) 



Keywords: primary productivity, algae, Spartina , Georgia 



II-C-3 



Gallagher, J.L., and F.C. Daiber. 1974. Primary production of edaphic 

 algal communities in a Delaware salt marsh. Limnology and Oceanog- 

 raphy 19:390-393. 



Gross primary production of edaphic algae was estimated for five 

 areas in a high salinity tidal marsh near Lewes, Delaware. Salt pan 

 and bare bank (free of angiosperms) algal production did not vary 

 significantly from one part of the year to another. Algal productivity 

 in the tal 1 Spartina alterni flora and Distichlis spicata areas was 

 greatest from mid-January to mid-May. In the short Sj_ alterni flora 

 area, algal productivity did not decrease in the warmest part of 

 the year as it did in the two other grass areas. Annual cycles of light, 

 temperature, and salinity were measured. Gross algal production was 

 about one-third of the angiosperm net production. Since much of the 

 algal production occurs when angiosperms are dormant, it complements 

 the pattern of angiosperm energy fixation. (A. A. -reduced) 



Keywords: primary productivity, algae, Spartina alterni flora (tall 

 and short), Delaware 



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