curves with changing diffusion constants, curves with more morning 

 production, curves with more afternoon production, curves indicating 

 cloud effects and curves with midday depression. 



Production per area is greatest in very shallow clear bays and least 

 in turbid deeper bays where the turbidity is due to inorganic matter. 

 Bays with bottom plants maintain relatively stable metabolism, whereas 

 plankton-dominated bays fluctuate more widely. Diurnal curve measure- 

 ments generally exceed bottle measurements especially in shallow bays 

 in benthic plant communities like Redfish Bay, Port Aransas, where 

 diurnal curve metabolism is 100 times bottle metabolism. Bottle and 

 free water methods may be similar in plankton blooms but ordinarily 

 bottle methods in shallow marine waters do not provide community 

 metabolism figures. Bottle methods were used in this study to estimate 

 plankton activity. 



The sum of metabolic rates from bottle measurements and bell jar 

 measurements was less than values from diurnal curve methods. Rate 

 data from enclosures containing benthos are believed to be low. 

 Photosynthesis may exceed respiration on single days in all bays, but 

 in bays with little river inflow, respiration is about equal to photo- 

 synthesis within accuracy of methods. With river inflow, respiration 

 may greatly exceed photosynthesis, indicating support of the community 

 from imported organic matter. The curve of percent saturation indicates 

 dominance of heterotrophic energy support when values remain undersaturated 

 through the day. In the upper Laguna Madre and Redfish Bay, production 

 is maximal in the spring-summer season and minimal in the winter 

 season as roughly correlated with light intensities and the presence 

 of migratory faunas. 



Diffusion constants calculated from diurnal curve analysis ranged 

 0.5 to 3.8 gm oxygen/m2/hr. at percent saturation. These constants 

 were correlated with wind, current, and wave action. The diffusion 

 constant, as measured with the diurnal curve method, may be used to 

 compute the steady state pollution load necessary to maintain oxygen 

 above anaerobic levels. Total respiration (natural plus that in 

 pollution load) must be maintained less than R = 24 KS + P (gm/m2/day). 

 The efficiency of photosynthesis in natural community conditions was 

 found to decrease with light intensity during the middle of the day, 

 although the total production generally increases with light intensity. 

 A light saturation point was rarely found for community photosynthesis 

 although in individual plants of the community, light may exceed 

 optimum intensities for these cells. Detailed instructions are given 

 for routine bottle and diurnal curve work in shallow marine waters. 

 (G.S. and author's summary) 



Keywords: metabolism, estuarine systems, primary production, Texas, 

 North Carolina 



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