from the water while decomposing the organic 

 matter and thus lessen the concentrations of 

 nitrogen and phosphorus available to the phyto- 

 plankton. 



7. Experiments on the exchange rate of 

 phosphorus through the various compartments 

 indicate that the exchange rates are rapid. 

 Nitrate may be more limiting than phosphorus 

 to phytoplankton growth in the estuaries near 

 Beaufort, because the exchange rates of nitro- 

 gen are slow as compared with those of phos- 

 phorus. 



DECOMPOSITION OF CORD GRASS 

 m THE ESTUARY 



Joseph Ustach 



Objective: 



To correlate the loss of previously in- 

 corporated radioactivity with the organic de- 



composition of cord grass in the Beaufort, 

 N.C. estuary. 



Justification: 



The large areas of marsh grasses of estu- 

 aries represent a large reserve of nutrients 

 and energy for the ecosystem. The release of 

 this energy store depends on decomposition by 

 bacteria, fungi, and other microorganisms. 

 Estimates of these rates of decomposition are 

 necessary for the evaluation of the total con- 

 tribution of cord grass to estuarine produc- 

 tivity. 



Experimental Procedure: 



The project will consist of: (1) following 

 decomposition in the field via the changes in 

 ash weight and ash-free dry weight of packaged 

 cord grass, (2) labeling cord grass with carbon 

 14, (3) measuring the loss of radioactivity of 

 this label in controlled laboratory conditions, 

 and (4) analyzing qualitatively the dissolved 

 organic material given off during the laboratory 

 experiments . 



ESTUARINE ECOLOGY PROGRAM 



Richard B. Williams, Acting Chief 



For most of this year, the Acting Program 

 Chief has been on educational leave taking 

 training on mathematical aspects of ecology 

 at ORNL (Oak Ridge National Laboratory), Oak 

 Ridge, Tenn. The training he is receiving in 

 systems analysis and in the use of computers 

 should facilitate achieving the research goal 

 of the Estuarine Ecology Program- -prediction 

 of the fate of radionuclides introduced into the 

 estuarine environment. The technique of sys- 

 tems analysis was applied to previously 

 gathered data on needle rush to obtain from 

 these data an estimate of annual production. 

 This analysis, done at ORNL, made use of 

 both analog and digital computers. 



COMPARTMENTAL ANALYSIS OF 



PRODUCTION AND DECAY 



OF Juncus roemerianus^ 



Richard B. Williams 



Juncus roemerianus , or needle rush, grows 

 in the upper intertidal zone and covers ex- 

 tensive areas along the shore of North Carolina 

 and elsewhere on the Atlantic coast. Juncus 

 culms grow from perennial rhizomes and 

 occasionally reach a height of 2 m. The mature 



culms persist green and alive for some period 

 after reaching their full height, then slowly 

 die--downwards from tip to base, remain 

 standing although dead for some period, and 

 ultimately fall to the ground and decay. All 

 three types of culms--live, dying, and dead-- 

 are present throughout the year. 



Rate of production of Juncus was measured 

 as part of a study of total plant production in 

 the estuarine area near Beaufort, N.C. The 

 standing crop of Juncus was measured at 

 5-week intervals for a year. The sample, 

 consisting of all the above-ground material 

 from two 1-m. squares, was collected, sorted 

 on the basis of live, dying, and dead, and these 

 portions dried and weighed. Most of the biomass 

 was dead (fig. 1), indicating that the turnovers 

 of dead Juncus and of the total Juncus biomass 

 were slow. I assumed that the average total 

 biomass, 2,454 g./nn. , was present throughout 

 the year and that the distribution of this 

 average biomass by categories of live, dying, 

 and dead was proportionate to that in the 

 samples. Seasonal cycles were suggested; 

 values were higher for the live material in 

 summer and fall, for the dying in spring and 

 summer, and for the dead in winter and spring 

 (fig. 1). 



2 Analysis of data was completed during 1-year educa- 

 tional leave at ORNL. 



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