once per week. Some of the more important variables sampled included 

 chlorophyll, nitrogen, extinction coefficient, and primary production. 

 These data were used in a multiple linear-regression equation to predict 

 net production in Flax Pond. This equation predicted that in the marsh 

 11.8 grams of carbon were fixed as net production per square meter 

 per year, compared to 593 grams per square meter per year potentially 

 fixed in Long Island Sound. Samples collected by Brookhaven National 

 Laboratory in a concurrent study showed a large net flux of phytoplankton 

 from the Sound. Production within the marsh, as well as transport of 

 phytoplankton into Flax Pond, provided over nine kilograms of carbon 

 per square meter of marsh per year available to higher trophic levels. 

 Although chlorophyll measurements were significantly correlated with 

 productivity and total numbers of phytoplankton cells, previous 

 investigations suggested that these correlations should have been 

 higher. The relationship of pH and carbon dioxide to net production 

 was confounded due to high levels of respiration in the marsh and 

 the mixing effect of water brought in with the tides. A multivariate 

 analysis of variance showed that considerable variation is introduced 

 into the data by the effect of time of year. Lesser, but significant, 

 amounts of variation were introduced from the effect of time of day 

 within the photoperiod at which samples were taken and location of 

 sampling within the marsh. (A. A.) 



Keywords: primary productivity, phytoplankton, salt marsh. Long Island 



II-C-12 



Thayer, G.W. 1969. Phytoplankton production and factors influencing 



production in the shallow estuaries near Beaufort, North Carolina. 



Ph.D. Thesis. North Carolina State University at Raleigh. 179 pp. 



(Diss. Abstr. 31:7243-B) 



Three aspects of the ecology of phytoplankton in a system of shallow 

 estuaries near Beaufort, North Carolina, were examined in a yearlong 

 study: 1) the seasonal distribution of phytoplankton production and 

 inorganic nutrients; 2) identification of nutrients limiting for phyto- 

 plankton; and 3) the turnover of phosphorus. Photosynthesis was measured 

 under laboratory conditions using the carbon-14 method. Limiting nutrients 

 were identified with nutrient enrichment techniques. Phosphorous turnover 

 was estimated with radioactive phosphorus. 



Photosynthesis and chlorophyll a_ had pronounced and similar seasonal 

 distributions that followed the cycle in water temperature. Production 

 was minimum at most stations during December and maximum during June and 

 July. Annual phytoplankton production ranged from 16 g C/m^ in a small 

 embayment, having an average depth of 0.4 m, to 153 g C/m^ at the seaward 

 end of the Newport River estuary. Annual production for the system 

 averaged 66.6 g C/m^. Phosphorous concentrations were generally low 

 throughout the year. Maximum concentrations of phosphorus occurred 



72 



