Figure 7. — The rate at which carbon Is converted Into organic matter by marine phytoplankton — primary production — can 

 be measured by use of carbon 14. Investigator Is preparing to analyze phytoplankton cells for their carbon 14 content 

 with a gas-flow proportional detector equipped with an automatic sample changer. 



the need for collecting data under experimental 

 conditions that would enable us to make predic- 

 tions of dangers that might arise from inten- 

 tional or accidental pollution of an estuary or 

 ocean area. Emphasis was given to (1) flow 

 systems which make possible the duplication 

 of a natural environment in growing phyto- 

 plankton in the laboratory, (2) the simultaneous 

 accumulation of radionuclides by sediments 

 and the biota held in relatively large volumes 

 of sea water, (3) total-element measurement 

 so that specific activity in the different com- 

 ponents of a community can be compared, 

 (4) total-animal counting so that long-term 

 community studies are not disrupted by sac- 



rificing the animals for radioactivity measure- 

 ments, (5) observations of factors influencing 

 the cycling of radionuclides in estuaries, and 

 (6) the effects of external and internal radia- 

 tion. Also, it was hoped that a better under- 

 standing of the cycling of many radionuclides 

 in the estuary would be obtained by placing in- 

 creased effort on studies of energy flow. The 

 rate at which energy flows through the bio- 

 logical food chain no doubt influences the rate 

 at which many radionuclides circulate from 

 environment to organism and back again. 



Future research will attempt to understand 

 the factors that control production of fishery 

 organisms in estuaries. Natural estuarine 



