temperate, and tropical zones and for the oligotrophic, mesotrophic, and 

 eutrophic communities with primary productions of <100, 100-500, and 

 >500 mg Z/r\r per day. Sometimes mesotrophic waters are divided into 

 three types with primary productions of 100-150, 150-250, and 250-500 mg 

 C/m^ per day. Data for each type of water vary significantly. This 

 spread of data is caused both by natural fluctuations and by 

 methodologic errors, particularly biologic errors. 



1.1 Methodologic Problems 



Let us now discuss methods of measurement of the parameters of 

 primary production, which have significant influence on the factors 

 which we shall analyze below. Errors in biologic measurements--of 

 photosynthesis, concentrations of chlorophyll, and quantities of 

 phytoplankton--are 1 or 2 orders of magnitude greater than the errors in 

 measurement of chemical and physical quantities. Furthermore, different 

 authors use different modifications of methods of biologic measurements, 

 whereas the physical and chemical methods used d^re generally 

 standardized. 



Primary Production . As a result of many methodologic studies, it 

 has become clear that the radiocarbon method, in the form in which it 

 has been used to date, measures the increase only in the biomass of 

 phytoplankton, as a result of autotrophic fixation of COg- Dissolved 

 organic matter, synthesized by algae, and the increase in biomass of 

 phytoplankton resulting from heterotrophic nutrition, are not 

 measured. The results produced by this method are closer to net 

 production than to gross production, particularly when there is a 

 nutrient limitation (Ketchum et al . , 1958). 



In determining primary production, a distinction must be made 

 between measurement techniques, on the one hand, i.e., chemical and 

 radiochemical approaches to the measurement of the rate of 

 photosynthesis (production) in each individual sample and the 

 corrections which have been introduced to the final results, and on the 

 other hand, the plan of measurement, i.e., the conditions of exposure of 

 samples and the system of calculations used to consider changes in 

 production with depth. The simplest and most natural method is the plan 

 of experiments in situ . Unfortunately, under the complex conditions of 

 oceanographic expeditions, it is frequently impossible to perform such 

 measurements. Therefore, a number of plans have been suggested to allow 

 the measurement of primary production in the water column without 

 performing investigations. The first was suggested by Steemann Nielsen 

 (1952): the measurement of photosynthesis in samples taken from various 

 depths and incubated under conditions of standard illumination. The 

 second plan, suggested by Yu. I. Sorokin (1956), is based on the 

 measurement of photosynthesis of phytoplankton in a sample of water from 

 the surface of the sea, with subsequent introduction of corrections for 

 changes in its rate with depth. These corrections reflect the 

 unevenness of vertical distribution of phytoplankton, as well as the 

 change in the quantity of light energy, necessary for photosynthesis, 

 with depth, and are determined experimentally. A third plan, which has 

 become most widely used in recent times, consists in the measurement of 

 the intensity of photosynthesis in samples brought up from various 



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