TABLE 2 



Scheme of trophic relations and nutrition 

 selectivity coefficient (J). 



The supposition that the overall ration of each element of 

 the community [C(i)| consists of its particular rations [r,,,,] on 

 different food objects was used as the basis for the quantitative 

 assessment of the trophic relations (Vinogradov & Shushkina, 

 1987). 



The particular ration r,,,, of the i-th consumer on the j-th 

 prey element with the biomass B,j| was calculated by the 

 modified V.S. Ivlev's equation (Shushkina et ai. 1984); 



r,„-r,7[l-exp(-^„B,„)/E,„l (1) 



where E,,, is consumption of the j-th element by all its users; 



Since the value E,,, had not been known at the moment of 

 the calculation by the iteration method: first, the maximum 

 tension with respect to the j-th feed, 



K„ = Ir,7/B„„ (2) 



and an underrated approximate value r,,,, were calculated. Then 

 E|j =Zr|,j| was found and substituted into Equation ( 1 ) to obtain 

 a new value r„j|, etc., up to satisfying the equality: 



E,pZr,„=Zr-r[l-exp(-^„B„)/E,J (3) 



The value of the maximum particular ration r,™" was 



calculated by the relation: C 



^B,J, 



2:b,j„ (4) 



The maximum overall ration C""' was determined by the 

 balance equation (Vinbeig & Anisimov, 1966): 



C:-"^ = |P,"'-HR,] U, (5) 



where R is the metabolic rate of the i-th element 1/U, — the 

 assimilability coefficient of the i-th element; and P""* — the 

 maximum possible value of production of the i-th element was 

 calculated by the formula: ,^ __ K?,"' 



"' ~ ' l-KT,- (6) 



where K?;-" — coefficientofthe expenditure of food assimilated 

 by the i-th element in growth. 



The full real ration of each i-th consumer [C, ] was calculated 

 as a sum of particular real rations: 



C = I r, 



(7) 



and production of the i-th element, expect phytoplankton, as: 

 P, = C,„U;'-R, (8) 



All the dimensional and trophic elements were 

 characterized by the definite numbers N, average weight W. 

 and biomass B. Energy value of biomass was expressed in 

 calories on the basis of caloric content values K. It is known 

 that its average values for copepodite plankton are equal to 



0.7-0.8 cal/mg wet weight (Vinogradov & Shushkina, 1987). 

 At the same time, the caloric content of interzonal species of 

 Copepoda and Euphausiacea, playing an important role in the 

 trophic chain of the Bering Sea, increased at the expense of fat 

 inclusions up to 1 .0-1 .5 cal/mg wet weight (Shushkina, 1977). 

 The bodies of an overwhelming majority of these Crustacea, 

 found in the samples during the present investigations, contained 

 droplets of fat. In this connection, the caloric content value of 

 large euryphages was assumed equal to 1 .0 cal/mg wet weight. 



The values of the coefficient of the use of consumed food 

 in growth, in maximum meeting food requirements of consumers 

 K( 2i max), and food assimmilability 1/U(i ) of each element are 

 presented in Table 1. M. E. Vinogradov and E. A. Shushkina 

 (1987) believe that one may use in the calculations the values 

 of K(2 max) equal to 0.5-0.6 for elements including small 

 animals that quickly reproduce themselves: bacteria, protozoans, 

 and fine nannophage filters; and 0.4—0.5 for hydrobionts whose 

 size exceeds 1 .0 mm. Assimilability was assumed as a value 

 independent of the concentration of consumed objects — it was 

 established equal, on average, to 0.6 for plant food and 0.7 for 

 animal food (Sushchenya, 1975). It should be noted that 

 Japanese researchers (Ikeda & Motoda, 1978) and American 

 ones (Dagg et ai, 1982) used the value of the assimilability 

 equal to 0.7 for calculations of production of the herbivorous 

 plankton of the Bering Sea. 



The respiration rate of zooplankton was estimated with the 

 use of the general dependence of the metabolic rate R on the 

 weight of the body W at a water temperature of up to 20 grad, 

 which was obtained experimentally (Shushkina el ai. 1984; 

 Vinogradov & Shushkina, 1987): 



R = 0.6W"« (9) 



where R is measured in mcal/organism/day, and W in 

 meal/organisms. 



A correction for temperature allowing for Q( 10)=2.2 was 

 introduced into the values of the metabolic rate. 



The respiration expenditure of the bacterioplankton and 

 zooflagellates was determined by other methods. The 

 calculation for the bacterioplankton was carried out with 

 allowance for the production measured during the investigations 

 and the efficiency of the use of assimilated food in growth, 

 determined experimentally (Sorokin & Mamaeva, 1980): 

 K(2)=0.33. The value of R/W for zooflagellates was assumed 

 equal to 250%. It remained constant in all the calculations 

 (Shushkina t-rrt/.. 1984). 



At the productive stage of the development of plankton 

 communities, the main course of energy is the production of 

 photosynthesis, produced during the day under consideration. 

 At the same time, some elements of the community are able to 

 use the energy of autochthonous dead organic matter formed 

 inside the community for a day and allochthonous dead organic 

 matter introduced from outside or formed earlier, prior to the 

 period of observations. Inclusion of dead organic matter, 

 especially its dissolved fornis, into the trophic chain of a 

 community occurs mainly through bacterioplankton. 



At the destructive stage of the development of acommunity, 

 a situation may arise when the energy of autochthonous dead 

 organic matter will not be sufficient to cover the ration of 

 bacterioplankton. In this case, an element of self-regulation is 

 introduced, according to the calculation scheme (Shushkina 



203 



