Determination of the group growth of individuals can be based on 

 analysis of the dimensional and weight structure of a specific 

 population which, in species with intermittent (not year-round) 

 breeding, has generative discreteness (Golikov, 1970). Since in the 

 temperate and high latitudes, practically all species of marine animals 

 have intermittent breeding due to the elevated stenothermicity of 

 gametogenesis and the early stages of ontogenesis (Kinne, 1970), the 

 method of determination of the group growth and age of individuals on 

 the basis of generative discreteness in the structure of populations is 

 a universal one. When this method is used, one must first consider not 

 the frequency of occurrence of individuals of a given dimensional class, 

 as in determination of growth on the basis of the Petersen distribution 

 or the probability paper method, but rather the distribution of 

 individuals by actual dimensions, i.e., the presence or absence of 

 individuals of a given size at the moment of observation. It is 

 methodologically important to analyze the dimensional distribution of 

 individuals based on materials collected over a relatively short time 

 interval, so that the change in dimensions of individuals during the 

 process of growth will not mask the generative discreteness in the 

 structure of the population. 



It is characteristic that individual variations in the growth rate 

 of individuals within a generation, as a rule, do not exceed the 

 differences in dimensions of groups of individuals of successive 

 generations. This results from the unity of the gene pool of the local 

 population, the polygenous determination of individual variability of 

 growth and the similarity of phenotypic shifts in the growth rate for 

 all members of a population under the influence of identical 

 conditions. The variability in growth rate of individuals of one 

 generation is greater in species with an extended breeding period than 

 in those with short spawning times. Individuals born at the beginning 

 of a breeding period grow more rapidly, survive better and achieve 

 greater dimensions than individuals appearing near the end of the 

 breeding period, which are subjected to the unfavorable effects of 

 temperature in similar phases of ontogenesis (Golikov, 1975b). 



Due to the asymptotic nature of growth of the overwhelming majority 

 of marine benthic organisms, differences in the dimensions of 

 individuals in successive generations decrease with age. The method of 

 estimating the growth rate and age on the basis of the dimensional and 

 weight structure of populations is suitable for species which stop 

 growing in the later stages of ontogenesis, which usually is not 

 characteristic of poyki lothermic marine organisms. In this case, the 

 age of the oldest generations can be approximately determined on the 

 basis of the nonproportional increase in number of the last cohort: the 

 largest and oldest individuals having approximately the same 

 dimensions. Examples of generative discreteness in the structure of 

 local populations and determination of the growth rate and duration of 

 life of marine invertebrates on the basis of this characteristic have 

 been presented in a number of works (Golikov, Menshutkin, 1971; Golokov, 

 Menshutkin, 1973; Menshutkin, Golikov, 1971; Sirenko, 1973; Tabunkov, 

 1973, 1974; Menshutkina, 1975; and others), and are illustrated by data 

 on the structure of populations and growth of 2 species of gastropoda 

 with different life durations (Figs. 27 and 28). 



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