Recently, the processes of organochlorine pesticide accumulation in 

 trophic chains have been experimentally modeled to obtain more detailed in- 

 formation on the transformation mechanism in ecosystems. Metcalf, et^ al_. 

 (1971) used this experimental approach to select organochlorine pesticides 

 with lowest accumulation factors, i.e., those which were poorly accumulated, 

 and which were not transformed in trophic chains. 



The question of metabolic pathways in tissues of animals, and metabolic 

 transition through final products is of considerable ecological importance. 

 Though the DDT metabolic processes have been well described by Kelvin, et_ 

 a1 . (1959), additional detail for varying aquatic organisms are required. 

 The intent of this communication is to demonstrate the peculiarities of ac- 

 cumulation and distribution of residues of DDT and its metabolites in organs 

 and tissues of freshwater fish. Further, the factors characterizing the 

 development of intoxication will be considered. 



Experimental efforts directed toward three major areas: 1) a demonstra- 

 tion of the level of persistent pesticides in the aquatic ecosystems and the 

 organisms under examination; 2) perform experiments in vitro to demonstrate 

 the accumulation of residues of DDT and its metabolites in selected organs 

 and tissues of fish, and to describe the developmental characteristics of 

 the intoxification process in time; and 3) conduct studies in experimental 

 basins to establish accumulation and transformation of persistent pesticides 

 at different trophic levels. In these studies, the following fish species 

 were used: bream ( Abramis brama ), pike perch ( Lucioperca lucioperca ), pike 

 ( Esox esox ), perch ( Perca f luviatilis ), carp ( Cyprinus carp io), crucian carp 

 ( Carassius carassius ), silver carp ( Hypophthalmychthys mol itrix ) . The food 

 organisms tested included tubificids ( Tubifex tubifex ), and water fleas 

 ( Daphnia magna ) . 



The residue level of DDT and its metabolites in water, silt, and tissues 

 of fish was determined by the gas chromatography technique. 



Systematic examination for DDT and its metabolites (DDE and DDD) in the 

 water and sediments of the investigated water-bodies showed that this pesti- 

 cide was not always found. Their concentration in water were found to be in 

 the parts per trillion (ppt) and (ppb) parts per billion range. Sediment 

 values were in the range of parts per billion (ppb) and parts per million 

 (ppm). Since DDT solubility in water is expressed by a range of 1-5 ppb, 

 the availability of DDT and its metabolites in freshwater ecosystems is not 

 a function of physio-chemical transformations, but rather of biological 

 transformation of this substance, and its accumulation in trophic levels on 

 the basis of biological increases of 1 order of magnitude per trophic level. 

 As a result, it is possible to find rather high concentrations accumulated 

 in the second, third, and subsequent links of trophic chain. In both bio- 

 logic tissues and in the abiotic environment, DDT alone is not isolated. 

 Rather, the sum of its metabolites, DDD and DDE together with DDT proper is 

 usually expressed as the sum of DDT (DDE + DDD + DDT). 



In freshwater fish (pike perch, bream, pike, carp, perch, etc.) from the 

 water-bodies investigated, the distributions of accumulated DDT and its 

 metabolites in organs and tissues is rather clearly observed, although the 



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