Table 3. Natural, anthropogenic and toxic (for phytoplankton) levels of 

 the content of chemical ingredients in the euphotic layer of the marine 

 environment, ng/1 . 



Anthropogenic levels 

 Ingredients Natural Oceanic Neritic Threshold 



levels zone zone toxicity level* 



Dissolved petroleum 



products - lO^-lO^ 102-10^ lO^-lO^ 



Heavy metals o i o i i 



Mercury IQ-'^-lO-^ >10-'^ lO'l-lO IQ-^-lO 



Lead IQ-^-l IQ-l-l loO-lO^lO^- 



Cadmium lO-^-lO'l ? >1 10^-10^ 

 Chlorinated 

 hydrocarbons 



Aldrin - <10-2 ? IQ-l-lO"^ 



Benzyl hexachloride - <10"2 ? lO'l-lO 

 Polychlorinated 



biphenyls - lO'^-lQ-^ lO'^-lO IQ-^-lO 



Aliphatic 



hydrocarbons - 10--^-10-^ ? ? 



DDT and its 



metabolites - <10-2 10 10-1-10 



*Minimum concentration of toxicants in the environment at which 

 significant (usually 50% inhibition of photosynthesis or of cell 

 division of phytoplankton has been observed. 



Among the probable anthropogenic modifications of the normal course 

 of hydrobiologic processes in the ocean, which have never been studied, 

 we must also include such phenomena as disruption of the complex system 

 of external metabolic interactions in communities of marine organisms. 

 The exchange of metabolites among organisms, with the high intensity 

 inherent in it and the biochemical specificity of synthesis and 

 consumption of metabolites, plays an extremely important role as an 

 integrating and regulating factor in marine communities (Khailov, 

 1971). It is not difficult to imagine that even low concentrations of 

 pollutants foreign for the biotope (for example, dissolved petroleum 

 products) could block various metabolic interactions of the organisms 

 and thereby disrupt the system of biologic communication in communities 

 and, consequently, their structural and production characteristics. The 

 same is probably true as concerns sensory connections of hydrobionts, 

 their ethologic reactions, chemoreceptions and other phenomena, the 

 mechanism of which may be disrupted if small quantities of man-made 

 impurities are present. Due to the complexity and "veiled" nature of 

 such effects, little is known of them, but still, observed facts, such 

 as disruptions in the migrations of fish caused by pollution, indicate 

 that such ecologic anomalies are quite real. 



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