Another group of "critical" situations in marine communities is 

 related to the phenomenon of concentration of toxic microimpurities at 

 the boundary between the water and the atmosphere and between the water 

 and the bottom, which we mentioned earlier, and the influence of 

 toxicants on the most vulnerable organisms and communities of the 

 neuston and benthos. Whereas the reactions of the marine benthos to 

 toxic factors have been rather widely studied, particularly in areas of 

 high pollution (Bellan, Bellan-Santini, 1972) and in acute-toxicity 

 experiments (Stora, 1974), the neuston has as yet fallen outside the 

 sphere of marine ecologic-toxicologic studies, although its 

 vulnerability to the influence of toxic factors is known (Polikarpov, 

 Zaitsev, 1969). This opinion is reinforced by many reports concerning 

 increased sensitivity of the early stages of development of marine 

 organisms, many of which pass through a neustonic phase of life and are 

 subject to severe toxic and even mechanical effects resulting from 

 pollutants located in the biotope of the neuston during this period of 

 their life. For example, even such a common phenomenon as a thin film 

 of oil on the surface of the sea can cause the death of the larvae of 

 physostomous fishes, which it isolates from the atmosphere, preventing 

 filling of the swim bladder with air (Vinogradov, 1972). 



There are other ecologic situations and aspects of this problem, 

 for example the accumulation and migration of toxicants through the food 

 chain, the suppression of the reproductive functions of organisms, the 

 additive and synergic effects of toxic factors, the varying resistance 

 of organisms of various systematic groups, etc. 



In conclusion, let us emphasize once more the very important, in 

 our opinion, large-scale situation of superimposition of the band of 

 maximum pollution on the band of maximum biologic productivity of the 

 world ocean--the neritic zone of the temperate latitudes of the northern 

 hemisphere. It is in this very area, with its constantly increasing 

 background level of man-made impurities, that the effects and anomalies 

 which we have been discussing arise and propagate throughout the entire 

 ocean. It is here that both national and international efforts should 

 be concentrated for the protection of the marine environment from 

 pollution. 



417 



