Chapter X 



137 — 



Organic Matter 



removed from the oceans per year in the form of fish, whales, commercial 

 algae, and other products, and a similarly negligible amount is buried in 

 bottom deposits. This means that more than 99.9 per cent of the total 

 organic production in the sea must be decomposed. 



Plants oxidize some organic matter which they themselves have syn- 

 thesized, but most of the plant tissue is ingested by animals or decom- 

 posed by bacteria and allied microorganisms (see Figure 10). Grazing 

 animals ingest a proportion of the diatoms, dinoflagellates, and other 

 primary producers, converting some of the organic carbon into animal 



CARBON DIOXIDE 



® 



/ ii 



PLANTS 



--■©■-----> 



BACTERIA 



© 



Fig. 10. — Carbon cycle in the sea. Solid lines represent processes in which 

 bacteria exclusively participate, dot-dashed lines represent processes in which 

 bacteria may participate, and dashed lines represent processes in which bacteria 

 do not participate. Respiration (i), nutrition (2), decomposition (3), and CO2 fixa- 

 tion (4). 



tissue, excreting varying quantities, and oxidizing most of it as a source of 

 energy. Grazing animals in turn may be ingested by predatory animals. 

 In small inland lakes where such problems are more susceptible to 

 quantitative solution, Juday (1942) estimated that the total weight of 

 plants produced is about six to twenty times as great as the total weight of 

 animals (see Table XXXV on opposite page). Insufficient data are avail- 

 able to compare these estimates for lakes with conditions in the ocean. 

 Certainly the production of bottom flora is far less in the ocean than 

 in lakes because most of the ocean bottom lies beneath the levels that are 



