The Organic Budget 



179 



southern California may then be estimated 

 as 1.5 million tons dry weight. This is only 

 about 3.4 per cent of the annual production 

 of plants (Fig. 153). 



Much of the organic matter that reaches 

 the bottom escapes complete regeneration 

 during digestion by benthonic animals and 

 becomes buried under later layers of sedi- 

 ment. However, even after it is buried be- 

 yond reach of these animals, much of it is 

 regenerated by bacteria living in the sedi- 

 ments. As a result about one-third of the 

 organic matter present at the surface of the 

 sediment is gone by the time it is buried a 

 few meters. Essentially no losses of organic 

 matter to the bottom occur on the main- 

 land and island shelves and on bank tops 

 because the percentage of organic matter is 

 very low and the rate of deposition is ex- 

 tremely slow. Accordingly, significant losses 

 occur only in the deeper areas of fine-grained 



sediment. Radiocarbon measurements of 

 the rates of deposition and data on the or- 

 ganic content of sediment show that the loss 

 of organic matter to the bottom is about 0.3 

 million tons per year (dry weight) as will be 

 discussed in a later section. The annual 

 infall of organic matter to the bottom and 

 its fate may be summarized as follows: 



0.4 million tons, buried in sediment 

 — 0.13 million tons, regenerated within 



sediment 

 1.5 million tons, benthic production 

 1.0 million tons, energy loss of benthos 

 2.8 million tons, total dry weight 



reaching bottom 



Thus it appears evident that 7 per cent of 

 the organic matter produced reaches the bot- 

 tom in deep water, but that only about 0.6 

 per cent is permanently lost to it (Fig. 153). 



