PRIMARY PRODUCTION 523 



of a wide variety of environments have in general supported the 

 earUer ideas of Harvey (1942) and others showing that where 

 there is a good supply of nutrients to the upper waters there is 

 high plant production leading to good zooplankton crops; and 

 that where nutrients are low, the reverse is true. Quantitative 

 models of these relationships have been fairly successful (e.g., 

 Riley et al., 1949) suggesting that the interdependence is in fact 

 comparatively simple (Steele, 1959). However, there are occasions 

 when the results do not quite fit these patterns. It often happens 

 that, although the broad general picture just described may be 

 satisfied, when the details of the data are studied, many anomalies 

 appear. 



Because the general ideas seem fairly well established, the 

 emphasis is now turning more toward detailed attempts to show 

 quantitatively how causal relations operate in particular situa- 

 tions. The papers at this meeting have provided examples of this. 

 Riley (1959) has shown the significant roles of low respiratory rate 

 of the plants and low grazing rate of animals in permitting a winter 

 outburst in Long Island Sound. Menzel and Rythcr (1959) show, 

 by a detailed series of samples in the Sargasso Sea, that the produc- 

 tion is not necessarily at the constant low value that has sometimes 

 been supposed. Gushing suggested, as Beklemishcv (1957) has 

 also done, that the food supply of the bottom fauna may depend 

 on the inability of the zooplankton to assimilate the available 

 plants during short periods of high production, thus allowing 

 organic matter to sink to the bottom. In this way the bottom 

 fauna would depend for their food throughout the year, not on 

 the total yearly production but rather on the size of the produc- 

 tion peaks. These examples are all cases where events during a 

 quite short space of time may dominate the yearly picture, so that 

 detailed sampling is necessary to reveal them. They also show how 

 values are needed for what may be called the "biological con- 

 stants." Some of these have been mentioned, such as the respira- 

 tory rate of plants or the relation between light and photosynthe- 

 sis. Others are the sinking rate of plants, the efl^ects of low nutrient 

 concentrations, and the grazing rate of the animals. All these have 

 been studied in the laboratory but because of the unavoidable 



