T. F. GOREAV 



277 



fig carbon fixed per milligram nitrogen per hour. The highest calci- 

 fication and productivity values are observed in the calcareous algae. 

 In the light, the calcification rates in the two Halimedas are about 

 1.5 to 10 times faster than in the hermatypic corals, and about 20 to 

 40 times faster than in the ahermatypes. The carbon fixation rates in 

 the Halimedas are only from 2.5 to 4 times greater than those in 

 the hermatypic corals, the productivity values for the ahermatypes 

 being neglected as they have no zooxanthellae. 



The approximate diurnal calcification and carbon fixation rates 

 of the various species tested are shown in Table II. The daily cal- 

 cium deposition was calculated on the simplifying assumption of 

 twelve hours darkness and twelve hours sunshine equal in inten- 

 sity to the average isolation between 10 a.m. and 4 p.m. during a 

 late winter day in Jamaica. The daily productivity values were cal- 

 culated on a twelve hourly liasis since no photosynthesis occurs 

 at night. These figures are uncorrected for respiration. Tables 

 I and II show that the differences in the calcification rates be- 

 tween groups are far greater than the corresponding differences 

 in the carbon fixation rates, but more data are needed to establish 

 whether a quantitative correlation exists here. Obviously such com- 

 parisons can have meaning only on a broad ecological level since 

 we do not yet know if the physiological mechanisms of calcification 

 in the various groups of organisms used for these experiments 

 are equivalent. Nevertheless, the overall correlation is prob- 

 ably not due to chance; it emphasizes the fundamental role 



TABLE 2 

 Daily calcification and carbon fixation rates of hermatypic and ahermatypic organisms. 



