EFFECT OF ORGANIC SUBSTANCES ON OYSTERS 



177 



available through a 30-day period. This com- 

 parison was made, despite its recognized limitation, 

 to establish the relation over a long period. It is 

 quite evident from an examination of this figure 

 that such a definite relation does exist. 



Figures 10 and 11 illustrate the relation that 

 exists between carbohydrates and temperature as 

 factors influencing the average pumping rate. 

 Figure 10 is based on two defined temperature 

 ranges, while figure 11 is based on a division 

 according to season, i. e., the warm months, May 

 10 to November 13, and the cold months, Novem- 

 ber 13 to January 31, of the northern coast of the 

 Gulf of Mexico. 



It is apparent that water temperature above 

 25° C. are unfavorable for oysters in regions in 



which the production of the dissolved carbohy- 

 drates is low. 



ASSIMILATION OF CARBOHYDRATES 



The oysters can and do remove variable quan- 

 tities of carbohydrates from the water. This has 

 been ascertained by determining the amount of 

 carbohydrate in the water before it enters the 

 valves of the oyster and after it has passed through 

 the body. The quantities removed do not seem 

 to be related to any of the other measurable ac- 

 tivities of the oyster, and, of course, the results 

 could be affected by the oyster's waste metabo- 

 lites, which are present in the exhalant water. 

 The data of table 2 indicate that up to 50 mg./hour 

 are removed. This is a significant quantity of 

 such material, and assuming that all is utilized, 



£ 20 



LuL 



3 . 4 , 5 



9 10 II 

 L— I 



13 14 15 16 

 I I I I 



19 20 21 22 23 24 25 26 27 28 29 30 

 I I I I I I I 1 1 1 1 



CARBOHYDRATES 



20 



15 



10 

 8 



6 



1-2 



100 

 80 



60 



40 



20 



I ' 2 ' 3 ' 4 ' 5 ' 6 ' 7 ' 8 ' 9 ' 10' II ' 12' 13' 14" 15 ' 16' 17' 18' 19' 20' 21 22 23 24 25 26 27 28 29 30 



Figure 9. — -Relation between carbohydrates and average-cumulative-daily effluents of two to four oysters over a 30-day 

 period, June 1-30, 1949, plotted on a semilog scale. While data from four oysters were combined in establishing 

 this curve, mechanical difficulties reduced the number to two during part of the time. 



