d.<ygen never went below 86 percent of saturation. Loss of oxygen in the 

 upper water, which was noted at the other stations coincident with the 

 decline of the spring crop of plankton, was less noticeable here. The 

 sample of early July was taken on July 5, and judging from the data at 

 Stations 37A and l58, this was after the time of maximum withdrawal of 

 oxygen. On September 27, the surface water was supersaturated with oxygen. 

 In late June - early July the pH remained constant at the surface in spite 

 of a reduction of the deficit of free carbon dioxide. There was an excess 

 of free carbon dioxide at the surface on two dates, and the carbon dioxide 

 deficit was less marked than at the other stations. Methyl orange alka- 

 linity ranged from 86 to 98 parts per million and there was no evidence of 

 seasonal trend. 



Station 60. The data which have been presented show such uniform 

 conditions at the surface and bottom that it will be of interest to note 

 an unusual condition which existed in the last few days of May. May 27, 

 28, 29 and 30 were very warm cloudless days and there was almost no wind. 

 Owing to the fact that repairs were being made to the motor boat, it was 

 not possible to take samples at any of the regular stations, but on May 30 

 a row boat was used to get samples at Station 60, which is located in the 

 channel between Middle and South Bass. There was a temperature gradient of 

 9° C. between the surface and 7 meters; the surface was 21.75* and 7 meters 

 was 12.75*. The oxygen content at the surface was 11.8 parts per million 

 and at 7 meters, 9.2 parts per million, representing 133 and 87 per cent 

 saturation renoectively. At the surface there was a free carbon dioxide 

 deficit of 3.0 parts per million and at the bottom an excess of 1.0 part 

 per million. At the surface the pH was 8.)4 and at the bottom it was 7.8. 

 These data show clearly the influence of increased temperature and sunlight 

 on photo-synthetic activity of the plankton algae, ^^lthout doubt, conditions 

 similar to those at Station 6C existed at other stations in the Island Section. 

 On June 1 a brisk wind mixed the water from top to bottom. 



Season of 1930 



The data obtained in 1930 are more complete than those obtained in 

 1929 because a longer period of time was covered and because samples were 

 taken at more regular intervals. As in the discussion of the season of 

 1929, only the data from Stations 37A, 158, and 8F will be considered in de- 

 tail. 



Station 37A . Samples were taken at this station on 13 dates during a 

 period from early April to early October. The data (Table I8) are complete 

 except for the lack of temperatures on August 5 and September 6, and free 

 carbon dioxide on October 2. 



70 



