Equally interesting are data which were collected as functions of time and 

 station: 



Data expressed in ml/Na2S203 solution used to titrate samples. 



Table 2 suggests that the water mass generally is well mixed; it also shows 

 that there are significant diurnal variations. Although it is. not possible 

 to define exact maxima and minima in these cycles from the data accumulated 

 from Mission 1-50, it appears that the maxima occur between 1200 and 1800, 

 and that the minima probably occur at the beginning of the daylight hours. 

 On our return trip to TEKTITE II the diurnal oxygen samples were taken once 

 every hour for a period of 24 hours: those observations confirmed those 

 made during the first mission. It appears that the maximum in the oxygen 

 content is a broad one between 1400 and 1600 hours, and that the minimum, 

 also extremely broad, occurs between 0300 and 0600. 



Perhaps the most intriguing facet of the study was the discovery of an in- 

 duction period: when samples of sea water were suddenly sealed off from 

 sunlight, the oxygen concentration remained constant for about three hours. 

 The fact that it did not increase shows that the photosynthetic process did 

 not continue past the time of sealing; because it did not decrease indicates 

 that respiration, i.e., using up of available oxygen to produce CO2 did not 

 commence immediately. The organisms responsible for this process seemed to 

 be in a state of "limbo" for about three hours, after which time the oxygen 

 concentration decreased very rapidly. (An alternate explanation for this 

 phenomenon based on the existence of a steady state with a rate of oxygen 

 consumption equal to the rate of oxygen production over such a long period 

 of time must be rejected on kinetic grounds.) On the return trip to TEKTITE 

 induction period measurements were made both at night and during the day. 

 These measurements were made by taking down a number of sample bottles and 

 sealing all off at once. One sample was then fixed and returned to the 

 surface for analysis and the rest remained at the sample site. One sample 

 was fixed every hour for a period of four or five hours thereafter. Secur- 

 ing the samples at the sampling site until they were fixed minimized the 

 effects of pressure and temperature changes. Again there was conclusive 

 evidence that an induction period does indeed exist during the daytime and, 

 to our surprise, even at night: It is our feeling that as a sample of sea 

 water is suddenly sealed from sunlight, the organisms responsible for the 

 production--and consumption- -of oxygen are shocked into a state of inactivity; 

 at first glance it would seem that this "explanation" could not account for 

 the existence of a nocturnal induction period . It ^ possible that the dive 

 lights used at night could effectively shock these organisms into a state 



VI-19 



