of inactivity, thus prolonging the induction period even more (it was 

 noted in the second mission that the induction period at night extended 

 for a period of about 5-5 1/2 hours.) 



A third plausible explanation for this phenomenon is due to Dr. John Bunt 

 of the University of Miami. Dr. Bunt states that the induction period 

 could be explained on the basis of a build-up of bacteria in the sample 

 container. To account fully for the cause of this phenomenon will not be 

 any easy task; indeed, much additional work will be required before a 

 satisfactory mechanism can be proposed. It is hoped that this work may be 

 extended in the very near future, not only to additional seawater systems, 

 but also to fresh water lakes as well. 



Additional data obtained during Mission 1-50 may be summarized thusly: 

 (1) pH fluctuations follow very closely those for oxygen, i.e., when the 

 oxygen concentrations are high, ;j.ikewise are the pH values; (2) alkalinity 

 minima occurred at approximately the same times as oxygen maxima; (3) cal- 

 cium and magnesium concentrations were independent of time and of station; 

 calcium ion concentrations equal 0.01 M and the magnesium ion concentraO 

 tions equal 0,06 M. (4) The temperature showed a steady increase from 

 25.4° to 25.7° C during Mission 1-50 with perceptible diurnal fluctuations. 

 (5) Salinities ranged from 35.4 - 36.0 parts per thousand. 



Data gathered on the visibility experiment and on the internal wave motion 

 in Lameshur Bay have not yet been analyzed by the physical oceanographer and 

 the optical physicist; we trust when these data are analyzed the results 

 will be forthcoming at an early date. 



ADDENDUM 



If one were to depict graphically the concentration of oxygen (as the 

 ordinate) and the time (as the abscissa) a smooth sine wave curve would 

 result. Not infrequently we would note abrupt discontinuities in a few of 

 our values; at first, we attributed these to errors in sampling, fixing, 

 analysis, or a combination of these. 



During our return trip, we experienced a phenomenon that not only explained 

 these discontinuities in our data, but lends a strong argument for man-in- the 

 sea programs as well: during a night session, two of us (PDC and RJD) were 

 in the process of taking a sample for oxygen analysis when a surge of cold 

 water intruded. It came with such force that one of us (PDC) was literally 

 upended (and very nearly set upon a large black sea urchin). Fortunately, 

 the sampler was open during the surge of the cold water. Immediate fixing 

 and analysis of the sample showed an oxygen concentration equal to three 

 times that found in the maximum of our daylight samples . 



And herein lies the explanation: Since the solubility of oxygen in water is 

 greater at lower temperatures, the cold water was, obviously, rich in O2; 



VI-20 



