On Changes in the Sea and Their Relation to Organisms. 



229 



The number of cubic centimeters of O2 used per hour per kilogram by 

 various groups of animals is shown in table 10 (Krogh's average of 

 various species at 20°, and Montuori's at 25° as compared with my 

 determinations and calculations at 30°). 



Table 10. 



The discrepancies are due to differences in size, activity, and species. 

 The calculations (in parentheses) were made on the assumption that 

 the respiration at 30° is double that at 20° and 1.414 times that at 

 25°. A kilogram of the small fish I studied would use up all of the 

 O2 in 3,600 liters of the sea-water of the Gulf Stream in 24 hours. The 

 respiration of the very active animals studied by others is about half as 

 rapid and there is great variation with the species in sluggish animals. 



With 1 kg. of fish in 300,000 liters of warm sea-water we should be 

 able to detect a distinct fall in O2 concentration during the night. In 

 order to attain this effect there need be organisms, the equivalent of 

 1 kg. of fish, to 10 square meters of bottom in water 30 meters deep. 



It will be seen from the foregoing sections that the changes in the sea 

 that were considered are very complicated. If the dirunal curves are 

 plotted they show secondary notches. It was thought probable that 

 the secondary notches in the diurnal curves of the sea-water at station A 

 might be due to horizontal and vertical currents and eddies. In order 

 to exclude some of these currents the diurnal variation of a model 

 lagoon was studied. A glass tank about 4 by 6 by 4 feet was placed in 

 the open air and filled with sea-water and a few cassiopeas placed on 

 the bottom. Convection currents stirred up the water in the tank, but 

 there were necessarily no extensive horizontal currents over bottoms 

 of different character and depth. The curves of the diurnal variations 

 were smooth— that is, without secondary notches. The extremes 

 (maxima and minima) of the curves were at about 5M0™ a. m. and 

 4 p. m. The morning extreme was a little delayed, owing to partial 

 shading of the tank for a short time, before and after sunrise, but there 

 was a corresponding shading before sunset and therefore the curves 

 were not skewed. The smooth curves obtained with the tank indicate 

 that the notches in the diurnal curves at station A are due to currents 

 in the water and not to technical errors. On partially cloudy days 



