STUDIES IN MARINE ECOLOGY. 



24I 



Table XVII. 



Flat Series. 



Showing range of variation of temperature, oxygen content, salinity and pH 

 near the surface in the open water and at or near the bottom in other associations. 

 All tide stages considered. Ordinal ranking is based upon amount of variation 

 and relative location of extremes. 



The relative position of the extremes in salinity is much the 

 same as in the eroding shore series. At high tide the salinity is 

 practically constant throughout, but at low tide the lower limit 

 decreases regularly with distance from the open water. The 

 relations of oxygen content, pH, and temperature at the bottom 

 are exactly similar to those of the preceding series except that 

 they are more striking. 



The ranking in this series, as in Table XV, is based upon the 

 amount of range combined with the relative location of the 

 extremes. On this basis salinity, temperature, and pH arrange 

 the series in order of the ecological age of the different associa- 

 tions. On the basis of oxygen content, the marginal muck 

 association is much younger than is expected. The combination 



1 See note at bottom of Table XV. 



2 Water temperatures only considered. 



