70 



U. S. BUREAU OF FISHEEIES 



Figure 10. — y s- 

 ters forming a 

 " pillar " or a 

 unit of construc- 

 tion of the reef 

 shown in Figure 

 n. Actual length, 

 46.5 centimeters 

 I18V4 inches) 



importance. Each of these factors affecting the 

 life of the o3'ster may determine the suitability of 

 a given body of water for oyster farming. Except- 

 ing the character of the bottom, which in most 

 cases is not subject to sudden and wide changes, all 

 the other above-mentioned factors in the tidewater 

 region are unstable and fluctuate very widely. 



It is impossible, therefore, to regard the data 

 collected during a limited period of time as repre- 

 senting average or normal conditions of a given 

 region. While such a view would be permissible in 

 the case of an open sea or landlocked boch^ of water 

 where no significant seasonal changes in the chemi- 

 cal composition of the sea water could be expected, 

 it would be misleading to apply it to the case of a 

 coastal region, which is greatly affected by the stages 

 of the rivers, and where the sea water can be re- 

 placed for a varying period of time by fresh Avater. 

 Hence, we can not speak about normal conditions in 

 a region where wide fluctuations are the rule rather 

 than the exception. On the other hand, a knowledge 

 of the possible limits of fluctuations in physical and 

 chemical changes in the water may have an im- 

 portant bearing on practical ])roblems of the oyster 

 iudiistiv. It seemed desirable, theiefoi'e, to give in 

 (his ptiper the results of the observations carried 

 out ill Eebriiarv and March, l!)^."). They were made 

 just after a heavy flood which inundated the whole 

 coast of Georgia, and consequently tiiey should be 

 looked upon as representing conditions which occur 

 from time to time on that section of the coast. Ob- 

 servations were carried out between February 4 and 

 IT) and from Fel)i'uary 28 until jVIarch 1!^. During 

 the latter time, the flood subsided and (he stages of 

 the riA'ers were nearly normal. The results of the 

 observations are presented in Table 1; the salinity 

 readings are shoAvn also in Figures 1 and 2 beside 

 the circles and triangles which indicate the stations 

 made during the survey. (All the stations made be- 

 tween February 4 and 1(5 (flood conditions) are 

 shown in circles; those made during the second 

 part of the survey, February 28 to March 13, aie 

 shown in triangles.) 



