22 



sea weed are sometimes brought onto the oyster beds, covering 

 them to a depth of several inches. The masses of bruised, and 

 often decaying, sea weed will serve to stifle the oysters almost 

 as effectually as the covering of mud. 



The fry are more easily affected by the weather conditions 

 than are the adults. It has been recorded that they are killed by 

 thunderstorms, by cold rains, and by sudden falls in the tempera- 

 ture, so that the prevalence of stormy weather during the breed- 

 ing season may have a great effect on the set of spat that will be 

 secured in any year. 



In some especially severe winters ice forms over the oyster 

 beds in the shallow, brackish waters, while over the deeper beds 

 the temperature is lowered nearly to the freezing point. Some 

 of the beds that are in very shallow water, or which may be 

 exposed at low tide, are very much damaged. In the deeper 

 water there is little danger that the oysters will be destroyed; 

 but they may become unfit for the market so that their value 

 is lost for some time. 



CHARACTER OF THE BOTTOM AS AFFECTING THE 



DISTRIBUTION, GROWTH AND CONDITION 



OF OYSTERS. 



The character of the bottom of any area determines, more 

 than any other physical factor, the abundance and quality of the 

 oysters that may be produced there; and, indeed, this factor 

 may determine whether or not oysters can grow in a certain 

 locality without artificial conditions being brought to the aid 

 Ox the natural ones. 



In the formation of any natural reef, except in a few cases 

 M'here the reef is built up on a sandy or gravelly bottom, tne 

 area covered by the reef is the only hard bottom in the vicinity, 

 and the growth in size of the reef takes place by the breaking 

 off of shells from the body of the reef. These fall to the soft 

 bottom at the sides of the reef, the first ones sinking below the 

 surface of the mud and disappearing. As this goes on for some 

 time, it comes about that finally some of them are kept above 

 the deposits of sediment and on these the young oysters are en- 

 abled to find a place of attachment, thus extending the boundaries 

 of the reef. "When this new portion of the reef is once above 



