the Atchafalaya River, especially during 

 and since the 1973 flood (Coastal Envi- 

 ronments, Inc. 1977). They do attract 

 newly colonizing spat during some years, 

 but only those oysters that have not 

 been subjected to prolonged low salin- 

 ities grow to maturity. 



These oyster reefs are unimportant 

 for commercial harvesting because of the 

 limited number of live oysters and 

 because intertidal reef oysters often 

 tend to be too stunted and difficult to 

 harvest to be of marketable value (Bahr 

 and Lanier 1981). Their importance is 

 physical: as sediment traps and as bar- 

 riers to tidal and wind currents. 

 Reduced shoreline erosion within the 



Vermilion hydrologic unit has been 

 attributed to local offshore oyster 

 reefs. For example, the coastline along 

 Marsh Island was relatively stable from 

 1932 to 1969 where nearshore oyster 

 reefs were present (Adams et al. 1978). 



Manmade modification of the Ver- 

 milion basin includes water control 

 structures such as the Vermilion Locks 

 to prevent saltwater intrusion. Fresh 

 water is stored in the Mermentau River 

 basin for rice irrigation, and salt 

 water intrusion is a continuing problem. 

 Water control structures have greatly 



reduced water exchange with marshes 



(Byrne 1977). 



148 



