Dermocystidium marinum infects oysters usually during 

 high temperature periods and in salinities above 10 ppt . 

 Infection is usually lethal to the host oyster, but also 

 may cause loss of weight, castration, and failure to grow 

 normally. A change to a lower salinity achieved by fresh- 

 water flushing of the estuary is believed to be the best 

 way to rid the oyster bed of the fungus (Mackin, 1962). 



The conch Thais haemastoma hayse is common in the 

 northern Gulf waters. T^ haemastoma feeds on oysters and other 

 mollusks by drilling holes in the shell or penetrating the 

 shell from the edge by secreting enzymes that soften the 

 mollusks' shell. The conch has a high reproductive rate and 

 the larvae have a high survival rate. A salinity of 10 ppt 

 or lower will prevent the conch from entering waters and 

 exposure to a salinity of 7 ppt or lower for 1 or 2 weeks 

 is known to kill it. T^ haemastoma breeds in Louisiana during 

 a period beginning no later than the end of March and 

 ending in July. The conch's tendency to climb on rocks or 

 structures above ground to attach its eggcases has led 

 many oyster growers to erect stakes in the oyster grounds to 

 trap the animal (Galtsoff, 1964: 433). 



The majority of Louisiana's oyster production depends on "seed" oysters 

 taken from state-managed seed grounds east of the Mississippi 

 River and transported to private grounds for cultivation. 

 Cultivating oysters has become more important in Louisiana 

 with the depletion of natural oyster reefs. Some believe 

 that the decline in productivity in the natural oyster reefs 



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