Parasites and roullng Organisms 



Routine eocamlntations of oysters from the various reefs were 

 made for the relative number of associated fouling organisms on the 

 shells and for the presence of Internal parasites, especially the 

 gregarine pareisite Ilematopsis . This protozoan spends part of its 

 life cycle encysted in the tissue of oysters and some observers 

 believe it causes general debility and possible extensive mortality 

 in the oyster population in some areas. Nearly all oysters examined 

 were infested; the younger the oyster the fewer number of cysts were 

 found, as is to be expected. Compared with oysters growing near 

 Pensacola, Florida, all of the oysters examined had moderate to 

 very light infestations. Table 4 summarizes the recorded obser- 

 vations; numbers of cysts represent the average found per square 

 millimeter in the 100 square millimeters of oyster mantle tissue 

 examined for each station. 



The oysters examined at Stations 12 end 16 were spat less 

 than a year old. Presumably they had not had time to become 

 more heavily infested. Older oysters located on adjacent reefs 

 to either side of these stations contained many more cysts. 



The variation in numbers of cysts is believed to have little 

 significance geographically or with respect to the hydrographlc 

 conditions vfliere the oysters grew. I believe the occurrence of 

 this parasite has no importance in a consideration of the described 

 oyster mortalities. 



Many of the oysters examined had microscopic protozoan parasites 

 in their intestinal tracts. No damage could be connected with their 

 presence, and it is concluded that they were of no significance. Had 

 it not been for the absence of food material in the intestinal tract 

 of the oyster, these organisms would probably have not been detected. 



Oysters at all stations were examined routinely for the relative 

 numbers of associated animals. These vary from area to area but 

 include mussels, barnacles, boring clams, boring sponge, moss animals, 

 mud worms, and others. In nonaof the €a:eas examined ware they con- 

 sidered sufficiently numerous to be harmful. In general, their num- 

 bers were fairly low as a result, in all probability, of the lowered 

 salinity levels. 



Turbidity 



One factor in the environment on an oyster reef which is 

 demonstrably injurious is the presence, in excess, of particles 

 of silt and other debris, Uuch blame was attached in the original 



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