(growth anomalies) was more rapid than its lengthwise growth, and the 

 oyster took on a characteristic ball shape. These malformations were only 

 observed in Ci gigas and not in the European flat oyster (0^ edulis ) 

 present in the same waters. 



Recently, examples of these same malformations were reported in the U.S. 

 by Wolniakowski et al. (1987) in Joe Ney Slough and South Slough National 

 Estuarine Research Reserve of Coos Bay Estuary, located near Charleston, 

 Oregon (see Figure 4.2, from Wolniakowski et al., 1987). South Slough is 

 located adjacent to a boat yard that has used TBT paints for many years. 

 These examples of excessive shell thickness and chambering are the first 

 oyster malformations reported in the U.S. However, it should be noted 

 that definite chemical data were not available for South Slough when these 

 deformed oysters were found, therefore, additional studies in South Slough 

 are needed to validate these cause and effect relationships. 



IV-13 



