common names of mussel species used in this research is provided 

 in Appendix A. 



EFFECTS MEASURED 

 Shell Damage 



We considered mussels damaged if either valve showed chips, 

 cracks, and scrapes we felt were unnatural. What appeared to be 

 gradual wearing away of a valve near the umbones, due to scour or 

 the normal burrowing of the animal, was called erosion and was 

 not considered damage. Similarly, dents in the shells of the 

 fragile-shelled species were not considered damage. 



Damage rates were calculated as percentages by dividing the 

 number of damaged mussels by the total number of mussels taken. 



Mussels collected in 1984 were divided into two categories 

 for analysis of damage: those which were collected for the first 

 time, and those which were recaptured. Shells of newly-captured 

 mussels recorded damage accumulated during their adult life span 

 in the area in which they were found. Shells of recaptured 

 mussels recorded damage accumulated between the time they were 

 marked and the time they were recaptured (spanning the summer of 

 1984 in this study) in the area in which they were placed. 



According to spokesmen from Naples Terminal Company, 

 heaviest fleeting activity occurs between fall and spring rather 

 than in summer. In fall and winter, farmers harvest grain which 

 is shipped downriver to New Orleans. In winter and early spring, 



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