FISHERY BULLETIN: VOL. 86, NO. 3 



Table 2.— Means and standard deviations for volume (mL), condition index (g mL"') 

 and dry weight (g). Significance levels (sig.) from Duncan's multiple range test (o = 0.05). 

 A test was restricted to a single column. Groups having the same letter within a column 

 are not significantly different, n, see Table 1 . 



Table 3.— Mean and standard deviations for Perkinsus marinus 

 infection intensity among groups. Significance levels from Dun- 

 can's multiple range test (o = 0.05) apply to the infection intensity 

 data. Groups with the same letter are not significantly different. 

 Percent incidence is the number of oysters infected divided by the 

 number of oysters in the sample. Infection intensity was calculated 

 using the 5-point scale of Mackin (1962). n, see Table 1. 



Table 4. — Results of histological examination of gonadal samples 

 for each group. Significance levels (sig.) from Duncan's multiple 

 range test (a = 0.05) are for differences In the number of eggs 

 present per female in a histological section. Percent of females 

 spawning is the number of females with eggs observed in the 

 gonoducts divided by the number of females in the sample. 



term in the MANCOVA was also nonsignificant). 

 The number of eggs per microscopic field esti- 

 mated from histological sections, was significantly 

 lower in parasitized oysters after the 4-wk treatment 

 period (Table 4). No differences between controls 

 and previously parasitized oysters were present 

 after the 4-wk recovery period. The proportion of 

 oysters ready to spawn (female oysters which had 

 eggs visible in the gonoducts) was not significantly 

 different in parasitized and unparasitized oysters 

 during treatment or recovery (x^, a = 0.05). 



Biochemical Composition 



Mean levels of the various biochemical compo- 

 nents measured in adductor muscle and mantle 

 tissue are given in Tables 5 and 6. A comparison of 

 precontrol, treatment control, and recovery control 

 oysters documents the changes in biochemical com- 

 position produced by handling stress and natural 

 environmental changes that occurred during the 



experiment. Glycogen increased significantly in the 

 mantle tissue during the 4-wk treatment period, 

 then decreased during the recovery period (Table 

 7). Glycogen in the adductor muscle also decreased 

 during the recovery period (Table 7). Hypotaurine 

 increased in both tissues during the treatment 

 period (Table 8). Most other FAA and the total pool 

 dropped in concentration in the mantle tissue in the 

 first 4 weeks, but then stabilized. In contrast, in the 

 adductor muscle, significant increases in glycine and 

 hypotaurine during the treatment period were off- 

 set by a significant decrease in alanine, so the total 

 pool changed little. Again, the FAA pool stabilized 

 during the first 4 weeks. Hence, there was little 

 difference in treatment and recovery controls in any 

 measured biochemical component. 



Snail parasitized and control oysters did not differ 

 significantly in the concentration of any of the 

 biochemical components in either the mantle or 

 adductor muscle (Tables 7, 8). Only one biochemical 

 parameter differed between the recovery control 



558 



