ROBINSON ET AL: SEASONAL BIOCHEMICAL CHANGES IN PLACOPECTEN MAGELLANICUS 



the indices, data for each sex were combined. 

 Multiple range tests (least significant difference) 

 on the combined data indicated that GMI, DGI, 

 and CAI values all rose in the spring. QAI, CAI, 

 and DGI dropped in July, while GMI continued to 

 rise until spawning in late summer. The Septem- 

 ber and November samples showed a recovery of 

 QAI, CAI, and DGI, but a drop in GMI, represent- 

 ing a decline in the proportion of body mass 

 attributable to the gonad following spawning. The 

 late fall to early winter period showed a continued 

 decline in all four indices except possibly GMI, 

 with recovery evident by the subsequent March 

 sample. Both GMI and modal gametogenic values 

 (Figure 1) were much higher in the March 1980 

 sample than for the March sample of the previous 

 year, probably reflecting the mild 1979-80 winter. 

 Differences in total wet animal weight and total 

 wet body weight between samples were not sig- 

 nificant (ANCOVA: P>0.05). Variabihty of each 

 of these components was too high to discern 

 seasonal trends. 



5 On 



ra 4.0 



GONADAL MASS 



5 0-1 



2 4.0 



I- 



O 3.0 



■§, 2 0- 



cc 1.0 



Q 



9.0 



■S 8 

 7.0- 



h- 

 I 



O 6.0 



UJ 



$ 5.0- 

 > 4 

 ° 3 0-1 



DIGESTIVE GLAND 



M 



M 



M 



QUICK ADDUCTOR MUSCLE 



M 



M 



F M 



FIGURE 3.— Standard deep-sea scallop (120 mm shell height) 

 annual tissue dry weight fluctuations. • = female; o = male. 



Histochemical Localization of 

 Energy Reserves 



Appreciable concentrations of energy reserves 

 were detected in only the adductor muscle, diges- 

 tive gland, and gonadal mass. As indicated by 

 routine histochemical examinations, a shift of 

 energy reserves from these major areas to other 

 tissues did not occur during the study period. 



Glycogen was primarily concentrated in the 

 adductor muscle, although significant levels were 

 also seen in the digestive gland and the epithelium 

 of both male and female reproductive ducts during 

 most of the year. Concentrations were highest in 

 the spring and early summer within the adductor 

 muscle, ovary, and testes, but were only high in 

 the spring within the digestive gland. Glycogen 

 concentrations remained very low throughout the 

 year in the mantle, mantle edge, foot, and kidney. 



Lipid levels were highest throughout most of 

 the year in the digestive gland, with peak levels in 

 April-May 1979 and March 1980. High concentra- 

 tions were also found in the ovary, increasing 

 throughout the spring to a maximum in July, 

 declining slightly in September, and dropping 

 precipitously by November as a result of spawn- 

 ing. Significant lipid localization was not observed 

 in any other tissue. 



Dry Weight and Biochemical Analyses 



Seasonal fluctuations in gonadal mass, diges- 

 tive gland, and quick adductor muscle dry weights 

 are presented in Figure 3 for standard deep-sea 

 scallops of each sex. Following an initial increase 

 in the weight of all tissues in the spring, gonadal 

 dry weight continued to rise into July, whereas a 

 concomitant decrease occurred in the weight of the 

 adductor muscle and digestive gland. Gonadal dry 

 weight fell throughout the autumn and early 

 winter. The adductor and digestive gland on the 

 other hand, recovered in the autumn to about 

 their springtime levels, but then dropped during 

 the early winter. 



Calculated quantities of lipid and carbohydrate 

 in tissues of standard scallops of each sex are 

 shown in Figures 4 and 5. As with dry weights, 

 both reserves showed an initial rise in the spring 

 in all tissues although the rise in carbohydrate 

 in the gonadal mass and digestive gland was 

 slight. The amount of gonadal lipid and carbo- 

 hydrate continued to increase into midsummer, 

 whereas digestive gland lipid and adductor carbo- 



453 



