ROBINSON ET AL: SEASONAL BIOCHEMICAL CHANGES IN PLACOPECTEN MAGELLANICUS 



components of the adductor muscle, digestive 

 gland, and gonadal mass, analyses were made on 

 mantle, mantle edge, foot, and kidney tissue. For 

 glycogen staining, tissues were fixed in Rossman's 

 fluid (Humason 1972), embedded as before, and 

 stained with Best carmine (Humason 1972). Con- 

 trol slides were incubated with V/c ^-amylase 

 in 0.2 M phosphate buffer (pH 7.0) at 40° C 

 for 1 h. Lipid was localized in cryostat-sectioned 

 material, postfixed in 109f calcium-Formalin^ fix- 

 ative (Humason 1972), and stained with super- 

 saturated Oil red O (Lillie and Fullmer 1976). 

 Control slides were immersed for 10 min in 95% 

 ethanol to remove all lipid. 



Biochemical Analysis of Tissues 



As a result of the routine histochemical exam- 

 inations, only adductor muscle, digestive gland, 

 and gonadal mass were chosen for biochemical 

 determinations of lipid and carbohydrate concen- 

 trations. No other tissues contained appreciable 

 reserves of either lipid or carbohydrate at any 

 time during the year. Tissues from the 20 deep- 

 sea scallops chosen on each sampling date were 

 pooled by sex into groups of 3-10 animals depend- 

 ing on the size of tissue sample and time of year. 

 The pooled samples were freeze-dried to deter- 

 mine wet:dry weight ratios for each tissue. Sub- 

 samples of the dried tissue were used for bio- 

 chemical analyses. Lipid concentrations were 

 determined gravimetrically after extraction in 

 acetone-isooctane (Peterson et al. 1976). Glycogen 

 levels were determined on each of the four tissues 

 using the glucose-oxidase method as described by 

 Williams and Lutz (1975). All glycogen was first 

 converted to glucose by a 2-h incubation at 55° C 

 m 1% amyloglucosidase (Sigma A-7255). Glucose 

 concentrations were then measured spectrophoto- 

 metrically following a 30-min incubation at 37° C 

 with a mixture of glucose-oxidase and peroxidase 

 (Sigma Kit 510-A). The results give the combined 

 concentrations of both glucose and glycogen for 

 each tissue, and will hereafter be considered 

 "carbohydrate." Since initial results indicated 

 that wet:dry weight ratios, lipid, and carbohy- 

 drate concentrations were not significantly dif- 

 ferent in the catch and quick components of the 

 adductor muscle (March- April samples), analyses 

 of the smaller catch component was discontinued. 



' Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



Standard Scallop 



In order to account for the influences of animal 

 size on seasonal body changes, body component 

 dry weights, and biochemical constituents were 

 calculated for a "standard scallop" of 120 mm shell 

 height. This height was close to the mean (119.0 

 mm) and mode ( 115.2 mm) for the combined yearly 

 samples. Predictive regressions of wet tissue 

 weight (separately for gonadal mass, digestive 

 gland, and quick adductor) on shell height were 

 calculated for each sex within each sample. The 

 resulting regression equations were solved for the 

 standard deep-sea scallop (120 mm shell height). 

 These wet weight values were converted to esti- 

 mated dry weights of each tissue using the wet:dry 

 weight ratios. By multiplying the estimated 

 dry weights of each tissue by the corresponding 

 concentrations of lipid and carbohydrate, total 

 amount of each energy reserve per tissue was 

 calculated. These energy reserve levels were then 

 converted to caloric equivalents using the conver- 

 sion factors from Crisp (1971) (carbohydrate = 4.1 

 kcal/g; lipid = 9.45 kcal/g). Since the calculations 

 for dry weight, lipid, and carbohydrate were based 

 on mean values of pooled tissue samples and 

 regressions of wet tissue weight on shell height, 

 confidence limits could not be estimated for the 

 resulting values. All results have been presented 

 as total amount of each energy reserve per stan- 

 dard animal. 



RESULTS 



Gametogenic Cycle 



During most of the year, deep-sea scallops could 

 easily be sexed by visual examination, due to the 

 characteristic bright pink ovaries and opaque 

 white testes. Histological sections, however, were 

 necessary to determine the sex of spent individ- 

 uals in the September-January samples. Spent 

 gonads were shrunken, flaccid, and lacked charac- 

 teristic coloration, instead possessing semitrans- 

 parent epidermal and connective tissues. 



Gametogenesis, as followed histologically, con- 

 formed to the description of Naidu (1970). The 

 seasonal gametogenic cycle, based on modal 

 gametogenic values for each sample, is presented 

 in Figure 1. Modal values increased throughout 

 the winter, spring, and into the summer as 

 gametes differentiated and ripened. Spawning 

 was evident in 67% of the males (A^ = 9) and 64% 



451 



