ROBINSON ET AL: SEASONAL BIOCHEMICAL CHANGES IN PLACOPECTEN MAGELLANICUS 



winter months when food levels are low and 

 energy reserves in the adductor are falling. In 

 the southeast Newfoundland population of Placo- 

 pecten magellanicus , the initial rise in gonadal 

 DNA content proceeds the usual springtime phy- 

 toplankton bloom, occurring instead during the 

 period when both gonadal and somatic dry tissue 

 weights are at an ebb (Thompson 1977). The 

 initiation of gonadal growth in this Newfoundland 

 population, however, appears to be dependent on 

 available food. From measurements of seasonal 

 rates of respiration, excretion, consumption, and 

 filtration in P. magellanicus from Narragansett 

 Bay, Ehinger^ has concluded that intake of food is 

 necessary to meet the energy demands of repro- 

 duction. In the present study, the initiation of 

 gametogenesis is shown to occur at a time when 

 reserves, dry weights, and index values of the 

 digestive gland, adductor, and gonad are all 

 declining. Gonadal growth however occurs con- 

 currently with an early spring replenishment of 

 energy reserves. Final maturation of the gametes 

 although dependent on the transfer of energy 

 reserves per se, ultimately relies on the spring- 

 time availability of food for the buildup of 

 these reserves. 



ACKNOWLEDGMENTS 



We are indebted to D. Shick and C. Crosby, 

 Division of Marine Resources, State of Maine, 

 Boothbay Harbor, for both collection of deep-sea 

 scallops and their continued interest in this proj- 

 ect. Thanks are extended to J. Antonellis, K. 

 Gorman, M. Misci, G. Peterson, and D. Wayne for 

 help in sampling and histological preparations. 

 G. Lima and G. Stacey conducted the biochemical 

 determinations. We thank B. B. Collette, N. W. 

 Riser, and A. N. Sastry for critically reviewing 

 the manuscript. Special thanks are given to J. 

 Cusack for cheerfully typing each draft of this 

 paper. Research was supported by DOE contract 

 EE-77-S-02-4580 to the New England Aquarium, 

 Boston. 



LITERATURE CITED 



ALTOBELLO, M. A.. D. A. STOREY, AND J. M. CONRAD. 



1977. The Atlantic sea scallop fishery: a descriptive and 



'^Ruth E. Ehinger, State of New Jersey Department of En- 

 vironmental Protection, Trenton, NJ 08625, pers. commun. 

 June 1979. 



econometric analysis. Mass. Agric. Exp. Stn. Res. Bull. 

 643, 80 p. 

 ANSELL, A. D. 



1974. Seasonal changes in biochemical composition of the 

 bivalve Chlamys septemradiata from the Clyde Sea area. 

 Mar Biol. (Bed.) 25:85-99. 

 BaIRD, F. T, JR. 



1953. Observations on the early life history of the giant 

 scallop iPecten magellanicus). Maine Dep. Sea Shore 

 Fish. Res. Bull. 14, 7 p. 

 COE, W. R. 



1945. Development of the reproductive system and varia- 

 tions in sexuality in Pecten and other pelecypod mollusks. 

 Trans. Conn. Acad. ArtsSci. 36:673-700. 

 COMELY, C. A. 



1974. Seasonal variations in the flesh weights and bio- 

 chemical content of the scallop Pecten maximus L. in the 

 Clyde Sea area. J. Cons. 35:281-295. 



Crisp, D. J. 



1971. Energy flow measurements. In N. A. Holme and 

 A. D. Mclntyre (editors). Methods for the study of marine 

 benthos, p. 197-279. IBPdnt. Biol. Programme) Handb. 16. 



CULLINEY, J. L. 



1974. Larval development of the giant scallop Placopecten 

 magellanicus (Gmelin). Biol. Bull. (Woods Hole) 147: 

 321-332. 



DE ZwAAN, A., R. J. Thompson, and D. R. Livingstone. 



1980. Physiological and biochemical aspects of the valve 

 snap and valve closure responses in the giant scallop 

 Placopecten magellanicus. J. Comp. Physiol. 137(Ser B): 

 105-114. 

 DICKIE, L. M. 



1955. Fluctuations in abundance of giant scallop, Placo- 

 pecten magellanicus (Gmelin), in the Digby area of the 

 Bay of Fundy J. Fish. Res. Board Can. 12:797-857. 

 DREW, G. A. 



1906. The habits, anatomy, and embryology of the Giant 

 Scallop, (Pecten tenuicostatus , Mighels). Univ. Maine 

 Stud. 6, 71 p. 

 GABBOTT, P. A. 



1975. Storage cycles in marine bivalve molluscs: a hy- 

 pothesis concerning the relationship between glycogen 

 metabolism and gametogenesis. Proc. Ninth Europ. 

 Mar Biol. Symp., p. 191-211. 



GlESE, A. C. 



1966. Lipids in the economy of marine invertebrates. 

 Physiol. Rev 46:244-298. 



GlESE, A. C, M. A. HART, A. M. SMITH. AND M. A. CHEUNG. 



1967. Seasonal changes in body component indices and 

 chemical composition in the Pismo clam Tivela stultorum. 

 Comp. Biochem. Physiol. 22:549-561. 



GlESE, A. C, AND J. S. PEARSE. 



1974. Introduction: General principles. In A. C. Giese 

 and J. S. Pearse (editors). Reproduction of marine inver- 

 tebrates, Vol. L p. 1-49. Acad. Press, N.Y. 

 HUMASON, G. L. 



1972. Animal tissue techniques. 3ded. W.H. Freeman, 

 San Franc, 641 p. 



IDLER, D. R., T. TAMURA, AND T. WAINAI. 



1964. Seasonal variations in the sterol, fat and unsaponi- 



fiable components of scallop muscle. J. Fish. Res. Board 



Can. 21:1035-1042. 

 LILLIE, R. D., AND H. M. FULLMER. 



1976. Histopathologic technic and practical histochem- 

 istry. 4th ed. McGraw-Hill, N.Y, 942 p. 



457 



