Seasonal variations in biochemical composition during the reproductive cycle of the intertidal gastropod Thais lamellosa Gmelin (Gastropoda, Prosobranchia)

Seasonal variations in biochemical constituents of Thais lamellosa Gmelin in relation to the reproductive cycle were studied. Digestive gland, foot muscle, and gonad were analyzed for protein, glycogen, lipid, and ash for 1 year. Data on feeding and gamete maturation were obtained from histological sections of digestive gland and gonad. Major periods of feeding activity occurred in April and August. The spawning peak was in March and gametogenesis began in July. Maximum glycogen levels coincided with major feeding periods but reserves in the digestive gland were mainly lipid. This lipid reserve was used during the winter. Glycogen was at a relatively low level in all tissues and appeared to be used by the developing gonad. The foot muscle stored neither lipid nor glycogen to any appreciable extern.During winter the digestive gland index decreased as reserves were used. The ovary index held constant from October to February then dropped sharply with spawning. Animals kept for the same period under artificial summer conditions showed no decrease in the digestive gland index, but a decrease in the ovary index. Few oogonia reached maturity and many were resorbed. Starved animals used more protein from the ovary than fed animals.