Abstract

We investigated the reproductive cycle with gonad developmental phases of Solen grandis by histological observations. Seasonal changes in biochemical components of the adductor muscle, visceral mass, foot muscle and mantle were studied by biochemical analysis, from January to December, 2005. The reproductive cycle of this species can be classified into five successive stages: early active stage (December to January), late active stage (January to March), ripe stage (March to July), partially spawned stage (June to July) and spent/inactive stage (July to December). Total protein content was the highest in the foot muscle, the content was high in January (early active stage), the lowest in April (ripe stage), and was the highest in August (partially spawned stage). In the visceral mass, total protein content began to increase in February (late active stage) and reached a maximum in March (ripe stage). Thereafter, it gradually decreased between June and July (partially spawned stage). There was a strong negative correlation in total protein contents between visceral mass and mantle (r = -0.594, p = 0.042). Meanwhile there was a positive correlation between the adductor muscle and foot muscle, the correlation was not statistically significant (r = 0.507, p = 0.093). Total lipid content was the highest in the visceral mass; it was more than 2 to 5-fold higher than that in the adductor muscle, foot muscle, and mantle. Monthly changes in total lipid content were also most dynamic in the visceral mass. It was relatively higher between January and February, showed a maximum in March (the ripe stage), decreased rapidly from April to July (ripe and partially spawned stage), and gradually decreased from September to December (spent/inactive stage). There was a strong positive correlation in total lipid content between foot muscle and adductor muscle (r = 0.639, p = 0.025). Tthough a negative correlation was found between visceral mass and mantle (r = -0.392), the correlation was not statistically significant (p = 0.208). Glycogen contents changed within relatively narrow range and were similar among different tissues. There was no statistically significant correlation in glycogen contents among tissues.