Energy storage and utilization in relation to the reproductive cycle in the razor clam Ensis arcuatus (Jeffreys, 1865)

Seasonal changes in condition indices and biochemical components of the digestive gland, anterior adductor muscle, foot, and gonad of Ensis arcuatus (Jeffreys, 1865) were analysed from February 1998 to June 1999 in relation to environmental conditions and reproductive events. During summer, E. arcuatus accumulated lipids, particularly triacylglycerols, in the digestive gland and glycogen in the anterior adductor muscle and foot while the gonad was in sexual rest. Phytoplankton blooms caused by the upwelling of cold waters, rich in nutrients, from offshore are responsible for the high availability of food during reserve storage. In autumn, when gametogenesis started, oceanographic conditions changed to a situation with low temperature throughout the water column because of the vertical mixing, and food became scarce. At that point in time, the energy requirements for basal metabolism and the reproductive process were provided by the mobilization of triacylglycerols and glycogen stored in the digestive gland and muscle tissues, respectively. The pattern exhibited by E. arcuatus based on the accumulation of reserves in summer and the subsequent mobilization during gonadal development seems to follow a conservative pattern.