Effects of environmental oxygen deficiency on embryos and larvae of bay scallop,Argopecten irradians irradians

The experimental results showed that: 1) The embryonic development of bay scallop is inhibited at a dissolved oxygen range of 1.38–3.64×10⁻³ at 23°C, and completely blocked below the lower limit. 2) The tolerance of larvae to anoxia increased with larval sizes and was related to their oxygen debt. 3) The scallop larvae exhibited specific behavioral responses to oxygen deficiency, which finally led to velum disintegration and larval death. The possible relationship between environmental oxygen deficiency and the disease of disintegration of the larval velum is also discussed. In this study, considerable oxygen debt was found in bay scallop larvae, which was greater in small animals. Based on the works of previous authors, a new concept is proposed for the estimation of oxygen debt, namely, the compensatory rate of oxygen debt (CROD). This can be used in intra—or interspecific comparison of oxygen debt. The results can be helpful in the management of water quality and for the prevention of larval diseases encountered in scallop culture. Contribution No. 2167 from the Institute of Oceanology, Chinese Academy of Sciences.