YAN Tian, LI Jun, YU Rencheng, WANG Yunfeng, ZHOU Mingjiang, Institute of Oceanology, The Chinese Academy of Sciences, Qingdao

Abstract

Theeffects of dinoflagellate Alexandrium tamarence on Mysid Neomysis awatschensis were studied using acute and chronic tests. The results showed that A. tamarence can affect the survival, growth and reproduction of N. awatschensis, and the effects increased with the algal concentration. In acute experiment, the mortality rate in 9000 cells/ml A. tamarence and 96hLC₅₀ of N. awatschensis was 55% and 7000 cells/ml, respectively. There were 25% N. awatschensis which died in the cell-free filtrate after 96 hour exposure; Chronic experiment (62days) showed that in 900 cells/ml A. tamarence, the mortality rate of N. awatschensis was 37%, the number of juveniles was 27 which was only 16.4% of that of the control; The parent shrimps had three times interval during the reproduction period at this concentration and the first date of reproduction was prolonged for three days compared with the control. A. tamarence can affect the growth of the parent shrimps, in 900cells/ml A. tamarence, the length and weight of parent shrimps was 95.6% and 81.9% respectively of those of the control, but the difference was not significant (P>0.05