塔玛亚历山大藻对黑褐新糠虾存活、生长以及种群繁殖的影响

通过塔玛亚历山大藻 ( Alexandrium tamarense)对黑褐新糠虾 ( N eomysis awatschensis)的急性和慢性毒性作用研究 ,发现塔玛亚历山大藻对黑褐新糠虾的存活、生殖、生长等有不利影响 ,影响程度随塔玛亚历山大藻藻细胞密度的增加而增加。在 96 h急性毒性实验中 ,塔玛亚历山大藻对黑褐新糠虾的半致死密度为 70 0 0 cells/ml,去藻过滤液中糠虾的死亡率为 2 5 %。在 6 2 d的慢性毒性实验中 ,密度为 90 0 cells/ml的塔玛亚历山大藻对黑褐新糠虾的繁殖有严重影响 ,在此影响下的实验组亲虾产幼虾总数只有 2 7尾 ,仅为对照组产幼虾数目的 1 6 .4 % ;其总产幼虾天数、日最高产幼数分别只有对照的 32 %、4 1 % ,其初次产虾日期也推迟了 3d,并出现了 3次生殖中断。塔玛亚历山大藻对黑褐新糠虾亲虾的存活、生长也有一定的影响 ,处在密度为 90 0 cells/ml塔玛亚历山大藻中的黑褐新糠虾亲虾的存活率只有对照的 6 3% ,糠虾亲虾的体长和体重分别为对照组亲虾的 95 .6 %和 81 .9% ,但差异尚不显著 ( P>0 .0 5 )

The Effects of Alexandrium tamarense on Survival,Growth and Reproduction of Neomysis awatschensis

The effects of dinoflagellate Alexandrium tamarense on Mysid Neomysis awatschensis were studied using acute and chronic tests. The results showed that A. tamarense could affect the survival, growth and reproduction of N. awatschensis, and the effects increased with the algal concentration. In acute experiment, the mortality rate in 9 000cells/ml A. tamarense was 55%, over 10% shrimps died in 900cells/ml A. tamarense, and 96hLC50 of N. awatschensis was 7 000cells/ml. There were 25% N. awatschensis which died in the cell-free filtrate after 96 hour exposure. The acute results also showed that the cell-free filtrate of A. tamarense could effect survival rate of N. awatschensis significantly in a short time. Chronic experiment (62days) showed that A. tamarense could affect the total juvenile population of N. awatschensis. The total numbers of juveniles produced were only 106, 32 and 27 in algal concentrations of 90, 450, 900 cells/ml, respectively, while 164 juveniles were released in the control group during the period. The first releasing time, total releasing days, reproductive of break the parent mysids and the highest number of juveniles per day were also influenced significantly by this toxic dinoflagellate. In concentration of 900 cells/ml, the first releasing day was prolonged for 3 days compared with the control; the total releasing days was 9, while it was 28 in control; the adult shrimps had 3 reproductive breaks during the reproduction period. The highest number of juveniles produced per day was 7 at this concentration, while it was 17 in control. It was also found that A. tamarense can affect the survival and growth of the adult mysid: in 900cells/ml A. tamarense, the mortality rate of N. awatschensis was 37%. The length and weight of adult shrimps were 95.6% and 81.9% respectively of those of the control, but the difference was not significant (P>0.05). The harming mechanism of A. tamarense to N. awatschensis needs further exploring.