Alexandrium Tamarense And Heterosigma Akashiwo On The Early Development Of Several Fisheries Biological Impact

Alexandrium tamarense and Heterosigma akashiwo are two kinds of toxic agles that are often seen.In this dissertation, the effects and their ways that lead to toxicity of the two kinds of toxic agles on early development of three kinds of fish -Paralichthys olivaceus, Engraulis japonicus, Lateolabrax japonicus, a specie of mollusk: Chlamys farreriand, a specie of shrimp: Penaeus japonicus Bate in the lab by the use of the semi-static water experimental method, And the values of EC50, LC50 of correspondent time have been calculated by the Moving Average-angle Method, consequently, we constructed the quantitative relations between the density of toxic algal and the toxic effects on the above mentioned marine organism in early development stage.The main contents are as followed:1. The evaluation of creature toxicity of Alexandrium tamarense and Heterosigma akashiwoIn the experiments, Anemia sinica serves as the standard experimental creature and the creature toxicity of Alexandrium tamarense and Heterosigma akashiwo are evaluated by the ARC-test method.the values of 2,6,12 and 24h EC50 are 3492 cells / ml, 4630 cells / ml, 5495 cells /ml, 10658cells/ml, correspondent to the effect of algal culture of Heterosigma akashiwo on Anemia sinica larvae. The algal culture and cell fragments of Heterosigma akashiwo had the remarkable harmful influence on activity of Artemia sinica, none the cell contents and cell-free medium.The survival rate was 82.2%, 89% and 94.6% separately when Anemia sinica were exposed for 24 hours to algal culture, cell contents and cell fragment medium of Alexandrium tamarense at a high concentration of 5 000cells/ml, which were lower than that in cell-free medium (P<0.05).2. The effects and their ways that lead to toxicity of Alexandrium tamarense and Heterosigma akashiwo on early development of fishery organism.The results indicated that: (Din the experimental conditions, the Alexandrium tamarense had the remarkable harmful influence on all the experimental organisms. And Heterosigma akashiwo had the remarkable harmful influence on the early development of Paralichthys olivaceus Engraulis japonicus and Lateolabrax japonicus, none on the Penaeus japonicus Bate , Chlamys farreri. (2) The different cell contents of Alexandrium tamarense and Heterosigma akashiwo had different effects. The cell-free medium of both the algal had not the clear advert influence on all the experimental organisms and the effects of algal culture, cell contents and cell fragments on the organisms depend on the species. (3)The sensitivity of organisms on toxin differs at different development stage: in common, the embryo before blastula (including blastula) was more sensitive to toxin. The early D-shape larvae of Chlamys farreri are more sensitive than embryo. But the embryo of Paralichthys olivaceus, Engraulis japonicus, Lateolabrax japonicus had the less sensitivity before hatching, relatively more after hatching. (4) The ways leading fishery organism of the two kinds of algal to toxicity are not only by eating algal causing the accumulation in body of algal toxin, but the direct touching of algal cell to fertilized eggs and larvae or the toxin produced by the algal cell emitting in surrounding seawater, which cause toxic effect by the medium of seawater can also serves as the other cause. And some unknown toxin may exist in the surface or outside of Alexandrium tamarense cell.