赤潮异弯藻对黑鲷仔鱼的毒性研究

Study on toxicities of Heterosigma akashiwo on Sparus macrocephalus juvenile

以黑鲷(Sparus macrocephalus)仔鱼致死率为指标,进行了赤潮异弯藻鱼毒性源起的探寻。分别就赤潮异弯藻细胞数、种群生长时期、去藻滤液、藻粉提取液的毒性特征进行了研究。实验结果表明:(1)赤潮异弯藻藻细胞数越高,对黑鲷仔鱼的致死性越大。当藻细胞数达到105/mL时,5 h内出现明显致死现象。毒性作用主要源于细胞外分泌物质。(2)不同种群生长期的赤潮异弯藻去藻过滤液对黑鲷仔鱼的毒性存在差异:指数生长期产生的毒性相对较弱,平台期和衰亡期呈现显著的5 h急性致死作用。(3)用活性炭对平台期和衰亡期的去藻过滤液进行吸附处理,可以使去藻过滤液对黑鲷仔鱼的5 h致死率明显减弱。但24 h致死率仍为100%。(4)利用冻干藻粉溶液过滤液对黑鲷仔鱼的毒性实验结果发现:冻干藻粉溶液过滤液仍然呈现出与浓度相关的毒性作用特征,滤液对黑鲷仔鱼的24 h半致死浓度相当于每mL溶液中含0.1 mg的干藻粉形成的溶液浓度。赤潮异弯藻的细胞和生长水体中都具有典型的鱼毒性特征。

The mortality of ichthyotoxic Heterosigma akashiwo （Hada） Hada on Sparus macrocephalus juvenile was studied. Mortalities of S. macrocephalus juvenile were studied through the following aspects： （1） the different algal cell number, （2） culture supematants of different algal growth phases, （3） the culture supematants being treated with active charcoal, and （4） the extract from the lyophilized algal powder （LAP）. The results showed that the toxic effect became significant when the algal number reached 2.7 × 10^5/ml, 70% of the juveniles died in 5 h. The culture supematant from the exponential phase is much less toxic than that from stationary phase and crash phase. After being treated with active charcoal, the acute mortality from the culture supematant of stationary phase and crash phase significantly dropped. But all the juveniles died in 24 h. The toxicity of the extract from LAP was density related. In 24 h, LC50 =0.1 nag LAP extract per milliliter. Both of the cell and the culture supematant have the typical ichthyotoxic characteristics.