Milkfish (Chanos chanos Forsskal) fingerlings were treated with toxic, nontoxic dinoflagellate Alexandrium minutum cells or toxic algal extract in the water medium without any aeration. Mortality of fish increased with increasing concentrations of toxic, nontoxic algal cells and water-soluble toxic algae extract. Milkfish fingerlings, which were exposed to toxic algae (1.5x10(4)-3.0x10(4) cells/ml) or algal extract [5.13x10(3)-2.05x10(4) cells/ml, 0.195 MU/10(4) cells (toxin concentration)] for 24 h, revealed by light microscopic observations a noticeable edema, hyperplasia and necrosis of secondary gill lamellae. The same toxicological symptom was observed in fish exposed to pure saxitoxin (STX) (6.475x10(-2) &mgr;g/ml) in the water medium. A higher critical oxygen pressure and oxygen consumption rate were also found in the milkfish fingerlings exposed to toxic algae extract (5.13x10(3)-2.05x10(4) cells/ml) and STX (6.475x10(-2) &mgr;g/ml). The cells of nontoxic A. minutum did not cause the gill damage to milkfish, and the extract of nontoxic algae did not cause an increase in oxygen consumption rate or critical oxygen demand of milkfish. From these results, we infer that toxic cells and its extract cause nonspecific response in gill tissues of milkfish. An instant increase in oxygen consumption rate and oxygen demand may be one of the major causes of fish death.

中文翻译：

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暴露于有害甲藻亚历山大藻的遮目鱼鱼种的鱼鳞毒性研究

遮目鱼 (Chanos chanos Forsskal) 鱼种在水介质中用有毒、无毒的甲藻亚历山大藻细胞或有毒藻类提取物处理，没有任何曝气。鱼的死亡率随着有毒、无毒藻细胞和水溶性有毒藻提取物浓度的增加而增加。暴露于有毒藻类（1.5x10(4)-3.0x10(4) 个细胞/ml）或藻类提取物 [5.13x10(3)-2.05x10(4) 个细胞/ml，0.195 MU/10(4) ) 细胞（毒素浓度）] 24 小时，通过光学显微镜观察显示次生鳃片有明显的水肿、增生和坏死。在暴露于水介质中的纯石房蛤毒素 (STX) (6.475x10(-2) &mgr;g/ml) 的鱼中观察到相同的毒理学症状。在暴露于有毒藻类提取物（5.13x10(3)-2.05x10(4) 个细胞/ml）和 STX（6.475x10(-2) &mgr;g/）的遮目鱼鱼种中也发现了更高的临界氧压和耗氧率毫升）。无毒A. minutum细胞未对遮目鱼造成鳃损伤，无毒藻类提取物未引起遮目鱼耗氧率或临界需氧量增加。根据这些结果，我们推断有毒细胞及其提取物会在遮目鱼的鳃组织中引起非特异性反应。耗氧率和需氧量的瞬间增加可能是鱼类死亡的主要原因之一。无毒藻类提取物不会引起遮目鱼耗氧率或临界需氧量的增加。根据这些结果，我们推断有毒细胞及其提取物会在遮目鱼的鳃组织中引起非特异性反应。耗氧率和需氧量的瞬间增加可能是鱼类死亡的主要原因之一。无毒藻类提取物不会引起遮目鱼耗氧率或临界需氧量的增加。根据这些结果，我们推断有毒细胞及其提取物会在遮目鱼的鳃组织中引起非特异性反应。耗氧率和需氧量的瞬间增加可能是鱼类死亡的主要原因之一。