An outbreak of harmful algal blooms (HABs) often leads to the death of fish and other marine organisms and causes serious losses to human economic activities. Modified clay (MC) technology is an effective way to control HABs. Although the material and preparation process are based on the premise of green and safety, the potential eco-environmental impacts of MC on non-target organisms should still have to receive attention before field applications can occur. Therefore, the effects of one commonly used modified clay, polyaluminum chloride-modified clay (PAC-MC), on the survival, growth, and oxidative stress of the marine medaka (Oryzias melastigma) were studied. The toxicity test results showed that the 96-h median lethal concentration (96-h LC₅₀) of PAC-MC for newly hatched medaka larvae was 5.204 g/L, which was much higher than the concentration used on site (4–10 t/km²). Within the concentration range of PAC-MC used in this experiment (≤2 g/L), the morphology, heart rate, growth, and aluminum content of larvae did not change with the increase in the modified clay concentration. Low concentrations of PAC-MC (≤0.5 g/L) did not significantly affect catalase (CAT) activity, superoxide dismutase (SOD) activity, peroxidase (POD) activity, and the content of malondialdehyde (MDA), but higher concentrations of PAC-MC (such as 2 g/L) caused oxidative damage to the larvae and increased the antioxidant enzyme activity of the larvae. The present study revealed that under an effective dosage for treating harmful algal blooms on site, PAC-MC had no adverse effects on the survival, growth, oxidative stress, and aluminum content of the newly hatched marine medaka, which provides a scientific basis for the field application of modified clay.

中文翻译：

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改性粘土对海洋青鳉 (Oryzias melastigma) 新孵化幼虫的生长动力学和生理生化反应的影响

有害藻华 (HAB) 的爆发通常会导致鱼类和其他海洋生物死亡，并对人类经济活动造成严重损失。改性粘土 (MC) 技术是控制 HAB 的有效方法。虽然材料和制备过程是以绿色和安全为前提的，但在现场应用之前，MC对非目标生物的潜在生态环境影响仍需引起关注。因此，研究了一种常用的改性粘土——聚氯化铝改性粘土（PAC-MC）对海洋青鳉（Oryzias melastigma）的存活、生长和氧化应激的影响。毒性试验结果表明，96-h 中位致死浓度（96-h LC ₅₀) PAC-MC 对新孵化的青鳉幼虫的浓度为 5.204 g/L，远高于现场使用的浓度 (4-10 t/km ²）。在本实验所用PAC-MC的浓度范围内（≤2 g/L），幼虫的形态、心率、生长和铝含量不随改性粘土浓度的增加而变化。低浓度PAC-MC（≤0.5 g/L）对过氧化氢酶（CAT）活性、超氧化物歧化酶（SOD）活性、过氧化物酶（POD）活性和丙二醛（MDA）含量没有显着影响，但较高浓度的PAC -MC（如2g/L）对幼虫造成氧化损伤，增加幼虫的抗氧化酶活性。目前的研究表明，在现场处理有害藻华的有效剂量下，PAC-MC对新孵化的海洋青鳉的存活、生长、氧化应激和铝含量没有不利影响，