Reducing the time to settlement and metamorphosis of abalone larvae is critical for ensuring that abalone larvae settle within the seeding site for ocean ranching or to increase production in hatcheries. This study investigated the effect of biological (planktonic Nitzschia sp.) and chemical (potassium chloride) cues in inducing settlement and metamorphosis of abalone larvae Haliotis midae on diatom-coated plastic sheets. Larvae were exposed to different concentrations of KCl (10–20 mM), with settlement being highest at 10 mM in the first 20 h. Settlement of larvae exposed to a combined KCl and Nitzschia treatment for 24 h was highest, followed by larvae exposed to KCl for 12 h, while larvae exposed to KCl for 24 h, and both controls (12 and 24 h) had the lowest settlement. However, in both experiments, larval settlement in all treatments declined after 24 h of exposure, while that of the controls (no added settlement cues) increased and surpassed the other treatments after 24 h. Finally, the settlement was very low on uncoated sheets, compared to diatom-coated sheets, regardless of exposure to different combinations of KCl and Nitzschia. The exposure period's results should be interpreted with caution when drawing biological conclusions for field studies. This is due to the dramatic decrease in mean settlement post-exposure to the cue. Therefore, we hypothesize that exposure of H. midae larvae to 10 mM KCl and Nitzschia sp. will not enhance settlement in the ocean, as the inducers are primarily only effective at a KCl concentration level equal to 10 mM for 12 h. However, long-term exposure to KCl and Nitzschia over 24 h could be used in hatcheries to improve the settlement of H. midae larvae.

中文翻译：

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使用化学和生物沉降线索增强鲍鱼（Haliotis midae）幼体沉降：对孵化场和海洋牧场的影响

缩短鲍鱼幼虫的沉降和变态时间对于确保鲍鱼幼虫在海洋牧场的播种地点沉降或提高孵化场的产量至关重要。本研究调查了生物（浮游菱形藻）和化学（氯化钾）信号对诱导鲍鱼幼虫Haliotis midae在硅藻涂层塑料片上沉降和变态的影响。幼虫暴露于不同浓度的 KCl (10-20 mM)，前 20 小时内沉降最高，浓度为 10 mM。暴露于 KCl 和菱形藻联合处理 24 小时的幼虫沉降最高，其次是暴露于 KCl 12 小时的幼虫，暴露于 KCl 24 小时的幼虫，并且两个对照（12 和 24 小时）的沉降最低。然而，在这两个实验中，所有处理中的幼虫沉降在暴露 24 小时后均下降，而对照组（未添加沉降线索）的幼虫沉降在 24 小时后增加并超过其他处理。最后，与硅藻涂层片材相比，无论暴露于 KCl 和菱形藻的不同组合，未涂层片材的沉降都非常低。在得出现场研究的生物学结论时，应谨慎解释暴露期的结果。这是由于暴露于提示后平均沉降急剧下降。因此，我们假设H. midae幼虫暴露于 10 mM KCl 和菱形藻。不会增强海洋中的沉降，因为诱导剂主要仅在 KCl 浓度水平等于 10 mM 时有效 12 小时。然而，在孵化场中，长期暴露于 KCl 和菱形藻超过 24 小时可改善H. midae幼虫的沉降。