Larval production of giant river prawn Macrobrachium rosenbergii and water quality in a commercial hatchery using a closed recirculation system (RAS) with artificial seawater, considering water used during 240 days (E1) and freshly prepared water (E2), was evaluated. An average of 100 larvae L⁻¹ (zoea I) was stocked in four tanks of 1000 L; in both treatments, they were fed Artemia and egg custard. Survival and larval stage index (LSI) were estimated, every 5 days. Temperature, salinity and pH were monitored daily, while nitrogen compounds and ions were monitored every 5 days. Spearman and Pearson correlations were performed between larval survival and ion concentration and Mg/Ca ratio. Final larval survival differed significantly between treatments E1 (32% ± 7.5%) and E2 (50% ± 7.5%). Larval cycle lasted 23 and 21 days for E1 and E2 respectively. LSI did not differ significantly between the treatments. Water quality parameters were appropriate for the specie, although nitrate (NO₃) increased to 500 mg L⁻¹ in E1 treatment. Reused water showed a depletion of magnesium (~half of it) when compared to freshly prepared water. Magnesium and potassium concentrations decreased in both treatments during E1 cycle. A positive correlation was found between larval survival and magnesium (r = 0.54) and potassium (r = 0.78) in E1, but the same was not observed in E2. Mg/Ca ratio in E1 showed an average of 1.2, whereas, in E2, the average ratio was 2.1. The depletion of magnesium and potassium ions, through the continuous use of the water in RAS, could affect the survival of larvae.

中文翻译：

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大河虾罗氏沼虾幼虫在人工海水商业再循环系统中的生存和变态

考虑到 240 天期间使用的水 (E1) 和新鲜制备的水 (E2)，评估了使用封闭再循环系统 (RAS) 和人工海水的商业孵化场罗氏沼虾的幼体产量和水质。平均 100 只幼虫 L ^-1(zoea I) 储存在四个 1000 L 的罐中；在这两种治疗中，它们都喂食卤虫和蛋羹。每 5 天估计一次存活和幼虫阶段指数 (LSI)。每天监测温度、盐度和 pH 值，而每 5 天监测一次氮化合物和离子。Spearman 和 Pearson 相关性在幼虫存活率和离子浓度和 Mg/Ca 比率之间进行。处理 E1 (32% ± 7.5%) 和 E2 (50% ± 7.5%) 之间的最终幼虫存活率显着不同。E1 和 E2 的幼虫周期分别持续了 23 天和 21 天。LSI 在治疗之间没有显着差异。水质参数适合该物种，尽管硝酸盐 (NO ₃ ) 增加到 500 mg L ^-1在 E1 治疗中。与新鲜制备的水相比，重复使用的水显示出镁的消耗（约一半）。在 E1 周期期间，两种处理的镁和钾浓度均降低。 在 E1中发现幼虫存活与镁 ( r  = 0.54) 和钾 ( r = 0.78)之间存在正相关，但在 E2 中未观察到相同的情况。E1 中的 Mg/Ca 比率平均为 1.2，而 E2 中的平均比率为 2.1。通过在 RAS 中连续使用水，镁和钾离子的消耗会影响幼虫的存活。