2010 BKC larval rearing 190s

Experiments conducted in the 190 L tanks investigated effects of diet and stocking density. Larvae were reared at densities of 50 and 75 larvae L-1 and fed either San Francisco Bay or Great Salt Lake enriched Artemia. Larvae were reared at 10°C. Unfortunately, high pulses of mortality were observed beginning in the early Z3 stage (Fig. 1). These pulses of mortality occurred in all diet, temperature, and density treatments and were characterized by generally greater than 90% mortality over an approximate three day period after onset in all tanks, However, onset of this mortality was not synchronous in all tanks and occurred over a period of about two weeks in the hatchery. Specific causes of this mortality are unknown; however theories include narrow temperature tolerances and bacterial infection. The experimental design was aborted at the mid Z3 stage due to low survival. The pulses of mortality during the experiment make interpretations of diet and density effects impossible. As such, surviving larvae in each of the remaining tanks were placed in four sterile tanks in an attempt to salvage surviving individuals by reducing density. The remaining tanks survived to the glaucothoe stage resulting in 1800 glaucothoe produced.

本实验于190升（L）养殖桶中开展，旨在探究日粮与放养密度对实验幼体的影响。实验幼体以50尾·L⁻¹和75尾·L⁻¹的密度培育，分别投喂经强化处理的旧金山湾卤虫（Artemia）或大盐湖卤虫（Artemia），培育水温设置为10℃。

遗憾的是，自溞状幼体第三期早期（Z3 stage，图1）起，观测到突发性高死亡率事件。此类死亡暴发在所有日粮、水温及放养密度处理组中均有发生，表现为各养殖桶在死亡事件起始后的约3天内，死亡率普遍超过90%。但各桶的死亡暴发时间并不同步，在孵化场中，死亡事件的发生跨度约为两周。本次死亡事件的具体诱因尚未明确，现有推测包括温度耐受范围过窄与细菌感染两类假说。

由于幼体存活率过低，实验在溞状幼体第三期中期（Z3 stage）被迫终止。实验期间暴发的死亡事件，使得无法对日粮与放养密度的影响进行有效解读。为此，研究人员将各剩余养殖桶中的存活幼体转移至4个无菌养殖桶中，通过降低放养密度以尝试挽救存活个体。剩余养殖桶中的幼体最终发育至大眼幼体期（glaucothoe stage），共获得1800只大眼幼体。