To test the hypothesis that rotifers release one or more chemical microalgal growth inhibitors in addition to devouring the microalgal cells, the effects of different concentrations of filtered, bacteria‐free, rotifer culture filtrate (RCF) on the growth and physiological parameters of Chlorella sp., and the response of Chlorella sp. at different starting cell densities to 10% RCF, were studied. The results show that RCF significantly decreased Chlorella cell densities during the incubation, suggesting that rotifers release some chemical(s) that inhibit microalgal cell growth. Chlorella cell densities decreased with increasing RCF concentration. Increasing the initial cell density of Chlorella dispersed the inhibitory chemical(s) present in 10% RCF over more cells, reducing their effect. The results confirm that the action of the chemical(s) released by rotifers on microalgal cell growth was dependent on both the RCF concentration and the exposure time. They also demonstrate that ≥10% RCF significantly inhibited photosynthesis and respiration, which would account for some of the decreased Chlorella cell growth in the presence of RCF. Calculations based on the data indicate that the rotifer‐derived chemical(s) released hourly from each rotifer inhibits growth by 45.5 microalgal cells in addition to the rotifer predation, with a 48 h LC₅₀ value of 18.8% RCF. Based on these results, fresh medium instead of the old culture medium was contaminated by the rotifers.

中文翻译：

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小球藻的化学抑制。由轮虫。

为了检验轮虫除吞食微藻细胞外还释放一种或多种化学微藻生长抑制剂的假设，研究了不同浓度的过滤，无菌，轮虫培养滤液（RCF）对小球藻生长和生理参数的影响。 ，以及小球藻的反应。研究了在不同起始细胞密度下达到10％RCF的情况。结果表明，在培养过程中，RCF显着降低了小球藻的细胞密度，这表明轮虫释放出一些抑制微藻细胞生长的化学物质。小球藻细胞密度随着RCF浓度的增加而降低。增加小球藻的初始细胞密度将存在于10％RCF中的抑制性化学物质分散在更多的细胞上，从而降低其作用。结果证实，轮虫释放的化学物质对微藻细胞生长的作用取决于RCF浓度和暴露时间。他们还证明，≥10％的RCF会显着抑制光合作用和呼吸作用，这可能是存在RCF时小球藻细胞生长下降的原因。根据数据进行的计算表明，除了轮虫捕食外，每小时每只轮虫释放的轮虫衍生化学品还抑制了45.5个微藻细胞的生长，其48 h LC ₅₀值为18.8％RCF。根据这些结果，轮虫污染了新鲜培养基而不是旧培养基。