Abstract Testate amoebae are ubiquitous unicellular eukaryotic micro-organisms. They occur in high abundances in terrestrial habitats and contribute to important ecological and biogeochemical processes like silicon cycling. Little is known about the growth of testate amoeba populations under hyperosmotic stress, as caused by salinity pulses due to coastal flooding. Given the increasing sea-levels in response to climate change we address this knowledge gap by jointly considering results from a laboratory experiment and a field study in Tuvalu (South Pacific). In the laboratory experiment, Trinema galeata cultures tolerated up to 1 g NaCl L−1 but showed a pronounced decrease in growth rate probably due to interactions with other micro-organisms. Tracheleuglypha dentata cultures had the highest growth rate at 0.5 g NaCl L−1. At higher salt concentrations (5–10 g NaCl L−1), a strongly reduced growth and rapid closing of the shell aperture with a plug occurred, which can be considered as rapid pre-encystment. Euglypha rotunda cultures had the highest growth rates at 1 g NaCl L−1. At higher salt concentrations (5–10 g NaCl L−1), a strongly reduced growth and spherical shrinking of cell plasma occurred, which is again considered as rapid pre-encystment. After seven weeks of exposure, a replacement of the 5 and 10 g NaCl L−1 culture medium by NaCl-free medium resulted in a quick recovery of T. dentata and E. rotunda cultures, but not of T. galeata cultures. Generally, cultures of T. dentata showed the highest growth rates and shortest generation times (up to 0.37/1.91 day−1, respectively). In the field study, different flooding regimes resulted in fundamental changes of the composition of soil amoeba communities. In conclusion, terrestrial testate amoebae can tolerate at least short periods of exposure to moderate salinity caused by flooding stress due to their ability to form cysts and fast growth rates.

中文翻译：

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在实验室条件下和在南太平洋，有遗嘱的变形虫物种对海平面上升的耐受性

摘要 睾丸变形虫是普遍存在的单细胞真核微生物。它们在陆地栖息地中大量存在，并有助于重要的生态和生物地球化学过程，如硅循环。对由于沿海洪水引起的盐度脉冲引起的高渗压力下有遗嘱变形虫种群的增长知之甚少。鉴于气候变化导致海平面上升，我们通过共同考虑图瓦卢（南太平洋）的实验室实验和实地研究的结果来解决这一知识差距。在实验室实验中，Trinema galeata 培养物可耐受高达 1 g NaCl L-1，但由于与其他微生物的相互作用，其生长速度显着降低。Tracheleuglypha dentata 培养物在 0.5 g NaCl L-1 时具有最高的生长速率。在较高的盐浓度（5-10 g NaCl L-1）下，发生强烈减少的生长和带有塞子的壳孔快速关闭，这可以被认为是快速的预包囊。Euglypha Rotunda 培养物在 1 g NaCl L-1 时具有最高的生长率。在较高的盐浓度（5-10 g NaCl L-1）下，发生细胞血浆的生长强烈减少和球形收缩，这再次被认为是快速的前包囊。暴露七周后，将 5 克和 10 克 NaCl L-1 培养基替换为不含 NaCl 的培养基会导致 T. dentata 和 E. rotunda 培养物快速恢复，但 T. galeata 培养物不会。通常，T. dentata 的培养物显示出最高的生长速率和最短的世代时间（分别高达 0.37/1.91 天-1）。在实地考察中，不同的洪水状况导致土壤变形虫群落的组成发生根本变化。总之，陆地有遗嘱变形虫可以耐受至少短期暴露于由洪水压力引起的中等盐度，因为它们具有形成包囊的能力和快速的生长速度。