Bodur Seda Ozer, Samuel Solomon Oloruntoba, Polat Muhammet Fatih, Aycan Murat, Asiloglu Rasit
Laboratory of Applied Protistology, Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan.
Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC 27695, USA.
Sci Total Environ. 2025 Jun 15;981:179606. doi: 10.1016/j.scitotenv.2025.179606. Epub 2025 May 7.
One of the most important climate change-related issues that has extremely negative impacts on terrestrial life is soil salinization, especially in lowland paddy fields. Despite the enormous impact of salinity on microbial life, the majority of research focused on bacteria and fungi, neglecting the vast majority of eukaryotic diversity, the protists. Here we aimed to understand the sole impact of the soil salinity on protist communities in paddy field soil. To exclude the variations in other environmental factors that co-varies with the soil EC, we conducted a controlled in vitro experiment to study the direct effect of gradually increased salinity levels (ranging from 0.1 dS m to 12 dS m) on protists in three non-saline (<0.3 dS m) paddy field soils. Then, our in vitro results were confirmed in a field study, in which seawater intrusion caused the accumulation of sea salts in paddy fields along a river. The results of the in vitro and field studies were consistent, showing that alpha and beta diversities of protists are affected by soil salinity. While protist alpha diversity exhibited inconsistent patterns across soil types, beta diversity showed strong and consistent clustering by the salinity gradient. Although salinity significantly shifted protist communities and caused a 10-fold decrease in 18S rRNA gene abundances of protists, protists maintained functional stability, suggesting that even with the compositional shifts, the critical ecosystem functions, such as predation and primary production, remained intact. These results underscore the importance of functional redundancy in sustaining ecosystem functions under salinity stress.
土壤盐渍化是与气候变化相关的最重要问题之一，对陆地生物具有极其负面的影响，尤其是在低地稻田。尽管盐分对微生物生命有巨大影响，但大多数研究集中在细菌和真菌上，而忽略了绝大多数真核生物多样性，即原生生物。在这里，我们旨在了解土壤盐分对稻田土壤中原生生物群落的唯一影响。为了排除与土壤电导率共同变化的其他环境因素的影响，我们进行了一项体外对照实验，以研究盐度水平逐渐增加（范围从0.1 dS/m到12 dS/m）对三种非盐渍（<0.3 dS/m）稻田土壤中原生生物的直接影响。然后，我们在一项田间研究中证实了体外实验结果，在该研究中，海水入侵导致河流沿岸稻田中海盐的积累。体外和田间研究结果一致，表明原生生物的α多样性和β多样性受土壤盐分影响。虽然原生生物的α多样性在不同土壤类型中表现出不一致的模式，但β多样性在盐度梯度下表现出强烈且一致的聚类。尽管盐分显著改变了原生生物群落，并导致原生生物18S rRNA基因丰度下降了10倍，但原生生物保持了功能稳定性，这表明即使组成发生变化，诸如捕食和初级生产等关键生态系统功能仍保持完整。这些结果强调了功能冗余在盐度胁迫下维持生态系统功能的重要性。
