Mukherjee Indranil, Grujčić Vesna, Salcher Michaela M, Znachor Petr, Seďa Jaromír, Devetter Miloslav, Rychtecký Pavel, Šimek Karel, Shabarova Tanja
Biology Centre of the Czech Academy of Sciences, Institute of Hydrobiology, Na Sádkách 7, 37005, Ceske Budejovice, Czech Republic.
Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden.
Environ Microbiome. 2024 May 8;19(1):31. doi: 10.1186/s40793-024-00574-5.
Protists are essential contributors to eukaryotic diversity and exert profound influence on carbon fluxes and energy transfer in freshwaters. Despite their significance, there is a notable gap in research on protistan dynamics, particularly in the deeper strata of temperate lakes. This study aimed to address this gap by integrating protists into the well-described spring dynamics of Římov reservoir, Czech Republic. Over a 2-month period covering transition from mixing to established stratification, we collected water samples from three reservoir depths (0.5, 10 and 30 m) with a frequency of up to three times per week. Microbial eukaryotic and prokaryotic communities were analysed using SSU rRNA gene amplicon sequencing and dominant protistan groups were enumerated by Catalysed Reporter Deposition-Fluorescence in situ Hybridization (CARD-FISH). Additionally, we collected samples for water chemistry, phyto- and zooplankton composition analyses.
Following the rapid changes in environmental and biotic parameters during spring, protistan and bacterial communities displayed swift transitions from a homogeneous community to distinct strata-specific communities. A prevalence of auto- and mixotrophic protists dominated by cryptophytes was associated with spring algal bloom-specialized bacteria in the epilimnion. In contrast, the meta- and hypolimnion showcased a development of a protist community dominated by putative parasitic Perkinsozoa, detritus or particle-associated ciliates, cercozoans, telonemids and excavate protists (Kinetoplastida), co-occurring with bacteria associated with lake snow.
Our high-resolution sampling matching the typical doubling time of microbes along with the combined microscopic and molecular approach and inclusion of all main components of the microbial food web allowed us to unveil depth-specific populations' successions and interactions in a deep lentic ecosystem.
原生生物是真核生物多样性的重要贡献者，对淡水生态系统中的碳通量和能量转移有着深远影响。尽管其具有重要意义，但关于原生生物动态的研究仍存在显著空白，尤其是在温带湖泊的较深水域。本研究旨在通过将原生生物纳入捷克共和国里莫夫水库已充分描述的春季动态研究中，来填补这一空白。在从混合期到稳定分层期的两个月时间里，我们从水库的三个深度（0.5米、10米和30米）采集水样，每周采样频率高达三次。使用小亚基核糖体RNA（SSU rRNA）基因扩增子测序分析微生物真核生物和原核生物群落，并通过催化报告沉积 - 荧光原位杂交（CARD - FISH）对主要的原生生物类群进行计数。此外，我们还采集了水样用于水化学、浮游植物和浮游动物组成分析。
随着春季环境和生物参数的快速变化，原生生物和细菌群落从均匀的群落迅速转变为不同深度特定的群落。在上层水体中，以隐藻为主的自养和混合营养原生生物的盛行与春季藻华特化细菌相关。相比之下，中层和下层水体展示了一个以假定寄生的 Perkinszoa、碎屑或颗粒相关的纤毛虫、丝状足虫、端毛类和挖掘类原生生物（动质体目）为主的原生生物群落的发展，这些原生生物与湖泊雪相关细菌同时出现。
我们的高分辨率采样与微生物典型的倍增时间相匹配，结合显微镜和分子方法，并纳入了微生物食物网的所有主要组成部分，使我们能够揭示一个深水湖泊生态系统中特定深度种群的演替和相互作用。
