Nutrient availability and grazing influence the strength of priority effects in bacterial freshwater communities (data set)

We conducted an experiment to investigate the importance of priority effects in bacterial communities with regard to nutrient availability and grazing. In the course of the experiment, we measured nutrient availability as total phosphorus (TP) spectrophotometrically. Total nitrogen (TN), as well as total organic carbon (TOC) levels, were obtained by catalytic thermal decomposition method. The combined dataset shows the nutrient values for the original lakes, the sterile media used in the experiment as well as all experimental samples for both sampling occasions (day 10 and day 15). Bacterial abundances were monitored using flow cytometry (FC) count data. The combined dataset includes bacterial count data from the pre-cultivation of the bacterial communities before the start of the experiment. Bacterial count data from the running experiment are included afterward. Heterotrophic nanoflagellates (HNF) as the bacterial grazers were counted microscopically. The dataset shows HNF counts from grazing treatments in the experiment starting from day 3. On experimental days 3 and 10, additional non-grazing treatments were included to examine the potential presence of HNF. When bacterial communities mix, immigration history can fundamentally affect the community composition as a result of priority effects. Priority effects arise when an early immigrant exhausts resources and/or alters habitat conditions, thereby influencing the establishment success of the late arriver. The strength of priority effects is context dependent and expected to be stronger if environmental conditions favor the growth of the first arriver. In this study we conducted a two-factorial experiment testing the importance of nutrient availability and grazing on the strength of priority effects in complex aquatic bacterial communities. We did so by mixing two dissimilar communities, simultaneously, and with a 38 hours’ time-delay. Priority effects were measured as the invasion resistance of the first community to the invading second community. We found stronger priority effects in treatments with high nutrient availability and in absence of grazing, but in general the arrival timing was less important than the selection by nutrients and grazing. At the population level, the results were complex, but priority effects may have been driven by bacteria belonging to for example the genera Rhodoferax and Herbaspirillum. Our study highlights the importance of arrival timing in complex bacterial communities especially in environmental conditions which favor rapid community growth. The dataset was originally published in DiVA and moved to SND in 2024.本研究开展一项实验，以探究优先效应（priority effects）在细菌群落中对养分有效性与捕食作用的重要性。 实验过程中，我们采用分光光度法测定总磷（total phosphorus, TP）以表征养分有效性；总氮（total nitrogen, TN）与总有机碳（total organic carbon, TOC）水平则通过催化热分解法测定。本整合数据集涵盖原始湖泊、实验所用无菌培养基，以及两次采样（第10天与第15天）的全部实验样品的养分含量数据。 细菌丰度通过流式细胞术（flow cytometry, FC）计数数据进行监测。本整合数据集涵盖实验开始前细菌群落预培养阶段的细菌计数数据，以及实验运行期间的细菌计数数据。 作为细菌捕食者的异养纳米鞭毛虫（heterotrophic nanoflagellates, HNF）通过显微镜计数法完成计数。数据集包含实验中第3天起捕食处理组的异养纳米鞭毛虫计数数据；实验第3天与第10天还设置了额外的非捕食处理组，以检测异养纳米鞭毛虫的潜在存在情况。 当细菌群落发生混合时，定殖历史会通过优先效应从根本上改变群落组成。优先效应指早期定植的类群消耗资源或改变生境条件，进而影响后期定植类群的定殖成功率。优先效应的强度依赖于环境背景，若环境条件更利于早期定植类群的生长，则优先效应通常更强。本研究开展了一项双因素实验，以探究养分有效性与捕食作用对复杂水生细菌群落中优先效应强度的影响。实验通过将两个异质群落分别设置为同步混合与38小时延迟混合两种处理方式。本研究以第一个群落对第二个入侵群落的入侵抗性作为优先效应的衡量指标。研究结果显示，在高养分有效性且无捕食作用的处理组中，优先效应更强；但总体而言，定植时间的重要性低于养分与捕食作用的筛选作用。在种群水平上，实验结果较为复杂，但优先效应可能由特定菌属的细菌驱动，例如红育菌属（Rhodoferax）与草螺菌属（Herbaspirillum）。本研究强调了定植时间在复杂细菌群落中的重要性，尤其是在利于群落快速生长的环境条件下。 本数据集最初发布于DiVA数据库，并于2024年迁移至SND数据库。