背景:基地矿湖(BML)是加拿大油砂采矿业的第一个全尺寸端坑湖。BML将油砂尾矿隔离在淡水帽下,并旨在发展成为可以整合到当地分水岭中的功能性生态系统。成功开垦的第一阶段需要建立一个浮游植物群落,以支持典型的北方湖泊食物网。为了评估此开垦阶段BML中浮游植物群落的多样性和动态,并为将来的监测设定基线,我们使用分子方法检查了2016年至2021年BML中的浮游植物群落(针对23S,18S,和16SrRNA基因)和显微镜方法。附近的水体被用作淡水环境和活跃尾矿池的对照。
结果:浮游植物群落由典型的北方湖泊的多种细菌和真核生物组成。显微镜和分子数据都确定了在门水平上与自然北方湖泊相当的浮游植物群落,以绿藻门为主,Cryptophyta,和蓝藻,一些芽孢杆菌,绿藻,和Euglenophyta。尽管在BML和对照淡水水库中,许多相同的属都很突出,物种或ASV水平存在差异。BML的总多样性也始终低于对照淡水站点,但始终高于对照尾矿库。在5年的研究期间,BML中的浮游植物群落组成发生了变化。2016-2019年存在一些分类单元(例如,在2021年不再检测到Choricystis),而从2019-2021年开始,一些dinophytes和haptophytes被少量检测到。不同的定量方法(23SrRNA基因的qPCR分析,和微观估计的种群和总生物量)在5年的研究中没有显示出总浮游植物一致的方向趋势,浮游植物物种多样性也没有持续增加。5年的时间可能不足以检测社区趋势,因为浮游植物群落在属和种水平上变化很大。
结论:BML支持与控制地点(活跃尾矿和淡水湖)有些独特的浮游植物群落组成,并且随着时间的推移仍在变化。然而,最丰富的属是典型的自然北方湖泊,有可能支持复杂的水生食物网,已知其许多已确定的主要浮游植物成分是北方湖泊环境中的主要生产者。
BACKGROUND: Base Mine Lake (BML) is the first full-scale end pit lake for the oil sands mining industry in Canada. BML sequesters oil sands tailings under a freshwater cap and is intended to develop into a functional ecosystem that can be integrated into the local watershed. The first stage of successful reclamation requires the development of a phytoplankton community supporting a typical boreal lake food web. To assess the diversity and dynamics of the phytoplankton community in BML at this reclamation stage and to set a baseline for future monitoring, we examined the phytoplankton community in BML from 2016 through 2021 using molecular methods (targeting the 23S, 18S, and 16S rRNA genes) and microscopic methods. Nearby water bodies were used as controls for a freshwater environment and an active tailings pond.
RESULTS: The phytoplankton community was made up of diverse bacteria and eukaryotes typical of a boreal lake. Microscopy and molecular data both identified a phytoplankton community comparable at the phylum level to that of natural boreal lakes, dominated by Chlorophyta, Cryptophyta, and Cyanophyta, with some Bacillariophyta, Ochrophyta, and Euglenophyta. Although many of the same genera were prominent in both BML and the control freshwater reservoir, there were differences at the species or ASV level. Total diversity in BML was also consistently lower than the control freshwater site, but consistently higher than the control tailings pond. The phytoplankton community composition in BML changed over the 5-year study period. Some taxa present in 2016-2019 (e.g., Choricystis) were no longer detected in 2021, while some dinophytes and haptophytes became detectable in small quantities starting in 2019-2021. Different quantification methods (qPCR analysis of 23S rRNA genes, and microscopic estimates of populations and total biomass) did not show a consistent directional trend in total phytoplankton over the 5-year study, nor was there any consistent increase in phytoplankton species diversity. The 5-year period was likely an insufficient time frame for detecting community trends, as phytoplankton communities are highly variable at the genus and species level.
CONCLUSIONS: BML supports a phytoplankton community composition somewhat unique from control sites (active tailings and freshwater lake) and is still changing over time. However, the most abundant genera are typical of natural boreal lakes and have the potential to support a complex aquatic food web, with many of its identified major phytoplankton constituents known to be primary producers in boreal lake environments.