Zoology Department, Faculty of Science, Damietta University, Damietta, Egypt.
College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK, USA.
Sci Rep. 2024 Jul 16;14(1):16382. doi: 10.1038/s41598-024-66583-z.
The relationship between the protozoan communities and environmental variables was studied in the Nile River to evaluate their potential as water quality indicators. Protozoans were sampled monthly at six sampling sites in the Nile's Damietta Branch across a spatial gradient of environmental conditions during a 1-year cycle (February 2016-January 2017). The Protozoa community was comprised of 54 species belonging to six main heterotrophic Protozoa phyla. The abundance (average, 1089 ± 576.18 individuals L) and biomass (average, 86.60 ± 106.13 μg L) were comparable between sites. Ciliates comprised the majority of protozoan species richness (30 species), abundance (79.72%), and biomass (82.90%). Cluster analysis resulted in the distribution of protozoan species into three groups, with the most dominant species being the omnivorous ciliate Paradileptus elephantinus. Aluminium, fluoride, and turbidity negatively affected abundance and biomass, while dissolved oxygen and potassium positively impacted biomass. Of the dominant species recorded over the study area, the amoebozoa Centropyxis aculeata was associated with runoff variables, while the bacterivorous ciliates Colpidium colpoda, Glaucoma scintillans, and Vorticella convallaria were related to the abundance of heterotrophic bacteria, phytoplankton biomass, and total organic carbon. Total dissolved salts, PO, NH NO, dissolved oxygen, and total organic carbon were the strongest causative factors for protozoa distribution. The α-Mesosaprobic environment at site VI confirmed a high load of agricultural runoffs compared to other sites. This study demonstrates that protozoans can be a potential bioindicator of water quality status in this subtropical freshwater river system.
本研究旨在调查尼罗河原生动物群落与环境变量之间的关系，评估其作为水质指标的潜力。在为期 1 年的时间里（2016 年 2 月至 2017 年 1 月），在尼罗河达米埃塔支流的 6 个采样点逐月采集原生动物样本，跨越环境条件的空间梯度。原生动物群落由 6 个主要异养原生动物门的 54 个物种组成。丰度（平均为 1089 ± 576.18 个个体 L）和生物量（平均为 86.60 ± 106.13 μg L）在各采样点之间相当。纤毛虫构成了原生动物物种丰富度（30 种）、丰度（79.72%）和生物量（82.90%）的主要组成部分。聚类分析将原生动物物种分为 3 组，其中最占优势的物种是杂食性纤毛虫 Paradileptus elephantinus。铝、氟化物和浊度对丰度和生物量有负面影响，而溶解氧和钾对生物量有积极影响。在所研究的区域内记录的优势物种中，肉足类原生动物 Centropyxis aculeata 与径流量变量有关，而细菌食性纤毛虫 Colpidium colpoda、Glaucoma scintillans 和 Vorticella convallaria 则与异养细菌丰度、浮游植物生物量和总有机碳有关。总溶解盐、PO、NH 4 -N、溶解氧和总有机碳是原生动物分布的最强因果因素。与其他采样点相比，第六采样点的α-中污带环境证实了农业径流的高负荷。本研究表明，原生动物可以成为这个亚热带淡水河流系统水质状况的潜在生物指标。
