Bacterioplankton Community as a Biological Element for Reservoirs Water Quality Assessment

Dynamics of Bacterioplankton Communities during Wet and Dry Seasons in the Danjiangkou Reservoir in Hubei, China

Water quality is directly linked to drinking water safety for millions of people receiving the water. The Danjiangkou Reservoir is the main water source for the Middle Route of the South-to-North Water Diversion Project (MR-SNWDP), located in the vicinity of Henan and Hubei provinces in China. Aquatic microorganisms are key indicators of biologically assessing and monitoring the water quality of the reservoir as they are sensitive to environmental and water quality changes. This study aimed to investigate the spatiotemporal variations in bacterioplankton communities during wet (April) and dry (October) seasons at eight monitoring points in Hanku reservoir and five monitoring points in Danku reservoir. Each time point had three replicates, labeled as wet season Hanku (WH), wet season Danku (WD), dry season Hanku (DH), and dry season Danku (DD) of Danjiangkou Reservoir in 2021. High-throughput sequencing (Illumina PE250) of the 16S rRNA gene was performed, and alpha (ACE and Shannon) and beta (PCoA and NDMS) diversity indices were analyzed. The results showed that the dry season (DH and DD) had more diverse bacterioplankton communities compared to the wet season (WH and WD). Proteobacteria, Actinobacteria, and Firmicutes were the most abundant phyla, and Acinetobacter, Exiguobacterium, and Planomicrobium were abundant in the wet season, while polynucleobacter was abundant in the dry season. The functional prediction of metabolic pathways revealed six major functions including carbohydrate metabolism, membrane transport, amino acid metabolism, signal transduction, and energy metabolism. Redundancy analysis showed that environmental parameters greatly affected bacterioplankton diversity during the dry season compared to the wet season. The findings suggest that seasonality has a significant impact on bacterioplankton communities, and the dry season has more diverse communities influenced by environmental parameters. Further, the relatively high abundance of certain bacteria such as Acinetobacter deteriorated the water quality during the wet season compared to the dry season. Our findings have significant implications for water resource management in China, and other countries facing similar challenges. However, further investigations are required to elucidate the role of environmental parameters in influencing bacterioplankton diversity in order to devise potential strategies for improving water quality management in the reservoir.

A Preliminary Study of Bacterioplankton Community Structure in the Taiyangshan Wetland in Ningxia and Its Driving Factors

The Taiyangshan Wetland, a valuable wetland resource in the arid zone of central Ningxia, is critical for flood storage and drought resistance, climate regulation, and biodiversity protection. Nevertheless, the community structure and diversity of bacterioplankton in the Taiyangshan Wetland remains unclear. High-throughput sequencing was used to analyze the differences in bacterioplankton structure and major determinants in the Taiyangshan Wetland from April to October 2020. The composition and diversity of the bacterioplankton community varied significantly in different sampling periods but showed negligible differences across lake regions. Meanwhile, the relative abundances of bacterioplankton Bacteroidetes, Actinobacteria, Firmicutes, Chloroflexi, Tenericutes, Epsilonbacteraeota, and Patescibacteria were significantly different in different sampling periods, while the relative abundances of Cyanobacteria in different lake regions were quite different. Network analysis revealed that the topological attributes of co-occurrence pattern networks of bacterioplankton were high, and bacterioplankton community compositions were complicated in the month of July. A mantel test revealed that the bacterioplankton community in the entire wetland was affected by water temperature, electrical conductivity, dissolved oxygen, salinity, total nitrogen, ammonia nitrogen, chemical oxygen demand, fluoride, and sulfate. The bacterioplankton community structure was affected by ten environmental parameters (e.g., water temperature, dissolved oxygen, salinity, and permanganate index) in April, while the bacterioplankton community was only related to 1~2 environmental parameters in July and October. The bacterioplankton community structure in Lake Region IV was related to seven environmental parameters, including dissolved oxygen, pH, total nitrogen, and chemical oxygen demand, whereas the bacterioplankton community structures in the other three lake regions were related to two environmental parameters. This study facilitates the understanding of the bacterioplankton community in wetlands in arid areas and provides references to the evaluation of aquatic ecological management of the Taiyangshan Wetland.

Moroccan Lagoon Microbiomes

Lagoons are fragile marine ecosystems that are considerably affected by anthropogenic pollutants. We performed a spatiotemporal characterization of the microbiome of two Moroccan lagoons, Marchica and Oualidia, both classified as Ramsar sites, the former on the Mediterranean coast and the latter on the Atlantic coast. We investigated their microbial diversity and abundance using 16S rRNA amplicon- and shotgun-based metagenomics approaches during the summers of 2014 and 2015. The bacterial microbiome was composed primarily of Proteobacteria (25–53%, 29–29%), Cyanobacteria (34–12%, 11–0.53%), Bacteroidetes (24–16%, 23–43%), Actinobacteria (7–11%, 13–7%), and Verrucomicrobia (4–1%, 15–14%) in Marchica and Oualidia in 2014 and 2015, respectively. Interestingly, 48 strains were newly reported in lagoon ecosystems, while eight unknown viruses were detected in Mediterranean Marchica only. Statistical analysis showed higher microbial diversity in the Atlantic lagoon than in the Mediterranean lagoon and a robust relationship between alpha diversity and geographic sampling locations. This first-ever metagenomics study on Moroccan aquatic ecosystems enriched the national catalog of marine microorganisms. They will be investigated as candidates for bioindication properties, biomonitoring potential, biotechnology valorization, biodiversity protection, and lagoon health assessment.

Assessment of the Benthic Macroinvertebrate Communities in the Evaluation of the Water Quality of Portuguese Reservoirs: An Experimental Approach

Reservoirs are dynamic ecosystems subject to different pressures that influence and compromise their ecological structure. The main objective of this study was to evaluate the potential of using the macroinvertebrate to assess the water quality of four reservoirs (one site in Miranda—M and Pocinho—P; four sites in Aguieira—Ag1 to Ag4; and five sites in Alqueva—Al1 to Al5). The sites were sampled in autumn 2018 (A18), spring and autumn 2019 (S19 and A19) and spring 2020 (S20). In situ physical and chemical parameters were measured and a sample of water and macroinvertebrate were collected for further analyses. Total phosphorus exceeded the allowed concentrations (maximum values recorded: M—0.13 mg/L, P—0.09 mg/L, Ag3—0.22 mg/L and Al5—0.18 mg/L). Total abundance varied between 4 and 3088. Taxonomic richness was always low, between 1 and 12 taxa. The highest Shannon–Wiener value (1.91) was recorded in Ag1_A18 and Al2_A18. Pielou’s evenness varied widely across all reservoirs, from 0.06 to 0.92. Almost all the organisms found were associated with polluted water, according to the index ratings. Organisms tolerant of disturbances (e.g., Chironomidae and Oligochaeta) were associated with sites with the worst water quality, according to the Water Framework Directive (WFD), (M, Ag3, Ag4 and Al5) while organisms with moderate tolerance to disturbances (e.g., Cordullidae and Polycentropodidae) were associated with sites with better water quality (P, Ag1, Ag2 and Al1 to Al4). The macrozoobenthos index (MZB) used proved to be a sensitive tool to Portuguese reservoirs, corroborating most of the results obtained in the remaining analyses, as well as providing a clear ecological potential complementing the analysis carried out by the WFD. Based on this, the macroinvertebrate community appeared to be sensitive and able to characterize the reservoirs’ water quality.