Fine-scale spatiotemporal variations in bacterial community diversity in agricultural pond water

Authors: Stocker (ctr), Matthew; SMITH, JACLYN - University Of Maryland; Pachepsky, Yakov; BLAUSTEIN, RYAN - Orise Fellow

Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2024
Publication Date: 3/10/2024
Citation: Stocker, M.D., Smith, J.E., Pachepsky, Y.A., Blaustein, R.A. 2024. Fine-scale spatiotemporal variations in bacterial community diversity in agricultural pond water. Applied and Environmental Microbiology. 915: Article e170143. https://doi.org/10.1016/j.scitotenv.2024.170143.
DOI: https://doi.org/10.1016/j.scitotenv.2024.170143

Interpretive Summary: Monitoring the water quality of ponds and lakes in agricultural environments, which serves as a critical resource for crop irrigation, has important implications for food safety and public health. Improving risk mitigation strategies requires understanding how water quality properties, which are in constant flux with microbial community interactions, vary across space and time. Here, we report that depth-dependent gradients of water quality parameters (e.g., pH, dissolved oxygen, temperature) correlate with water microbiome diversity in a model irrigation pond, suggesting applications for microbiome surveillance to support monitoring strategies. Within the pond, time of day and sampling depth are both significantly associated with water chemistry and the concomitant microbiome. Developing a better understanding of the intricate relationships between pond water quality and microbial diversity is essential to ensuring the safety of these critical surface water resources.

Technical Abstract: Freshwater bacteria are responsible for a wide range of processes which affect water quality. Therefore, understanding the relative abundance and diversity of aquatic bacteria is important when conducting water quality assessments. The aim of this work was to document intra-daily changes in bacterial community composition and diversity at different sampling depths in an irrigation pond. Water samples were collected across the pond at 9:00, 12:00, and 15:00 from 0, 1, and 2m depths and field and laboratory physicochemical water quality measurements were collected. 16S rRNA sequencing was performed and bacterial a- and ß-diversity metrics were computed. Proteobacteria, Bacteroidetes, Cyanobacteria, and Verrucamicrobia were stable in the water column across time of day and sampling depth, but Acidobacteria and Chloroflexi significantly differed across those factors (PERMANOVA p < 0.05 for both). Both a- and ß-diversity metrics significantly differed with time and depth. On average, a-diversity increased from morning to afternoon and with depth and showed significant negative correlation with chlorophyll, phycocyanin, conductivity, and colored dissolved organic matter. ß-diversity showed weak yet significant associations with most abiotic measurements suggesting a complex network of variables responsible for shaping community composition. The results of this work emphasize the importance of accounting for the time of day and water sampling depth when surveying the microbiomes of small freshwater sources such as irrigation ponds.