Redox gradients drive microbial community assembly patterns and molecular ecological networks in the hyporheic zone of effluent-dominated rivers

Yuming Wang; Yutao Wang; Jiahui Shang; Longfei Wang; Yi Li; Ziyi Wang; Yina Zou; Wei Cai; Linqiong Wang

doi:10.1016/j.watres.2023.120900

Redox gradients drive microbial community assembly patterns and molecular ecological networks in the hyporheic zone of effluent-dominated rivers

Water Res. 2024 Jan 1:248:120900. doi: 10.1016/j.watres.2023.120900. Epub 2023 Nov 20.

Authors

Yuming Wang¹, Yutao Wang¹, Jiahui Shang¹, Longfei Wang², Yi Li³, Ziyi Wang¹, Yina Zou⁴, Wei Cai⁵, Linqiong Wang⁶

Affiliations

¹ Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu, 210098, PR China.
² Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu, 210098, PR China. Electronic address: lfwang@hhu.edu.cn.
³ Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing, Jiangsu, 210098, PR China. Electronic address: envly@hhu.edu.cn.
⁴ Yangtze Institute for Conservation and Development, Hohai University, Nanjing 210098, China.
⁵ College of Environmental Science and Engineering, Yangzhou University, Huayang West Road #196, Yangzhou 225009, PR China.
⁶ College of Oceanography, Hohai University, Nanjing, Jiangsu, 210098, PR China.

PMID: 38000224
DOI: 10.1016/j.watres.2023.120900

Abstract

The impacts of effluent discharge on receiving waterbodies have been a research hotspot. Nonetheless, limited information is available on the microbial community assembly patterns in the hyporheic zones (HZ) responding to the changes in the microenvironments, e.g., solute transport and redox gradient variations. Using two representative effluent-dominated rivers as model systems, the spatio-temporal bacterial community dynamics and assembly patterns in oxic and suboxic zones in the shallow riverbed sediments were disentangled via null model- and neutral model-based approaches. Bacterial dynamics in community composition were observed driven by environmental filtering, i.e., impacts of environmental variables, more than geographic distances, i.e., the depths of sediments. The communities in samples collected in summer were largely shaped by stochasticity, in which homogeneous selection occupied a higher proportion in oxic (∼39%) than in suboxic zone (∼23%). Deterministic processes contributed to a more complex community structure for samples from oxic zones, whereas weakened the interspecies interactions in suboxic zones. The richness and abundances of non-neutral community were confirmed governing the deterministic assembly in oxic zones. Key species ascribed to 'connectors' and 'network hubs' dominated the community assembly variations in samples collected in winter, and in oxic zones, respectively. Significant positive relationships between β-nearest taxon index and dissolved organic nitrogen (DON) and nitrate highlighted their vital roles in community assembly via deterministic selective pressures in oxic zones. The significance thresholds of nitrogen species for community transition in winter (ΔDON: 2.81 mg-N/L, ΔNO₃^-: 1.09 mg-N/L) were lower than in summer, probably implying that stricter effluent quality standards should be established in colder seasons. Combined, our work poses first insights on the roles of redox zonation in driving microbial community assembly in HZ, which is of significance in guiding ecological remediation processes in effluent-dominated rivers.

Keywords: Bacterial community; Deterministic assembly; Dissolved organic nitrogen; Effluent-dominated river; Hyporheic zone; Stochastic assembly.

MeSH terms

Bacteria*
Microbiota*
Nitrates
Organic Chemicals
Rivers / chemistry

Substances

Organic Chemicals
Nitrates