Hypoxia and salinity constrain the sediment microbiota-mediated N removal potential in an estuary: A multi-trophic interrelationship perspective

Xin Ma; Yi Li; Linqiong Wang; Lihua Niu; Jiahui Shang; Jinhai Zheng

doi:10.1016/j.watres.2023.120872

Hypoxia and salinity constrain the sediment microbiota-mediated N removal potential in an estuary: A multi-trophic interrelationship perspective

Water Res. 2024 Jan 1:248:120872. doi: 10.1016/j.watres.2023.120872. Epub 2023 Nov 15.

Authors

Xin Ma¹, Yi Li², Linqiong Wang³, Lihua Niu⁴, Jiahui Shang⁵, Jinhai Zheng⁶

Affiliations

¹ College of Hydrology and Water Resources, Hohai University, Nanjing 210098, China.
² College of Hydrology and Water Resources, Hohai University, Nanjing 210098, China; Research Institute of Mulan Ecological River, Putian 351100, China. Electronic address: envly@hhu.edu.cn.
³ College of Oceanography, Hohai University, Nanjing 210098, China.
⁴ Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China; Research Institute of Mulan Ecological River, Putian 351100, China. Electronic address: niulh@hhu.edu.cn.
⁵ Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098, China.
⁶ College of Harbour, Coastal and Offshore Engineering, Hohai University, Nanjing 210098, China; Research Institute of Mulan Ecological River, Putian 351100, China.

PMID: 38006831
DOI: 10.1016/j.watres.2023.120872

Abstract

Reactive nitrogen (N) enrichment is a common environmental problem in estuarine ecosystems, while the microbial-mediated N removal process is complicated for other multi-environmental factors. Therefore, A systematic investigation is necessary to understand the multi-trophic microbiota-mediated N removal characteristics under various environmental factors in estuaries. Here, we studied how multiple factors affect the multi-trophic microbiota-mediated N removal potential (denitrification and anammox) and N₂O emission along a river-estuary-bay continuum in southeastern China using the environmental DNA (eDNA) approach. Results suggested that hypoxia and salinity were the dominant environmental factors affecting multi-trophic microbiota-mediated N removal in the estuary. The synergistic effect of hypoxia and salinity contributed to the loss of taxonomic (MultiTaxa) and phylogenetic (MultiPhyl) diversity across multi-trophic microbiota and enhanced the interdependence among multi-trophic microbiota in the estuary. The N removal potential calculated as the activities of key N removal enzymes was also significantly constrained in the estuary (0.011), compared with the river (0.257) and bay (0.461). Structural equation modeling illustrated that metazoans were central to all sediment N removal potential regulatory pathways. The top-down forces (predation by metazoans) restrained the growth of heterotrophic bacteria, which may affect microbial N removal processes in the sediment. Furthermore, we found that the hypoxia and salinity exacerbated the N₂O emission in the estuary. This study clarifies that hypoxia and salinity constrain estuarine multi-trophic microbiota-mediated N removal potential and highlights the important role of multi-trophic interactions in estuarine N removal, providing a new perspective on mitigating estuarine N accumulation.

Keywords: Estuarine ecosystem; Hypoxia; Interspecific interactions; Multi-trophic microbiota; N removal.

MeSH terms

Denitrification
Estuaries*
Geologic Sediments / chemistry
Humans
Hypoxia
Microbiota*
Nitrogen / metabolism
Phylogeny
Salinity

Substances

Nitrogen