Salinity as a major influence on groundwater microbial communities in agricultural landscapes

Tess Nelson; Grant C. Hose; Jodie Dabovic; Kathryn L. Korbel

doi:10.1071/MF23014

RESEARCH ARTICLE (Open Access)

Next Contents Vol 75(1)

Salinity as a major influence on groundwater microbial communities in agricultural landscapes

Tess Nelson

^A , Grant C. Hose

^A ^* , Jodie Dabovic ^B and Kathryn L. Korbel

^A

+ Author Affiliations

- Author Affiliations

^A School of Natural Sciences, Macquarie University, Sydney, NSW 2109, Australia.

^B Department of Planning and Environment, Water, Parramatta, NSW 2124, Australia.

^* Correspondence to: grant.hose@mq.edu.au

Handling Editor: Anthony Chariton

Marine and Freshwater Research 75, MF23014 https://doi.org/10.1071/MF23014

Submitted: 25 January 2023 Accepted: 3 December 2023 Published: 8 January 2024

© 2024 The Author(s) (or their employer(s)). Published by CSIRO Publishing. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Context

Understanding the impacts of salinity on groundwater microbial communities is imperative, because these communities influence groundwater chemistry, quality, and its suitability for use by humans and the environment.

Aim

To assess groundwater salinisation and its influence on groundwater microbial communities within the Murray–Darling Basin (MDB), Australia.

Methods

Alluvial aquifers were sampled from 41 bores, within the Lachlan, Murrumbidgee and Murray catchments. Environmental DNA (eDNA), microbial activity and water-quality variables were measured to evaluate microbial communities, which were then correlated with electrical conductivity (EC) and other environmental variables.

Results

Our results indicated widespread groundwater salinisation within the MDB, with EC ranging from 63 to 51 257 μS cm⁻¹. The highest EC values were recorded in the Murray catchment; however, mean EC values did not differ significantly among catchments (P > 0.05). The composition of microbial communities differed significantly between sites with low (<3000 μS cm⁻¹) and high (>3000 μS cm⁻¹) EC. Microbial activity, richness and abundances were all greater at low- than high-EC sites.

Conclusions

Changes to microbial communities as demonstrated here may have impacts on biogeochemical cycling and ecosystem resilience.

Implications

The detrimental ecological impacts of salinity are not limited to groundwater microbes, but present a larger ecological issue affecting all groundwater-dependent ecosystems.

Keywords: 16S rRNA, agricultural landscape, aquifer, groundwater quality, microbial community, Murray–Darling Basin, salinisation, subterranean ecosystems.

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