Saltwater Intrusion Impacts Microbial Diversity and Function in Groundwater Ecosystems

Background: Groundwater ecosystem services provided by microbial communities are essential for the maintenance of water quality. For example, nitrate contamination is a recognised health and issue in most groundwater systems, often alleviated through processes. The effects climate change, including increasing salinity from rising sea levels, or over-abstraction, on these largely unknown. Methods: This study uses combination culture-dependent (growth curves, isolation bacteria) culture-independent (16S rRNA gene sequencing) methods to identify potential saltwater intrusion microbes their functions. Results: Some negatively impacted chloride concentrations, declines bacteria responsible ammonia removal. These ecosystems should be prioritised future protection level rise increased extraction agriculture other uses. Other stimulated presence chloride, caused an increase abundance salt-tolerant heterotrophic using sugars, peptides, organic acids energy. Conclusion: There have been no previous studies investigating impact Aotearoa New Zealand groundwaters. identification keystone species that affected salinity, which disproportionately large effect low functional redundancy, essential. Water management decisions about abstraction limits defences against can underpinned robust scientific knowledge community sensitivity salinity.