Bacteria in tropical floodplain soils are sensitive to changes in saltwater

Tiffanie M. Nelson*, Claire Streten, Karen S. Gibb, Anthony A. Chariton

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


Bacterial communities in floodplain and wetland soils cycle elements essential for flora and fauna. The coastal habitats of northern Australia are threatened with increasing saltwater intrusion (SWI) events that will destroy freshwater habitats. The effect of the impending SWI on bacterial communities is unknown. Here, we examined the bacterial communities of a tropical river floodplain located in World Heritage Kakadu National Park. Using 16S rRNA gene pyrosequencing, we measured the baseline bacterial communities from three morphologically distinct regions of the floodplain (lower, upper and backwater swamp), within three zones of the South Alligator River (upstream, cuspate and estuarine funnel or sinuous). Significant differences in the bacterial community were observed at each category of floodplain morphology and river zone. The greatest differences were due to pH and salinity. Large changes in bacterial compositions are predicted to occur with increases in salinity and pH. Saltwater intrusion is predicted to increase substantially in the next decades with sea-level rise, and is likely to cause large and significant changes to the bacterial community with unknown consequences for biogeochemical cycling. Kakadu National Park may benefit from incorporating bacteria into routine studies, because we have shown here that they are sensitive indicators of change, even across small ranges of abiotic variables.

Original languageEnglish
Pages (from-to)1110-1123
Number of pages14
JournalMarine and Freshwater Research
Issue number7
Publication statusPublished - 2018
Externally publishedYes


  • biogeochemistry
  • biomonitoring
  • hydrology
  • microbiology
  • tropics


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