Miss Tess Nelson1
1Macquarie University, Sydney, Australia
The salinisation of groundwater within the Murray Darling Basin (MDB), Australia, threatens ecosystems and industries that are dependent on this water. Understanding how microbial communities shift in response to groundwater salinity is imperative, as these communities influence overall groundwater chemistry, quality, and suitability for agricultural and domestic use. Traditionally, knowledge of groundwater microbial communities was limited due to the inability to successfully culture microbes from these low biomass environments. Here we employed eDNA techniques to characterise the microbial communities of alluvial aquifers within three sub-catchments of the MDB and assess the impacts of water quality (including salinity) on these communities. Our analysis identified a total of 13,190 OTUs from 166 identified orders. The data indicated a clear relationship between electrical conductivity (EC) and microbial assemblage structure, with evidence that a unique microbial assemblage existed at high EC (>3000 µS/cm). Microbial communities were influenced by several water quality variables, of which EC was the primary influence, with high levels of EC (<3000 µS/cm) correlating with low relative abundance, diversity and microbial activity. We expect detrimental ecological impacts of salinity have a broader influence beyond groundwater ecosystems, presenting a larger ecological issue impacting all groundwater dependent ecosystems, e.g. wetlands and rivers. Here eDNA techniques are beneficial for assessing human impacts on groundwater ecosystems due to the ability to detect changes in microbial communities. Our understanding remains limited on how these ecological changes will impact groundwater quality into the future, especially as demand for water increases to meet growing populations and agricultural demands.
Biography:
I am a PhD student, my research focuses on groundwater dependent subsurface ecosystems, invertebrate and microbial communities, and their response to groundwater drawdown. I utilise my experience in groundwater invertebrate taxonomy and environmental DNA (eDNA) techniques to characterise the composition and function of groundwater ecosystems. I compare these biological characteristics alongside abiotic environmental factors, such as water quality variables and groundwater depth, to assess the impact groundwater drawdown has on these ecosystems. To do this I utilise multiple field based experimental approaches, as well as, lab based manipulative studies assessing stygofauna’s ability to “move” in response to drawdown.