Wells provide a distorted view of life in the aquifer: implications for sampling, monitoring and assessment of groundwater ecosystems

Abstract

When compared to surface ecosystems, groundwater sampling has unique constraints, including limited access to ecosystems through wells. In order to monitor groundwater, a detailed understanding of groundwater biota and what biological sampling of wells truly reflects, is paramount. This study aims to address this uncertainty, comparing the composition of biota in groundwater wells prior to and after purging, with samples collected prior to purging reflecting a potentially artificial environment and samples collected after purging representing the surrounding aquifer. This study uses DNA community profiling (metabarcoding) of 16S rDNA and 18S rDNA, combined with traditional stygofauna sampling methods, to characterise groundwater biota from four catchments within eastern Australia. Aquifer waters were dominated by Archaea and bacteria (e.g. Nitrosopumilales) that are often associated with nitrification processes, and contained a greater proportion of bacteria (e.g. Anaerolineales) associated with fermenting processes compared to well waters. In contrast, unpurged wells contained greater proportions of pathogenic bacteria and bacteria often associated with denitrification processes. In terms of eukaryotes, the abundances of copepods, syncarids and oligochaetes and total abundances of stygofauna were greater in wells than aquifers. These findings highlight the need to consider sampling requirements when completing groundwater ecology surveys.

Non‐random processes determine the colonization of groundwater sediments by microbial communities in a pristine porous aquifer

“…It has to be noted that the sediment microcosms were incubated in groundwater monitoring wells. It is known that communities found inside monitoring wells may differ from the communities that are actually present in the surrounding groundwater of an aquifer (Griebler et al ., ; Korbel et al ., ). In fact, previous analyses of our samples by T‐RFLP fingerprinting did indeed reveal some differences between groundwater and well water microbial communities (Zhou et al ., ).…”

3D conservation planning: Including aquifer protection in freshwater plans refines priorities without much additional effort

“…The Hunter region is one of the few areas in Australia in which detailed studies of groundwater ecosystems have been undertaken (Hose, Janardhanan, Barron, & Pollino, 2015). A list of known taxa was compiled from available data sources (Asmyhr, 2013;Asmyhr & Cooper, 2012;Hancock & Boulton, 2008, 2009Hose, Janardhanan, et al, 2015;Hose, Symington, Lott, & Lategan, 2016;Korbel, Chariton, Stephenson, Greenfield, & Hose, 2017;Lategan, Torpy, Newby, Stephenson, & Hose, 2012). A basic typology of aquifers was established derived from the existing aquifer mapping and classification (DECCW, 2010).…”

“…Depending on the taxa and the molecular marker in question, various threshold levels of genetic divergence between sequences can be used to differentiate between taxa (Hebert, Cywinska, Ball, & deWaard, 2003). Molecular tools can thus be used as a screening tool for groundwater systems (Korbel et al, 2017), and levels of genetic diversity used as an indicator of species diversity (Asmyhr & Cooper, 2012).…”

Highly diverse fungal communities in carbon-rich aquifers of two contrasting lakes in Northeast Germany

“…Fungi are also an ecologically important and diverse component of groundwater microbial communities (Lategan et al, 2012;Lategan and Hose, 2014;Sohlberg et al, 2015;Nawaz et al, 2016Nawaz et al, , 2018Korbel et al, 2017). Moreover, groundwater can be a conduit for the exchange of spores and propagules between surface waters and soils (Brad et al, 2008).…”