Sampling groundwater fauna: efficiency of rapid assessment methods tested in bores in eastern Australia

Abstract

Summary 1. Growing recognition of the ecological significance and biodiversity of groundwater fauna in Australia has led to statutory requirements for monitoring these communities prior to resource development. However, the efficiency of methods for assessing community composition and taxa richness remains untested, hampering the collection of reliable data for compliance. 2. We assessed the efficiency of two commonly‐used methods to sample groundwater fauna (net hauls and pumping) in bores in two contrasting regions (Dubbo and upper Hunter Valley) of eastern Australia. Repeated sets of seasonal samples from the upper Hunter Valley bores were used to test whether once‐off sampling was sufficient for compliance purposes. 3. All taxa collected by the net method were also captured in pump samples. In addition, pumping yielded more taxa, higher total abundances, and higher numbers of the two most common taxa (syncarids and copepods) than the net. Ten net hauls in the upper Hunter Valley bores collected, on average, 64% of the taxa and 44% of total abundance. When combined with the first 100 L from pumping, cumulative totals rose to 92.5% and 74.5% respectively. Similar trends occurred in bores near Dubbo, indicating that net hauls alone under‐sampled groundwater faunal communities. Multivariate analyses revealed substantial differences in community composition as each incremental subsample was added. 4. Temporal changes in community composition in the Hunter Valley aquifer were marked yet inconsistent across the bores. Initial once‐off sampling collected 30–87% of the total taxa from each bore and new taxa were still being collected after four sampling periods in over half the bores. This shows that more than one sampling occasion is needed for comprehensive assessments of groundwater biodiversity. 5. Successful compliance monitoring of groundwater fauna requires cost‐effective sampling that will not overlook potentially vulnerable taxa or miss ecologically relevant changes in community composition. Currently, a lack of suitable bores seems to be the main constraint on accurate assessment of groundwater invertebrate community composition in these two areas of eastern Australia.

Differences in aquatic microcrustacean assemblages between temporary and perennial springs of an alpine karstic aquifer

“…Sampling effort and sampling methodology can produce different species richness estimations (Hancock and Boulton, 2009). The latter authors demonstrated that a single sampling collected 30-87 % of the total species.…”

An inter-catchment comparison of groundwater biota in the cotton-growing region of north-western New South Wales

“…Groundwater (300 L) was pumped and passed through a 63-mm mesh sieve to collect stygofauna following Hancock and Boulton (2009). The sieve contents were preserved in 100% ethanol, stained with Rose Bengal, and later sorted under a microscope (Â60 magnification).…”

“…Geological history is thought to have a major influence on stygofauna composition, due to its role in supporting evolutionary divergence of species through isolation (Boulton et al 2003;Humphreys 2008;Griebler and Lueders 2009). Geology and water quality influence biotic distribution as they determine water flow, energy exchange, and habitat structure Hahn 2006;Hancock and Boulton 2009;Griebler and Lueders 2009). Other influences on the distribution of groundwater biota include climate, vegetation, water quality, links with the hyporheic zone, and human activities (Galassi et al 1999a(Galassi et al , 1999bCho and Kim 2000;Jasinska and Knott 2000;Schmidt et al 2007;Tomlinson 2008;Griebler and Lueders 2009;Hahn and Fuchs 2009;Stein et al 2010; Korbel et al 2013).…”

Towards an integrated understanding of how micro scale processes shape groundwater ecosystem functions

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