Author: Anna Edgar
Edgar, Anna, 2024 Hydrogeological and environmental controls on stygofauna distribution in northern Australia, Flinders University, College of Science and Engineering
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The presence of stygofauna in aquifers is an important consideration in the approval of groundwater-affecting activities, including mining. Understanding hydrogeological and environmental factors that are conducive to supporting stygofauna communities is thus important to inform sampling campaigns. The study utilises commonly available hydrogeological parameters from large scale datasets to quantitatively assess bores for their suitability to support stygofauna across Northern Australia. The parameters assessed were chosen because of their association to the life and habitat requirements of stygofauna and because they could function as proxies for the key requirements of carbon (food), pore space, oxygen and water chemistry. The relationships between the presence or absence of stygofauna and hydrogeological parameters across four regions in northern Australia; Pilbara, Kimberley, Northern Territory and Queensland were assessed using univariate and multivariate statistical analyses. Shallower bores, shallower water depths and lower water temperatures all correlated with higher probability of stygofauna presence. A likely explanation is that these three parameters act as proxies for food availability near the surface where food inputs are higher. Larger flow rates in bores were correlated with stygofauna presence and assumed to act as a proxy for pore space availability. Increased dissolved oxygen and nitrate content, and lower manganese concentrations were correlated with stygofauna presence, with nitrate and manganese acting as proxies for oxygen availability. Evidence of correlations between salinity and pH with stygofauna presence were not found across multiple regions, probably due to a bias in bore location, with bores frequently positioned to provide access to freshwater. These results are based on the largest collation of stygofauna data across Australia. Study results inform the selection of bores for stygofauna sampling programs for research and environmental assessment.
Keywords: Hydrogeology, Stygofauna, Subterranean Fauna, groundwater, Northern Australia, Groundwater Habitats
Subject: Engineering thesis
Thesis type: Masters
Completed: 2024
School: College of Science and Engineering
Supervisor: Dylan Irvine