Department of Water and Environmental Regulation

The response of groundwater recharge to climate change needs to be understood to enable sustainable management of groundwater systems today and in the future, yet observations of recharge over long-enough time periods to reveal responses to climate trends are scarce. Here we present a meta-analysis of 60 years of recharge studies over the Gnangara Groundwater System of South-West Western Australia, covering a period of sustained drying consistent with climate change projections. The recharge process in the area is defined by a wet winter during which rain saturates a deep, highly permeable soil profile with very low water storage capacity. Measurements of recharge since the 1960s show near-linear reductions in potential recharge of 50%, in response to a 20% reduction in rainfall. For the best-represented land cover in the dataset (Banksia woodland), the reduction in potential recharge was closer to 70%. A simple analytical model suggests that reductions in the duration of winter, coupled with a decreased frequency of winter storms, were most responsible for these declines, and reveals the potential for nonlinear relationships between the recharge fraction (recharge/precipitation) and climatic variables such as mean storm frequency, mean storm depth, and the length of the winter wet season. Overall, results suggest that recharge declines in drying Mediterranean groundwater systems are likely to outstrip the declines in rainfall, and that leveraging existing observation networks worldwide to characterise recharge responses to changing climate is needed to overcome existing interpretation challenges created by inconsistent sites, methods and durations of recharge estimation.

The pseudoscorpion genus Indohya Beier, 1974 is known to occur in three Gondwanan fragments around the Indian Oceansouthern India, Madagascar and north-western Australiasuggesting that the genus had evolved prior to the breakup of Gondwana and was present on each landmass as they rifted apart during the Mesozoic. The Australian fauna is the most diverse, with nine species previously described from Cape Range and the Kimberley region of north-western Australia. The present study documents the genus Indohya in Australia using a combination of morphology and DNA sequence data. We found a total of 36 species, including 27 new species. The majority of the Pilbara fauna consist of blind troglobites collected from subterranean ecosystems, with an additional three eyed species from epigean habitats. The new species consist of one from Cape Range (I. anastomosa Harvey & Burger, n. sp.), 21 from the Pilbara (I. adlardi Harvey & Burger, n. sp., I. alexanderi Harvey & Burger, n. sp., I. aphana Harvey & Burger, n. sp., I. aquila Harvey & Burger, n. sp., I. arcana Harvey & Burger, n. sp., I. arnoldstrongi Harvey & Burger, n. sp., I. boltoni Harvey & Burger, n. sp., I. cardo Harvey & Burger, n. sp., I. catherineae Harvey & Burger, n. sp., I. cockingi Harvey & Burger, n. sp., I. cribbi Harvey & Burger, n. sp., I. draconis Harvey & Burger, n. sp., I. furtiva Harvey & Burger, n. sp., I. incomperta Harvey & Burger, n. sp., I. jessicae Harvey & Burger, n. sp., I. lynbeazlyeae Harvey & Burger, n. sp., I. morganstrongi Harvey & Burger, n. sp., I. rixi Harvey & Burger, n. sp., I. sagmata Harvey & Burger, n. sp., I. scanloni Harvey & Burger, n. sp. and I. silenda Harvey & Burger, n. sp.) and five from the Kimberley (I. currani Harvey & Burger, n. sp., I. finitima Harvey & Burger, n. sp., I. julianneae Harvey & Burger, n. sp., I. karenae Harvey & Burger, n. sp. and I. sachsei Harvey & Burger, n. sp.). The study is augmented with sequence data from 29 species of Indohya, including all of the 24 species recorded from the Pilbara and Cape Range, and five of the 12 known Kimberley species. Seven clades recovered during the molecular analysis are only represented by nymphs, but we used COI sequence data to diagnose these species in the absence of adult morphological data.

Prorocentrum comprises a diverse group of bloom-forming dinophytes with a worldwide distribution. Although photosynthetic, mixoplanktonic phagotrophy has also been described. Recently, the small P. cf. balticum was shown to use a remarkable feeding strategy by crafting globular mucus traps to capture and immobilize potential prey. Here we present evidence showing that two additional related species, the recently described P. pervagatum and the cosmopolitan bloom-forming P. cordatum, also produce large (80-120 µm) mucus traps supporting their mixoplanktonic activity. Prey are captured within the traps either through passive entanglement upon contact with the outside surface, or through active water movement created by rotating Prorocentrum cells eddying particles to the inside surface where trapped live prey cells became immobilized. Entrapment in mucus assisted deployment into the prey of a peduncle extruded from the apical area of the Prorocentrum cell. Phagotrophy by P. pervagatum supported faster growth compared to unfed controls and time series quantification of food vacuoles revealed ingestion rates of ca. 10-12 Teleaulax prey cells day-1. Model calculations show clear advantages of deploying a mucus trap for increasing prey encounter rates. This study demonstrates that the large size and immobilization properties of mucus traps successfully increase the availability of prey for small Prorocentrum species, whose peduncle feeding mode impedes consumption of actively moving prey, and that this strategy is common among certain clades of small planktonic Prorocentrum species.

Simulation outputs from chemical transport models (CTMs) are essential to plan effective air quality policies. A key strength of these models is their ability to separate out source-specific components which facilitate the simulation of the potential impact of policy on future air quality. However, configuring and running these models is complex and computationally intensive, making the evaluation of multiple scenarios less accessible to many researchers and policy experts. The aim of this work is to present how Gaussian process emulation can provide a top-down approach to interrogating and interpreting the outputs from CTMs at minimal computational cost. A case study is presented (based on fine particle sources in the southwest of Western Australia) to illustrate how an emulator can be constructed to simultaneously evaluate changes in emissions from on-road transport and electricity sectors. This study demonstrates how emulation provides a flexible way of exploring local impacts of electric vehicles and wider regional effects of emissions from electricity generation. The potential for emulators to be applied to other settings involving air quality research is discussed.

Abstract Disturbance or drainage of potential acid sulfate soils (PASS) can result in the release of acidity and degradation of infrastructure, water resources, and the environment. Soil processes affecting shallow groundwater quality have been investigated using a numerical code that integrates (bio)geochemical processes with water, solute, and gas transport. The patterns of severe and persistent acidification (pH < 4) in the sandy, carbonate‐depleted podzols of a coastal plain could be reproduced without calibration, based on oxidation of microcrystalline pyrite after groundwater level decrease and/or residual groundwater acidity, due to slow vertical solute transport rates. The rate of acidification was limited by gas phase diffusion of oxygen and hence was sensitive to soil water retention properties and in some cases also to oxygen consumption by organic matter mineralization. Despite diffusion limitation, the rate of oxidation in sandy soils was rapid once pyrite‐bearing horizons were exposed, even to a depth of 7.5 m. Groundwater level movement was thus identified as an important control on acidification, as well as the initial pyrite content. Increase in the rate of Fe(II) oxidation lead to slightly lower pH and greater accumulation of Fe(III) phases, but had little effect on the overall amount of pyrite oxidized. Aluminosilicate (kaolinite) dissolution had a small pH‐buffering effect but lead to the release of Al and associated acidity. Simulated dewatering scenarios highlighted the potential of the model for risk assessment of (bio)geochemical impacts on soil and groundwater over a range of temporal and spatial scales.