Parts Of South-eastern Australia Research Articles

Characterisation of Nematoda and Digenea in selected Australian freshwater snails

Freshwater snails are integral to local ecosystems as a primary food source for various vertebrate species, thereby contributing significantly to ecological food webs. However, their role as intermediate hosts also makes them pivotal in the transmission of parasites. In Australia, research on freshwater snails has predominantly focused on their role as intermediate hosts for livestock parasites, while there has been limited exploration of the impact of these parasites on snail health and population dynamics. The aim of this study was to determine parasitic infection in freshwater snails. This study was conducted in the south-eastern region of Australia, in 2022. A total of 163 freshwater snails from four different species were collected and examined in the Murrumbidgee catchment area in the southeastern part of Australia during the Southern Hemisphere summer and autumn months (February to May). The species included Isidorella hainesii, Glyptophysa novaehollandica, Bullastra lessoni (endemic species), and Physella acuta (an introduced species). Through the analysis of sequence data from the various regions of the nuclear ribosomal DNA, we determined that the Digenea species in this study belonged to three distinct species, including Choanocotyle hobbsi, Petasiger sp. and an unidentified species belonging to Plagiorchioidea. Additionally, analysis of the sequences from Nematoda found in this study, revealed they could be categorized into two separate taxa, including Krefftascaris sp. and an unidentified nematode closely associated with plant and soil nematodes. This research holds significant implications for the future understanding and conservation of Australian freshwater ecosystems. Most parasites found in the present study complete their life cycle in snails and turtles. As many of freshwater snail and turtle species in Australia are endemic and face population threats, exploring the potential adverse impacts of parasitic infections on snail and turtle health, is crucial for advancing our understanding of these ecosystems and also paving the way for future research and conservation efforts. While none of the native snail species in the present study have been listed as endangered or threatened, this may simply be attributed to the absence of regular population surveys.

Regional significance of historical trends and step changes in Australian streamflow

Abstract. The Hydrologic Reference Stations is a network of 467 high-quality streamflow gauging stations across Australia that is developed and maintained by the Bureau of Meteorology as part of an ongoing responsibility under the Water Act 2007. The main objectives of the service are to observe and detect climate-driven changes in observed streamflow and to provide a quality-controlled dataset for research. We investigate trends and step changes in streamflow across Australia in data from all 467 streamflow gauging stations. Data from 30 to 69 years in duration ending in February 2019 were examined. We analysed data in terms of water-year totals and for the four seasons. The commencement of the water year varies across the country – mainly from February–March in the south to September–October in the north. We summarized our findings for each of the 12 drainage divisions defined by Australian Hydrological Geospatial Fabric (Geofabric) and for continental Australia as a whole. We used statistical tests to detect and analyse linear and step changes in seasonal and annual streamflow. Monotonic trends were detected using modified Mann–Kendall (MK) tests, including a variance correction approach (MK3), a block bootstrap approach (MK3bs) and a long-term persistence approach (MK4). A nonparametric Pettitt test was used for step-change detection and identification. The regional significance of these changes at the drainage division scale was analysed and synthesized using a Walker test. The Murray–Darling Basin, home to Australia's largest river system, showed statistically significant decreasing trends for the region with respect to the annual total and all four seasons. Drainage divisions in New South Wales, Victoria and Tasmania showed significant annual and seasonal decreasing trends. Similar results were found in south-western Western Australia, South Australia and north-eastern Queensland. There was no significant spatial pattern observed in central nor mid-west Western Australia, with one possible explanation for this being the sparse density of streamflow stations and/or the length of the datasets available. Only the Tanami–Timor Sea Coast drainage division in northern Australia showed increasing trends and step changes in annual and seasonal streamflow that were regionally significant. Most of the step changes occurred during 1970–1999. In the south-eastern part of Australia, the majority of the step changes occurred in the 1990s, before the onset of the “Millennium Drought”. Long-term monotonic trends in observed streamflow and its regional significance are consistent with observed changes in climate experienced across Australia. The findings of this study will assist water managers with long-term infrastructure planning and management of water resources under climate variability and change across Australia.

Hot, unpredictable weather interacts with land use to restrict the distribution of the Yellow-tailed Black-Cockatoo

ABSTRACT Conserving nomadic species is challenging due to the difficulty in monitoring their characteristically transient populations, and thereby detecting range-wide declines. An example is the Yellow-tailed Black-Cockatoo (YTBC; Zanda funerea), which disperses widely in search of food and is regularly – but sporadically – observed across eastern Australia. Under climate warming, a general southward shift in species distributions is expected in the southern hemisphere, with the extreme southern margins being truncated by an ocean barrier. Given these constraints, we ask whether sufficient refugia will exist for the YTBC in the future, by: (i) modelling habitat relationships within the current geographic range of the YTBC based on weather, climate, vegetation, and land use, and (ii) using this framework, coupled with climate-model projections, to forecast 21st century impacts. Intensive land use and high variability in temperature and rainfall seem to most limit YTBC occurrence. In contrast, areas with a cooler, stable climate and a network of old-growth forests, such as those in parts of south-eastern Australia and Tasmania, are most suitable for the species. As Australia becomes progressively hotter under climate change, the preferred bioclimatic envelope of the YTBC is forecast to contract poleward (as a general pattern) and to fragment within the existing range. However, despite an extensive loss of climatically suitable regions, the YTBC might find stable refugia at the southern margins of its geographic range, although continued loss of old-growth forests undermines their nesting potential. Therefore, beyond habitat conservation, creating nesting opportunities within plantation forests would likely be an effective conservation strategy to preserve habitat quality in climate refugia.

Review of the Paraplea Esaki amp; China (Hemiptera: Heteroptera: Nepomorpha: Pleidae) of Australia, with description of a new species.

The family Pleidae is represented in Australia only by members of the genus Paraplea. Paraplea brunni (Kirkaldy, 1898) has a widespread distribution in Australia and is also known from New Guinea. Paraplea halei (Lundblad, 1933) appears to be an endemic species occurring only in the southeastern part of Australia. The widespread species P. liturata (Fieber, 1844) occurs in Australia but only in the Northern Territory and Western Australia. The description of P. bifurcata n. sp. documents a fourth pleid species, being known only from the Northern Territory. Paraplea bifurcata n. sp. is easily differentiated from other species of Paraplea by having a bifurcated abdominal keel. An identification key and discussion of morphological characters of the four species of Paraplea from Australia is given.

S- to I- to A-type magmatic cycles in granitic terranes are not globally recurring progressions. The cases of the Cape Granite Suite of Southern Africa and central Victoria in southeastern Australia

AbstractRecurring progression from S- to I- to A-type granites has been proposed for a subset of granitic rocks in eastern Australia. The wider applicability and the validity of this idea is explored using the Cape Granite Suite (CGS) of South Africa and the granitic and silicic volcanic rocks of central Victoria, in southeastern Australia. Within the CGS there is presently little justification for the notion that there is a clear temporal progression from early S-type, through I-type to late A-type magmatism. The I- and S-type rocks are certainly spatially separated. However, apart from a single slightly older pluton (the Hoedjiespunt Granite) there is no indication that the S- and I-type granites are temporally distinct. One dated A-type granitic sample and a syenite have poorly constrained dates that overlap with those of the youngest S-type granites. In central Victoria, the granitic magma types display neither a spatial separation nor a temporal progression from one type to another. All magma varieties are present together and were emplaced within a far narrower time window than in the CGS. Thus, a progression may or may not exist in a particular region, and the occurrence of such a progression does not hold true even in a part of southeastern Australia, which afforded the type example. Thus, the idea that, globally, there should be a progression from S- to I- to A-type magmatism is unjustified. The critical factor in determining the temporal relationship between granitic magmas of different types is probably the compositional structure of the deep crust in a particular region, a reflection of how the individual orogen was assembled. In turn, this must reflect significant differences in the tectonic settings.

Effect of stubble-height management on crown temperature of perennial ryegrass, tall fescue and chicory

Defoliating pasture to shorter stubble heights (height above the soil surface) may increase temperature at the plant crown (plant–soil interface). This is especially relevant to summer C3 pasture production in parts of south-eastern Australia, where above-optimal ambient temperatures (≥30°C) are often recorded. A rainfed field experiment in north-west Tasmania, Australia, quantified the effect of stubble-height management on the upper distribution of crown temperatures (90th and 75th percentiles) experienced by three pasture species: perennial ryegrass (Lolium perenne L.), tall fescue (Festuca arundinacea Schreb.; syn. Schedonorus arundinaceus (Schreb.) Dumort.; syn. L. arundinaceum (Schreb.) Darbysh.), and chicory (Cichorium intybus L.). Three stubble-height treatment levels were evaluated: 35, 55 and 115mm. Defoliation to shorter stubble heights (35 or 55mm cf. 115mm) increased the crown temperature of all species in the subsequent regrowth cycle (period between successive defoliation events). In the second summer, defoliating to shorter stubble heights increased the 90th percentile of crown temperature by an average of 4.2°C for perennial ryegrass, 3.6°C for tall fescue and 1.8°C for chicory. Chicory and second-year tall fescue swards experienced less-extreme crown temperatures than perennial ryegrass. This may partly explain why these two species often outyield perennial ryegrass in hotter summer environments than north-west Tasmania, and hence the increasing interest in their use.

Relating ocean-atmospheric climate indices with Australian river streamflow

The relationship between climate indices with Australian river streamflow (ASF) may provide valuable information for long-lead streamflow forecasting for Australian rivers. The current study examines the correlations between three climate indices (SST, 500 mb meridional wind -U500 and 500 mb geopotential height-Z500) and 135 unimpaired ASF gauges for 1971–2011 using the singular value decomposition (SVD) method. First, SVD method was applied to check the SST-ASF correlated regions of influence and then extended SST-ASF variabilities were used to determine the correlated regions within Z500 and U500 fields. Based on the teleconnection, the most correlated region (150°E to 105°W and 35°S to 5°N) was identified and its persistency was checked by lag analysis up to 2 years from seasonal to yearly time-scale. The results displayed positive correlation for the south and south-eastern part of Australia while negative correlation prevails in the north-eastern region (at 95% significance level). The most correlated region was found situated along the South Pacific Convergence Zone (SPCZ) axis which may be considered as a probable climate driver for ASF. The persistency of this region was checked by a separate climate indicator (mean vertical velocity-500 mb) and found prominent in dry period than the wet period. This persistent teleconnected region may be potentially useful for long-lead forecasting of ASF.

‘Anthropological Investigation has Very Little Interest for Me’: Notes from Moravian Missionaries in Australia

ABSTRACTAs some of the first people to spend extended amounts of time with Indigenous peoples, missionaries were well placed to provide information to European and colonial audiences on non-European peoples. Moravian missionaries arrived in Australia in the mid-nineteenth century and over the next six decades worked amongst numerous Indigenous groups in the south-eastern part of Australia, in the interior, and in northern Queensland. This paper will trace the contributions made by German Moravian missionaries to anthropological and ethnographical knowledge both in the colonies as well as in Germany. It will particularly focus upon the connections forged in religious and scientific networks through anthropological work. The paper contends that a unified German identity was forged through scientific work that transcended denominational boundaries. Moreover, the ability to disseminate ethnographical knowledge within secular circles, both in the colonies and in Germany, provided legitimisation to missionary work and embedded missionaries within global knowledge networks. Through examining the work of one individual missionary, Friedrich Hagenauer, the fragility of these global knowledge networks is explored.

From ISO14046 to water footprint labeling: A case study of indicators applied to milk production in south-eastern Australia

ISO14046 sets out principles, requirements and guidelines for the quantification of a water footprint taking a life cycle perspective. The international standard is intended to support product water footprint labeling and corporate sustainability reporting. However, the document is not prescriptive in regard to the use of any one specific water footprint indicator. In this study, water scarcity footprints were calculated for milk production on 75 farms in three parts of south-eastern Australia. Three indicators, with distinctly different conceptual basis and model structure, were applied. Included was the AWARE indicator recently developed under the UNEP-SETAC Life Cycle Initiative. The different indicator results were highly correlated (Spearman's rank correlation 0.91–0.99) and the life cycle stages and processes identified as important were the same. Therefore, all three indicators were considered suitable for informing internal strategic action. However, the different indicators produced results which differed greatly in absolute value, in some cases by a factor of >300. To enable consumers and others to make comparisons between the water scarcity footprints of different products or organisations, program (or scheme) operators will need to specify the indicator to be used. The three indicators were assessed according to scaling, interpretability and coherence with LCA results, and found to differ in terms of suitability for use in a water footprint program. The AWARE indicator was deemed to be least suitable.

A climatology of atmospheric pressure jumps over southeastern Australia

Black Saturday provided the first evidence of an atmospheric bore affecting the behaviour of a bushfire. As the bore passed, the fire unexpectedly strengthened. This behaviour highlighted the lack of understanding of how common bores are in the southeastern part of Australia, a region of relatively high bushfire risk. The present study addresses that lack of understanding. Pressure jumps are identified in the 1 min records at four automatic weather stations in southeastern Australia by correlating the pressure time series with a large‐amplitude step function. These jumps are then separated into two classes: bores and frontal pressure jumps. Bores are defined as pressure jumps without a change in relative humidity whereas frontal pressure jumps are defined by jumps with an accompanying decrease in temperature greater than 3 °C. About 15 pressure jumps per station per year are found. Most jumps are found in the spring and summer and fewest in winter. Bores are found most frequently in the early morning and late evening at most stations, whereas frontal pressure jumps are most frequently found in the late afternoon or early evening. Following their passage, frontal pressure jumps are associated with higher 30 min mean wind speeds than bores (9.0 and 6.1 m s−1 respectively), both of which are higher than climatology (4.7 m s−1).

Invasive predator influences habitat preferences in a freshwater fish

Invasive species are an important contributor to global biodiversity loss. This is particularly true in freshwater ecosystems, where introduced species have contributed to native fish extinctions, altered native fish communities and modified aquatic ecosystem structure and function. Native species can potentially mitigate the impact of invasive predators and competitors by altering their behaviour, for example by reducing activity such as foraging or by increasing their use of shelter. This study investigated interactions between an introduced salmonid, the rainbow trout (Oncorhynchus mykiss), and a native fish, the riffle galaxiid (Galaxias arcanus), that currently co-inhabit streams in parts of south-eastern Australia. We used three separate sets of behavioural experiments to test whether riffle galaxiids avoided trout under different substrate conditions. We hypothesised that habitat selection in the presence of a predator could be an important factor in facilitating galaxiid and trout co-existence. We found that interactions between the two fish differed depending on substrate. Galaxiids avoided trout when only sand substrate was available, but did not avoid trout when cobble substrate was available. The complex structure of cobbles may afford riffle galaxiids protection from trout, thereby facilitating their current existence in trout-inhabited streams.

A new precise date for the Tolmie Igneous Complex in northeastern Victoria

Among the Devonian igneous complexes of central and northeastern Victoria, the S-type Tolmie Igneous Complex (TIC) occupies a unique spatial position, astride the Governor Fault and the Mount Wellington Greenstone Belt, a probable terrane boundary, and also bridges the boundary between the Strathbogie and Tabberabbera granite provinces. This stitching position makes it important to determine the nature of the crustal source involved in its genesis. Here we present a new U–Pb zircon age for a sample of the Toombullup Ignimbrite, which forms a large part of the TIC. This age (377 ± 2 Ma) allows us to comment far more reliably on the initial Sr and Nd isotope ratios of the TIC magmas. The corrected data (initial 87Sr/86Sr = 0.70804 to 0.71085, εNdt = –0.08 to 0.44) confirm a heterogeneous sediment-dominated protolith, but unlike those of other S-type granitic and felsic volcanic rocks of the region, one composed of materials that had not long previously been extracted from the mantle. This finding has importance in the context of future models for the geological and tectonic development of this part of southeastern Australia.

A Historical Perspective on Southeastern Australian Rainfall since 1865 Using the Instrumental Record

Abstract The instrumental record for rainfall across Australia is regarded as being sufficiently reliable to produce national monthly gridded rainfall analyses from 1900 onward. Prior to 1900, the rainfall gauge network is much sparser. The possibility of using those nineteenth-century observations that do exist to construct an estimate of rainfall across the southeastern part of Australia (SEA) is explored by constructing a network based on 11 locations comprising either single observing sites or composites of nearby observing sites with long continuous records. It is shown that, during the period 1900–2010, the monthly rainfall reconstruction based on this network captures 98% of the variability of SEA monthly average rainfall. This network, which extends back to 1865, provides a useful view of the Federation Drought, making a comparison possible with other long-term droughts observed in SEA, around the time of the Second World War and the Millennium Drought from 1997 to 2009. A comparison of these three historical low-rainfall periods was conducted using the drought–depth–duration criteria: the ongoing decline in southeastern Australia is seen as being notably worse than the previous two historical droughts. The network also provides an insight into the decadal variability of SEA rainfall in the later part of the nineteenth century; it includes a high peak in the 1870s comparable to similar wet decadal peaks in the 1950s and 1970s. The implications of this longer perspective on the decadal variability in southeastern Australia in light of the current understanding of the ongoing rainfall deficit are discussed.

Responses of Eastern Yellow Robins Eopsaltria australis to translocation into vegetation remnants in a fragmented landscape.

Many species of Australian robins (Petroicidae) are declining in wooded landscapes across southern Australia, perhaps because they are unable or unwilling to disperse across the matrix between remnants, or because they experience high mortality while doing so. Eastern Yellow Robins Eopsaltria australis have declined in parts of southeastern Australia, and have gone extinct in some woodland remnants. We translocated adult Yellow Robins to remnants from which they had disappeared, and followed their survival and behaviour. Nine Yellow Robins were translocated to a 100 ha remnant in 2001 (seven birds) and 2002 (two birds). One bird disappeared immediately and a second after 2 weeks, but the rest stayed for at least 2 months, with two birds surviving to at least 4 and 5 years. One reintroduced pair bred each year from 2001 to 2005, producing six fledglings. Two colour-banded Yellow Robins also arrived unaided from another remnant 7 km away. Fifteen Yellow Robins were translocated to nine small remnants (<60 ha) in 2005– 06. Seven birds disappeared within 3 days of their release, apparently killed by predators. The remainder survived for up to 7 weeks, but none was found breeding. Translocated Robins moved up to 3 km from their release sites through natural or planted corridors, and up to 1 km through a matrix of scattered trees. Small remnants, which surviving Robins ultimately vacated, had fewer shrubs than sites where they bred. The results suggest that Eastern Yellow Robins can disperse through a landscape with corridors or scattered trees. However, they may suffer predation and reject sites that are too small or of poor habitat quality. Management to retain Eastern Yellow Robins in a fragmented landscape should enlarge remnants, protect scattered trees, plant or regenerate strategic clumps of trees and shrubs in gaps between remnants, and allow shrubs to regenerate within remnants.

Foehn-Like Winds and Elevated Fire Danger Conditions in Southeastern Australia

AbstractBushfires in southeastern Australia are a serious environmental problem, and consistently cause loss of life and damage to property and other assets. Understanding synoptic processes that can lead to dangerous fire weather conditions throughout the region is therefore an important undertaking aimed at improving community safety, protection of assets, and fire suppression tactics and strategies. In southeastern Australia severe fire weather is often associated with dry cool changes or coastally modified cold fronts. Less well known, however, are synoptic events that can occur in connection with the topography of the region, such as cross-mountain flows and foehn-like winds, which can also lead to abrupt changes in fire weather variables that ultimately result in locally elevated fire danger. This paper focuses on foehn-like occurrences over the southeastern mainland, which are characterized by warm, dry winds on the lee side of the Australian Alps. The characteristics of a number of foehn-like occurrences are analyzed based on observational data and the predictions of a numerical weather model. The analyses confirm the existence of a foehn effect over parts of southeastern Australia and suggest that its occurrence is primarily due to the partial orographic blocking of relatively moist low-level air and the subsidence of drier upper-level air in the lee of the mountains. The regions prone to foehn occurrence, the influence of the foehn on fire weather variables, and the connection between the foehn and mountain waves are also discussed.

The resolution and potential value of Australian seasonal rainfall forecasts based on the five phases of the Southern Oscillation Index

We assess the resolution of the Southern Oscillation Index (SOI) seasonal rainfall forecasting system and calculate the loss in potential value of the forecasting system using a cost/loss model. Forecasts of the probability of a ‘dry’ autumn, winter, spring, and summer were obtained for 226 towns across Australia, based on the 5 phases of the SOI. For every town the variance ratio, the observed forecast variance as a proportion of the variance of a perfect forecasting system, was calculated for each season. Value score curves, showing the expected value of the forecasts as a proportion of the expected value of perfect information, were calculated for every town for each season. Maps of variance ratio and maps of mean value scores across Australia were produced by ordinary kriging. In all seasons and regions the SOI forecasting system had a variance ratio of less than 0.20, indicating that resolution and skill were never high. Variance ratios greater than 0.10 only occurred in parts of south-eastern Australia and the Cape York region during spring and in the Townsville region during summer. The variance ratio was less than 0.05 for the majority of Australia during autumn, winter, and summer. The mean value scores for actions that are only triggered by a large shift in the forecast from climatology were uniformly close to zero in all seasons and regions, indicating that little or no value can be derived in such cases. Actions triggered by a moderate shift of the forecast were also generally associated with low value scores. Mean value scores above 0.20 were limited to actions with a decision threshold close to climatology and only occurred in parts of south-eastern Australia and the Cape York region during spring and in the Townsville region during summer. We conclude that the imperfect resolution of the SOI forecasting system has a substantial effect on potential value. The forecasting system can potentially deliver value to users with actions that are triggered by a small shift in the forecast from climatology, especially in eastern Australia during spring, but not to users with actions that are only triggered by a large shift of the forecasts from climatology.

Natural Resources: Australia’s War on Drought

Watering the lawn and washing the car are quintessential parts of summer. Yet, in some parts of Australia these activities are illegal. That’s because water is fast becoming the most precious commodity Down Under, so precious that every major urban center is under heavy water restrictions, and scientists are scouring the land for more water. The shortage results partly from changing weather patterns—rain is falling at different times of the year and in shorter bursts. Australia is uniquely vulnerable to climate change, given the proportion of its relatively small land mass to the ocean that surrounds it; sea surface variations such as those seen with the El Nino–Southern Oscillation have a more profound effect here. According to the governmental State of the Environment 2006 report, Australia—though a land of many climates—is overall the driest inhabited continent in terms of rainfall and streamflow. Increased urbanization also plays a role. “The southeastern part of Australia where most people live is getting hotter and drier,” says Tom Hatton, director of the Water for a Healthy Country Flagship, the water research arm of Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO). “If you project the demand of the five or six largest cities in the next twenty-five years, those cities are going to need up to forty percent more water, which we simply don’t have.” CSIRO, in partnership with universities, governments, and private research agencies, has undertaken a massive project to find that water, spending AUS$80 million per year to find ways to increase the value that the country derives from water. One such innovation is the use of so-called Fleck sensors to monitor groundwater salinity, flow, and levels in virtual real time in a key agricultural area of Queensland. These wireless devices, which fit in the palm of a hand, feature long-range communication and solar recharging capabilities. The data they yield can be used, for example, to alert nearby sugarcane farmers if they are pumping too much ground-water before coastal seawater intrudes into the watershed. The Fleck sensors are just one part of CSIRO’s larger Water Resources Observation Network (WRON). The goal of the network is to collect current data quickly and accurately. “To produce a national report on water resources using manual methods would be hugely costly, [and] takes about six months and an army of people producing reports that are almost instantly out of date,” says WRON manager Ross Ackland. “We need information systems that can produce something much quicker.” The network is organizing all water information using a common framework. Some 100 to 200 different governmental, utility, industry, and research organizations currently collect water resource data, most of which is in proprietary formats. However, the new Web 2.0 technology of data aggregators—a news RSS feed is one well-known example—can help gather Australia’s water information together. Visitors to the WRON website can download a Mac or Windows “widget” that collects data on Australia’s dam levels and assimilates them into a standard format. Although better management of water resources may help save water, it won’t create more potable water—but desalination plants can. That’s why the Water for a Healthy Country Flagship is also researching better ways to desalinate and recycle water. In May 2007, CSIRO and nine of Australia’s universities combined their research efforts to form the Advanced Membrane Technologies for Water Treatment Research Cluster, with the goal of reducing the energy requirements of desalination by up to 50% and developing new materials to improve membrane performance. Many desalination plants force water through semipermeable membranes to reduce salts and contaminants. Over time, these contaminants build up on the membrane, requiring cleaning or replacing and more energy to force water through the membrane’s shrinking area. CSIRO is therefore exploring the use of membranes that bristle with carbon nanotube “forests,” which trap contaminants while letting water flow through almost without friction, allowing a lower-energy method of desalination. The CSIRO Water Reuse Technologies project is also tackling the hot issue of water reuse and recycling with a little help from Mother Nature, injecting wastewater into underground aquifers to remove a variety of pathogens, endocrine disruptors, and disinfection by-products. The rate of contaminant decay depends on the geochemical composition and biotic communities present in the aquifer. One town south of Perth reuses sewage water for irrigation after it spends only 30 to 40 days in an aquifer. The lead scientist on the project, Simon Toze, says, “The phosphates are probably removed by chemical properties or absorbed by limestone, whereas most of the nitrogen and pathogens are taken out by organisms using the contaminants as a food source.” This practice not only improves water quality but may also give Australians a cheap and practical way to store water—a large concern as regular rainfall becomes more sporadic.

Ecological Restoration and Large‐Scale Ecological Disturbance: The Effects of Drought on the Response by Fish to a Habitat Restoration Experiment

Abstract Human‐induced erosion regularly delivers massive quantities of fine sediments into streams and rivers forming large static bodies of sediment known as sand slugs, which smother in‐stream habitat, alter community structure, and decrease biodiversity. Sand slugs are widespread in parts of southeastern Australia as well as in many other parts of the world, and there is now considerable interest in restoring such affected streams. The reintroduction of large timber is widely suggested as a strategy for restoring habitat complexity, but this has rarely been tested in sand slug–affected streams. We examined the response of fish populations to wood addition to two streams in southeastern Australia that have been impacted by sand slugs. Manipulated sites (three per treatment) had either one or four timber structures added, and these sites were compared with (three) unmanipulated (control) sites before and after the manipulation occurred. Despite a supraseasonal drought during the study, we observed short‐term increases in the abundance of Mountain galaxias (Galaxias olidus) at the four‐structure sites, while both the four‐structure and the one‐structure treatments appeared to buffer against drought‐induced declines in two other species, River blackfish (Gadopsis marmoratus) and Southern pygmy perch (Nannoperca australis), relative to controls. However, drought eventually caused the complete loss of surface water from these streams and the loss of fish from both manipulated and unmanipulated sites. Thus, although the study supports the use of timber structures as a means of increasing local fish abundances, these beneficial effects were, in these streams, contingent upon permanency of flow. Because sedimentation has depleted the number of permanent refuge pools in these creeks, recovery rates of the fauna (i.e., resilience) are likely to be slow. We therefore conclude that in streams subjected to frequent disturbance, restoring refugia may be as, if not more, important as restoring what we term residential habitat.

A technique for detecting burn scars using MODIS data

The Moderate Resolution Imaging Spectroradiometer (MODIS) instruments onboard the National Aeronautics and Space Administration Terra and Aqua spacecrafts have several visible and near-infrared (NIR) channels with resolutions of 250, 500, and 1 km for remote sensing of land surfaces and atmosphere. The MODIS data directly broadcasted to ground receiving stations can have many practical applications, including the rapid assessment of fires and burned areas. In this paper, we describe an empirical technique for remote sensing of burn scars using a single dataset of MODIS NIR channels centered near 1.24 and 2.13 /spl mu/m. These channels are sensitive to changes in the surface properties induced by the fire and are not obscured by smoke. Therefore, they allow remote sensing of burn scars in the presence of smoke. Detection of burn scars from single MODIS images, without the need of data from previous days, is very useful for near real-time burn scar recognition in operational direct broadcasting systems. The technique is applied to MODIS data acquired over the western U.S. during the summer fire season, the southeastern part of Canada during the summer and spring seasons, and the southeastern part of Australia. The burnt areas estimated from MODIS data are consistent with those estimated from the high spatial resolution Landsat 7 imaging data.

Invasion of native vegetation by Coolatai Grass Hyparrhenia hirta: impacts on native vegetation and management implications

Coolatai Grass Hyparrhenia hirta is an exotic perennial grass and environmental weed that is spreading rapidly in parts of southeastern Australia. This study examined the effects of Coolatai Grass invasion on the composition of ground strata vegetation within Kwiambal National Park in northern New South Wales. Plots that were heavily infested with Coolatai Grass together with matching control plots were surveyed. Coolatai Grass infestation reduced the richness of native ground strata plants and their projected groundcover, but did not affect the number of exotic species in plots. The control plots varied markedly in floristic composition, but infested sites were more homogenous, with Coolatai Grass clearly dominating the ground strata vegetation. Coolatai Grass appears to increase in abundance following fire; it persists under heavy grazing and is resistant to many herbicides. Spot spraying small swards and isolated tussocks with glyphosate or flupropanate provides prospects of control on a small scale, but there are no suitable methods for largescale control. Changes to roadside management practices could help to reduce the spread of Coolatai Grass, but research into seed bank dynamics and appropriate control techniques is required, as well as increased awareness of the threat to native vegetation posed by the species.