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News Article | May 4, 2017
Site: phys.org

But for some animals, the impact of the modern human environment on their habitat can cause confusion, leading to bad decisions and possible extinction. Many insects, for example, are attracted to light reflected off water, but artificial surfaces like roads and the sides of buildings can mimic these natural reflective surfaces. The end result is that when the insects lay its eggs, they can't hatch. Similarly, some species of marine turtles use moonlight to navigate toward the ocean after hatching but may instead head inland, attracted by streetlights along the shoreline. What these animals are experiencing is an 'ecological trap' – when they are attracted to places where their chances for survival and reproduction are much poorer. If an ecological trap is so attractive that is draws animals away from their natural, good-quality habitats, their failure to survive and breed could lead to population collapses and local extinction. The ecological trap concept was originally developed by researchers studying birds in Europe and North America. Support for the concept is strong in terrestrial habitats, but there is a paucity of research on ecological traps in aquatic environments. This is a knowledge gap that we are working hard to address at the Research on the Ecology and Evolution of Fishes (REEF) group in the School of BioSciences at the University of Melbourne. REEF is studying ecological traps in a variety of freshwater and marine systems to determine how they affect aquatic animals and how they might be mitigated. A major focus of our research is to better understand how our attempts to restore habitats could inadvertently create these traps. When humans rehabilitate or restore areas like forests, wetlands or coral reefs, we tend to focus on the major structural elements such as trees, water bodies or corals. The problem is that we aren't always aware of all the additional resources animals use and need in their daily lives. If these resources aren't present and animals colonise these areas, thinking it's a good habitat, then our laudable attempts to restore degraded habitats into something we perceive will be good for biodiversity, may ultimately backfire. All drains don't lead to the ocean In Melbourne, southeast Australia, over 600 wetlands have been constructed to filter pollutants from storm water run-off. We are working with Dr Rhys Coleman from Melbourne Water, Dr Vincent Pettigrove from the Centre for Aquatic Pollution Identification and Management, Professor Raoul Mulder from the School of BioSciences, and Associate Professor Kirsten Parris from the School of Ecosystem and Forest Sciences, to better understand how these wetlands perform as habitats for animals, and whether some are ecological traps. "Aquatic animals that inhabit stormwater wetlands are exposed to a range of pollutants capable of reducing survival and reproductive success, but which may not be detected," says PhD student Michael Sievers, who is working on this project for his thesis. "I am trying to evaluate how these artificial habitats are affecting native frogs, and determine whether frogs are capable of evaluating habitat quality when selecting breeding sites." As part of the study, we are also exploring whether some wetlands are traps for a small, conservation-listed fish, the dwarf galaxias (Galaxiella pusilla). We're testing if the growth, survival and reproduction of these fish varies among wetlands with different water and sediment qualities, as well as tree and macrophyte (aquatic plant) cover. These are all factors that are likely to influence which wetlands are suitable or not for this native fish. A complementary study by University of Melbourne Masters student Tim Brown is focused on better understanding the effects of the exotic mosquitofish (Gambusia holbrooki) on the population of dwarf galaxias. "We know from previous work that mosquitofish harass adults but what surprised us was just how voracious a predator they are on the larval stages," says Mr Brown. "What's most worrying is that dwarf galaxias don't seem to recognise mosquitofish as a threat, which makes trying to manage their recovery a real challenge when mosquitofish are pretty much everywhere." It's hoped that these two studies will help inform waterway managers on how best to provide suitable conditions for wetland animals. Meanwhile, out at sea, invasions by exotic seaweeds might themselves create ecological traps for fish. Many reef fishes in southern Australia rely on seaweed for food and shelter, but in Port Phillip Bay in Victoria, the exotic seaweed Undaria frequently invades and outcompetes native seaweeds. The danger is that these new habitats might be ecological traps - attracting fish without offering the same quality of availability and shelter from prey species. Alternatively, Undaria may actually be a good-quality habitat that fish avoid because it looks different. Both of these outcomes exacerbate the effects of urban marine degradation on fish populations by causing fish to make bad habitat selection decisions. "We sometimes find fish living in Undaria patches in Port Phillip Bay, but we don't know how this works for them in terms of survival and reproduction" says PhD student Luke Barrett, who is researching this invasive seaweed. Do artificial reefs help or hinder? Millions of dollars have already been spent globally on Artificial Reefs (ARs), but often with a focus on enhancing recreational fishing. However, many other non-fished species may be attracted to ARs. But what if the attraction doesn't come with any benefit for these species? If these reefs attract fish but lack the food or shelter requirements many species of reef fish need, then they may be functioning as ecological traps. One case could be that of the southern hulafish (Trachinops caudimaculatus) which is being investigated by PhD student Valeriya Komyakova. According to her research, hulafish are three times more likely to settle on ARs than natural reefs, but are nine times more likely to die. "This is a really important finding as it's some of the first documented evidence that ecological traps can form in the ocean," says Ms Komyakova. Humans are altering coastal marine ecosystems at unprecedented rates. The rapid environmental changes associated with pollution, invasive species, harvesting, and habitat modification in coastal oceans are creating a wealth of 'ecological surprises' that animals have never had to face during their evolutionary history. What the REEF group is just starting to uncover is that these new man-made environments have great potential to create possibly deadly ecological traps. Explore further: Researchers find wealth of fish at deep Hawaiian reef

Rajeev P.,Monash University | Kodikara J.,Monash University | Chiu W.K.,Monash University | Kuen T.,Melbourne Water
Key Engineering Materials | Year: 2013

Health monitoring of civil infrastructure systems has recently emerged as a powerful tool for condition assessment of infrastructure performance. With the widespread use of modern telecommunication technologies, structures could be monitored periodically from a central station located several kilometres away from the field. This remote capability allows immediate damage detection, so that necessary actions are taken to reduce the risk. Optical fiber sensors offer a relatively new technology for monitoring the performance of spatially distributed structures such as pipelines. In this regards, several commercially available strain and temperature sensing equipment such as discrete FBGs (Fibre Bragg Gratings) and fully distributed sensing techniques such as Raman DTS (distributed temperature sensor) and Brillouin Optical Time Domain Reflectometry (BOTDR) typically offer sensing lengths of the order of 100 km's. Distributed fiber optic sensing offers the ability to measure temperatures and/or strains at thousands of points along a single fiber. In this paper, the authors will give a brief overview of these optical fiber technologies, outline potential applications of these technologies for geotechnical engineering applications and experience in utilising BOTDR in water pipeline monitoring application. © (2013) Trans Tech Publications, Switzerland.

Forsyth D.M.,Arthur Rylah Institute for Environmental Research | Woodford L.,Arthur Rylah Institute for Environmental Research | Moloney P.D.,Arthur Rylah Institute for Environmental Research | Hampton J.O.,Ecotone Wildlife Veterinary Services | And 2 more authors.
PLoS ONE | Year: 2014

There is much interest in understanding how anthropogenic food resources subsidise carnivore populations. Carcasses of hunter-shot ungulates are a potentially substantial food source for mammalian carnivores. The sambar deer (Rusa unicolor) is a large (≥150 kg) exotic ungulate that can be hunted throughout the year in south-eastern Australia, and hunters are not required to remove or bury carcasses. We investigated how wild dogs/dingoes and their hybrids (Canis lupus familiaris/dingo), red foxes (Vulpes vulpes) and feral cats (Felis catus) utilised sambar deer carcasses during the peak hunting seasons (i.e. winter and spring). We placed carcasses at 1-km intervals along each of six transects that extended 4-km into forest from farm boundaries. Visits to carcasses were monitored using camera traps, and the rate of change in edible biomass estimated at ∼14-day intervals. Wild dogs and foxes fed on 70% and 60% of 30 carcasses, respectively, but feral cats seldom (10%) fed on carcasses. Spatial and temporal patterns of visits to carcasses were consistent with the hypothesis that foxes avoid wild dogs. Wild dog activity peaked at carcasses 2 and 3 km from farms, a likely legacy of wild dog control, whereas fox activity peaked at carcasses 0 and 4 km from farms. Wild dog activity peaked at dawn and dusk, whereas nearly all fox activity occurred after dusk and before dawn. Neither wild dogs nor foxes remained at carcasses for long periods and the amount of feeding activity by either species was a less important predictor of the loss of edible biomass than season. Reasons for the low impacts of wild dogs and foxes on sambar deer carcass biomass include the spatially and temporally unpredictable distribution of carcasses in the landscape, the rapid rate of edible biomass decomposition in warm periods, low wild dog densities and the availability of alternative food resources. © 2014 Forsyth et al.

Cinque K.,Melbourne Water | Jayasuriya N.,RMIT University
Journal of Water and Health | Year: 2010

To ensure the protection of drinking water an understanding of the catchment processes which can affect water quality is important as it enables targeted catchment management actions to be implemented. In this study factor analysis (FA) and comparing event mean concentrations (EMCs) with baseline values were techniques used to asses the relationships between water quality parameters and linking those parameters to processes within an agricultural drinking water catchment. FA found that 55% of the variance in the water quality data could be explained by the first factor, which was dominated by parameters usually associated with erosion. Inclusion of pathogenic indicators in an additional FA showed that Enterococcus and Clostridium perfringens (C. perfringens) were also related to the erosion factor. Analysis of the EMCs found that most parameters were significantly higher during periods of rainfall runoff. This study shows that the most dominant processes in an agricultural catchment are surface runoff and erosion. It also shows that it is these processes which mobilise pathogenic indicators and are therefore most likely to influence the transport of pathogens. Catchment management efforts need to focus on reducing the effect of these processes on water quality. © IWA Publishing 2010.

Hurst T.,Melbourne Water | Boon P.I.,Victoria University of Melbourne
Australian Journal of Botany | Year: 2016

It is often assumed that saline coastal wetlands experience environmental conditions so severe that they are largely immune to invasion by exotic plant species. The belief is implicit in many older reviews of threats to mangroves and coastal saltmarshes, where a limited range of vascular plant taxa, often focussing on∗Spartina, (throughout the paper an asterisk denotes an introduced (exotic) species as per Carr 2012) have been invoked as the major species of concern. Even though the weed flora of southern Australia is derived largely from agriculture and horticulture, neither of which includes many species tolerant of waterlogged, variably saline environments, a recent assessment of Victorian saline coastal wetlands indicated that exotic plants were the third-most pervasive threat, after land 'reclamation' and grazing. Tall wheat grass,∗Lophopyrum ponticum (Podp.) A.Love., is one of the most severe and widely distributed weeds of saline coastal wetlands in south-eastern Australia. It is promoted by the agricultural extension arm of the Victorian government as a salt-tolerant pasture grass; however, its broad ecological amplitude and robust life form make it a most serious invader of upper saltmarsh in Victoria. We assessed the effectiveness of different control measures, including slashing and herbicides, for the management of∗L. ponticum infestations (and their side effects on saltmarsh communities) in the Western Port region of Victoria. A nominally monocot-specific herbicide widely used to control∗Spartina, Fluazifop-P, was ineffective in controlling∗L. ponticum. The broad-spectrum systemic herbicide glyphosate was more effective in controlling∗L. ponticum, but had undesirable impacts on native plant species. Controlling weeds in coastal wetlands using available herbicides for use near coastal waterways would seem to remain problematic.

Turner S.W.D.,Cranfield University | Marlow D.,CSIRO | Ekstrom M.,CSIRO | Rhodes B.G.,Melbourne Water | And 2 more authors.
Water Resources Research | Year: 2014

Despite a decade of research into climate change impacts on water resources, the scientific community has delivered relatively few practical methodological developments for integrating uncertainty into water resources system design. This paper presents an application of the "decision scaling" methodology for assessing climate change impacts on water resources system performance and asks how such an approach might inform planning decisions. The decision scaling method reverses the conventional ethos of climate impact assessment by first establishing the climate conditions that would compel planners to intervene. Climate model projections are introduced at the end of the process to characterize climate risk in such a way that avoids the process of propagating those projections through hydrological models. Here we simulated 1000 multisite synthetic monthly streamflow traces in a model of the Melbourne bulk supply system to test the sensitivity of system performance to variations in streamflow statistics. An empirical relation was derived to convert decision-critical flow statistics to climatic units, against which 138 alternative climate projections were plotted and compared. We defined the decision threshold in terms of a system yield metric constrained by multiple performance criteria. Our approach allows for fast and simple incorporation of demand forecast uncertainty and demonstrates the reach of the decision scaling method through successful execution in a large and complex water resources system. Scope for wider application in urban water resources planning is discussed. © 2014. American Geophysical Union. All Rights Reserved.

Nolan M.J.,University of Melbourne | Jex A.R.,University of Melbourne | Koehler A.V.,University of Melbourne | Haydon S.R.,Melbourne Water | And 2 more authors.
Water Research | Year: 2013

There has been no large-scale systematic molecular epidemiological investigation of the waterborne protozoans, Cryptosporidium or Giardia, in southeastern Australia. Here, we explored, for the first time, the genetic composition of these genera in faecal samples from animals in nine Melbourne Water reservoir areas, collected over a period of two-years. We employed PCR-based single-strand conformation polymorphism (SSCP) and phylogenetic analyses of loci (pSSU and pgp60) in the small subunit (SSU) of ribosomal RNA and 60-kDa glycoprotein (gp60) genes to detect and characterise Cryptosporidium, and another locus (ptpi) in the triose-phosphate isomerase (tpi) gene to identify and characterise Giardia. Cryptosporidium was detected in 2.8% of the 2009 samples examined; the analysis of all amplicons defined 14 distinct sequence types for each of pSSU and p. gp60, representing Cryptosporidium hominis (genotype Ib - subgenotype IbA10G2R2), Cryptosporidium parvum (genotype IIa - subgenotypes IIaA15G2R1, IIaA19G2R1, IIaA19G3R1, IIaA19G4R1, IIaA20G3R1, IIaA20G4R1, IIaA20G3R2 and IIaA21G3R1), Cryptosporidium cuniculus (genotype Vb - subgenotypes VbA22R4, VbA23R3, VbA24R3, VbA25R4 and VbA26R4), and Cryptosporidium canis, Cryptosporidium fayeri, Cryptosporidium macropodum and Cryptosporidium ubiquitum as well as six new pSSU sequence types. In addition, Giardia was identified in 3.4% of the samples; all 28 distinct p. tpi sequence types defined were linked to assemblage A of Giardia duodenalis. Of all 56 sequence types characterised, eight and one have been recorded previously in Cryptosporidium and Giardia, respectively, from humans. In contrast, nothing is known about the zoonotic potential of 35 new genotypes of Cryptosporidium and Giardia recorded here for the first time. Future work aims to focus on estimating the prevalence of Cryptosporidium and Giardia genotypes in humans and a wide range of animals in Victoria and elsewhere in Australia. (Nucleotide sequences reported in this paper are available in the GenBank database under accession nos. KC282952-KC283005). © 2013.

Koehler A.V.,University of Melbourne | Haydon S.R.,Melbourne Water | Jex A.R.,University of Melbourne | Jex A.R.,Walter and Eliza Hall Institute | Gasser R.B.,University of Melbourne
Parasites and Vectors | Year: 2016

Background: In a long-term program to monitor pathogens in water catchments serving the City of Melbourne in the State of Victoria in Australia, we detected and genetically characterised Cryptosporidium and Giardia in faecal samples from various animals in nine water reservoir areas over a period of 4 years (July 2011 to November 2015). Methods: This work was conducted using PCR-based single-strand conformation polymorphism (SSCP) and phylogenetic analyses of portions of the small subunit of ribosomal RNA (SSU) and 60 kDa glycoprotein (gp60) genes for Cryptosporidium, and triose-phosphate isomerase (tpi) gene for Giardia. Results: The prevalence of Cryptosporidium was 1.62 % (69 of 4,256 samples); 25 distinct sequence types were defined for pSSU, and six for gp60 which represented C. hominis (genotype Ib - subgenotype IbA10G2), C. cuniculus (genotype Vb - subgenotypes VbA26, and VbA25), and C. canis, C. fayeri, C. macropodum, C. parvum, C. ryanae, Cryptosporidium sp. "duck" genotype, C. suis and C. ubiquitum as well as 12 novel SSU sequence types. The prevalence of Giardia was 0.31 % (13 of 4,256 samples); all three distinct tpi sequence types defined represented assemblage A of G. duodenalis. Conclusions: Of the 34 sequence types (genotypes) characterized here, five and one have been recorded previously for Cryptosporidium and Giardia, respectively, from humans. Novel genotypes of Cryptosporidium and Giardia were recorded for SSU (n = 12), gp60 (n = 4) and tpi (n = 1); the zoonotic potential of these novel genotypes is presently unknown. Future work will continue to monitor the prevalence of Cryptosporidium and Giardia genotypes in animals in these catchments, and expand investigations to humans. Nucleotide sequences reported in this paper are available in the GenBank database under accession nos. KU531647-KU531718. © 2016 The Author(s).

Greet J.,University of Melbourne | Rees P.,Melbourne Water
Ecological Management and Restoration | Year: 2015

Phragmites or Common Reed (Phragmites australis) is a natural component of many wetlands but can be highly invasive. Phragmites is encroaching into important mudflat habitat areas of the Ramsar-listed Seaford Wetlands (Melbourne, Victoria), which are critical for migratory birds. We assessed the efficacy of slashing as a means of controlling Phragmites by establishing twelve 5 m × 5 m quadrats within mature Phragmites reed beds and slashing half of them. The response of Phragmites to slashing was highly variable and dependent on the elevation (i.e. subsequent flooding) of the slashed quadrats. Phragmites regrowth was minimal in lower-lying quadrats which were wholly inundated for several months each of the following two years (to a mean depth of ~22 cm). In contrast, in quadrats of higher elevation, which were mostly only partially or shallowly inundated, Phragmites recovered almost completely within 10 months. In quadrats that were not slashed there was no change in Phragmites cover (i.e. it remained ~100%) irrespective of flooding extent. It is suspected that prolonged flooding above the height of the remaining stubble is necessary to prevent recovery. Thus, slashing may be a successful means of controlling Phragmites when low-lying areas are targeted and these are subsequently flooded to a sufficient depth (e.g. >20 cm) for at least several months. © 2015 Ecological Society of Australia.

Hart P.,Melbourne Water
50th Annual Conference of the Australasian Corrosion Association 2010: Corrosion and Prevention 2010 | Year: 2010

This paper describes a new approach taken to assess and manage the threat of interference with third party assets from Impressed Current Cathodic Protection systems. For each ICCP unit, the radius of a zone where the soil potential rise is expected to be greater than 200mV has been calculated and this has been compared to interference testing results where available. This provides a more robust assessment of the risk of interference from cathodic protection assets than simply considering known values such as current output and complements direct interference measurements in the field. A Geographical Information System (GIS) has been used to plot these zones in relation to surrounding streets, properties and aerial imagery. These zones have been prepared for upload to 'Dial Before you Dig' systems, so that Melbourne Water as owner of the cathodic protection assets can be notified of new underground assets being installed in locations near ICCP units which could potentially be affected by stray current corrosion.

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