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Michael Mahony - One of the best experts on this subject based on the ideXlab platform.
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wetland restoration for the threatened green and golden bell frog litoria aurea development of a breeding Habitat designed to passively manage chytrid induced amphibian disease and exotic fish
Natural Areas Journal, 2020Co-Authors: Chad T Beranek, John Clulow, Michael MahonyAbstract:Amphibians are under threat from many drivers resulting in declining populations. Restoration and Creation of Habitat is a method used to reverse amphibian declines. The green and golden bell frog (Litoria aurea) is distributed in southeastern Australia, and is threatened by the fungal pathogen Batrachochytrium dendobatidis (chytrid), an introduced fish (the plague minnow, Gambusia holbrooki), and Habitat loss. There have been numerous wetland restoration attempts to combat population declines in this species, which have been largely unsuccessful in producing persisting populations. Here we present a robust model for the Creation of breeding Habitat for the L. aurea population on Kooragang Island, New South Wales, which is based off thorough review of the literature and past pilot studies and experiments. We describe in detail the Habitat, land use history, and wetland Habitat design formulation and construction so that the context of the Habitat Creation is understood and so construction can be repeatable and the design can be further refined. The Habitat features passive controls for chytrid and G. holbrooki, and contains the most optimum breeding Habitat for L. aurea based upon current knowledge. This is the first attempt in our knowledge to create wetlands in an open system that have the potential to passively manage chytrid.
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informing compensatory Habitat Creation with experimental trials a 3 year study of a threatened amphibian
Oryx, 2017Co-Authors: Jose W Valdez, Michelle P Stockwell, John Clulow, Kaya Kloptoker, Loren Fardell, Simon Clulow, Michael MahonyAbstract:The Creation or restoration of Habitat to mitigate biodiversity loss is a common conservation strategy. Evidence-based research via an extensively monitored trial study should be undertaken prior to large-scale implementation to predict success and identify potential limiting factors. We constructed an experimental trial Habitat for the threatened green and golden bell frog Litoria aurea, in Australia, to inform a broader programme of compensatory Habitat Creation. Individuals were released into the trial plot and a nearby natural wetland for comparison to determine if the created Habitat would support their growth, survival and persistence. Half of the trial waterbodies were enclosed within an exclusion fence to separate the effects of Habitat suitability from ecological processes. We found the Habitat provided L. aurea with sufficient resources to grow, survive and persist for 3 years. However, no breeding occurred, and further investigations need to focus on understanding the drivers of reproduction. Although a disease outbreak occurred during the study, persistence continued for the next 2 years. This was attributed to the large number of individuals released, a strategy we recommend for future mitigation strategies to account for low survival and high turnover rates. Dispersal probably affected abundance in the unfenced areas, and landscape-level initiatives are suggested for this species. This study demonstrates that experimental trials are valuable, as they can inform future Habitat management by identifying limitations that could hinder success prior to the implementation of large-scale initiatives.
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the role of non declining amphibian species as alternative hosts for batrachochytrium dendrobatidis in an amphibian community
Wildlife Research, 2016Co-Authors: Michelle P Stockwell, Deborah S Bower, John Clulow, Michael MahonyAbstract:Context Pathogens with reservoir hosts have been responsible for most disease-induced wildlife extinctions because the decline of susceptible hosts does not cause the decline of the pathogen. The existence of reservoirs for Batrachochytrium dendrobatidis limits population recovery and conservation actions for threatened amphibians. As such, the effect of reservoirs on disease risk within host community assemblages needs to be considered, but rarely is. Aims In this study we aimed to determine if amphibian species co-occurring with the green and golden bell frog Litoria aurea, a declining species susceptible to B. dendrobatidis, act as alternate hosts. Methods We quantified B. dendrobatidis infection levels, sub-lethal effects on body condition and terminal signs of disease in amphibian communities on Kooragang Island and Sydney Olympic Park in New South Wales, Australia, where two of the largest remaining L. aurea populations persist. Key results We found L. aurea carried infections at a similar prevalence (6–38%) to alternate species. Infection loads ranged widely (0.01–11 107.3 zoospore equivalents) and L. aurea differed from only one alternate host species (higher median load in Litoria fallax) at one site. There were no terminal or sub-lethal signs of disease in any species co-occurring with L. aurea. Conclusion Our results suggest that co-occurring species are acting as alternate hosts to L. aurea and whether their presence dilutes or amplifies B. dendrobatidis in the community is a priority for future research. Implications For L. aurea and many other susceptible species, confirming the existence of reservoir hosts and understanding their role in community disease dynamics will be important for optimising the outcomes of threat mitigation and Habitat Creation initiatives for their long-term conservation.
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achieving no net loss in Habitat offset of a threatened frog required high offset ratio and intensive monitoring
Biological Conservation, 2013Co-Authors: Evan J Pickett, Michelle P Stockwell, Deborah S Bower, John Clulow, James I Garnham, Carla J Pollard, Michael MahonyAbstract:The use of Habitat offset to mitigate the impact of development on threatened species is becoming increasingly popular. Despite a plethora of theoretical work on the requirements of Habitat offset to achieve no net loss, there are very few examples of successful Habitat offset programs and monitoring regimes to detect success. We present a case study of a population of the threatened green and golden bell frog (Litoria aurea) which was impacted by urban development through the removal of nine ponds. Development was concurrent with Habitat offset and construction of a large number of ponds which resulted in a 19-fold increase in available pond area. Through the use of mark recapture surveys, the population size was determined pre- and post-development. Despite the Creation of ponds in the immediate vicinity of the development there was a decrease in the pond area and a measured decline in the population located within the area where the development occurred. However, the overall pond construction program also involved the addition of considerable Habitat away from the immediate vicinity of the development which resulted in a 19-fold increase in pond area and an approximate 1.2–3.5-fold increase in population size. No net loss in population size to 95% confidence was achieved only when including all pond construction. This study demonstrated that to achieve no net loss for a Habitat offset program can require extensive levels of Habitat Creation with intensive monitoring to detect it.
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management of freshwater wetlands for the endangered green and golden bell frog litoria aurea roles of Habitat determinants and space
Biological Conservation, 2002Co-Authors: Andrew J Hamer, Simon J Lane, Michael MahonyAbstract:The range of the green and golden bell frog (Litoria aurea) has undergone a widespread yet unexplained contraction in south-eastern Australia since the mid 1970s, and the species is now listed as endangered in the New South Wales Threatened Species Conservation Act 1995 and as vulnerable in the federal Environmental Protection and Biodiversity Conservation Act 2000. Although the cause of the range contraction is unknown, remedial action is necessary to ensure the long-term viability of remaining populations. This can include Habitat Creation around existing populations and reintroduction projects. However, the Habitat requirements of this species are poorly understood. We examined the Habitat at 43 waterbodies on Kooragang Island, Australia, with the aim of producing a set of variables which could differentiate between those occupied by L. aurea and those where the species was absent. L. aurea was found in 21 waterbodies and breeding was confirmed in four. Aspects of waterbody physiognomy and water chemistry could not explain L. aurea distribution. The plant species Juncus kraussii, Schoenoplectus litoralis and Sporobolus virginicus were significant predictors of the presence of L. aurea, as was the diversity of vegetation on the banks of waterbodies. The presence of the eastern mosquitofish (Gambusia holbrooki) did not influence waterbody occupancy and tadpoles were found co-existing with this introduced fish. The distribution of waterbodies occupied by L. aurea was aggregated. A waterbody was more likely to be occupied if neighbouring waterbodies within 50 m were also occupied. Habitat Creation projects for this species are most likely to succeed if wetland Habitat is created in proximity to an existing population.
Andrew J Hamer - One of the best experts on this subject based on the ideXlab platform.
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management of freshwater wetlands for the endangered green and golden bell frog litoria aurea roles of Habitat determinants and space
Biological Conservation, 2002Co-Authors: Andrew J Hamer, Simon J Lane, Michael MahonyAbstract:The range of the green and golden bell frog (Litoria aurea) has undergone a widespread yet unexplained contraction in south-eastern Australia since the mid 1970s, and the species is now listed as endangered in the New South Wales Threatened Species Conservation Act 1995 and as vulnerable in the federal Environmental Protection and Biodiversity Conservation Act 2000. Although the cause of the range contraction is unknown, remedial action is necessary to ensure the long-term viability of remaining populations. This can include Habitat Creation around existing populations and reintroduction projects. However, the Habitat requirements of this species are poorly understood. We examined the Habitat at 43 waterbodies on Kooragang Island, Australia, with the aim of producing a set of variables which could differentiate between those occupied by L. aurea and those where the species was absent. L. aurea was found in 21 waterbodies and breeding was confirmed in four. Aspects of waterbody physiognomy and water chemistry could not explain L. aurea distribution. The plant species Juncus kraussii, Schoenoplectus litoralis and Sporobolus virginicus were significant predictors of the presence of L. aurea, as was the diversity of vegetation on the banks of waterbodies. The presence of the eastern mosquitofish (Gambusia holbrooki) did not influence waterbody occupancy and tadpoles were found co-existing with this introduced fish. The distribution of waterbodies occupied by L. aurea was aggregated. A waterbody was more likely to be occupied if neighbouring waterbodies within 50 m were also occupied. Habitat Creation projects for this species are most likely to succeed if wetland Habitat is created in proximity to an existing population.
Jennifer C Wilson - One of the best experts on this subject based on the ideXlab platform.
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the potential for Habitat Creation around offshore wind farms
2011Co-Authors: Jennifer C WilsonAbstract:The growth of offshore renewable energy generation is the biggest expansion of development in the marine environment in recent years, with offshore wind farms at the forefront of this. Due to its favourable wind resource, Europe in particular is rapidly expanding its portfolio of offshore wind energy generation; however, the rest of the world is also beginning to take advantage of this natural resource. This is due, in part, to the fact that Europe, especially the north-west region, has ideal conditions for development, due to the high offshore wind levels, and the fact that its coasts slope gently away from the land. This means that water depths increase relatively slowly in most areas, making conditions highly suitable for offshore construction (Ackermann and Soder, 2002). In addition to this, the offshore wind environment is much more reliable than onshore wind, as it is less turbulent, and has a higher energy density. This is due to the convection caused by the differential heating and cooling of the land and sea over the daily cycle, making the offshore zone generally windier. Further offshore, the lack of surface roughness adds to average wind speeds, further increasing energy efficiency. It is estimated that an offshore wind farm can generate around 50% more electricity than can be generated from an equivalent sized land-based development (Linley et al., 2007). In the UK, the development of offshore wind energy generation has been undertaken in a series of Rounds. In April 2001, following a detailed consultation and application process, eighteen ‘Round 1’ sites were announced, with a maximum of 30 turbines (BWEA, 2005). Whilst these projects were in the planning stages, further consultation was undertaken, discussing topics which would be critical to future development, such as the consents process, legal frameworks and the electrical infrastructure required for future projects. Three Strategic Areas in UK waters were identified, with fifteen projects being granted permission to submit formal applications under ‘Round 2’. In January 2010, a further nine zones were allocated to developers through a competitive application process, under ‘Round 3’. On top of these, there have also been Round 2 extensions granted for certain projects, and a number of sites granted exclusivity agreements to apply for development in Scottish Territoral Waters. In 2008, the UK overtook Denmark to become the world-leader in generating energy from offshore wind (Jha, 2008). With current UK emphasis on the construction of Round 2 projects, and the early development phases of Round 2 extensions, Round 3 and Scottish Territorial Waters projects, there is the potential for thousands more turbines to be installed
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the Habitat Creation potential of offshore wind farms
Wind Energy, 2009Co-Authors: Jennifer C Wilson, Michael ElliottAbstract:Offshore wind farms are the subject of environmental impact assessments in which potential adverse effects are identified and quantified. Those impacts will then require to be mitigated through appropriate design, construction and operation methods. Where environmental impacts cannot be mitigated, operators would be required to compensate the environment or its users for any actual or potential damage. The present study shows that the placement of offshore wind turbines gives the potential for Habitat Creation, which may thus be regarded as compensation for Habitat lost. Using current design criteria and construction methods, the analysis here indicates that the net amount of Habitat created by the most common design of offshore wind turbine, the monopile, is up to 2.5 times the amount of area lost through the placement, thus providing a net gain even though the gained Habitat may be of a different character to the one that lost. Hence, the study raises important issues for marine nature conservation managers. The study also provides suggestions for further work in order to increase the empirical evidence for the value of mitigation, compensation and Habitat Creation. Copyright © 2009 John Wiley & Sons, Ltd.
David M Wilkinson - One of the best experts on this subject based on the ideXlab platform.
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is local provenance important in Habitat Creation
Journal of Applied Ecology, 2001Co-Authors: David M WilkinsonAbstract:Summary 1. Many Habitat Creation schemes specify that biological material of local provenance should be used in reintroductions. This has come to be the ‘text book’ approach. However, very little discussion of the theory underlying this idea has been published in the scientific literature. This paper aims to initiate this much-needed discussion. 2. A major reason for the use of local provenance is the claimed importance of conserving locally adapted genotypes, which are assumed to show high fitness. Using both genetic arguments and a consideration of Quaternary environmental change I argue that this reason will seldom be important. 3. I make tentative suggestions of when local provenance is likely to be important and when it can be given a low priority in Habitat Creation schemes.
John Clulow - One of the best experts on this subject based on the ideXlab platform.
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wetland restoration for the threatened green and golden bell frog litoria aurea development of a breeding Habitat designed to passively manage chytrid induced amphibian disease and exotic fish
Natural Areas Journal, 2020Co-Authors: Chad T Beranek, John Clulow, Michael MahonyAbstract:Amphibians are under threat from many drivers resulting in declining populations. Restoration and Creation of Habitat is a method used to reverse amphibian declines. The green and golden bell frog (Litoria aurea) is distributed in southeastern Australia, and is threatened by the fungal pathogen Batrachochytrium dendobatidis (chytrid), an introduced fish (the plague minnow, Gambusia holbrooki), and Habitat loss. There have been numerous wetland restoration attempts to combat population declines in this species, which have been largely unsuccessful in producing persisting populations. Here we present a robust model for the Creation of breeding Habitat for the L. aurea population on Kooragang Island, New South Wales, which is based off thorough review of the literature and past pilot studies and experiments. We describe in detail the Habitat, land use history, and wetland Habitat design formulation and construction so that the context of the Habitat Creation is understood and so construction can be repeatable and the design can be further refined. The Habitat features passive controls for chytrid and G. holbrooki, and contains the most optimum breeding Habitat for L. aurea based upon current knowledge. This is the first attempt in our knowledge to create wetlands in an open system that have the potential to passively manage chytrid.
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informing compensatory Habitat Creation with experimental trials a 3 year study of a threatened amphibian
Oryx, 2017Co-Authors: Jose W Valdez, Michelle P Stockwell, John Clulow, Kaya Kloptoker, Loren Fardell, Simon Clulow, Michael MahonyAbstract:The Creation or restoration of Habitat to mitigate biodiversity loss is a common conservation strategy. Evidence-based research via an extensively monitored trial study should be undertaken prior to large-scale implementation to predict success and identify potential limiting factors. We constructed an experimental trial Habitat for the threatened green and golden bell frog Litoria aurea, in Australia, to inform a broader programme of compensatory Habitat Creation. Individuals were released into the trial plot and a nearby natural wetland for comparison to determine if the created Habitat would support their growth, survival and persistence. Half of the trial waterbodies were enclosed within an exclusion fence to separate the effects of Habitat suitability from ecological processes. We found the Habitat provided L. aurea with sufficient resources to grow, survive and persist for 3 years. However, no breeding occurred, and further investigations need to focus on understanding the drivers of reproduction. Although a disease outbreak occurred during the study, persistence continued for the next 2 years. This was attributed to the large number of individuals released, a strategy we recommend for future mitigation strategies to account for low survival and high turnover rates. Dispersal probably affected abundance in the unfenced areas, and landscape-level initiatives are suggested for this species. This study demonstrates that experimental trials are valuable, as they can inform future Habitat management by identifying limitations that could hinder success prior to the implementation of large-scale initiatives.
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the role of non declining amphibian species as alternative hosts for batrachochytrium dendrobatidis in an amphibian community
Wildlife Research, 2016Co-Authors: Michelle P Stockwell, Deborah S Bower, John Clulow, Michael MahonyAbstract:Context Pathogens with reservoir hosts have been responsible for most disease-induced wildlife extinctions because the decline of susceptible hosts does not cause the decline of the pathogen. The existence of reservoirs for Batrachochytrium dendrobatidis limits population recovery and conservation actions for threatened amphibians. As such, the effect of reservoirs on disease risk within host community assemblages needs to be considered, but rarely is. Aims In this study we aimed to determine if amphibian species co-occurring with the green and golden bell frog Litoria aurea, a declining species susceptible to B. dendrobatidis, act as alternate hosts. Methods We quantified B. dendrobatidis infection levels, sub-lethal effects on body condition and terminal signs of disease in amphibian communities on Kooragang Island and Sydney Olympic Park in New South Wales, Australia, where two of the largest remaining L. aurea populations persist. Key results We found L. aurea carried infections at a similar prevalence (6–38%) to alternate species. Infection loads ranged widely (0.01–11 107.3 zoospore equivalents) and L. aurea differed from only one alternate host species (higher median load in Litoria fallax) at one site. There were no terminal or sub-lethal signs of disease in any species co-occurring with L. aurea. Conclusion Our results suggest that co-occurring species are acting as alternate hosts to L. aurea and whether their presence dilutes or amplifies B. dendrobatidis in the community is a priority for future research. Implications For L. aurea and many other susceptible species, confirming the existence of reservoir hosts and understanding their role in community disease dynamics will be important for optimising the outcomes of threat mitigation and Habitat Creation initiatives for their long-term conservation.
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achieving no net loss in Habitat offset of a threatened frog required high offset ratio and intensive monitoring
Biological Conservation, 2013Co-Authors: Evan J Pickett, Michelle P Stockwell, Deborah S Bower, John Clulow, James I Garnham, Carla J Pollard, Michael MahonyAbstract:The use of Habitat offset to mitigate the impact of development on threatened species is becoming increasingly popular. Despite a plethora of theoretical work on the requirements of Habitat offset to achieve no net loss, there are very few examples of successful Habitat offset programs and monitoring regimes to detect success. We present a case study of a population of the threatened green and golden bell frog (Litoria aurea) which was impacted by urban development through the removal of nine ponds. Development was concurrent with Habitat offset and construction of a large number of ponds which resulted in a 19-fold increase in available pond area. Through the use of mark recapture surveys, the population size was determined pre- and post-development. Despite the Creation of ponds in the immediate vicinity of the development there was a decrease in the pond area and a measured decline in the population located within the area where the development occurred. However, the overall pond construction program also involved the addition of considerable Habitat away from the immediate vicinity of the development which resulted in a 19-fold increase in pond area and an approximate 1.2–3.5-fold increase in population size. No net loss in population size to 95% confidence was achieved only when including all pond construction. This study demonstrated that to achieve no net loss for a Habitat offset program can require extensive levels of Habitat Creation with intensive monitoring to detect it.
