Aquatic polyculture has been recognised as a potential way of increasing the costeffectiveness of farming marron (Cherax tenuimanus), as it can lower average costs of production, increase system yields, and reduce economic risks associated with monoculture operations. Polyculture also increases ecological stability and assists recycling processes, which can result in synergistic benefits to participating species. In aquaculture, this synergism can result in increased profitability through advanced growth rates and/or reduced feed input. However, many of the inherent advantages of aquatic polyculture rely on cohabitants occupying distinct ecological niches within the system. In Western Australia, opportunities to multi-crop aquatic species are limited by species choice due to low natural diversity and strict translocation policies. This creates a situation where available aquaculture species exhibit overlaps in occupied niches. Effects of this overlap can include direct predation, increased intraspecific conflict, and competition for resources such as shelter and food. Prior to this study, silver perch (Bidyanus bidyanus) were identified as a prime candidate for duoculture with marron, based on favourable schooling and feeding characteristics, and preliminary trials demonstrated commercial benefits, including synergistic growth advantages to marron. However, investigations also showed that silver perch will predate on both small and moulting crayfish under certain conditions, and that growth of silver perch was inhibited when held in cages to prevent predation. The work reported in this thesis was undertaken to address the niche overlap existing between marron and silver perch, and therefore assist the marron industry in Western Australia in implementing appropriate management strategies for diversification. / Research focussed on investigating the ecological issues underlying interspecific interactions in marron polysystems, with the eventual aim of presenting information that could assist system managers in determining optimal conditions required to reduce antagonistic relationships and maximise synergism, ultimately leading to higher yields. Seven trials were conducted in three culture systems (54L aquaria, 250L aquaria and 720m2 experimental ponds) examining the ability of marron to detect, recognise and respond to a range of information cues (chemical, visual, tactile) from two potential predators (silver perch and Murray cod), with and without competition from conspecific and heterospecific crayfish (Cherax albidus). The ability of marron to interpret and respond appropriately to these variables was tested under a range of system-specific conditions, including stocking density, stocking size, shelter/habitat complexity, food availability, light intensity and life stage. Cage culture conditions were also examined to determine if the addition of shelter would mediate growth inhibition previously recorded, and to determine the desired stocking regime to return market sized fish in one growth season (8 months). Results from laboratory research and field-based trials did not support the free-range culture of marron and silver perch, even where turbidity and habitat complexity is high. Although both male and female marron (various sizes) demonstrated an ability to detect and differentiate between chemical and visual cues from potential predators, avoidance responses were only displayed upon attack from predators, or following predation of conspecifics; and avoidance strategies employed by marron were relatively ineffective. / Although marron showed some capacity to recognise an impending predatory threat, high initial mortalities and growth inhibition due to reduced foraging, would greatly reduce system yields. In addition, intraspecific competition between marron is likely to increase as avoidance responses would lead to high relative densities within shelters. The lack of avoidance behaviour displayed by marron when only visual and chemical cues from predators are present strongly supports cage culture of silver perch in marron ponds. As marron did not appear to alter their general behaviour (e.g. foraging) based on cues associated with silver perch held in cages they stand to benefit from cohabitation. Field-trials examining the pond culture of marron and caged silver perch demonstrated synergistic growth advantages to marron, compared to monoculture, and also identified several system variables that appear to improve polyculture production. The addition of bank shelters (within 1m of waters edge) was suggested to give marron a competitive advantage when moulting, expressed through growth and survival. Survival of marron was also increased in caged polyculture ponds, compared to monoculture, most likely due to increased health status (due to improved recycling) and/ or increased habitat complexity owing to the presence of fish cages. Growth inhibition previously reported when silver perch are held in cages was mediated to some degree by cage shelters, which appeared to increase feeding behaviour, reduce general anxiety and resulted in increased growth. The introduction of advanced silver perch fingerlings in order to produce market-sized fish in one growth season was also supported. However, it is recommended that cage culture dynamics require further elucidation if silver perch are to be commercially successful as a stand-alone crop using this growout strategy. / Significantly, the synergistic growth advantages experienced by marron when grown with fish demonstrate value from polyculture even if fish are not depended on as a secondary income. In this case, other species may also provide similar advantages, and a native candidate such as freshwater cobbler (Tandanus bostocki) would also redress problems associated with translocation laws restricting the use of silver perch in some areas of Western Australia. As no density effects were recorded in any of the trials conducted for either species, further investigation into increased system loads is required. In addition, as nutrient loads, and thus phytoplankton density, usually increases proportionately with pond biomass it is recommended that an additional herbivorous species, for example white eye mullet (Mugil cephalus), be examined in conjunction with increased density trials. Field research reported in this thesis was carried out in earthen ponds utilising remediated water from a acidified mine lake. Over a three-year period water quality parameters were maintained within optimal ranges for marron and silver perch, and survival and growth of both species was comparable to industry levels. These results validate the effectiveness of mine-water treatment technology; and accordingly, results support commercial viability of crayfish polyculture utilising remediated acid mine water. The large water resources offered by the numerous artificial lakes created from open cut mining has the potential to sustain a large successful aquaculture industry for Collie (Western Australia), and in other areas with extension of water treatment technology. / The incorporation of caged silver perch into marron ponds not only takes advantage of the inherent economic and risk-spreading benefits from a diversified management strategy, but also incorporates a number of within-system benefits due to synergism between species. The ecological approach to aquatic polyculture research reported in this thesis has elucidated key communication factors underlying interactions within crayfish polysystems, which is critical to a knowledge-based approach to system management.

Members of the family Chenopodiaceae are routinely used as colonizer plant species to rehabilitate waste and tailings materials on mine sites in the Eastern Goldfields of Western Australia. These are specifically selected for their salt and drought tolerance and also because they are representative of the surrounding natural vegetation. Where these have been sown, competition between several species has been observed. The resulting plant community structure is typically lower in species diversity than the initial seed mixture. This study aimed to determine whether competition was occurring between five of the species commonly used and some of the mechanisms that determine community structure on the rehabilitated areas of waste material. Atriplex bunburyana, Atriplex codonocarpa, Maireana brevifolia, Maireana georgei and Enchylaena tomentosa were selected for the study, which was conducted in three parts. Firstly, different plant densities and species combinations were studied in the field and in a pot trial to determine whether or not competition was occurring and to determine the resources that the plants were competing for. The results of the field trial revealed that competition was occurring, but that it formed only one component of the complex interactions between plant species, density and soil characteristics (i.e. pH and salinity). The pot trial complemented the outcome of the field trial. In addition, it showed that competition was occurring, but was even more pronounced. This was most likely due to the lack of nutrients and the limited availability of space in the pots. / In the second part of this study, the ability of each species to survive and grow when subjected to adverse environmental conditions, such as low moisture availability, high salinity and low light availability, was examined in relation to competition. All five species were treated with different water regimes and soil salinity. Salt played an important role, especially for the Atriplex spp. and M. brevifolia, in ensuring survival when moisture availability was low. The effect of shade on the Maireana species and E. tomentosa was also researched after field observations suggested that M georgei was adversely affected when growing within the canopy of A. bunburyana. The pot trial showed that growth of M. georgei was affected by progressively more shade, whereas E. tomentosa was facilitated by shade. Maireana brevifolia exhibited significant tolerance to low light intensity. In the last part of this three-part study, all five chenopods were screened for allelopathy. Allelopathy may play an important role in determining community structure in successive plant generations. All chenopod species produced allelopathic substances, which were isolated from their leaves. The inhibition of seed germination was found to be speciesspecific and occurred only at certain concentrations. The seed of the Atriplex spp. was not affected by M. georgei and E. tomentosa extracts.

Abstract not available

Reintroduction programs have often been used to help redress serious declines across species' former ranges, but they suffer from high expense and low success rates. Tourism is one tool that could be used to support such programs, by generating funding for the programs and the local community, and by educating tourists about reintroductions and conservation. However, if tourism is not incorporated successfully into reintroduction programs, it may not provide any advantages and may even harm the reintroduction. There is a need to find ways to ensure efforts to integrate tourism and reintroductions achieve positive conservation outcomes. This is a topic that has been little researched to date. To achieve positive conservation outcomes, the enterprises must have financial sustainability and sustainable mammal populations. This thesis investigates ways to achieve these dual goals. The international literature is reviewed to establish what can be learnt from previous reintroduction attempts to increase the likelihood of reintroductions of mammals being successful. A number of broad measures are established, including starting the enterprises by reintroducing herbivores and early breeders, preferably wild caught, and then moving to carnivores or omnivores and captive-bred animals when staff have more experience. Some new ideas are developed for experimental releases that will add to the available knowledge on how to increase the chance of successful reintroductions. Tourism enterprises based on reintroductions of threatened native mammals in Australia and South Africa are reviewed. The review shows tourism enterprises based on reintroductions make significant contributions to conservation, but enterprises in Australia need to diversify further. It also describes a number of significant obstacles that enterprises in Australia and South Africa face in achieving financial sustainability and sustainable mammal populations. It then provides recommendations for dealing with the problems, such as employing staff or consultants with knowledge of wildlife management and marketing, and allowing tourists to view wildlife only on guided tours. Finally, the review identifies ways that government bodies in Australia could better facilitate enterprises based on reintroductions, such as making endangered species available free of charge or heavily subsidised at this stage, and then later running wildlife auctions. Legislation systems applying to tourism enterprises based on mammal reintroductions in Australia and South Africa are also reviewed. The review identifies a number of shortcomings of the current Australian legislation that affects the ability of government bodies to facilitate the development of such enterprises. Certain changes to the legislation are suggested. The international literature on factors influencing tourist satisfaction is reviewed and field research at an Australian case study site described, to determine ways tourism enterprises based on reintroductions can maximise tourist satisfaction. The field research draws out a number of new lessons for satisfying tourists, including: placing supplementary food or building waterholes in grasslands and areas with sparse vegetation; providing supplementary food for some species of wildlife; and providing pamphlets with information on the wildlife. The field research also illustrates some new ideas for tests to determine which methods should be used to maximise tourist satisfaction at a specific site, such as testing whether it is better to run tours in vehicles or on foot. The published international literature on minimising impacts of tourism on wildlife is reviewed and field research at one Australian case study site and one Chinese case study site described, to determine how to minimise the negative impacts of tourists on wildlife. The field research illustrates some new ideas for tests to determine which techniques should be used to minimise the impacts of tourism on wildlife at a specific site, such as tests to determine whether it is necessary to ensure tourists remain on the path at all times. The thesis then brings all these elements together into a flow chart giving recommendations to increase the rate of success of tourism enterprises that reintroduce mammals in achieving financial sustainability and sustainable mammal populations.

Doctor of Philosophy(PhD), / Until recently, Northwestern Australia was thought to be relatively free of serious fruit fly pests. Although a noxious strain, present in Darwin since 1985, was widely believed to be an infestation of the Queensland fruit fly, Bactrocera tryoni, from the East coast, the fruit flies present outside this area were believed to be the benign endemic species, B. aquilonis. However, during the year 2000, infestations of fruit flies were discovered on major commercial crops in both Western Australia and the Northern Territory. It was not known whether these outbreaks were due to an invasion of the major pest species, Bactrocera tryoni, a change in the behaviour of B. aquilonis, or a hybridisation event between the two species. Finding the source of these outbreaks has been complicated by the fact that, since B. tryoni and B. aquilonis are virtually indistinguishable morphologically, it was not known which species are present in the region. Traditionally any tryoni complex fly caught in the Northwest was called B. aquilonis based solely on location. In order to get a good population profile of the region, an extensive trapping program was set up to include flies from urban areas, commercial crops and natural areas where the benign strain is thought to remain. Tests of genetic differentiation and clustering analyses revealed a high degree of homogeneity in the Northwest samples, suggesting that just one species is present in the region. The Northwest samples were genetically differentiated from the Queensland samples but only to a small degree (FST =0.0153). MtDNA sequencing results also showed a small degree of differentiation between these regions. A morphological study of wing shape indicated that there are some minor identifiable morphological differences between East coast and Northwest laboratory reared flies. This difference was greater than that seen between B. jarvisi populations across the same geographic range. The results suggest that the flies caught in the Northwest are a separate population of B. tryoni. Soon after pest flies were discovered in Darwin, a population became established in Alice Springs. This population had a low genetic diversity compared with Queensland and Darwin populations, and showed evidence of being heavily founded. In 2000, an outbreak was discovered in the nearby town of Ti Tree. Due to the geographic and genetic similarity of these populations, Alice Springs was determined to be the source of the Ti Tree outbreak. To investigate the founding of these populations, a program was developed to estimate the propagule size. Using a simulation method seven different statistics were tested for estimating the propagule size of an outbreak population. For outbreaks originating from populations with high genetic diversity, the number of alleles was a good estimator of propagule size. When, however, the genetic diversity of the source population was already reduced, allele frequency measures, particularly the likelihood of obtaining the outbreak population from the source population, gave more accurate estimates. Applying this information to the Alice Springs samples, it was estimated that just five flies were needed to found the major population in and around Alice Springs. For Ti Tree, the propagule size was estimated to be 27 flies (minimum 10). In 2000, a much larger outbreak occurred in the developing horticultural region of Kununurra in northern Western Australia. An important question for the management of the problem is whether there is an established fly population or the flies are reinvading each year. This population was found to have a large amount of gene flow from the Northern Territory. Within the Kununurra samples, one group of flies was genetically differentiated from all the other samples. This group came from a small geographic area on the periphery of Kununurra and appeared to be the result of an invasion into this area at the time when the population was building up following the dry season. A further threat to the Northwest horticultural regions comes from B. jarvisi. A recent increase in the host range of this species has lead to speculation that it may become a greater pest in Northwestern Australia. At the present time, protocols for the population monitoring and disinfestation of this species are not in place. Here it is shown that B. jarvisi eggs are more heat tolerant than B. tryoni eggs and that monitoring of B. jarvisi populations is possible using cue lure traps placed according to fruiting time and location of their favoured host, Planchonia careya.

The secondary productivity of communities is inherently influenced by the availability and quality of food resources. Movement of organic matter (OM) across landscapes can connect adjacent systems by providing subsidies of carbon and nutrients, implying that alterations of environments from their natural state may affect the productivity of neighboring food webs. The intact terrestrial and marine environments of Fiordland provide a setting to study linkages between the land and the sea. The first general objective of this study was to determine if large but nutritionally poor (nitrogen-poor, carbon-rich) inputs of forest litter support marine secondary production, and to identify pathways for incorporation of this material into upper trophic levels. Pools of marine and terrestrial OM had distinct values of [delta]�⁵N, [delta]��C and [delta]�⁴S, providing high power to estimate the relative use of these sources by the food webs of the fjord-head deltas. Deposit feeding invertebrates (e.g. Echinocardium cordatum, Pectinaria australis) directly assimilated plant detritus. Heterotrophic bacteria on the surface of the sediment assimilated forest litter and provided a potential food source for invertebrates. Chemoautotrophic bacteria fix CO₂ that originates from decomposing forest litter, thus providing an indirect pathway for incorporation of forest litter into the food webs. In the deep basins the strength of the flux of uptake by chemoautotrophic bacteria through the benthic food web into the upper trophic levels was demonstrated by hagfish (Eptatretus cirrhatus) obtaining 38-51% of their nutrition from these bacteria. The ability of a community to utilize discrete sources of OM relies on the presence of specific functional feeding guilds. Marine algae provide a highly nutritive (nitrogen-rich) food source for the fjord communities and fluxes of algae into food webs are facilitated by grazing invertebrates and filter feeders. The second general objective of this study was to determine how the effective loss of filter feeders from inner Doubtful Sound would alter the flux of marine-derived OM to the food webs of the delta communities. The low salinity environment imposed by the hydroelectric power station in Doubtful Sound caused a large reduction in the abundance of the infaunal bivalves Austrovenus stutchburyi and Paphies australis from delta habitats. Clams could tolerate periods of freshwater exposure of [less than or equal to]20 days duration, but the constant freshwater conditions in Doubtful Sound decreased survivorship. In 2004/05 the biomass of these species in inner Doubtful Sound (7.28 tonnes) was 29 times smaller than in Bradshaw Sound (214.12 tonnes). The associated loss of biodeposits (~91 tonnes(DW) yr⁻� in Bradshaw Sound vs. 1 tonne(DW) yr⁻� in inner Doubtful Sound) may have also altered the flux of nutritive OM to the infaunal community. The river delta communities in inner Doubtful Sound appear to have a higher reliance on forest litter than those in Bradshaw Sound, which is apparent as low values of [delta]�⁵N and [delta]��C for estuarine fish (Notolabrus celidotus, Hemerocoetes monopterygius), which act as integrators of the benthic community. This study demonstrates important linkages between terrestrial and coastal marine ecosystems and highlights the role of functional diversity in facilitating fluxes of organic material through food webs.

This study arose from a conservation dilemma between the need to conserve a population of the endangered pink tailed legless lizard, Aprasia parapulchella and crucial upgrading of Canberra's sewerage treatment plant. The study focused on conservation biology and how it could be applied to the management of A. parapulchella. As little biological information was available on A. parapulchella, research was focused on obtaining data that would be beneficial in the conservation management of the species. This included the dietary and habitat requirements, population status and structure and population relocation and habitat restoration. A. parapulchella was found to occur in low relative densities at all sites (maximum 9.1 lizards per 1000 rocks turned, Mt Taylor). Populations of the species appear to be larger than has been considered previously, however numbers are still below 500 individuals per site. Sexual dimorphism is present in the species with females achieving longer snout-vent lengths than males. Sex ratios were equal in all sites, however average size of lizards was different at the four main study sites, indicating differences in population structure. The life history of A. parapulchella can be summarised as long-lived, late maturing (3rd or 4lh year of life) with a low reproductive rate (single clutch of two eggs per year). A. parapulchella is a dietary specialist feeding on about 11 different species of ants. Interestingly, the lizards also live with the same species that they feed upon. By far the most important species in the diet and homesite requirements of A. parapulchella is the ant Iridomyrmex rufoniger. A. parapulchella shows positive selection towards the species in homesite choice, is found most commonly in the nests of this ant, and selects its brood over the brood of other ant species in diet experiments. In addition this ant was represented in the diet of A. parapulchella more commonly than any other ant. The relationship between ants and A. parapulchella appears to be unique and the mechanisms of this specialisation require further investigation. The vegetation associations where A. parapulchella occur are different across the range of the species. Sites at Bendigo and West Wyalong support mallee communities, while in the ACT region, Bathurst and Tarcutta, A. parapulchella appears to be a habitat specialist, being found most commonly in sites dominated by grass species, both native and introduced. A. parapulchella lives beneath rocks in grassland sites. Rocks that the species uses for homesites are commonly between 100 and 150 mm wide, 120-220 mm long and 50 and 150 mm thick. There were significant differences between the sizes of rocks used at different sites and between different seasons. Rocks used by females were significantly larger than rocks used by juvenile lizards. Twelve other species of reptile were found to use rocks in grassland sites, with rocks partitioned within the community on the basis of size and shape. An experimental relocation of A. parapulchella was conducted to try to determine ideal habitat conditions for the survival of relocated individuals. Unfortunately of the 114 lizards released, only 15 were recaptured. Although recaptures were low, trends indicated that treatments of Themeda triandra and very high rock densities had the highest survival rates. Key habitat variables were reinstated at the Lower Molonglo Dam site however restoration is preliminary with more time needed for the habitat to be suitable for occupation by A. parapulchella. What started as a situation that was likely to have a deleterious impact on A. parapulchella has been turned into a conservation success story. Without the involvement of ACT Electricity and Water, much of the basic biology of A. parapulchella would still be unknown. The findings will now form a solid basis from which to effectively conserve A. parapulchella. The project provides an example of the conservation success that can be achieved between industry and conservation partnerships.

The study aimed to gain understanding about diversity, patterns and processes in natural temperate grassland sites in the ACT. Thirty natural grassland sites were surveyed for plant composition, soil invertebrate abundance and site attributes. Floristic associations were identified using multivariate analysis. These were compared to the other site attributes to determine related characteristics. Total plant species richness was 191 species, of which 41% were exotics. Forbs comprised 56% of the total species, with 69 native forb species. There were 10 native grass species and 12 sub-shrubs recorded. The number of species found within ten 1 m2 quadrats measured in each site ranged from 23 to 56 species. Three floristic associations were identified through classification analysis using frequency data. The Danthonia association occurred in well drained sites on soils with high clay content and low nutrient levels and a greater percentage of bare ground. The sites were assessed as having been subject to moderate to high disturbance in the past and 46% were grazed and 46% mown. Species richness of both natives and exotics was high (quadrat richness averaged 37 species, with 32.8% exotic cover in spring). The Wet Themeda association occurred in poorly drained sites and had also been subject to moderate to high disturbance; 67% of sites were grazed and 25% mown. Phosphorus levels were higher in these sites and the acidity of the soil was also greater. Quadrat richness averaged 39 species, with 35.5% exotic cover in spring. The Dry Themeda association was well drained. These sites had a lower native and exotic diversity, with a mean quadrat richness of 30 species, and 11.1% exotic species cover in spring, but a high species richness in the sites (mean 65.4 species) and a high litter cover of 39.9%. All have been subject to low disturbance and none were grazed. Phosphorus levels were low (7.9 ppm). Wet Themeda grassland sites were more similar to Danthonia grassland sites in terms of species occurrence and frequency than Dry Themeda grasslands, despite both associations being dominated by Themeda australis. While trends emerged regarding management and disturbance levels in the three associations, these were not major differentiating attributes. Invertebrates were collected from soil samples from the sites and identified to order level. Twenty two orders were found, but only three orders, Acarina, Collembola and Coleoptera, were sufficiently abundant to enable statistical tests to be undertaken. Invertebrate order richness and abundance showed strong relationships with vegetation attributes that measured or reflected vegetation structure, with higher abundance in sites dominated by T. australis and where wet soil colour was darker. Both order richness and total abundance of invertebrates were highest in mown sites and lowest in grazed sites. The invertebrate order richness and abundance did not have significant relationships with the floristic associations. A field experiment was conducted in which above- and below-ground gaps were created using the herbicide, Glyphosate, to remove interspecific competition and comparing responses between the Dry Themeda and Danthonia associations. Litter load and soil disturbance were also manipulated. The subsequent establishment of species was studied over two growing seasons, a period of 18 months. Both native and exotic forb richness and cover increased as a result of gap formation. Exotic grass cover and richness showed a strong increase in the first season, but after 18 months had decreased to levels similar to those prior to the application of treatments. Native grasses had not recovered to pre-treatment levels after 18 months. Native forb richness and cover were not inhibited by litter retention, but exotic forb richness and cover were higher in treatments with litter removal. Soil disturbance to a depth of 20 mm had no significant effect on the recruitment of the species. Recommendations for protection and management of the sites were developed from the study. Conservation recommendations are based on the aim of maintaining or enhancing native species diversity and habitat, while protecting threatened species and their habitat. Management plans should recognise requirements based on the floristic associations, diversity of native species, drainage conditions and retention of invertebrate habitat, including structural requirements. Grazing should be retained as a viable management regime, particularly in sites where small species occur. Future research should aim towards a greater understanding of the effects of management on species diversity, including invertebrates, and include a monitoring component with which to determine if management actions should be modified.

Habitat requirements and habitat use for Pseudophryne australis and Heleioporus australiacus were investigated to aid management of these threatened frogs around Sydney, Australia. Much of the work focussed on roads, commonly encountered features in the habitat of both species. The habitat requirements based on locality records of both frogs in the Sydney Basin were investigated at four spatial scales. Both species are habitat specialists. They showed a strong geological association with Hawkesbury Sandstone and occupy upper topographic areas with ephemeral watercourses of gentle gradients. Both frogs occur predominantly in areas of higher precipitation and milder temperature regimes compared to averages representative of the region. Leaf litter is an important feature of P. australis breeding sites, whereas H australiacus generally associate with crayfish burrows. Both species are dependent on natural vegetation with a complex structure. H australiacus have a relatively long larval period (3 - 12 months) and breed in ephemeral pools, exposing their tadpoles to the risk of dying due to early pond drying. In the laboratory, tadpoles responded to decreasing water levels by shortening their larval periods and metamorphosing earlier than siblings held at constant water level. Despite this plastic response, a number of pools in the field failed to produce metamorphs due to early drying, an observation also made on P. australis. Regular monitoring of breeding sites revealed increased reproductive success away from roads for both species probably because of relatively longer hydroperiods. Spatial distributions and associations with habitat features, and movement patterns of both frogs were further investigated using mark-recapture methods. Both species showed strong site fidelity. P. australis formed small aggregations and predominantly selected leaf litter piles despite their relatively low availability. Leaf litter piles in creeks moved over time and the animals moved with these piles. In contrast, H australiacus individuals formed no aggregations and showed no preference for any available structural vegetation type. Locations of individuals were independent of relative distances to creeks and artificial drains, but males appeared to be more common near culverts. However, individuals were randomly distributed in space and nearest-neighbour distances were high relative to individual movement distances, suggesting minimal overlap between relatively large home ranges. Radio-telemetry demonstrated that some H australiacus individuals burrow in the road environment. There they would be at risk of being dug up and possibly injured during road works. The results are discussed in relation to the spatial requirements of both species and the protection of utilised habitat features. Management options are suggested to mitigate the impacts of road works. Differences in spatial dynamics of both frogs with overlapping habitats highlighted in this study require species-specific management approaches.

Habitat requirements and habitat use for Pseudophryne australis and Heleioporus australiacus were investigated to aid management of these threatened frogs around Sydney, Australia. Much of the work focussed on roads, commonly encountered features in the habitat of both species. The habitat requirements based on locality records of both frogs in the Sydney Basin were investigated at four spatial scales. Both species are habitat specialists. They showed a strong geological association with Hawkesbury Sandstone and occupy upper topographic areas with ephemeral watercourses of gentle gradients. Both frogs occur predominantly in areas of higher precipitation and milder temperature regimes compared to averages representative of the region. Leaf litter is an important feature of P. australis breeding sites, whereas H australiacus generally associate with crayfish burrows. Both species are dependent on natural vegetation with a complex structure. H australiacus have a relatively long larval period (3 - 12 months) and breed in ephemeral pools, exposing their tadpoles to the risk of dying due to early pond drying. In the laboratory, tadpoles responded to decreasing water levels by shortening their larval periods and metamorphosing earlier than siblings held at constant water level. Despite this plastic response, a number of pools in the field failed to produce metamorphs due to early drying, an observation also made on P. australis. Regular monitoring of breeding sites revealed increased reproductive success away from roads for both species probably because of relatively longer hydroperiods. Spatial distributions and associations with habitat features, and movement patterns of both frogs were further investigated using mark-recapture methods. Both species showed strong site fidelity. P. australis formed small aggregations and predominantly selected leaf litter piles despite their relatively low availability. Leaf litter piles in creeks moved over time and the animals moved with these piles. In contrast, H australiacus individuals formed no aggregations and showed no preference for any available structural vegetation type. Locations of individuals were independent of relative distances to creeks and artificial drains, but males appeared to be more common near culverts. However, individuals were randomly distributed in space and nearest-neighbour distances were high relative to individual movement distances, suggesting minimal overlap between relatively large home ranges. Radio-telemetry demonstrated that some H australiacus individuals burrow in the road environment. There they would be at risk of being dug up and possibly injured during road works. The results are discussed in relation to the spatial requirements of both species and the protection of utilised habitat features. Management options are suggested to mitigate the impacts of road works. Differences in spatial dynamics of both frogs with overlapping habitats highlighted in this study require species-specific management approaches.