Dissertations / Theses on the topic 'Wetland ecology Australia'

Perched, seasonal claypans of southwestern Australia are poorly understood in terms of their ecological character, such as relationship between hydrology and their biota. An example is Little Darkin Swamp, located on the Darling Plateau in southwestern Australia. The overall aim of this thesis was to describe its ecological character, to understand what drives this claypan system and how its ephemeral nature affects wetland processes and functions. This study first comprised a detailed characterisation of the wetland’s attributes, following the geomorphic-hydrological approach proposed by Semeniuk and Semeniuk (2011). This revealed that its hydrology is highly dependent on rainfall, that it is an endorheic system, with a basin that is structurally spatially heterogeneous with distinct vegetation zones, and that surface waters have nutrient levels that are similar to oligotrophic systems. These features make it similar to other claypan wetlands of southwestern Australia and vernal pools of California, USA. Continuous high-frequency dissolved oxygen data during the hydroperiod showed that there are large temporal and spatial variations in ecosystem metabolism, and that the trophic status of the wetland is finely balanced, fluctuating between auto- and heterotrophy due to its ephemeral nature. Due to its oligotrophic nature, rates of gross primary production (GPP) and respiration (R) were overall low, and the wetland was overall slightly autotrophic over the study period. Furthermore, dual isotope analysis of δ13C and δ15N of sources and consumers revealed that aquatic macrophytes make a higher contribution to the food web compared to other sampled sources. However, the food web was also supported by sources of carbon that were not sampled, probably filamentous algae and methanotrophic bacteria. Experimental re-hydration of dried sediments emphasized that the seasonality of the water regime, and the shallow bathymetry of the basin, influences organic matter content, nutrient levels, oxygen consumption, plant growth and macroinvertebrate richness, differently between the centre of the wetland versus the edges. These results confirmed that there are at least two distinct zones in the wetland in terms of biotic response following rewetting, caused by the differences in duration and frequency of inundation of the sediments. The outcomes of this study showed that the ephemerality (i.e. seasonal drying and wetting) of Little Darkin Swamp drives important internal ecosystem processes, such as ecosystem metabolism, nutrient cycling, and primary production, which in turn determine the trophic status and distribution of biotic communities in the wetland. Therefore, any changes to the hydrological regime will greatly affect how these system functions and can potentially negatively impact such unique shallow, seasonal perched systems of southwestern Australia.

This thesis investigates nutrient contribution to six hyper-eutrophic lakes located within close proximity of each other on the Swan Coastal Plain and 20 kilometres south of the Perth Central Business District, Western Australia. The lakes are located within a mixed land use setting and are under the management of a number of state and local government departments and organisations. These are a number of other lakes on the Swan Coastal Plain for which the majority are less than 3 metres in depth and considered as an expression of the groundwater as their base is below the regional groundwater table throughout most of the year. The limited amount of water quality data available for these six lakes and the surface water and groundwater flowing into them has restricted a thorough understanding of the processes influencing the water quality of the lakes. Various private and public companies and organisations have undertaken studies on some of the individual wetlands and there is a wide difference in scientific opinion as to the major source of the nutrients to those wetlands. These previous studies failed to consider regional surface water and groundwater effects on the nutrient fluxes and they predominantly only investigated single wetland systems. This study attempts for the first time to investigate the regional contribution of nutrients to this system of wetlands existing on the Swan Coastal plain. As such, it also includes new research on the nutrient contribution to some of the remaining wetlands. The research findings indicate that the lake sediments represent a considerable store of nutrients (nitrogen and phosphorus). These sediments in turn control the nutrient status of the lake's water column. Surface water is found to contribute on an event-basis load of nutrients to the lakes whilst the groundwater surprisingly appears to contribute a comparatively low input of nutrients but governs the water depth. Analysis of the regional groundwater shows efficient denitrifying abilities as a result of denitrifying bacteria and the transport is localised. Management recommendations for the remediation of the social and environmental value of the lakes include treatment of the lake’s sediments via chemical bonding or atmospheric oxidation; utilising the regional groundwater’s denitrifying abilities to ‘treat’ the surface water via infiltration basins; and investigating the merits of managed or artificial aquifer recharge (MAR).

This study takes as its focus the contrasting manner in which the Nyoongar indigenous people and the early European settlers utilised three wetland environments in southwest Australia over the century between 1829 and 1939. The thesis offers both an ecological and a landscape perspective to changes in the wetlands of Herdsman Lake, Lake Joondalup and Loch McNess. The chain of interconnecting linear lakes provides some of the largest permanent sources of fresh water masses on the Swan Coastal Plain. This thesis acknowledges the importance of the wetland system to the Nyoongar indigenous people. The aim of this research is to interpret the human intervention into the wetland ecosystems by using a methodology that combines cultural landscape, historical and biophysical concepts as guiding themes. Assisted by historical maps and field observations, this study offers an ecological perspective on the wetlands, depicting changes in the human footprint on its landscape, and mapping the changes since the indigenous people’s sustainable ecology and guardianship were removed. These data can be used and compared with current information to gain insights into how and why modification to these wetlands occurred. An emphasis is on the impact of human settlement and land use on natural systems. In the colonial period wetlands were not generally viewed as visually pleasing; they were perceived as alien and hostile environments. Settlers saw the land as an economic commodity to be exploited in a money economy. Thus the effects of a sequence of occupances and their transformation of environments as traditional Aboriginal resource use gave way to early European settlement, which brought about an evolution and cultural change in the wetland ecosystems, and attitudes towards them.

Giralang Pond was a water body, with little emergent or submerged vegetation, designed to trap fine sediment and buffer input of rising water to Ginninderra Wetland downstream. Ginninderra Wetland was designed to retain and use sediment nutrients and other potential hazardous materials in urban run-off. Water in the Wetland was more turbid and had lower magnesium concentration, redox potentials and dissolved oxygen concentration than did Giralang Pond. Water temperature was a minimum of 4 °C in the winter and reached a summer maximum of 30 °C Giralang Pond had more organisms but fewer taxa than Ginninderra Wetland. The greatest abundance in the pond resulted principally from high numbers of two numerically dominant species Calamoecia sp. and Micronecta sp.. More organisms were found in vegetated habitats of Ginninderra Wetland than open water habitats. The number of invertebrates and the number of taxa found in Typha domingensis did not differ significantly from similar estimates for Schoenplectus validus, Gambusia qffinis was the dominant predator in both water bodies. On one occasion, G. qffinis reached population densities of 35 individuals per m-2 . G. qffinis was five times more abundant in Gininnderra Wetland than in Giralang Pond and also showed a preference for vegetated areas. G. qffinis over-grazed it's prey on several occasions. G. qffinis, invertebrate predators and prey followed a pattern of a community in a stable predator-prey cycle. Prey in early spring increased population numbers and then decreased when G. qffinis and other predators increased their numbers. The pattern was further strengthened by occurring in both areas of open water and vegetated habitat types.

The development and local distribution of organic soils in Australia have been poorly documented. Within Western Australia, conditions conducive to the accumulation of organic matter are geographically restricted and generally occur in coastal and/or forested landscapes. An extensive system of wetlands with peal soils occurs in the Muir-Unicup region in the far south west of Western Australia. Bokarup Swamp, Kodjinup Swamp and Noobijup Lake are representative of the wetlands occurring in this region. They arc shallow (

Lake Monger (3204'S 115°20'E) was sampled intensively (18 occasions) between October 1988 and October 1989. Ordination and classification of the water chemistry, plankton and macroinvertebrates revealed three seasonal groups, spring/summer, summer/autumn and winter. In terms of the water chemistry these groups corresponded to periods of hypertrophy, eutrophy and mesotrophy respectively. The lake was found to be shallow (1-1.5 m deep) and polymictic. Internal release from the sediments was believed to be responsible for the high levels of P (> 700 jig L1) recorded during summer. In summer, the limiting nutrient for algal growth appeared to be N. Two species alternated in dominance of the zooplankton, the cladoceran Daphnia carinata King in winter and the copepod Mesocyclops sp in summer groups. These species accounted for >80% of the abundance and biomass of the zooplankton when they were dominant. Changes in the edibility of summer algal populations, rather than the effects of zooplanktivorous fish (Gambusia holbrooki (Girard)), invertebrate predators (e.g. hemipterans) or temperature was believed responsible for the summer declines in D. carinata. 70 macroinvertebrate taxa were recorded, substantially higher than found in other studies at the lake. Mean species richness was highest from areas of emergent reeds. Compilation of available data revealed a decline in water quality in the lake since European settlement, resulting from nutrient enrichment, introductions of exotic biota, removal of native vegetation, physical modification (landfill and dredging) and changes in hydrology (artificial maintenance of water levels). The study year (1988/89) appeared to be similar to other years in the late 1980's. Changes in fertilizer usage around the lake at the start of the 1990's appeared to have been responsible for subsequent significant improvements in the water quality. Twelve in-lake enclosures (1.5 m3) were used to assess the influence of predation by G. holbrooki, N limitation and gilvin (brown colour), on zooplankton and water chemistry. Increased levels of primary productivity were recorded in untreated control enclosures. Only low levels of gilvin were produced and these resulted in a slight increase in chlorophyll a rather than the anticipated decrease. Gambusia holbrooki was not found to be responsible for any changes in the zooplankton structure. Variability between replicate enclosures and P limitation in the lake meant that N limitation could not be established. The presence of large numbers of D. carinata was found to significantly improve water quality through grazing and removal of seston. There appeared to be a nutrient threshold of 150 fig T1 of P in the water column, above which algal composition or size was inedible for D. carinata. Biomanipulation, involving fish manipulations, appeared unlikely to be successful in improving water quality as the link between fish predation and summer declines in D. carinata appeared to be tenuous. Reductions in fertilizers used on lawns around the lake appeared to have had a significant effect on improving the water quality of the lake.

Conservation science in rivers is still lagging behind its terrestrial and marine counterparts, despite increasing threats to freshwater biodiversity and extinction rates being estimated as five times higher than in terrestrial ecosystems. Internationally, most protected rivers have been assigned reserve status in the framework of terrestrial conservation plans, neglecting catchment effects of disturbance. While freshwater conservation tools are mainly index based (e.g. richness, rarity), modern terrestrial and marine conservation planning methods use complementarity-based algorithms - proven to be most efficient at protecting a large number of taxa for the least cost. The few complementarity-based lotic conservation efforts all use broad river classifications instead of biota as targets, a method heavily disputed in the literature. They also ignore current condition and future vulnerability. It was the aim of this thesis to develop a framework for conservation planning that: a) accounts for the connected nature of rivers b) is complementarity based and uses biota as targets c) integrates current status and future vulnerability I developed two different approaches using macroinvertebrate datasets from Australia, Canada and the USA. The first new method was a site/based two-tiered approach integrating condition and conservation value, based on RIVPACS/AUSRIVAS � a modelling technique that predicts macroinvertebrate composition. The condition stage assesses biodiversity loss by estimating a site-specific expected assemblage and comparing it to the actual observed assemblage. Sites with significant biodiversity loss are flagged for restoration, or other management actions. All other sites progress to the conservation stage, in which an index of site-specific taxonomic rarity is calculated. This second index (O/E BIODIV) assesses the number of rare taxa (as defined by <50% probability of occurrence). Using this approach on a dataset near Sydney, NSW, Australia, I was able to identify three regions: 1) an area in need of restoration; 2) a region of high conservation value and 3) an area that had high conservation potential if protection and restoration measures could counteract present disturbance. However, a second trial run with three datasets from the USA and Canada highlighted problems with O/E (BIODIV). If common taxa are predicted at lower probabilities of occurrence (p<50%) because of model error, they enter the index and change O/E (BIODIV). Therefore, despite an attractive theoretical grounding, the application of O/E (BIODIV) will be restricted to datasets where strong environmental gradients explain a large quantity of variation in the data and permit accurate predictions of rare taxa. It also requires extensive knowledge of regional species pools to ensure that introduced organisms are not counted in the index. The second approach was a proper adaptation of terrestrial complementarity algorithms and an extension to the Irreplaceability-Vulnerability framework by Margules and Pressey (2000). For this large-scale method, distributions for 400 invertebrate taxa were modeled across 1854 subcatchments in Victoria, Australia using Generalised Additive Models (GAMs). The best heuristic algorithm to estimate conservation value was determined by calculating the minimum area needed to cover all 400 taxa. Solutions were restricted to include rules for the protection of whole catchments upstream of a subcatchment that contained the target taxon. A summed rarity algorithm proved to be most efficient, beating the second best solution by 100 000 hectares. To protect 90% of the taxa, only 2% of the study area need to be protected. This increases to 10% of the study area when full representation of the targets is required. Irreplaceability was calculated by running the heuristic algorithm 1000 times with 90% of the catchments randomly removed. Two statistics were then estimated: f (the frequency of selection across 1000 runs) and average c (contribution to conservation targets). Four groups of catchments were identified: a) catchments that have high contributions and are always selected; b) catchments that have high contributions and are not always selected; c) catchments that are always chosen but do not contribute many taxa; d) catchments that are rarely chosen and did not contribute many taxa. Summed c, the sum of contributions over 1000 runs was chosen as an indicator of irreplaceability, integrating the frequency of selection and the number of taxa protected. Irreplaceability (I) was then linked to condition (C) and vulnerability (V) to create the ICVframework for river conservation planning. Condition was estimated using a stressor gradient approach (SGA), in which GIS layers of disturbance were summarised to three principal axes using principal components analysis (PCA). The main stressor gradient � agriculture � classified 75% of the study area as disturbed, a value consistent with existing assessments of river condition. Vulnerability was defined as the likelihood that land use in a catchment would intensify in the future. Hereby current tenure was compared to land capability. If a catchment would support a land use that would have a stronger effect on the rivers than its current tenure, it was classified as vulnerable. 79% of catchments contained more than 50% vulnerable land. When integrating the three estimators in the ICV-framework, seven percent of catchments were identified as highly irreplaceable but in degraded condition. These were flagged for urgent restoration. Unprotected, but highly irreplaceable and highly vulnerable catchments that were still in good condition made up 2.5% of the total area. These catchments are prime candidates for river reserves. The ICV framework developed here is the first method for systematic conservation planning in rivers that is complementarity-based, biota-driven but flexible to other conservation targets and accounts for catchment effects, thus fulfilling all the gaps outlined in the aims.

The objective of this project was to determine if Galaxiella nigrostriata populations could belong to a metapopulation. Metapopulation theory describes how multiple populations with occasional connectivity are a ‘population of populations’. Some populations’ habitats have optimal conditions (source habitats), others experience regular extinctions (sink habitats). Connectivity allows repopulation of extinct or uninhabited habitats. Galaxiella nigrostriata occurred randomly in 11 seasonal wetlands in the Kemerton wetland complex in south-west Western Australia over a 16 year period. The wetlands did not appear to be connected. Around 70% of wetlands on the Swan Coastal Plain in south-west WA have been filled or degraded since European settlement around 180 years ago. Of those, seasonal wetlands are at most risk from degradation. Galaxiella nigrostriata mainly live in seasonal wetlands between Augusta and Albany and in three remnant populations on the Swan Coastal Plain. They are small freshwater fish (length), aestivate in moist wetland sediments when wetlands dry and live for about one year. Seasonal wetlands and G. nigrostriata are threatened by nutrient enrichment, salinity, introduced fish, landscape modification and changes to hydroperiod by groundwater abstraction and declining rainfall. Inundated wetlands that previously contained G. nigrostriata, and wetlands where they had not been recorded, were sampled throughout south-west WA. Fish and crayfish abundance was surveyed and water samples analysed on site and in a laboratory. Physical characteristics of each wetland and surrounding landscape were also recorded. Information about wetlands was analysed to determine if physico-chemical characteristics accounted for G. nigrostriata abundance or distribution between wetlands. Lentocorrals were then established in two Kemerton wetlands prior to inundation. They were sampled following inundation to determine how and where within a wetland G. nigrostriata entered the sediment to aestivate. Aestivation was examined to determine whether any physical features may be lacking which could inhibit population persistence. Galaxiella nigrostriata specimens from each population had morphological measurements and counts taken prior to tissue being removed for genetic analyses. Two mitochondrial DNA markers were used to investigate divergence and connectivity within and between populations and catchments. Most wetlands were small (mean 0.6 ha), had tannin-stained water and 41% vegetation cover. All wetlands exceeded guideline values for Fe and Zn and those near agricultural land exceeded guideline values for TN and TP. However, no physico-chemical water properties or habitat features impeded G. nigrostriata abundance or distribution between wetlands. Additionally, it was thought there may be a commensal relationship between G. nigrostriata and burrowing crayfish, with G. nigrostriata using burrows to enter the sediment. No relationship was found between G. nigrostriata, crayfish or their burrows, indicating an alternative way for them to enter the sediment. Genetic research and examination of wetland positions in the landscape confirmed G. nigrostriata populations (particularly Kemerton) are part of metapopulation. This research showed populations between catchments had not connected for thousands of years but populations in wetland complexes had recent connectivity. Management of wetlands requires investigation and monitoring of nearby wetlands which may be part of a metapopulation, and may affect population longevity of all wetlands.

This project is comprised of a creative work and accompanying exegesis. The creative work is a collection of poetry which examines the history and ecology of the wetlands and river systems of the Swan Coastal Plain, and which utilises the practice of walking as a research methodology. For the creative practitioner walking reintroduces the body as a fundamental definer of experience, placing the investigation centrally in the corporeal self, using the physical senses as investigative tools of enquiry. As Rebecca Solnit comments in her history of walking, ‘exploring the world is one of the best ways of exploring the mind, and walking travels both terrains’ (Solnit, 2000, p. 13). The context for my poetic walking project Swamp, is a local and global environment undergoing an unprecedented loss of biodiversity, mainly due to the destruction of habitat and changes in climatic conditions (Reid, Partha Dasgupta, Robert M. May, A.H. Zakri, & Henk Simons, 2005, pp. 438-442). The loss of species and ecosystems that have been a part of our earth home results in the human experience of ‘homesickness’ — a longing for the home places that we have known and which have diminished or disappeared. Before the arrival of the British colonists in 1829, the Swan River and adjacent wetlands were an integral part of the seasonal food source for the original inhabitants, the Noongar (Bekle, 1981). In addition wetland places were, and are, deeply embedded in the spiritual and cultural life of the Noongar people of the Swan Coastal Plain (O'Connor, Quartermaine, & Bodney, 1989). In less than two hundred years since the establishment of the Swan River Colony (Western Australia), the lakes and rivers of the Swan Coastal Plain have undergone extreme changes, often resulting in complete draining and in-filling of wetland areas as the city and its suburbs spread beyond the original town limits. This re–engineering of the landscape has had a dramatic and detrimental impact upon biodiversity, water quality and the sense of place experienced by residents. Swamp is a project that has three main facets: a) a body of original poetry which interprets the historical relationship between the British, European, and Chinese newcomers to Noongar country, and the wetlands lakes of the Swan Coastal Plain. The poetry contained in this thesis is copyright to the author, Anandashila Saraswati (Nandi Chinna). b)An essay which contextualises the project within the sphere of walking art, psychogeography, and the philosophical idea of ‘Homesickness’. c) A website, www.swampwalking.com.au, which displays photographs documenting the walks I have carried out over the three year period of the project from February 2009 to February 2012. The exegetical part of this project looks at the notion of ‘homesickness’ as a philosophical condition that can be seen as a motivating force in the practice of writing on walking. I use Debord’s theory of the dérive as a starting point for my walking methodology and examine nostalgia within the Situationist International (Debord, 1958) and subsequent psychogeographical movements. I also investigate the role of homesickness in the work of other writers who walk and who write about their walking practice. Finally I discuss homesickness in the epoch of the Anthropocene (Crutzen & Schwägerl, 2011), the era in which the earth’s biosphere is characterised by human interventions which have changed the meteorological, geological and biological elements of our earth home. In the Anthropocene, the wilderness view of nature needs to be re-evaluated. I posit that walking is a way of reconnecting with the physical landscape and building relationships with small wilds that exist in our home places, and that writing about the walking allows these relationships and encounters to ripple out to readers, contributing to and enabling the development of an ethic of care for ecosystems and beings other than human.

Non-native invasive plant species can often have negative effects on native ecosystems, such as altered nutrient cycling, decreased habitat for wildlife, and outcompeting native plants. Around the Great Salt Lake (GSL), Utah, the invasive wetland grass Phragmites australis has become abundant in wetlands around the lake. Phragmites is replacing many native wetland plants provide important waterfowl habitat around the GSL. For successful management of Phragmites in GSL wetlands, it is important to know the current distribution of Phragmites, as well as areas that might be vulnerable to future invasion by Phragmites. To do this, we used multispectral aerial imagery to map the current distribution of Phragmites. We then created a model that statistically related the Phragmites distribution data to a suite of environmental predictor variables such as salinity, proximity to nutrient sources, or proximity to roads. Results from our model suggest that Phragmites is more likely to be found in wetland areas close to point sources of pollution, with lower elevations with prolonged inundation, and with moderate salinities. We used these results to identify areas around GSL that might be vulnerable to future invasion. Results from our study will assist wetlands managers in prioritizing areas for Phragmites monitoring and control by closely monitoring areas of prime Phragmites habitat.

The recent and rapid expansion of Phragmites australis in North America provides an opportunity to relate dispersal patterns to landscape structure. Linear wetlands, such as roadside or agricultural ditches, may serve as corridors that facilitate dispersal at the landscape scale, but there is little quantitative information on patterns of invasion in these habitats. Remote sensing data, GIS, and field observations were used (1) to assess the feasibility of mapping populations of P. australis in linear wetlands and (2) to quantify and explain recent invasion patterns of P. australis in two periurban areas of southern Quebec. An accuracy assessment demonstrated the reliability of aerial photographs to map populations in linear habitats. The intrinsic growth rate observed is high compared to those reported in natural wetlands. Spatial analysis revealed that colonization events are not constrained by the network's configuration. Logistic regressions confirmed the effect of road corridors on the spread of P. australis.

Most studies of wetlands tend to focus on the biotic and abiotic interactions within the aquatic habitat. Though wetlands and associated biota may appear to be somewhat isolated from the influence of the wider landscape, wetland habitats are critically linked with adjacent terrestrial habitats and other wetlands through the two-way flows of energy and nutrients and provision of structure. While an understanding of these inter-habitat linkages is breaking down the perceived boundaries between "aquatic" and "terrestrial" ecosystems, there is more limited knowledge on the ecology of wetland animals that must meet critical needs in both aquatic and terrestrial habitats at some time during their life or seasonal cycles. Here, I examine the terrestrial ecology of a freshwater turtle, the eastern long-necked turtle (Chelodina longicollis) in the temporally dynamic and heterogeneous landscape of Booderee national park in south-east Australia by 1) providing a description of terrestrial behaviours, 2) identifying the factors driving terrestrial behaviour and its functional significance, 3) examining factors that may limit or constrain terrestrial behaviour and 4) demonstrating how various terrestrial behaviours can factor prominently in the overall biology of a nominally aquatic animal. Chelodina longicollis used terrestrial habitats for reasons other than nesting, including aestivation and movements between wetlands. Radio-telemetry of 60 turtles revealed that nearly 25 % of all locations were in terrestrial habitats up to 505 m from the wetland, where turtles remained for extended periods (up to 480 consecutive days) buried under sand and leaf litter in the forest. Individuals also maintained an association with a permanent lake and at least one temporary wetland within 1470 m, though some inter-wetland dispersal movements were much longer (5248 m). As a result of their associations with several wetlands and terrestrial aestivation sites, C. longicollis traversed large areas and long distances (13.8 +/- 2.8 ha home range, 2608 +/- 305 m moved), indicating that this species is highly vagile. In fact, a three-year capture-mark-recapture study conducted in 25 wetlands revealed that 33% of the population moved overland between wetlands. After scaling this rate to the number of generations elapsed during the study, C. longicollis moved between discrete water bodies at a rate of 88-132% per generation. This rate is not only high for freshwater turtles, but is among the highest rates of inter-patch movement for any vertebrate or invertebrate. Chelodina longicollis demonstrated an impressive capacity for individual variation in nearly every aspect of its behaviour examined. Most of the variation in space use, movements, terrestrial aestivation and activity could be attributed to extrinsic local and landscape factors, seasonal influences and rainfall, whereas intrinsic attributes of the individual such as sex, body size, body condition and maturity status were less important. Turtles increased movement distance and home range size in regions where inter-wetland distances were farther and with increasing wetland size. Individuals spent more time in terrestrial habitats with decreasing wetland hydroperiod and increasing distance to the nearest permanent lake. Overland movements between wetlands were correlated with rainfall, but the directionality of these movements and the frequency with which they occurred varied according to the prevalent rainfall patterns; movements were to permanent lakes during drought, but turtles returned to temporary wetlands en masse upon the return of heavy rainfall. However, deteriorating conditions in drying wetlands forced turtles to move even in the absence of rainfall. Captures at a terrestrial drift fence revealed that immature turtles as small as 72.3 mm plastron length may move overland between wetlands with similar frequency as larger adults. Taken together, these results suggest that C. longicollis behaviour is in part conditional or state-dependent (i.e., plastic) and shaped by the spatiotemporal variation and heterogeneity of the landscape. Perhaps the most surprising aspect of individual variation was the alternate responses to wetland drying. Turtles either aestivated in terrestrial habitats (for variable lengths of time), or moved to other wetlands. Movement to other wetlands was the near universal strategy when only a short distance from permanent lakes, but the proportion of individuals that aestivated terrestrially increased with distance to the nearest permanent lake. When long distances must be travelled, both behaviours were employed by turtles in the same wetland, suggesting that individuals differentially weigh the costs and benefits of residing terrestrially versus those of long-distance movement. I propose that diversity in response to wetland drying in the population is maintained by stochastic fluctuations in resource quality. The quality of temporary wetlands relative to permanent wetlands at our study site varies considerably and unpredictably with annual rainfall and with it the cost-benefit ratio of each strategy or tactic. Residency in or near temporary wetlands is more successful during wet periods due to production benefits (high growth, reproduction and increased body condition), but movement to permanent wetlands is more successful, or least costly, during dry periods due to the fitness benefits of increased survival and body condition. I used the doubly-labelled water (DLW) method to provide the first estimates of water and energy costs of aestivation and overland movement for any freshwater turtle behaving naturally in the field. Chelodina longicollis remained hydrated while terrestrial with water flux rates (14.3-19.3 ml kg-1 d-1) on par with those of strictly terrestrial turtles, but field metabolic rate during aestivation (20.0-24.6 kJ kg-1 d-1) did not indicate substantial physiological specializations in metabolism during aestivation. Energy reserves, but not water, are predicted to limit survival in aestivation to an estimated 49-261 days, which is in close agreement with the durations of natural aestivation. The energy costs of overland movement were 46-99 kJ (kg d)-1, or 1.6-1.7 times more expensive than aestivation. When a wetland dries, a turtle that foregoes movement to other wetlands can free sufficient energy to fuel up to 134 days in aestivation. The increasing value of this energy "trade-off" with travel distance fits our behavioural observations of variance in response to wetland drying. Taken together, this evidence indicates that terrestrial habitats provide more than just organic and structural inputs and filtering services and that nearby wetlands are important for reasons other than potential sources of occasional colonists to a population. Terrestrial habitats are used for aestivation in response to wetland drying and different wetlands are diverse in their functions of meeting the annual or life-cycle requirements of C. longicollis in temporally dynamic wetland systems. As overland movements between these various habitat types are in response to spatiotemporal variation in habitat quality and associated shifts in the fitness gradient between them, I suggest that terrestrial and different aquatic habitats in Booderee offer complementary resources contributing to regional carrying capacity and population persistence of the turtle population. Thus, important ecological processes regulating C. longicollis in a focal wetland should not be viewed as operating independently of other nearby wetlands and their adjacent terrestrial habitats. Collectively, these findings highlight the complex and dynamic associations between a population of freshwater turtles and the wider terrestrial and aquatic landscape, demonstrating that turtle populations and the factors that impact them can extend well beyond the boundaries of a focal wetland.

South Milton Ley is a small coastal wetland in Southern England. A sand-bar forms periodically at its seaward end and separates fresh water from the sea. The common reed Phragmites australis dominates the wetland and when a sand bar is present a shallow freshwater lake forms. Monthly water budgets were prepared for the years 1994, 1995 and 1996 and intermittent flooding of the Ley was also monitored. This information was used to calculate a range of residence times (between one hour and eleven days) and the characteristics of various flow regimes when the sandbar, which dams the Ley, is open or closed. Reed growth and the lake's ecology are potentially influenced by effluent from a sewage treatment works (STW) that discharges into the wetland. Water chemistry and hydrology of the wetland have been studied alongside experiments to investigate any effects of nutrient enrichment from the STW on reed growth. Inflowing and outflowing waters were analysed in order to determine concentrations of total oxidised nitrogen (TON), total dissolved nitrogen (TDN), soluble reactive phosphorus (SRP), total dissolved phosphorus (TDP) and potassium (K). Over the study period the annual load of SRP to the Ley increased from 3.65 gmˉ² aˉ¹ in 1992 to 8.1 gmˉ² aˉ¹ in 1996. TON load rose from 69.35 g mˉ² aˉ¹ in 1992 to 104.8 g mˉ² aˉ¹ in 1996. K fell from 97.3 g mˉ² aˉ¹ in 1994 to 96.4 g mˉ² aˉ¹ in 1996. The STW uses a Reedbed Treatment System (RBTS) to 'polish' its final effluent. The efficiency o f the RBTS was studied and during 1996 the efficiency rate for T ON was 20.9% and for SRP was 9.3%. Measurements of height, diameter, numbers of internodes, density and biomass of reeds collected from South Milton Ley were undertaken during August 1994 and 1995. Results of analyses for 1994 indicate that reeds were thinner and possessed fewer seedheads than those of 1995 but that density was greater. Reed fieldwork during 1994 found that height, diameter, numbers of internodes, biomass and number of seedheads were greater below the STW than above. During 1995 only seedhead production was greater below the outlet. The wettest area of the Ley contained reeds with greatest height and diameter. The driest area produced a higher density of reed growth. Laboratory experiments suggested that low N:K ratios and high P:K produced taller plants. Data from reed fieldwork together with results from hydrology and water chemistry studies were used in a statistical analysis in order to determine which, if any of these factors caused changes in reed growth. A conclusive link between water chemistry, hydrology and plant variables was not found. Correlation analysis for 1994 indicated that high concentrations of SRP and TON could produce thin reeds with low biomass. Analysis for 1995 suggested that elevated K values could produce a high density of short reeds. Water depth was found to have a significant effect (P < 0.001) on diameter. The key factors for reed decline (high water levels from spring to winter which can inhibit reed regeneration and increase residence times, increasing nutrient loads and changes in the ratio of N:P:K which could alter reed growth) are all present. At its present loading the Ley is nutrient rich and does not appear to be buffering wetland waters. After data analysis and fieldwork was completed a bloom of Oscillatoria sp.occurred at the seaward end of the Ley during August 1999. This, the first know occurrence of a bloom may be an indication that changes in the ecosystem of South Milton Ley are occurring. For the future, a programme of nutrient reduction, hydrological management and growing knowledge of wetland processes may prevent adverse changes.

Relatively little published information on cyanoprokaryote (blue-green algal) blooms in the freshwater wetlands in Western Australia is available. There has been little research on the urban lakes and rivers, examining the relationship between environmental conditions and toxin-producing blooms. In this project the ecology, morphology and toxicity of cyanoprokaryota blooms in 27 metropolitan lakes and sumplands, as well as three major rivers, from 2000 to 2003, on the Swan Coastal Plain (SCP) in the southwest of Western Australia were investigated.A total of 24 species were identified and described, of which nine species had not been previously documented in the area. This included the potentially toxic species Cylindrospermopsis raciborskii, Aphanizomenon ovalisporum and Anabaena bergii var. limnetica. An illustrated guide to the common bloom-forming species was generated using conventional taxonomic criteria.Microcystis flos-aquae and Microcystis aeruginosa were the dominant bloom-forming cyanoprokaryotes, widespread in their distribution. Anabaena circinalis, A. bergii var. limnetica and Anabaenopsis elenkinii were the common filamentous species. Anabaena circinalis was common to certain freshwater sites, while A. bergii var. limnetica and A. elenkinii occurred in salinity ranging from fresh (< 1ppt) to hyposaline (3-10 ppt). Sites with similar species assemblages were identified using two-way indicator species analysis and clustering analysis. From this, a distinct distribution pattern emerged, which was defined by the main genera observed in the lakes – Microcystis, Anabaena, Aphanizomenon and Anabaenopsis.The spatial and temporal distribution of the common bloom-forming cyanoprokaryote species was examined in conjunction with spring-summer physico-chemical data using principal component analysis. It was found that pH, water temperature and electrical conductivity/salinity accounted for variations among the lakes, with electrical conductivity the variable explaining the greatest variation. Lakes located on the coast, or further inland at the base of the Darling Scarp, were more hyposaline to saline, and the remaining lakes were fresh. Although the SCP lakes form consanguineous groups based on geochemistry and hydrology, no similarities among them were found in terms of water quality.The relationship between nitrogen (N) and phosphorus (P) concentrations (total and dissolved inorganic) and cyanoprokaryote community structure (N-fixing versus non-N-fixing species) was investigated in five selected lakes; Yangebup Lake, Bibra Lake, Blue Gum Lake, Tomato Lake and Emu Lake. The lakes ranged from mesotrophic to eutrophic and supported spring-summer blooms containing multiple species. Overall an inverse relationship between cyanoprokaryote abundance and total ambient nutrient concentrations at the time of the blooms was evident. No transition in dominance in the community was observed in Yangebup Lake, Emu Lake and Bibra Lake, as they were dominated by non-heterocytic species (M. aeruginosa and M. flos-aquae) throughout spring and summer. For Yangebup Lake and Bibra Lake, the abundance of non-heterocytic species decreased concomitantly with decreasing dissolved inorganic N. In contrast, heterocytic species (A. circinalis) dominated the spring community in Tomato Lake, and summer community in Blue Gum Lake, when N and P concentrations were at their highest.The presence of microcystins in Microcystis dominated blooms was examined using high performance chromatography. A total of 32 natural bloom samples, representing 13 lakes, were analysed for microcystin variants; -LR, -RR and -YR. Twenty-eight samples proved to be toxic with the highest total microcystin concentration from 1645 to 8428.6 µg L[superscript]-1, the lowest concentrations were less than 10 µg L[superscript]-1 with some below the detection limit. Microcystis aeruginosa and M. flos-aquae were associated with these microcystin-containing blooms, although M. flos-aquae appear to be less toxic. The presence of Nodularia spumigena in the Lake Yangebup was associated with high concentrations of nodularin (1664 µg L[superscript]-1).Employing enzyme-linked immunosorbent assay for microcystins and the brine shrimp (Artemia) bioassays allowed a greater number of lake samples to be analysed and provided a rapid assessment of toxicity. The three methods for cyanotoxin detection verified Yangebup Lake, Herdsman Lake, Hyde Park, Jackadder Lake and Emu Lake as highly toxic sites. Low toxicity was demonstrated in samples from Lake Goollelal, Lake Joondalup, Lake Claremont, Blue Gum Lake and North Lake. These results provided the first evidence of cyanotoxin producing blooms in urban lakes of the SCP.A comparative study on cyanoprokaryota blooms in Swan River estuary, upper Canning River and upper Serpentine River found that these sites, although hyposaline to saline, contained species that were common in the freshwater lakes. Sampling the river systems showed M. aeruginosa, M. flos-aquae, A. circinalis, A. elenkinii and Planktothrix planctonica to be cosmopolitan in distribution, present in SCP wetlands of varied salinity. Similarities between the upper Canning River and lakes in environmental conditions and species assemblage were demonstrated using multivariate analyses.Toxin analysis of bloom samples from the Swan River and upper Canning River revealed microcystin concentrations were less than that of the surrounding lakes (1.05-124.16 µg L[superscript]-1). Similarly, nodularin concentrations were higher in Yangebup Lake than the upper Serpentine River. However, the dominance of Anabaena in Canning River samples, and the highly toxic result from the Artemia bioassay suggests microcystin is not the predominant cyanotoxin in this wetland.This study has produced an overview of the distribution and morphology of cyanotoxin-producing cyanoprokaryotes in the SCP wetlands. The data presented provide the basis for further cyanoprokaryote research in Western Australia, in particular the molecular characterisation of bloom-forming toxic species.

Phragmites australis (hereafter Phragmites) often forms dense monocultures, which displace native plant communities and alter ecosystem functions and services. Managers tasked with controlling this plant need science-backed guidance on how to control Phragmites and restore native plant communities. This study took a large-scale approach - to better match the scale of actual restoration efforts - to compare two herbicides (glyphosate vs. imazapyr) and application timings (summer vs. fall). Five treatments were applied to 1.2 ha plots for three consecutive years: 1) summer glyphosate; 2) summer imazapyr; 3) fall glyphosate; 4) fall imazapyr; and 5) untreated control. Dead Phragmites following herbicide treatments was mowed in the first two years. Efficacy of treatments and the response of native plant communities were monitored for three years. We report that fall herbicide applications were superior to summer applications. No difference was found between the two herbicides in their ability to reduce Phragmites cover. Plant communities switched from emergent to open water communities and were limited by Phragmites litter and water depth. Although, some plant communities showed a slow trajectory towards one of the reference sites, cover of important native emergent plants did not increase until year three and remained below 10%. These results suggest that fall is the best time to apply herbicides for effective large-scale control of Phragmites. Active restoration (e.g. seeding) may be needed to gain back important native plant communities. Methods to reduce Phragmites litter after herbicide applications should be considered.

Relatively little published information on cyanoprokaryote (blue-green algal) blooms in the freshwater wetlands in Western Australia is available. There has been little research on the urban lakes and rivers, examining the relationship between environmental conditions and toxin-producing blooms. In this project the ecology, morphology and toxicity of cyanoprokaryota blooms in 27 metropolitan lakes and sumplands, as well as three major rivers, from 2000 to 2003, on the Swan Coastal Plain (SCP) in the southwest of Western Australia were investigated.
A total of 24 species were identified and described, of which nine species had not been previously documented in the area. This included the potentially toxic species Cylindrospermopsis raciborskii, Aphanizomenon ovalisporum and Anabaena bergii var. limnetica. An illustrated guide to the common bloom-forming species was generated using conventional taxonomic criteria.
Microcystis flos-aquae and Microcystis aeruginosa were the dominant bloom-forming cyanoprokaryotes, widespread in their distribution. Anabaena circinalis, A. bergii var. limnetica and Anabaenopsis elenkinii were the common filamentous species. Anabaena circinalis was common to certain freshwater sites, while A. bergii var. limnetica and A. elenkinii occurred in salinity ranging from fresh (< 1ppt) to hyposaline (3-10 ppt). Sites with similar species assemblages were identified using two-way indicator species analysis and clustering analysis. From this, a distinct distribution pattern emerged, which was defined by the main genera observed in the lakes – Microcystis, Anabaena, Aphanizomenon and Anabaenopsis.
The spatial and temporal distribution of the common bloom-forming cyanoprokaryote species was examined in conjunction with spring-summer physico-chemical data using principal component analysis. It was found that pH, water temperature and electrical conductivity/salinity accounted for variations among the lakes, with electrical conductivity the variable explaining the greatest variation. Lakes located on the coast, or further inland at the base of the Darling Scarp, were more hyposaline to saline, and the remaining lakes were fresh. Although the SCP lakes form consanguineous groups based on geochemistry and hydrology, no similarities among them were found in terms of water quality.
The relationship between nitrogen (N) and phosphorus (P) concentrations (total and dissolved inorganic) and cyanoprokaryote community structure (N-fixing versus non-N-fixing species) was investigated in five selected lakes; Yangebup Lake, Bibra Lake, Blue Gum Lake, Tomato Lake and Emu Lake. The lakes ranged from mesotrophic to eutrophic and supported spring-summer blooms containing multiple species. Overall an inverse relationship between cyanoprokaryote abundance and total ambient nutrient concentrations at the time of the blooms was evident. No transition in dominance in the community was observed in Yangebup Lake, Emu Lake and Bibra Lake, as they were dominated by non-heterocytic species (M. aeruginosa and M. flos-aquae) throughout spring and summer. For Yangebup Lake and Bibra Lake, the abundance of non-heterocytic species decreased concomitantly with decreasing dissolved inorganic N. In contrast, heterocytic species (A. circinalis) dominated the spring community in Tomato Lake, and summer community in Blue Gum Lake, when N and P concentrations were at their highest.
The presence of microcystins in Microcystis dominated blooms was examined using high performance chromatography. A total of 32 natural bloom samples, representing 13 lakes, were analysed for microcystin variants; -LR, -RR and -YR. Twenty-eight samples proved to be toxic with the highest total microcystin concentration from 1645 to 8428.6 µg L[superscript]-1, the lowest concentrations were less than 10 µg L[superscript]-1 with some below the detection limit. Microcystis aeruginosa and M. flos-aquae were associated with these microcystin-containing blooms, although M. flos-aquae appear to be less toxic. The presence of Nodularia spumigena in the Lake Yangebup was associated with high concentrations of nodularin (1664 µg L[superscript]-1).
Employing enzyme-linked immunosorbent assay for microcystins and the brine shrimp (Artemia) bioassays allowed a greater number of lake samples to be analysed and provided a rapid assessment of toxicity. The three methods for cyanotoxin detection verified Yangebup Lake, Herdsman Lake, Hyde Park, Jackadder Lake and Emu Lake as highly toxic sites. Low toxicity was demonstrated in samples from Lake Goollelal, Lake Joondalup, Lake Claremont, Blue Gum Lake and North Lake. These results provided the first evidence of cyanotoxin producing blooms in urban lakes of the SCP.
A comparative study on cyanoprokaryota blooms in Swan River estuary, upper Canning River and upper Serpentine River found that these sites, although hyposaline to saline, contained species that were common in the freshwater lakes. Sampling the river systems showed M. aeruginosa, M. flos-aquae, A. circinalis, A. elenkinii and Planktothrix planctonica to be cosmopolitan in distribution, present in SCP wetlands of varied salinity. Similarities between the upper Canning River and lakes in environmental conditions and species assemblage were demonstrated using multivariate analyses.
Toxin analysis of bloom samples from the Swan River and upper Canning River revealed microcystin concentrations were less than that of the surrounding lakes (1.05-124.16 µg L[superscript]-1). Similarly, nodularin concentrations were higher in Yangebup Lake than the upper Serpentine River. However, the dominance of Anabaena in Canning River samples, and the highly toxic result from the Artemia bioassay suggests microcystin is not the predominant cyanotoxin in this wetland.
This study has produced an overview of the distribution and morphology of cyanotoxin-producing cyanoprokaryotes in the SCP wetlands. The data presented provide the basis for further cyanoprokaryote research in Western Australia, in particular the molecular characterisation of bloom-forming toxic species.

Phragmites australis is a plant that is causing problems in wetlands by outcompeting native plants that provide food and shelter for millions of migratory birds. Currently, managers try to control Phragmites australis by spraying herbicide, burning, and mowing, but these methods are costly, time consuming, and have low levels of success. Adding grazing as a tool to control Phragmites australis provides a cheap and low labor alternative. However, there are many concerns regarding if grazing will cause nutrient loading in our wetlands that will decrease water quality and alter beneficial functions of wetlands. To better understand the effects of grazing in wetlands, we proposed a two-year study and received funding from many organizations including the Utah Department of Fire, Forestry, and State Lands, South Davis Sewer District, and the Utah Department of Environmental Quality and Water Quality. Also, the Utah Department of Natural Resources helped tremendously in allowing access to the sites, in the actual implementation of the project, coordinating with local ranchers who allowed for their cattle to be in the study, managed their cattle during the study, and assisted with fence installation, and many volunteers from Utah dedicated hunters helped with the fence installation. We collected water, manure, soil, and leaf samples over time to analyze nutrient changes and measured changes in the plants, water levels, soil cover, and litter cover over time. We then compiled and analyzed this information to better understand how grazing impacts our wetlands. As a result, we were able to make some recommendations for future research and how best to graze in wetlands with minimal impacts according to the information we found.

Biological invasions have adverse economic, cultural, and ecological effects worldwide. Among the most impactful in North America is the invasion of Phragmites australis (Phragmites), a large-scale clonal grass that rapidly colonizes wetlands. Phragmites crowds out native plants and alters habitat for native fauna. In doing so, Phragmites also alters human access to water resources and has adverse economic effects, including decreasing property value, inhibiting recreational use, and limiting populations of game species. The efforts described in this dissertation are a component of a large, multidisciplinary effort to better understand the anthropogenic stressors to Chesapeake Bay, Maryland, at the land/water interface. Utah State University worked in collaboration with the Smithsonian Environmental Research Center and other academic and public organizations to address this problem from multiple directions. The diverse and extensive studies ranged from aquatic and avian faunal composition and submerged aquatic vegetation to our work on the invasive wetland grass, Phragmites. Having assessed the existing literature and its shortcomings, we conducted a large-scale, long-term study of the effects of Phragmites removal on the Bay. By removing Phragmites from plots in select sub-estuaries of Chesapeake Bay through herbicide spraying, leaving associated plots intact, and comparing both with native wetland conditions, we sought to better understand herbicidal management of Phragmites and the potential for wetland plant community recovery. Although sprayings decreased the relative cover, stem diameters, and stem densities of Phragmites, we found that herbicide treatment alone was not adequate to restore native plant communities or significantly affect seedbank composition. Our results demonstrate the resilience of Phragmites and call for a diverse range of control measures, including mowing, grazing, burning to expose the seedbank to germination, and—if economics allow—active revegetation to establish the desired plant community composition. This dissertation provides beneficial data for those who seek to manage Phragmites in wetland plant communities, but there is much work still to be done. The literature review, seedbank study, and community analysis included in this volume are components of a larger research program on Phragmites management. Future studies should, in particular, investigate revegetation and nutrient amelioration as means to recover pre-invasion vegetation.

Invasive plants can outcompete native plants, replacing diverse plant communities with monocultures, which can negatively impact the whole ecosystem. One invasive plant, Phragmites australis, has invaded wetlands across North America. In Utah’s Great Salt Lake, it has greatly reduced the area of native plants that are important habitat for migratory birds. Here we describe experiments that assess multiple treatments for Phragmites removal and evaluate the return of native plants after Phragmites management. The treatments were applied to Phragmites patches at two scales (small 1/4-acre plots and large 3-acre plots) and across multiple sites to evaluate how patch size and environmental differences can influence the plants that return after Phragmites removal. The treatments (applied over 3 years and monitored two more) compared two different herbicides (glyphosate and imazapyr) and different herbicide and mowing timings. The treatments evaluated in the large patch study were 1.) untreated control 2.) fall glyphosate, winter mow, 3.) summer imazapyr, winter mow, 4.) summer glyphosate, winter mow. The treatments evaluated in the small patch study included treatments 1-4 above plus 5.) summer mow, fall glyphosate, 6.) summer mow, then black plastic solarization. In the small patches, we also monitored the seeds in the soil to assess how Phragmites management treatments can change the densities of Phragmites and native seeds. Fall glyphosate treatments were superior for Phragmites cover reduction. After the initial treatment, summer herbicide and mow treatments reduced Phragmites seed production, while fall glyphosate did not. Phragmites seeds were plentiful in the soil but were reduced following three years of all herbicide treatments. Native plant recovery following Phragmites management was extremely variable across sites. Sites with high soil moisture had better Phragmites removal and more native plants. But when flooding was deep, native plants were rare. Native seed density in the soil did not change due to Phragmites management, but soil seed densities were different across sites, which influenced native plant recruitment. Phragmites was removed more effectively and native plants returned in greater numbers in small patches compared with large. This was because small patches were typically near established native plant communities, which likely provided more native plant seeds and had hydrology that was less disturbed by human activity. In sites where native plants do not return after Phragmites management, practitioners may need to try revegetation with native plant seeds to restore important native plant communities.

Thesis (M.S.)--Kent State University, 2008.
Title from PDF t.p. (viewed Oct. 27, 2009). Advisor: Laura Leff. Keywords: Phragmites australis; Scirpus cyperinus; glyphosate; microbes; ergosterol; invertebrates. Includes bibliographical references (p. 47-59).

The Upper South East (USE) region of South Australia covers over 1M ha and is the largest area affected by dryland salinity in South Australia. In 1999, it was estimated that 40% of the region was affected by salinity. To mitigate the threat of flooding and secondary salinisation, an extensive network of drains has recently been constructed. Whilst these drains may have a positive effect on the agricultural land, the impacts they will have on the hundreds of wetlands in the region is as yet, unknown. It is likely that the hydrologic regimes the wetlands are exposed to will be highly modified and the quality of the water that supplies them will be greatly affected by high salinity levels. This work examined the impact of these landscape scale changes on wetlands in the South East region of South Australia and investigated ways in which water from the drainage system might be used for ecological benefit in wetlands. The aims were to: • determine whether there have been changes in species composition that can be linked to changes in the salinity and hydrology regimes experienced in the wetlands and to gain a better understanding of the processes and mechanisms that drive the change in species composition and cause salt to accumulate in wetlands via the development of a conceptual model; • produce curves predicting the probability of occurrence in relation to salinity for species common in wetlands in the South East of South Australia; • investigate the effects of an increase in salinity with decreasing water depth as a result of evapoconcentration on the growth and survival of three common freshwater macrophytes, and to determine the consequences of longterm exposure to elevated salinity conditions; • assess the impact of a pulsed discharge of saline drainage water of varying concentrations and durations on key wetland species in an effort to determine how to make best use of the scarce water resources in the region and; and • assess the combined effects of salinity and hydrology on the seed banks of wetlands that have experienced drought and elevated salinity conditions. The results of vegetation surveys conducted pre-2000 and post-2000, indicate an overall change in species composition; species requiring fresh conditions are rarer or not recorded and are replaced by species preferring more saline conditions. This change is accompanied by a shift from fresher to saltier conditions and from wetter to drier conditions. Data from groundwater observation bores coupled with flow volumes in the local watercourses supports the process of salt accumulation in wetlands described in the conceptual model. The curves predicting the probability of occurrence in relation to salinity display a wide range in tolerances across the 15 species for which they were constructed, and highlight the variance due to between wetland differences. These curves, used in combination with knowledge gained from other studies will enable salinity thresholds to be set for many of the common species found in the South East region. Employing these thresholds to drain operation will allow wetlands to be managed in a way that will promote the occurrence of target species. The study on evapoconcentration effects showed that the percentage of biomass allocated to below ground structures was > 95, > 90, > 75 and > 80% for adult and juvenile T. procerum, and for B. arthrophylla and B. medianus respectively, across all salinity treatments suggesting that long term exposure to elevated salinity conditions results in a large investment in below ground biomass by all species. This study also indicated that the initial lifestage at time of exposure to the salinity regimes had a significant effect on the final dry weights of the T. procerum plants. The differences in the dry weights and leaf length and number were greatest between adults and juveniles in the lower salinity treatments (1500 and 6250 μS cm⁻¹), with the adults having much larger weights and measures. At higher salinities (12500 and 18750 μS cm⁻¹), there were no differences. Salinities refer to the salinity of the surface water, not soil salinity. For the plants tested in the pulse salinity regime experiment, the immediate effect of high salinity environments on non-halophytic plants was not detectable after three to six weeks of exposure, but the short term impact of the pulse did affect the ability of submerged plants to recover. The seed bank trial showed that the previous drought and salinity conditions experienced by a wetland did affect the seed bank however the water and salinity regime imposed mitigated these impacts. The study provides evidence that extended periods of drought conditions may lead to a seed bank which has a reduced abundance of seeds and repeated exposure to high salinity changes the species composition of the seed bank and reduces the overall diversity. Our knowledge of wetland plants, habitats, individual wetlands and their pattern in the landscape enables interpretation of how wetland plants have changed and will continue to change in the landscape. The challenge is to use, and build on this knowledge to predict what future wetland landscapes might look like under different management or development scenarios in the USE and to decide what is sustainable.
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences and School of Civil, Environmental and Mining Engineering, 2012

Bibliography: leaves 103-120.
1 v. (various pagings) : ill. (some col.), maps ; 30 cm.
Species interactions are dependent on the water regime, which affects the relative allocation to below (sediment resource acquisition) and above ground (C acquisition) parts. At shallow and regularily exposed sites, Baumea is the superior competitor. In Hacks and Bool Lagoon, South Australia, changing distribution patterns occur in deep and permanently flooded conditions, where Baumea dies back, paving the way for Triglochin to passively take it's place.
Thesis (Ph.D.)--Dept. of Botany, University of Adelaide, 1993

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library.
"The Lower Murray dairy swamps were once part of a series of freshwater wetlands stretching along the Murray to the Cooring. Of the original 5700 hectares of wetlands only 500 hectares remain today. While the dairy industry that has developed on the swamp has considerable commercial value, it has destroyed the natural water filtration function that the wetlands provided. The industry also causes high levels of dairly effluent to enter the River Murray, contributing to blue-green algae outbreaks and associated economic losses for the local tourism industry. This thesis provides valuable cost-benefit results on a set of three mutually exclusive land use and management options for dealing with the joint problems of water filtration and blue-green algae. The most important options examined involve the return of this area to wetlands for water filtration rather continuing to use it for dairy farming." --p. ix.
http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1284108
Thesis (Ph.D.) -- University of Adelaide, School of Economics, 2007

"The Lower Murray dairy swamps were once part of a series of freshwater wetlands stretching along the Murray to the Cooring. Of the original 5700 hectares of wetlands only 500 hectares remain today. While the dairy industry that has developed on the swamp has considerable commercial value, it has destroyed the natural water filtration function that the wetlands provided. The industry also causes high levels of dairly effluent to enter the River Murray, contributing to blue-green algae outbreaks and associated economic losses for the local tourism industry. This thesis provides valuable cost-benefit results on a set of three mutually exclusive land use and management options for dealing with the joint problems of water filtration and blue-green algae. The most important options examined involve the return of this area to wetlands for water filtration rather continuing to use it for dairy farming." --p. ix.
Thesis (Ph.D.) -- University of Adelaide, School of Economics, 2007

This study has several objectives. Firstly, to investigate the sexual reproductive ecology and germination requirements of Bolboschoenus caldwellii and Bolboschoenus medianus. Secondly, to examine the asexual growth mechanisms and responses of Bolboschoenus caldwellii and Bolboschoenus medianus to interesting salinity. Thirdly, to assess the genetic diversity of Bolboschoenus caldwellii and Bolboschoenus medianus stands from three wetlands with contrasting environmental conditions in the Gippsland Lakes region.

The effects of plant invasions on ecosystem structure and function are well studied but the pathways and mechanisms that underlie these effects remain poorly understood. In depth investigation of invasion mechanisms is vital to understanding why invasive plants impact only certain systems, and why only some invaders have disproportionately large impacts on the invaded community. There are many mechanisms such as lack of natural enemies or control mechanisms, the individual characteristics of the invader and invaded communities, direct and indirect resource competition, evolution or hybridisation, altered ecosystems processes, and allelopathy that may explain the invasion processes of plant species. Among these possible influences on invasion, allelopathy has received increased attention and study with the rise in understanding of its implications and potential disproportionate influence. However, identifying allelopathy and consequent phytotoxic effects as an important mechanism of plant invasion is a difficult task due to the potential for an individual plant to have many component chemicals with multiple modes of action, interactive effects, and synergistic interactions. For allelopathy to be implicated as a mechanism that facilitates invasion, multiple aspects of the plant species allelopathic properties must be examined. This research investigated allelopathy as a mechanism of the invasion process in Phragmites australis by a series of ecologically realistic experiments in the laboratory, greenhouse and field.

Au cours des dernières décennies, une grande variété de pesticides émergents, tels que le chlorantraniliprole (CAP), ont été introduits malgré le manque de connaissance approfondie de leur risque écotoxicologique. Les marais filtrants (TW) sont des technologies écologiques et durables qui ont montré un grand potentiel d’atténuation des polluants agricoles communs, tels que les pesticides dans le ruissellement. L’objectif de cette étude était d’optimiser l’utilisation du marais filtrant sous-surfacique à écoulement horizontal (HSSF) en déterminant: a) l'effet d’un amendement de biochar au substrat et b) la performance de trois espèces de macrophytes (Phragmites australis subsp. americanus, Scirpus cyperinus et Sporobolus michauxianus) dans l'abattement du CAP du ruissellement agricole. L'efficacité d'abattement a été calculée en utilisant la méthode du bilan de masse dans des mésocosmes HSSF matures alimentés avec un ruissellement agricole synthétique contenant du CAP pendant une période d'un mois. Les mésocosmes avec l’ajout de biochar se sont avérés très efficaces dans l’abattement du CAP (90 à 99%) et ils le sont restés tout au long de la période expérimentale. Cette efficacité est probablement due à la grande capacité d’adsorption du biochar, bien que ce mécanisme n’ait pas été directement mesuré. En revanche, l'abattement du CAP dans les mésocosmes plantés sans biochar était faible et limité et il n’y avait pas de différence entre les espèces, bien qu’elles aient eu des différences dans leur biomasse aérienne et leur taux d'évapotranspiration (ET). Cependant, les traitements plantés ont agi comme zone tampon, en atténuant la masse du CAP de l'influent et en la libérant lentement dans l'effluent. Le taux d'ET de Scirpus et Phragmites était plus élevé que celui de Sporobolus, ce qui s’est traduit par un meilleur effet tampon. Cette étude suggère que l'ajout de biochar au substrat HSSF TW est prometteur pour l'atténuation du CAP dans le ruissellement agricole, mais leur efficacité à long terme reste à être étudiée. Malgré tout, les TW devraient être utilisés comme un outil complémentaire, dans le cadre d'actions plus larges visant à réduire la pression des polluants sur les écosystèmes aquatiques.
Over the past decades, a wide variety of emergent pesticides, such as chlorantraniliprole (CAP), have been introduced despite the lack of in-depth knowledge of their ecotoxicological risk. Treatment wetlands (TWs) are environmentally friendly and sustainable technologies that have shown great potential to mitigate common agricultural pollutants, such as pesticides in runoff. The objective of this study was to optimize the use of the horizontal subsurface flow treatment wetlands (HSSF TWs) by determining a) the effect of biochar amendment to the substrate and b) the performance of three species of macrophytes (Phragmites australis subsp. americanus, Scirpus cyperinus and Sporobolus michauxianus) in CAP removal from agricultural runoff. The removal efficiency was calculated using the mass balance method in mature HSSF mesocosms fed with synthetic agricultural runoff containing CAP for a period of one month. Mesocosms with the addition of biochar were very effective in removing CAP (90-99%) and remained so throughout the experimental period. This efficiency is likely due to the high adsorption capacity of biochar, although this mechanism has not been directly measured. In contrast, CAP removal in mesocosms planted without biochar was low and limited and there was no difference between species, although there were differences in their above-ground biomass and their evapotranspiration (ET) rate. However, the planted mesocosms acted as buffer zones, reducing the CAP mass of the influent and slowly releasing it into the discharge. The ET rate of S. cyperinus and P. australis was higher than that of S. michauxianus, resulting in a better buffering effect. This study suggests that adding biochar to the HSSF TW substrate is promising for CAP attenuation in agricultural runoff, but their long-term effectiveness remains to be investigated. Nevertheless, TWs should be used as a complementary tool, as part of wider actions aimed at reducing the pressure of pollutants on aquatic ecosystems.