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Records of human occupation from Pleistocene river terrace and aeolian sediments in the Arneiro depression (Lower Tejo River, central eastern Portugal)

Cunha, Pedro Proença; Almeida, Nelson; Aubry, Thierry; Martins, António Antunes; Murray, Andrew; Buylaert, Jan-Pieter; Sohbati, Reza; Raposo, Luis; Rocha, Leonor
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
POR
Relevância na Pesquisa
56.17%
In the uppermost reach of the Lower Tejo River (eastern central Portugal), where the river crosses two quartzite ridges that separate the Ródão (upstream) and Arneiro (downstream) depressions, Palaeolithic artefacts have been recovered from three lower river terrace levels and a cover unit of aeolian sands. This paper presents data on the discovery of archaeological artefacts from the terrace levels and the aeolian sands that can be linked to Middle and Upper Palaeolithic industries from new field sites at Tapada do Montinho and Castelejo. The archaeological data when placed in a geomorphological, sedimentary and chronological framework,contribute new information on the understanding of human occupation in western Iberia during cold climate episodes of the last 62 to 12 ka; and especially during the cooler and driest conditions that occurred between 32 and 12 ka, when the climate favoured aeolian sediment transport. In the Lower Tejo River, the integration of absolute age datasets with archaeological, geomorphological and sedimentary data indicate that in westernmost Iberia the first appearance of artefacts in river terrace sediments suggests that the earliest marker for human occupation dates from the lower Acheulian (Lower Palaeolithic)...

Does salinity influence the distribution of exotic willows (Salix spp.) along the Lower River Murray?

Kennedy, S.; Ganf, G.; Walker, K.
Fonte: C S I R O Publishing Publicador: C S I R O Publishing
Tipo: Artigo de Revista Científica
Publicado em //2003 EN
Relevância na Pesquisa
66.16%
The weeping willow Salix babylonica and crack willow S. fragilis dominate the riparian vegetation of the River Murray between Mannum and Wellington, South Australia, Australia. The presence of S. fragilis is confirmed, over-riding earlier, informal references to S. × rubens. In this region S. babylonica is represented by females and S. fragilis is represented by males. The flowering times of the two species overlap but the growing season begins earlier for the former. No evidence of hybridization was found, although this is not conclusive. Salix babylonica is most common upstream of Murray Bridge whereas S. fragilis occurs mainly downstream. A field survey in 1999 showed that estimated soil water conductivity varied between sites (median 6.0 mS cm–1) along the river, but this was not reflected in the distributions of the species. In a glasshouse experiment, cuttings of both species proved intolerant of conductivities exceeding 7 mS cm–1. In the field, foliar salt levels indicated that neither species was salt-stressed, despite growing in moderately saline soil. Also, it appears that the trees may access less saline river water in preference to that in the soil. The distributions of the two species in this region could reflect the history of planting rather than salinity tolerance.; Shaun A. Kennedy...

Tree water sources over shallow, saline groundwater in the lower River Murray, south-eastern Australia: implications for groundwater recharge mechanisms

Holland, K.; Tyerman, S.; Mensforth, L.; Walker, G.
Fonte: C S I R O Publishing Publicador: C S I R O Publishing
Tipo: Artigo de Revista Científica
Publicado em //2006 EN
Relevância na Pesquisa
66.04%
The decline of riparian vegetation in the lower River Murray, south-eastern Australia, is associated with a reduction in flooding frequency, extent and duration, and increased salt accumulation. The plant water sources of healthy Eucalyptus largiflorens trees growing over highly saline (>40 dS m⁻¹) groundwater were investigated during summer when water deficit is greatest. The study found low-salinity soil water overlying highly saline groundwater at most sites. This deep soil water, rather than the saline groundwater, was identified as the plant water source at most sites. Stable isotopes of water and water potential measurements were used to infer how the deep soil water was recharged. The low-salinity, deep soil water was recharged in the following two ways: (1) vertically through the soil profile or via preferential flow paths by rainfall or flood waters or (2) horizontally by bank recharge from surface water on top of the saline groundwater. Vertical infiltration of rainfall and floodwaters through cracking clays was important for trees growing in small depressions, whereas infiltration of rainfall through sandy soils was important for trees growing at the break of slope. Bank recharge was important for trees growing within ~50 m of permanent and ephemeral water bodies. The study has provided a better understanding of the spatial patterns of recharge at a scale relevant to riparian vegetation. This understanding is important for the management of floodplain vegetation growing in a saline...

Regional scale modelling of the lower River Murray wetlands: a model for the assessment of nutrient retention of floodplain wetlands pre- and post-management.

Bjornsson, Kjartan Tumi
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2008
Relevância na Pesquisa
86.34%
Most of the lower River Murray and its floodplain wetlands are impacted upon by degradation caused by river regulation. Increasingly the restoration of these ecosystems and the river water quality has become a high priority for federal and state governments and associated departments and agencies. Public concern is adding to the pressures on these departments and agencies to restore these ecosystems and to sustainably maintain the river water quality. The long term monitoring of floodplain wetlands has been limited, compounding the difficulties faced by managers and decision makers on assessing the potential outcome of restoration options. The role of this project in the broad scheme of restoration/rehabilitation is to contribute to the construction of a model capable of increasing managers and decision makers understanding, and build consensus of potential outcomes of management option. This model was to use available data. The developed model, based on WETMOD developed by Cetin (2001), simulates wetland internal nutrient processes, phytoplankton, zooplankton and macrophyte biomass as well as the interaction (nutrient and phytoplankton exchange) between wetlands and the river. The model further simulates the potential impact management options have on the wetlands...

The roles of seed banks and soil moisture in recruitment of semi-arid floodplain plants: the River Murray, Australia.

Jensen, Anne Elizabeth
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2008
Relevância na Pesquisa
66.37%
The decline of floodplain vegetation along the Lower River Murray, South Australia, has evoked recommendations for ‘environmental flows’ to restore and maintain the health of the ecosystem. To assist managers to maximize benefits from environmental flows, this thesis considers the significance of water for germination and recruitment in key floodplain plant species. Three dominant species are considered, including two trees, river red gum (Eucalyptus camaldulensis) and black box (E. largiflorens), and an understorey shrub, tangled lignum (Muehlenbeckia florulenta). The soil seed bank was dominated by terrestrial annual native plants. Among 1400 seedlings, a single river red gum was found, and no black box or lignum, suggesting that these species do not contribute to the persistent soil seed bank and rely instead on aerial seed banks (serotiny). Sampling of the soil seed bank was continued to determine when seed fall might coincide with appropriate soil moisture conditions. Responses of the soil seed bank to varied water regimes were compared to determine requirements for seedling survival. The results indicated that species richness, rapidity of response and survival time were all promoted by sustained soil moisture. Stands of eucalypts in various states of health (from very stressed to very healthy) were monitored to identify seasonal patterns in bud crops...

Freshwater snails in competition: alien Physa acuta (Physidae) and native Glyptophysa gibbosa (Planorbidae) in the River Murray, South Australia

Zukowski, S.; Walker, K.
Fonte: C S I R O Publishing Publicador: C S I R O Publishing
Tipo: Artigo de Revista Científica
Publicado em //2009 EN
Relevância na Pesquisa
66.13%
Physa acuta (Draparnaud), an invasive species from Europe, is the most abundant freshwater snail in the Lower River Murray. Its ascendancy follows a general decline of native species, including the morphologically and ecologically similar Glyptophysa gibbosa (Gould). We began with two hypotheses. The first required comparisons of the salinity and temperature tolerances and other attributes of eggs, juveniles and adults to reveal differences that might account for the relative abundances of the species. As anticipated, P. acuta proved to have higher fecundity, shorter hatching time and higher salinity and temperature tolerances than G. gibbosa. The second hypothesis concerned a possible competitive interaction between the species. This was confirmed, as when juveniles were kept together, under laboratory conditions, the growth rate of P. acuta increased and that of G. gibbosa decreased (with some mortality). We suggest that the apparent decline of G. gibbosa in the Lower Murray may reflect its sensitivity to salinity and its vulnerability in interactions with P. acuta. This is a global concern as P. acuta has spread also to North America, Japan and South Africa, and there have been reports of impacts on local species.; Sylvia Zukowski and Keith F. Walker; © CSIRO 2009

The impact of regulation and salinisation on floodplain lakes: the lower River Murray, Australia

Gell, P.; Tibby, J.; Little, F.; Baldwin, D.; Hancock, G.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica
Publicado em //2007 EN
Relevância na Pesquisa
76.22%
Floodplain lakes along the lower River Murray are subject to a wide range of human impacts including regulation, abstraction, elevated saline groundwater tables, increased nutrient and sediment fluxes and introduced biota. These perturbations are superimposed on those arising from high inter-annual rainfall variability, driven, at least in part, by variations in the southern oscillation. Sediment-based archives from two lakes within a complex of wetlands, situated near to the first site of irrigation development in the lower River Murray, reveal substantial changes over the last 800 years. While high levels of salinity are not foreign to the sites, the recent trend is towards sustained high salinity levels. As a result of European impact, freshwater diatom plankton now dominates Loch Luna, whilst Loveday Wetland is both more saline and nutrient rich than in the pre-European period. In Loveday Wetland, the post-1960 increase in Haslea spicula (Hickie) Lange-Bertalot, may be driven by increases in sulphur salt concentrations that are believed to be a cause of recent acidification episodes. A recent increase in more salt tolerant diatoms in Loch Luna suggests that this site, which has been largely buffered from substantial change, is becoming more vulnerable to perturbation.; Peter Gell...

The role of hydrology in determining the distribution patterns of invasive willows (Salix) and dominant native trees in the lower River Murray (South Australia).

Gehrig, Susan L.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2010
Relevância na Pesquisa
96.32%
This thesis explores the hydrological factors that may contribute to the observed distribution patterns of invasive willows (Salix) and native trees (Eucalyptus camaldulensis, E. largiflorens and Acacia stenophylla) along the Lower River Murray (LRM) in southern Australia. An initial survey, establishing the diversity and flowering biology of Salix taxa was carried out to ascertain the extent of invasion, and the likelihood of hybridisation, which may accelerate invasion. S. babylonica, S. fragilis, S. × chrysochoma and S. × rubens occur in the study region, each represented by a single gender. None were present on floodplains, but the most dominant taxon, S. babylonica, occurred along the entire length of the main channel. No seed or seedlings were observed; hence reproduction is likely to be asexual. More detailed survey work was then carried out to characterise the distribution patterns of the dominant S. babylonica and co-occurring natives (Eucalyptus camaldulensis, E. largiflorens and Acacia stenophylla) along a hydrologic gradient produced by the extensive weir system in the LRM. In weir pools, variation in daily water levels of weir pools is low (± 0.1 m) immediately upstream of the weir...

Larval fish assemblages in the Lower River Murray, Australia: examining the influence of hydrology, habitat and food.

Cheshire, Katherine Jane-Maree
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2010
Relevância na Pesquisa
76.54%
The major assumption of currently accepted fish recruitment hypotheses (e.g. flood pulse concept and flood recruitment model) is that in the absence of overbank flows the main river channel does not provide adequate food and habitat for larvae and juveniles. However, periods of low flows are common throughout floodplain rivers, and there are a wide diversity of life history strategies exhibited by riverine fish. Therefore, the broad applicability of these assumptions to the management of all fish species and floodplains rivers has been questioned. The low flow recruitment hypothesis pioneered the concept that some fishes can successfully spawn and recruit during low flows by utilising main channel habitats. Characteristics of the river channel, flow regime and level of regulation are often distinctly different both within and between rivers, and many of the recruitment models and indeed the life history strategies of fishes, remain untested in alternative floodplain river systems. River regulation has resulted in altered flow regimes in river systems throughout the world, and in turn, has a range of negative impacts on the fish populations. The Murray-Darling Basin is Australia’s largest river catchment and has been severely affected by river regulation. To test some of the assumptions of the previously described recruitment models larval fish and zooplankton sampling was conducted in the main channel environments of the Lower River Murray...

Acid sulfate soil toposequences in wetlands of the Lower River Murray

Grealish, G.; Fitzpatrick, R.; Shand, P.
Fonte: UWA; DVD Publicador: UWA; DVD
Tipo: Conference paper
Publicado em //2010 EN
Relevância na Pesquisa
66.04%
Water levels have fallen dramatically in wetlands along a 250 kilometre length of the lower River Murray between Blanchetown (Lock 1) and Wellington, South Australia, in many cases exposing acid sulfate soil materials. The objective of this study was to provide critical baseline information to support management decisions for the soils and wetlands to minimise impact of these inland region acid sulfate soils. This paper: 1) presents an overview of the acid sulfate soil characteristics, 2) demonstrates the utility of toposequence models to provide an understanding of soil variation, and 3) describes how the information is used to support planning of management options. For 62 wetlands, a total of 198 sites were investigated. Acid base accounting data identified 534 out of 653 samples (82%) as having a positive net acidity. Classification of soil material based on pH and chromium reducible sulfur values identified acid sulfate soil material in 270 out of 638 samples (43%). Forty-seven of the sixty-two wetlands (71%) have an acid sulfate soil extent within the wetland that is of concern. Conceptual toposequence models were developed which identified a recurring pattern of soil variation and provided a useful means to communicate information to decision makers and managers.; http://trove.nla.gov.au/work/37679232; http://www.iuss.org/19th%20WCSS/19th%20WCSS_Handbook_REAL%20HANDBOOK_V10_BACK%20COVER%20change.pdf; Gerard Grealish...

Origin and age of the Mantung High Plain, a karst surface in the western Murray Basin of South Australia

Twidale, C.
Fonte: Gebruder Borntraeger Publicador: Gebruder Borntraeger
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
56.22%
The Mantung High Plain of the western Murray Basin is a karstic surface of low relief developed on the Early Miocene Mannum Limestone. Dissected by the River Murray in its Gorge section it is exposed for some tens of kilometres on either side of the River Murray and to the east persists in unconformity beneath a thin sedimentary cover. The Plain is attributed to corrosion planation, i.e. dissolution and collapse down to the Pliocene water table associated first with the ancestral allogenic and exoreic River Murray that then flowed in shallow valley graded to a relatively high regional baselevel, and in later Pliocene times to the estuary that inundated the valley. During the Quaternary the Plain was left high and dry (and converted to the High Plain) by the incision of the Murray and becoming graded to lower baselevels and water tables. Conservation was enhanced by the widespread formation of a calcrete duricrust.; C.R. Twidale

GIS-based back analysis of riverbank instability in the lower River Murray

Liang, C.; Jaksa, M.; Ostendorf, B.
Fonte: Australian Geomechanics Society Publicador: Australian Geomechanics Society
Tipo: Artigo de Revista Científica
Publicado em //2012 EN
Relevância na Pesquisa
86.29%
Over the last 4 years or so, unprecedented low river levels, combined with current loading conditions, have adversely contributed to more than 137 riverbank collapse-related incidents and a long term metastable condition along the Lower River Murray, which have recently been considered as the dominating factors inducing bank collapse. With high resolution aerial photographs and digital elevation models (DEMs), this study has established the riverbank geometry prior to collapse of 26 2-dimensional cross section models. Based on government inventories, the collapsed riverbank sections were identified and vectorized using visual interpretation under ArcGIS. In order to obtain appropriate soil parameters for the study area, 5 back analytical models have been conducted at collapsed riverbank sections adjacent to Long Island Marina, Murray Bridge, South Australia. The slope stability analysis software SVSlope was employed in the back-analysis with soil data obtained from two nearby site investigations. Factors of safety were calculated to examine the potential for riverbank collapse with respect to varying river levels. The results indicate that, when the river levels return to 0 to 0.5 m AHD, a portion of the riverbank is close to collapse...

Within-channel flows promote spawning and recruitment of golden perch, Macquaria ambigua ambigua - implications for environmental flow management in the River Murray, Australia

Zampatti, B.; Leigh, S.
Fonte: C S I R O Publishing Publicador: C S I R O Publishing
Tipo: Artigo de Revista Científica
Publicado em //2013 EN
Relevância na Pesquisa
66.19%
Restoring fish populations in regulated rivers requires an understanding of relationships between hydrology and population dynamics. In the present study, spawning and recruitment of golden perch, Macquaria ambigua ambigua, were investigated in relation to flow in the regulated lower River Murray. All life stages were sampled in three successive years, with peak flows of 8500 (2004–05), 15 000 (2005–06) and 7000 ML day⁻¹ (2006–07). Larvae occurred only in November/December 2005, and young-of-year fish only in early 2006. Counts of daily increments in otolith microstructure indicated spawning in late October/early November 2005. Back-calculated birth years for adults, derived from otoliths and compared with the hydrograph for the preceding 25 years, revealed the dominance of three year classes spawned in association with increased discharge in 2000, 1998 and 1996. In 2007, an additional year class of 1-year-old fish appeared, following spawning in 2005. In each case, strong recruitment followed spring–summer spawning, when peak flows were >14 000 ML day⁻¹ and water temperatures would have exceeded 20°C. Restoration of within-channel flows of 15–25 000 ML day⁻¹ from late spring through summer would promote spawning and recruitment and improve the resilience of golden perch populations in the lower Murray.; Brenton P. Zampatti and Sandra J. Leigh

Movement and mortality of Murray cod, Maccullochella peelii, during overbank flows in the lower River Murray, Australia

Leigh, S.; Zampatti, B.
Fonte: C S I R O Publishing Publicador: C S I R O Publishing
Tipo: Artigo de Revista Científica
Publicado em //2013 EN
Relevância na Pesquisa
76.31%
Conservation of Murray cod (Maccullochella peelii), a large endangered fish species of Australia’s Murray–Darling Basin, relies on a detailed understanding of life history, including movement patterns and habitat use. We used radio-tracking to investigate the movement of 36 Murray cod in main channel and anabranch habitats of the lower River Murray during a flood and associated hypoxic blackwater event. During a flood peak of ~93 000 ML day⁻¹, dissolved oxygen decreased to 1.2 mg L⁻¹. Four movement types were observed: (1) localised small-scale movement, (2) broad-scale movement within anabranch habitats, (3) movement between anabranch and main channel habitats, and (4) large-scale riverine movement. Murray cod exhibited high fidelity to anabranch habitats but also moved extensively between anabranches and the main channel. Fish were consistently located in the main channel or permanent anabranches, suggesting that use of ephemeral floodplain habitats is limited, and highlighting the importance of connectivity between off-channel and main channel habitats. Mortality of radio-tagged fish was considerable (25%) in association with low dissolved oxygen concentrations, indicating that hypoxic blackwater may have had a substantial impact on Murray cod populations in the lower River Murray.; Sandra J. Leigh and Brenton P. Zampatti

Methods to assess environmental flow and groundwater management scenarios for floodplain tree health in the Lower River Murray.

Overton, Ian Clifford
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2013
Relevância na Pesquisa
86.39%
Riparian environments have degraded world-wide as a consequence of human development and climatic change. The native floodplain tree communities of semi-arid river systems are under stress from reduced flooding frequencies as a consequence of water extractions, river regulation and climate change. In regions with saline aquifers, river regulation and land management have also caused soil salinisation, further impacting on floodplain tree health. The lower River Murray in south-eastern Australia is a major ecological asset considered as an area of international significance. The dominant floodplain vegetation is suffering severe decline in health, with approximately 80% of floodplain trees reported as being in poor condition or dead. A reduction in water availability from reduced flooding and soil salinisation, has been identified as the primary cause. This has resulted from large irrigation extractions across the Murray-Darling Basin and elevated saline groundwater levels due to river regulation and land clearance. Management of these ecosystems needs to address both surface and groundwater changes. Increasing flooding regimes from environmental flow management and lowering of groundwater in regions of shallow saline aquifers are the most common scenarios adopted world-wide. Traditionally the assessment of management options for floodplain habitats has focussed on changes in river flow with no consideration given to surface water and groundwater interactions. In addition groundwater has been treated as a single homogenous unit. Wide floodplains have high spatial variability of habitats due to historic meandering anabranch creek systems that cause changing elevations and soil types. This in turn creates a highly variable pattern of surface and groundwater interactions. This thesis investigates the major causes of floodplain tree decline and develops methods for predicting the spatial impacts on floodplain tree health from a range of management scenarios. Surface and groundwater changes are often highly inter-connected but are usually considered separately at regional scales because of the complexity of management and modelling of surface and groundwater interactions over large areas. This thesis addresses the surface and groundwater changes at the regional scale of the lower River Murray. A floodplain inundation model for the River Murray (RiM-FIM) is developed to predict the extent of flooding at various magnitudes of flow and river regulation and a ‘drought index’ was used to indicate the risk to floodplain tree health of changing flow regimes. A floodplain impacts model (FIP) was applied spatially to predict groundwater discharge onto the floodplain and model vegetation risk. At the floodplain scale...

Floodplain connectivity facilitates significant export of zooplankton to the main River Murray channel during a flood event

Furst, D.J.; Aldridge, K.T.; Shiel, R.J.; Ganf, G.G.; Mills, S.; Brookes, J.D.
Fonte: Freshwater Biological Association Publicador: Freshwater Biological Association
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
76.27%
This study assessed the role that floods play in providing lateral connectivity between riverine habitats and floodplains, stimulating productivity and contributing zooplankton from the floodplain to the river channel. The study took place on the Chowilla Floodplain of the River Murray, Australia, and the adjacent River Murray Channel throughout the 2010–2011 floods. We found that a considerable transfer of zooplankton from the floodplain into the river channel occurred. Average zooplankton abundance was higher on the floodplain than the main river channel and increased the zooplankton abundance in the river channel downstream. At the peak of the flood, flows reached ~93 000 megalitres per day (ML d−1), inundating ~67 km2 of floodplain. At the time of this study, up to 6.3 ± 1.6 (SD) tonnes per day of zooplankton (dryweight) was being exported from the Chowilla floodplain. Differences in species assemblages were also observed within the River Murray, which seemed to be caused by the influence of the Chowilla Floodplain. This study demonstrated that floodplains provide significant zooplankton biomass, which constitutes a resource input into the riverine food web. These results provide some evidence for the Flood Pulse Concept, which highlights the importance of lateral hydrological connectivity between riverine habitats and floodplains in stimulating productivity and providing a linkage between habitats for biota. Management of regulated lowland rivers should consider not only the provision of water to the floodplain...

Flow-induced alterations to fish assemblages, habitat and fish-habitat associations in a regulated lowland river

Bice, C.M.; Gehrig, S.L.; Zampatti, B.P.; Nicol, J.M.; Wilson, P.; Leigh, S.L.; Marsland, K.
Fonte: Springer Netherlands Publicador: Springer Netherlands
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
66.21%
Understanding the cause–effect response of aquatic biota to hydrological variability is fundamental to the restoration of regulated rivers. Spatio-temporal variation in fish assemblage structure, microhabitat cover and fish–habitat associations were investigated in the main channel of the regulated lower River Murray, Australia, during a prolonged period of low within-channel flows and following a high flow event and flood. Several small-bodied species (e.g. carp gudgeon, Hypseleotris spp.), were abundant and significantly associated with submerged macrophytes during low flows, but were absent or significantly less abundant following flooding, and the loss of these microhabitats. Large-bodied riverine species that spawn in response to increases in flow (e.g. golden perch, Macquaria ambigua ambigua) or spawn and recruit in inundated floodplain habitats (e.g. common carp, Cyprinus carpio), exhibited flexible microhabitat use and were significantly more abundant following flooding. In the lower River Murray, high flow events appear integral in structuring fish assemblages, indirectly influencing the abundance of small-bodied fish by re-structuring macrophyte cover and directly influencing the abundance of large-bodied species by facilitating critical life history processes (e.g. recruitment). These results highlight species-specific differences in cause–effect responses to flow variability and have implications for managing flow in regulated rivers.; C. M. Bice...

The influence of water regime on the floristic composition of Lower River Murray wetlands / Mark Anthony Siebentritt.

Siebentritt, Mark Anthony
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado Formato: 198634 bytes; application/pdf
Publicado em //2003 EN
Relevância na Pesquisa
66.16%
This thesis examines the influence of 'water regime', or spatial and temporal patterns in the presence of water, on the floristic composition of wetlands on the River Murray in South Australia. It explores the hypothesis that the composition of wetland vegetation is determined by components of the water regime, namely depth, duration and the rate and timing of flood and drawdown.; Thesis (Ph.D.)--University of Adelaide, Cooperative Research Centre for Freshwater Ecology and School of Earth and Environmental Sciences, Discipline of Environmental Biology, 2004; "October 2003"; Errata inside front cover.; Bibliography: p. 289-313.; iii, 334 p. : ill., map, photo (col.) ; 30 cm.; Title page, contents and abstract only. The complete thesis in print form is available from the University Library.

Carp exclusion screens on wetland inlets: their value for control of common carp (Cyprinus carpio L.) and effects on offstream movements by other fish species in the River Murray, Australia.

Hillyard, Karl Aaron
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2011
Relevância na Pesquisa
66.2%
Carp screens are used in the Murray-Darling Basin (MDB) to prevent invasive alien common carp, Cyprinus carpio L. from entering wetlands, minimising their ecological impacts and denying them access to spawning habitat. The effectiveness of existing screen designs has not been evaluated, however, and little is known of their incidental effects on the lateral (instream-offstream) movements of other fish and aquatic fauna. This study investigates new screen designs that are based on carp morphology, with allowances for the lateral movements of carp and other species. The aims were (1) to determine the spatial and (2) temporal nature of lateral fish movements in the River Murray, South Australia, (3) to describe the location and design of existing carp screens across the Murray-Darling Basin, (4) develop new designs optimised to prevent the passage of sexually-mature carp, and (5) to compare and evaluate the new and existing designs. The spatial movements of fish between the Murray and six perennially-inundated wetlands were monitored using directional fyke nets set in wetland inlets from August to November 2006. Some 210,000 juvenile and adult fish from 18 species (14 native, four alien) were recorded over 13 weeks. The spatial movements of fish varied among wetlands...

The role of disturbance in the ecology of biofilms in the River Murray, South Australia / by Adrienne Burns.

Burns, Adrienne, 1971-
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado Formato: 283405 bytes; application/pdf
Publicado em //1997 EN
Relevância na Pesquisa
66.36%
This thesis explores the impact of sustained disturbances on the ecology of algal dominated biofilms in the Lower River Murray, South Australia. It focuses on the physical effects of regulation through changes to the light environment and water level regime, and the local effects of grazing. The nutritional signficance of biofilms for the abundant populations of prawns and shrimps in the Lower Murray is also examined.; Thesis (Ph.D.)--University of Adelaide, Dept. of Zoology, 1997?; Copy of author's previously published article inserted.; Bibliography: leaves 198-217.; 249 leaves : ill., maps ; 30 cm.