Keith Walker

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In October 2000, the flow of the River Murray entering South Australia was increased from 32 000 to 42 050 ML day 1 by release of water from an offstream reservoir, and a downstream weir was raised by 500 mm to impound the flood and enhance local floodplain inundation. The flood was maintained for about two weeks, although the duration of inundation was(More)
Stable water levels and turbidity associated with flow regulation in the River Murray have promoted the growth of filamentous green algae and Cyanobacteria in biofilms on submerged wood. We investigated the assimilation of biofilm algae by two dominant consumers, the decapod crustaceans Macrobrachium australiense (Palaemonidae) and Paratya australiensis(More)
The present study validates age estimates from a suite of calcified structures (scales, opercular bones and otoliths), assesses the consistency of age interpretations and evaluates growth models in common carp from the lower Murray River, Australia. Marginal increment analysis was used to validate annulus counts, with attention to the 'edge interpretation(More)
In the Lake Eyre Basin, the Australian hyriid genus Velesunio is represented by three undescribed species, each of which are highly divergent genetically, but morphologically similar to Velesunio wilsonii (Lea 1859). A fourth species, Velesunio ambiguus (Philippi 1847), occurs not only in the Lake Eyre Basin but throughout much of eastern Australia,(More)
The breakdown of litter from eight common plants was investigated in Sunnyside Swamp, a wetland connected to the River Murray. Breakdown rates were related to the content of structural carbohydrate tissue in each species. Burial in wetland sediments inhibited the breakdown of relatively fast-decomposing species (e.g. Myriophyllum caput-medusae), but did not(More)
This article presents and explains a "Framework for Exploring Adolescent Wellness" and outlines a research approach used to explore adolescent wellness specific to the discipline of nursing. The "Framework for Exploring Adolescent Wellness" assessed the concept of wellness through the perceptions of youth and sought to explain the relationship between(More)
Notopala sublineata, Notopala hanleyi(Viviparidae) andThiara balonnensis (Thiaridae) are prosobranchgastropodsthat were once abundant in the lower River Murray. These andothersnail taxa have declined markedly over the last 50 years,coinciding with increased flow regulation by dams and weirs.Inthis paper we speculate that the decline may be linked(More)
We present a method to describe the behaviour of a mobile robot quantitatively, using methods from dynamical systems theory, time series analysis and deterministic chaos theory. Experimental results obtained with a Pioneer II mobile robot demonstrate the use of the method, and show that robot behaviour exhibits deterministic chaos, and is substantially(More)
The conservation biology of Australasian freshwater mussels is hindered by lack of a taxonomic framework that employs molecular data as a complement to shell characters, larval forms and internal anatomy. The fauna includes more than 32 known species (30+ Hyriidae, 2 Unionidae), but has not been revised for 55 years, despite minor amendments. The hyriids(More)
PURPOSE The purpose of this study was to explore the details of the experiences and meanings that adolescents associate with spirituality. DESIGN AND METHODS This exploratory qualitative study used focus group discussions to uncover the experiences of 22 adolescents ages 16-19 years from two midwestern Canadian high schools. RESULTS Three themes(More)