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No description available.

Much attention has been paid to the effects of anthropogenic impacts upon physical and chemical conditions in freshwater ecosystems. However, impacts upon the functioning of these ecosystems and services that they provide remain relatively unknown. The objective of this thesis was to examine the validity of the general hypothesis that the deterioration of ecosystems may be reflected in their capacity to process resources. Changes in stream phosphorus retention and metabolism were investigated across a rural-urban gradient in the Torrens River Catchment, South Australia, where channel structures of rural reaches are less modified than urban reaches. In a stream with an intact upper rural catchment (First Creek), a reach with an un-modified channel structure retained 60% ± 12.1 filterable reactive phosphorus (FRP) and had an average uptake length of 79 m ± 3.4. In comparison, degraded and engineered reaches of First Creek retained less FRP and had longer uptake lengths. In Fourth Creek, which is influenced by agriculture, there were no differences in FRP retention between the reaches. Reduced FRP retention in impacted reaches were a result of decreased contact time, reduced period of continuous flow and increased nutrient availability. Although abiotic benthic FRP uptake rates (up to 6.8 μg m [ superscript minus 2 ] s [ superscript minus 1 ] ± 0.36) were consistently greater than biotic uptake rates (up to 3.6 μg m [ superscript minus 2 ] s [ superscript minus 1 ] ± 0.52), decreased total benthic uptake rates in impacted reaches were mainly due to decreased biotic uptake. Metabolic rates were measured within benthic chambers containing rocks and gravel and scaled up to the stream reach. At chamber and reach scales, metabolic rates in the unmodified reach of First Creek were consistently low (community respiration (CR) up to 113 mg O [ subscript 2 ] m [ superscript minus 2 ] day [ superscript minus 1 ] ± 47.4 and gross primary production (GPP) up to 234 mg O [ subscript 2 ] m [ superscript minus 2 ] day [ superscript minus 1 ] ± 89.5), with a positive net ecosystem production (NEP). In comparison, the degraded reach of First Creek switched between having a negative and positive NEP. Reaches of Fourth Creek also experienced considerable variation and had higher metabolic rates than First Creek (CR up to 371 mg O [ subscript 2 ] m [ superscript minus 2 ] day [ superscript minus 1 ] ± 62.1 and GPP up to 847 mg O [ subscript 2 ] m [ superscript minus 2 ] day [ superscript minus 1 ] ± 66.1). Increased metabolic rates in impacted reaches were attributed to increased light availability and reduced grazing by higher trophic levels, promoting autotrophic organisms. The altered ecosystem functions were considered to reflect a reduced capacity of deteriorated streams to process resources. However, the addition of coarse particulate organic matter to a degraded-urban stream reach increased CR and reduced NEP to levels more akin to those experienced within pristine streams. Furthermore, percent FRP retention increased, primarily through increased demand for phosphorus of the microbial community. Although this demonstrated that rehabilitation of in-stream attributes might restore important ecosystem functions in impacted streams, successful restoration will only be achieved if the over-riding causes of in-stream degradation are addressed. / Thesis (Ph.D.)--School of Earth and Environmental Sciences, 2005.

<p></p><p>In Sweden, the County Administration board is responsible for improving the water quality in lakes and watercourses according to the European Union Water Framework Directive. In Västmanland county, where river Lillån is situated, the County Administration of Västmanland have the main responsibility for the aquatic environment in that area. The knowledge about the different watercourses in the chatchment of river Lillån is today limited. The aim with this study was to evaluate the ecological quality of River Lillån based on water chemistry analyses and benthic fauna investigations. The aim was also for the benthic fauna to compere different samplingsites and sampling methods with each other in order to see how the species composition changes in the river, and to see the advantages and disadvantages with different sampling tecniques. The methods used for the assessment was presented in a handbook composed by the Swedish Environmental Protection Agency. The results of the study showed that Lillån have good quality concerning acidity and the general ecological status. The benthic fauna investigations indicated high levels of nutrients and thereby resulted in poor status concerning that parameter. The conclusion of the study was that river Lillån does not fulfill the criteria of good status according to the Water Framework Direcive composed by the European Union.</p><p> </p><p><em>Keywords: Water directive, water quality evaulation, benthic fauna, acidification, nutrients, methods for sample-taking.</em></p><p><em></em></p><p><em>Nyckelord: Vattendirektiv, statusbedömning, bottenfauna, försurning, näringsämnen, provtagningsmetoder.</em></p><p> </p>

In Sweden, the County Administration board is responsible for improving the water quality in lakes and watercourses according to the European Union Water Framework Directive. In Västmanland county, where river Lillån is situated, the County Administration of Västmanland have the main responsibility for the aquatic environment in that area. The knowledge about the different watercourses in the chatchment of river Lillån is today limited. The aim with this study was to evaluate the ecological quality of River Lillån based on water chemistry analyses and benthic fauna investigations. The aim was also for the benthic fauna to compere different samplingsites and sampling methods with each other in order to see how the species composition changes in the river, and to see the advantages and disadvantages with different sampling tecniques. The methods used for the assessment was presented in a handbook composed by the Swedish Environmental Protection Agency. The results of the study showed that Lillån have good quality concerning acidity and the general ecological status. The benthic fauna investigations indicated high levels of nutrients and thereby resulted in poor status concerning that parameter. The conclusion of the study was that river Lillån does not fulfill the criteria of good status according to the Water Framework Direcive composed by the European Union.   Keywords: Water directive, water quality evaulation, benthic fauna, acidification, nutrients, methods for sample-taking. Nyckelord: Vattendirektiv, statusbedömning, bottenfauna, försurning, näringsämnen, provtagningsmetoder.

No description available.

No description available.

Thesis (M.Sc.)--York University, 2006. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 88-108). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR19705

Thesis (M.S.)--Baylor University, 2007. / Includes bibliographical references (p. 62-73).

Thesis (M.S.)--University of Nevada, Reno, 2007. / "August 2007." Includes bibliographical references (leaves 100-106). Online version available on the World Wide Web.