Diatoms are a large and diverse group of algae which are distributed throughout the world in all types of aquatic systems and are one of the most important food resources in freshwater ecosystems. The need to sample diatoms arises from the necessity to know the history of the water quality. Diatom communities reflect the overall ecological integrity by integrating various stressors and as result provides a broad measure of their impacts. They are recognized as valuable organisms for bio assessment, due to their ease of identification, rapid life cycle and their visibility to the naked eye. Diatom communities provide interpretable indications of specific changes in the water quality Environmental gradients and assemblage composition in the Mnweni River catchment revealed that water chemistry, habitat structure, flow type and land use were the most important environmental factors for diatom assemblage composition in the Mnweni River. The results indicates that the diatom diversity and assemblage composition in the Mnweni River shows that changes in the water chemistry as well as organic pollution, but also indicate changes in the habitat character which is related to the water flow, river bank character and catchment land use. The diatom assemblages that were found at the sites are typical of clean or mildly enriched water conditions. The changing salinity in St. Lucia is the main physical factor that is driving the constant change in ecological conditions within the estuary. The changes in the diatom community structure in the estuarine system indicate the variable nature of the benthic communities under different salinity conditions. Contrary to the drought conditions that are being experienced, the diatom biomass did not show any significant changes or differences. This may be due to the rapid recovery ability that diatom communities exhibit in response to changes that are occurring in their environment. / Thesis (M.A.)-University of KwaZulu-Natal, 2006.

Macroinvertebrate assemblages were semi-quantitatively sampled from the Little Blue River and an isolated headwater stream in Wilbur Wright Fish and Wildlife Area from March through November of 2000. Physicochemical conditions and qualitative habitat characteristics were recorded at each site. Each stream contained unique community assemblages based on taxa richness, composition, functional feeding groups, behavioral groups, reproductive habits, and drought tolerance/avoidance. Collections from the first-order stream contained fewer taxa and a greater proportion of non-insects and tolerant taxa than those from the Little Blue River. Taxa from the Little Blue River were adapted for filtering/collecting and for swimming or clinging, while taxa from the first-order stream were primarily gathering/collecting and swimming or sprawling. The proportion of taxa with adaptations for drought resistance or avoidance was significantly higher in the first-order stream than in the Little Blue River (p<0.001). / Department of Biology

The Lesotho Highlands Development Authority routinely uses the South African Scoring System version 4 (SASS4) in conjunction with water chemistry to monitor water quality of rivers in the Lesotho Highlands Water Project areas. The objective of this study was to test the efficiency of SASS4 in these areas.

Thesis (M.S.)--Missouri State University, 2008. / "December 2008." Includes bibliographical references (leaves 63-74). Also available online.

Thesis (Ph. D.)--University of California, Los Angeles, 2003. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 98-108). Also available on the World Wide Web.

Thesis (M. Sc. (Environmental Science))--Rhodes University, 2005.

Thesis (M.S.)--Eastern Illinois University, 2009. / Includes bibliographical references (leaves 65-72).

Thesis (Ph. D.)--University of Alabama at Birmingham, 2006. / Description based on contents viewed Jan. 26, 2007; title from title screen. Includes bibliographical references (p. 98-105).

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