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Development of a diatom index for wetland health
Expanded Title:This study set out to determine whether diatom indices, currently used to assess water quality of rivers and streams could be applied successfully to wetlands. The distribution of diatoms in different wetlands was examined, as well as the correlation of diatom communities to water quality variables,. Then the applicability of diatom indices in South African wetlands was tested using the OMNIDIA software. The index is to be based on species commonly occurring in the examined wetlands, and will yield information on trophic status, levels of organic pollution, oxygen saturation, salinity and pH. Traditionally in South Africa, the quality of water has always been monitored by means of physico-chemical analysis; this method of analysis can be very expensive and only reflects conditions at the exact time of sampling. Biomonitoring is a more recently used technique which examines the behavioural and physiological response of living organisms to their environment. However, since the biota commonly used to indicate aquatic conditions are not always present in wetlands, this study tested the use of diatoms (a group of algae found in all aquatic ecosystems) as bio-indicators in wetlands. Several diatom indices were tested and applied for water quality analysis in thirteen wetlands in the Western Cape Province, South Africa. The indices tested included the BDI, EPI, GDI, SHE, SPI, and the WAT index. These indices were useful for indicating water quality conditions in wetlands when compared to measured physico-chemical parameters. In addition, most diatom species found are common to both riverine and wetland environments, making the transfer of ecological optima possible. The ultimate aim is to contribute to the development of a diatom-based water quality protocol for the assessment of wetlands in South Africa and the formulation of a diatom index for South African wetlands. The index is to be based on species commonly occurring in the examined wetlands, and will yield information on trophic status, levels of organic pollution, oxygen saturation, salinity and pH. This index will then be used to assess the general quality or health of South African Wetlands. The objective of the study was to provide a preliminary diatom-based index for wetlands. However, given the relatively small study area and the strong bias towards coastal wetlands, it was deemed inadvisable to construct such an index at this time, instead several indices are recommended for interim use in wetlands, until further research has been conducted that more comprehensively covers wetlands in South Africa. It is thus the recommendation of this study that more data are collected for comparison to other wetlands and that in the interim indices such as SPI be applied for routine biomonitoring of these environments.
Date Published:01/11/2011
Document Type:Research Report
Document Subjects:Ecosystem - Biodiversity protection
Document Keywords:Water Quality
Document Format:Report
Document File Type:pdf
Research Report Type:Consultant
WRC Report No:KV 270/11
ISBN No:978-1-4312-0111-2
Authors:Matlala MD; Taylor JC; Harding WR
Project No:K8/734
Organizations:North West University; DH Environmental Consulting
Document Size:2 749 KB
Attachments:TABLE OF CONTENTS for KV 270.pdf
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