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The South African diatom index (SADI) – A preliminary index for indicating water quality in rivers and streams in Southern Africa
Expanded Title:The core aim of this project was to provide a water quality index, informed by diatom species and abundance, which would encompass South African river and stream conditions and, at the same time, incorporate ecologically relevant characteristics of endemic species – i.e., supporting the derivation of ecological inferences from diatom assemblages. The use of previously-available indices was constrained by their lack of autecological information on southern African diatoms. Creation of the first version of the South African Index has been achieved through the collection, processing, examination and analysis of 768 individual samples – together with their associated water quality information. All of the samples have been curated in the South African Diatom Collection. In addition the extensive notes on the ecology of SA diatoms, compiled by BJ Cholnoky, have been included in this index.The index has been provided in the form of an upgrade addition to the existing OMNIDIA software, with the intention being that the index will form part of future releases thereof. In this format, the South African Diatom Index (SADI) constitutes the second largest index supported by autecological data currently provided by OMNIDIA. The SADI is based on the same platform as the majority of European diatom indices but, in particular, on the Specific Pollution sensitivity Index (SPI) - see discussion in literature review. The SPI index has the broadest species base of any index currently in use. This species base has been augmented by the addition of endemic SA diatom species, with scores modified for other cosmopolitan and commonly occurring species found in South Africa, thus increasing the accuracy of diatom-based water quality assessments in South Africa. A secondary aim of the project was to enable skills transfer and training in the use of diatoms as a means to assess lotic environments and to draw ecological inferences therefrom. In this regard the project has been particularly successful, as is evident from the Capacity Building Report. The tools and methods developed during Phase 2 of the Diatom Assessment Protocol have been widely accepted (locally and internationally) and South Africa now has two commercial laboratories offering the procedure. In addition, the DWA is in the process of establishing the protocol across the RHP sites. This phase of the work also saw the second version of the taxonomic key being produced. This version is being hosted on the Internet for both local and international use.
Date Published:01/10/2011
Document Type:Research Report
Document Subjects:Ecosystem - Biodiversity protection
Document Keywords:Water Quality
Document Format:Report
Document File Type:pdf
Research Report Type:Standard
WRC Report No:1707/1/11
ISBN No:978-1-4312-0172-3
Authors:Harding WR; Taylor JC
Project No:K5/1707
Originator:WRC
Organizations:DH Environmental Consulting; Department of Biological Sciences, North West University, Potchefstroom
Document Size:59 334 KB
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