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Elucidation of foodweb interactions in South African reservoirs using stable isotopes
Expanded Title:This research project examined the food web structure of the Rietvlei Dam in order to determine the possibilities for fishery biomanipulation (foodweb management) as a tool for attenuating the impacts of eutrophication. This concept presumes that the phytoplankton comprises species that are edible by zooplankton, and that the fishery comprises obligate zooplanktivorous species. This linear feeding pattern is not always the case, especially in non-natural water bodies, such as impoundments. To track the Rietvlei food web, the study employed stable isotope analysis (SIA) techniques for the first time in a South African reservoir. None of the findings gleaned from this study suggested that zooplanktivory has a significant influence on zooplankton community structure or abundance levels. The evidence obtained, using SIA, indicates that trophic pathways leading to fish primarily follow benthic, rather than planktonic routes. The same results cannot be assumed for other eutrophic dams due to spatial complexity of the impoundments in South Africa. Caution should therefore be taken (in South Africa) to assume manipulation of fishery will result in the attenuation of eutrophication. The results indicate that foodweb-manipulation cannot be applied to manage eutrophication in the Rietvlei dam. The good outcome of the study is that, a method now exists, in South Africa, to track cautiously the feeding regimes in an impoundment.
Date Published:01/08/2012
Document Type:Research Report
Document Subjects:Water Resource Management/IWRM - Planning and development, Ecosystem - Resource Economics
Document Format:Report
Document File Type:pdf
Research Report Type:Standard
WRC Report No:1918/1/12
ISBN No:978-1-4312-0299-7
Authors:Harding WR; Hart RC; Muller LG
Project No:K5/1918
Originator:WRC
Organizations:DH Environmental Consulting
Document Size:1 658 KB
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