Food web (bio-)manipulation of South African reservoirs – viable eutrophication management prospect or illusory pipe dream? A reflective commentary and position paper

Abstract

An overview of prospects and limitations for the application of ‘classical’ top-down biomanipulation as a management tool to ameliorate the consequences of eutrophication under the conditions applicable to reservoirs in South Africa is presented. This is structured by considering successive stages in reservoir food-web structure and function as far as can be generalised for South African biophysical conditions. Features and conditions that influence the potential vulnerability of local reservoirs to the effects of eutrophication, and prospects for its amelioration by biomanipulation intervention are examined. Physical factors linked to latitude (irradiation pattern and water-column stability) enhance the potential severity of eutrophication consequences in local reservoirs, although conversely, these are offset by suspended-clay turbidity. The predominance of Microcystis in local eutrophic waters is perceived as a primary major constraint in implementing ‘classical’ food-web manipulation.

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