Browsing by Author "Ashton, PJ"
Author: Oberholster, Paul J ; Botha, AM ; Ashton, PJ Date: Apr 2009 Data generated during 12 field trips in 2006 were used to investigate possible changes in the biota communities of Lake Tswaing after a borehole was sunk in 1988/1989 near the centre of the crater lake. The Tswaing meteorite crater lake is a ... Read more
Bioaccumulation of aluminium and iron in the food chain of Lake Loskop, South Africa
Author: Oberholster, Paul J ; Myburgh, JG ; Ashton, PJ ; Coetzee, JJ ; Botha, A-M Date: Jan 2012 Concentrations of total aluminium (Al) and iron (Fe) were determined in Lake Loskop over a period of four months in 2009 in samples of phytobenthos, phytoplankton, macroinvertebrates, amphibians and fish. The highest concentrations of Al and ... Read more
Bridging the science-management divide: moving from unidirectional knowledge transfer to knowledge interfacing and sharing
Author: Roux, DJ ; Rogers, KH ; Biggs, H ; Ashton, PJ ; Sergeant, A Date: Jun 2006 Sustainable ecosystem management relies on a diverse and multi-faceted knowledge system in which techniques are continuously updated to reflect current understanding and needs. The challenge is to minimize delay as ideas flow from intent ... Read more
Control options for river water improvement: a case study of TDS and inorganic nitrogen in the Crocodile river (South Africa)
Author: Deksissa, T ; Ashton, PJ ; Vanrolleghem, PA Date: Mar 2003 Using a simple conceptual dynamic river water quality model, the effects of different basin-wide water quality management options on downstream water quality improvements in a semi-arid river, the Crocodile River (South Africa) were investigated. ... Read more
Demise of the Nile crocodile (Crocodylus niloticus) as a keystone species for aquatic ecosystem conservation in South Africa: the case of the Olifants River
Author: Ashton, PJ Date: Jun 2010 The water quality of almost all of South Africa’s river systems has worsened progressively as a result of increasing urbanization and industrialization; the adverse effects of poor water quality have been compounded by the operation of water ... Read more
Designing protected areas to conserve riverine biodiversity: Lessons from a hypothetical redesign of the Kruger National Park
Author: Roux, JR ; Nel, JL ; Ashton, PJ ; Deacon, AR ; de Moor, FC ; Hardwick, D ; Hill, Liesl ; Kleynhans, CJ ; Maree, GA ; Moolman, J ; Scholes, RJ Date: Jan 2008 The process of designing protected areas to represent all ecosystems in an area adequately is becoming increasingly sophisticated. To date freshwater aquatic ecosystems have seldom been considered in this process. How much of a difference ... Read more
Development of South African water quality guidelines for the natural aquatic environment
Author: MacKay, HM ; Roux, DJ ; Ashton, PJ ; Van Vliet, HR ; Jooste, S Date: 1995 This paper describes the progress made by the Department of Water Affairs and Forestry in the development of documented water quality guidelines for aquatic ecosystems in South Africa, which will be able to take into account local and ... Read more
Author: Ashton, PJ Date: 2007 Recent years have been marked by a growing awareness that the world’s freshwater supplies represent a scarce and critically important resource that is also extremely vulnerable to human activities (Biswas 1993; Delli Priscoli 1998). Indeed, ... Read more
Exploring the government society and science interfaces in integrated water resource management in South Africa
Author: Ashton, PJ ; Turton, AR ; Roux, DJ Date: Dec 2006 Most modern approaches to water resource management acknowledge that the entire river basin or catchment should form the basic management unit if water resources are to be managed effectively and efficiently. In addition, since surface and ... Read more
Author: Oberholster, Paul J ; Ashton, PJ ; Fritz, GB ; Botha, AM Date: Apr 2010 Ophrydium versatile (Müller 1786) Ehrenberg 1830 – a symbiotic ciliate that forms gelatinous colonies – is widely distributed in temperate lakes in Europe and America, but has not previously been recorded from rivers. In this paper we report ... Read more
Author: Chamier, J ; Schachtschneider, K ; Le Maitre, David C ; Ashton, PJ ; Van Wilgen, BW Date: Apr 2012 We review the current state of knowledge of quantified impacts of invasive alien plants on water quality, with a focus on South Africa. In South Africa, over 200 introduced plant species are regarded as invasive. Many of these species are ... Read more
Improving cross-sector policy integration and co-operation in support of freshwater conservation
Author: Roux, DJ ; Ashton, PJ ; Nel, JL ; Mackay, HM Date: 2008 To achieve effective conservation of freshwater ecosystems, close coordination and cooperation is required among sectors responsible for protection and management of water resources, biodiversity conservation, land-use management (including ... Read more
Limnology of hartbeespoort dam
Author: Ashton, PJ ; Chutter, PM ; Cochrane, KL ; De Moor, FC ; Hely-Hutchinson, JR ; Jarvis, AC ; Robarts, RD ; Scott, WE ; Thornton, JA ; Twinch, AJ ; Zohary, T ; Bostock, LB ; Combrink, S ; Fenn, TA ; Grimbeek, LM ; Herbst, HM ; Hills, MJ ; Mitchell, RF ; Pais Madeira, AM ; van Blommestein, SD Date: 1985 Hartbeespoort Dam is a hypertrophic, warm, monomictic impoundment. With a mean depth of 9.6 m and a surface area of 20 km2, the system demonstrates that hypertrophy is not confined to small shallow lakes as concluded by Barica (1981). The ... Read more