Mining is of great importance to the South African economy. It should however be recognised that the processes of prospecting, extracting, concentrating, refining and transporting minerals have great potential for disrupting the natural environment (Rabie et al., 1994). The environmental effects caused by the mining of sand from a river, is no exception, often causing adverse impacts to biota and their habitats.

Filamentous algae biomass is very limited in aerobic constructed wetlands and totally absent in anaerobic constructed wetlands. Its contribution to the removal of sulphur from acid mine drainage will therefore rarely reach a significant level if not used in association with secondary algae treatment ponds as part of a biological hybrid treatment system. Although a high sulphur concentration has a lower environmental impact than dissolved metals and acidity, it does have an adverse impact on water quality. The current study employed selected macroalgal species under laboratory conditions to determine the bioaccumulation of sulphur (S) and other important algal growth elements such as calcium (Ca), magnesium (Mg) and phosphorus (P) from acid mine drainage (AMD) water and treated constructed wetland water at different pH values. Following exposure of the macroalgae to AMD and treated constructed wetland water for 192 h, Microspora tumidula showed the highest bioaccumulation of S and P which occurred at a pH of 5. Oedogonium crassum showed the highest bioaccumulation of Ca and Mg at a pH of 7. The results also showed that the accumulation efficiency of Mg by all three macroalgal species increased significantly as the pH increased. The filamentous species Oedogonium crassum and Klebsormidium klebsii showed very little increase in chl-a (mg g−1 fw) and ash free dry weight (mg g−1 AFDW) after exposure to the mine and treated constructed wetland water after 192 h at all four pH ranges in comparison to the species M. tumidula. However, the species M. tumidula show significant increases in both chl-a (mg g−1 fw) and mg g−1 AFDW at pH values 5, 6.14 and 7. The study established that the species M. tumidula is a good candidate for use in a biological hybrid system for treating sulphur-rich acid mine drainage.

South Africa is prone to droughts and is heavily dependent on stored water resources. Few studies in South Africa have investigated the impact of drought on water quality when rainfall resumes and reservoir sediments are rewet. Other research has shown that several negative impacts may occur with rewetting, including eutrophication, and acidification with increased metal solubility. In this study, the impact of drying and rewetting sediments on the mobility of nutrients and metals is explored using sediments from Loskop Reservoir. Rarely exposed sediments were collected from three sites, dried at 35°C for 36 days, and then rewet under aerobic conditions. Filtered water samples were collected on Days 1, 2 ,4, 7, 11 and 16 following rewetting, and analysed for NH 4 + , NO 3 - , NO 2 - , total N, total P, PO 4 3- , dissolved Al, Fe, Mn, and SO 4 2- . Results were expressed as mass/m 2 , and were compared to reference (non-drought) treatments that were maintained under saturated conditions. Acute toxicity tests were performed using Daphnia magna to establish if toxic effects were associated with changes in water quality following sediment rewetting. Following rewetting, elevated SO 4 2- indicated the mobilisation of acid from sulfide oxidation, with an associated reduction in pH. Nitrification was evident as high quantities of organic N and NH 4 + were initially released, followed by increases in NO 2 - + NO 3 - . Total P increased, but PO 4 3- reduced. This was attributed to complexes formed between PO 4 3- and Fe (FePO 4 ) and Al (AlPO 4 ). Amounts of Fe and Al released were lower following rewetting due to the formation of relatively immobile (hydr)oxides. In contrast, Mn increased substantially reaching maximum values > 2 300 mg/m 2 (14 000 μg/L). There were no acute toxic effects observed to D. magna. This study highlights the potential for acidification, mobilisation of nutrients, SO 4 2- , and Mn following rewetting of reservoir sediments under aerobic conditions. This information may be incorporated into reservoir and catchment management plans in the form of revised water quality guidelines and a better ability to predict how drought impacts water quality in our stored water resources. Keywords : sediment, drought, drying, rewetting, nutrient and metal release, Loskop Reservoir

Although bioassay approaches are useful for identifying chemicals of potential concern, they provide little understanding of the mechanisms of chemical toxicity. Without this understanding, it is difficult to address some of the key challenges that currently face aquatic ecotoxicology. To overcome this, the toxicity potential of the water samples was assessed and surviving organisms (Physa acuta) were used for protein activity measurements and gene expression profiling by making use of complementary DNA amplified fragment length polymorphism (cDNA-AFLP) analysis. From the data it was evident that the impacts of specific pollutants (e.g. sewage) on organisms at the cellular level could be identified, and that the expressed stressor genes can be used as bioindicators/markers/genetic signatures or fingerprints during identification of point source pollution. From an ecosystem management point of view these insights could assist with the forecasting and reduction of environmental risks on catchment level by implementing suitable management interventions.

Knowledge co‐production and boundary work offer planners a new frame for critically designing a social process that fosters collaborative implementation of resulting plans. Knowledge co‐production involves stakeholders from diverse knowledge systems working iteratively toward common vision and action. Boundary work is a means of creating permeable knowledge boundaries that satisfy the needs of multiple social groups while guarding the functional integrity of contributing knowledge systems. Resulting products are boundary objects of mutual interest that maintain coherence across all knowledge boundaries. We examined how knowledge co‐production and boundary work can bridge the gap between planning and implementation and promote cross‐sectoral cooperation. We applied these concepts to well‐established stages in regional conservation planning within a national scale conservation planning project aimed at identifying areas for conserving rivers and wetlands of South Africa and developing an institutional environment for promoting their conservation. Knowledge co‐production occurred iteratively over 4 years in interactive stake‐holder workshops that included co‐development of national freshwater conservation goals and spatial data on freshwater biodiversity and local conservation feasibility; translation of goals into quantitative inputs that were used in Marxan to select draft priority conservation areas; review of draft priority areas; and packaging of resulting map products into an atlas and implementation manual to promote application of the priority area maps in 37 different decision‐making contexts. Knowledge co‐production stimulated dialogue and negotiation and built capacity for multi‐scale implementation beyond the project. The resulting maps and information integrated diverse knowledge types of over 450 stakeholders and represented >1000 years of collective experience. The maps provided a consistent national source of information on priority conservation areas for rivers and wetlands and have been applied in 25 of the 37 use contexts since their launch just over 3 years ago. When framed as a knowledge co‐production process supported by boundary work, regional conservation plans can be developed into valuable boundary objects that offer a tangible tool for multi‐agency cooperation around conservation. Our work provides practical guidance for promoting uptake of conservation science and contributes to an evidence base on how conservation efforts can be improved .

A SYSTEMATIC CONSERVATION PLANNING APPROACH FOR FRESHWATERS • Explicit criteria for identifying priority areas were developed with stakeholders (Table 1). • GIS data for each criterion were collated and used within a systematic conservation planning framework to identify priority rivers and wetlands (Figure 2). • The Marxan conservation planning software (Possingham et al., 2000) was adapted to take into account longitudinal connectivity (Nel et al., 2009; Linke et al., 2011). Modelled hydrologically-linked catchments accounted for lateral connectivity.

The responsibility for managing and conserving freshwater ecosystems is typically shared by multiple organizations with sometimes conflicting policy mandates. However, scorecard-based approaches for measuring management effectiveness in natural resource management are usually confined to single organizations. This paper describes a social learning approach which acknowledges cooperation as an essential precondition for effective management and that encourages reflective coassessment of cooperative relationships. The approach was pilot tested with eight participating organizations in one water management area in South Africa. It specifically aimed to allow for a multiagency reflective assessment of issues determining cooperative behavior, allow context-specific adaptations, and be embedded in adaptive management. It involved development of a spreadsheet-based scorecard-type tool that can be used to facilitate a multiagency workshop. This workshop serves to bring parties face-to-face and helps them codiscover their interdependence, shortcomings, and strengths. The spreadsheet structures reflection on their respective roles and effectiveness while the reflective coassessment motivates participants to address shortcomings. Overall, insights that emerged included: cooperation should be an explicit component of each organization's operational strategy; facilitation of appropriate cooperative behavior could be very effectively achieved by external "bridging organizations"; the reflective assessment process must be followed by purposefully adaptive interventions; the ability of the scorecard to be contextually adaptive was important; and institutional readiness requires investigation as the approach does sit somewhat uncomfortably with much current practice.

Within South Africa, active public participation in decision-making processes and policy development is a requirement for governance to be successful. Similarly, ecosystem governance requires active public participation in environmental issues. For the public to become progressively more involved in decision-making, an increase in public understanding of, active involvement in and engagement with science, is needed. This emphasises the importance of sound science communication strategies that will lead to informed responses to environmental issues.This Chapter describes the role of communication between the components of the ecosystem governance Trialogue Model, namely science, society and government. The focus is directed particularly towards the role of communication in the society-science interface, highlighting the lessons learnt and communication challenges arising from the South African River Health Programme's State-of-Rivers reporting component.

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 does it make when they are considered as well?This study examined the conservation of riverine biodiversity within 17 assessment units contained by the catchment areas of five perennial rivers flowing through Kruger National Park and two seasonal rivers that are largely contained within this park. Physical river types, fish species and invertebrate families or genera were used as surrogates of riverine biodiversity. Conservation planning software was used to select an optimal set of planning units to represent and maintain riverine biodiversity.The current spatial configuration of Kruger National Park, largely an accident of history, is particularly poor when assessed against the objective of conserving riverine biodiversity. Several alternative layouts are examined. These options are theoretical since there is little current opportunity to reassign land uses in the region. This study shows that substantially improved layouts for both riverine and terrestrial biodiversity are possible, under the constraint of the same total area under protection. The study also shows that even these optimal layouts are only partially successful in efforts to conserve fully representative samples of riverine biodiversity. Because of the longitudinal connectivity of rivers, conservation strategies that extend beyond protected areas are essential. Explicit conservation visions, targets and strategies need to be included in integrated water resource management plans.Based on the results of this study, nine recommendations are provided for increasing the effectiveness of current and future protected areas in conserving riverine biodiversity. These are to use systematic conservation planning to make biodiversity benefits explicit; mend the disconnect between terrestrial and freshwater conservation; use multiple surrogates wherever possible; be strategic about the collection and management of primary data; strive for maximum hydrologic connectivity; resist development pressure; foster good relationships across park fences; where relevant, pursue multi-national cooperation at the basin scale; and engage the value debate and resolve awareness and capacity constraints. (c) 2007 Elsevier Ltd. All rights reserved.

The River Health Programme (RHP) is being designed to generate information regarding the ecological state of riverine ecosystem s in South Africa. An adaptive assessment and management procedure is suggested as a means of linking the monitoring outcomes of the RHP with water resource management decisions. The potential of such a procedure is demonstrated, using data that have been collected, through the pilot application of the RHP, on the Crocodile and Elands Rivers, Mpumalanga. In order to assess the collected data relative to a reference state, homogeneous river segments were identified. Each segment was classified in terms of its relative ecological integrity, based on three biological indicators (fish, benthic invertebrates, ri parian vegetation). These assessments of current integrity were compared with management goals and quality objectives for the respect ive river segments. Finally, river segments were ranked in terms of priority for receiving management attention, and an example is given of formulating appropriate management actions for addressing a high priority need. The systematic following of the step-wise procedure would facilitate and formalise the linking of data collection and assessmen t, the setting of management goals and quantifiable objectives, the selection of management options, and the monitoring of respons es to chosen management actions.