The degradation of rivers in urban landscapes is alarming and impaired their ecological functions and the services they provide to society. In African cities, urban rivers are among the most degraded ecosystems, yet ecologically sustainable utilisation of river resources can contribute to and support sustainable urban development. In this paper, we identify and analyse key governance and institutional drivers of ecological change in urban river systems in the Swartkops catchment in South Africa and the Federal Capital Territory (FCT) in Nigeria. Our results indicate that poor ecological conditions of rivers in the two urban landscapes can be attributed to: (1) a lack of system view of the water value chain and associated infrastructure, (2) ambiguity in roles, responsibilities, and poor accountability, (3) prioritizing short-term social–economic–political agenda over long-term environmental sustainability goals, (4) institutional silos and failure of cooperative governance, and (5) over-centralised, top-down, state-centric governance processes. Strengthening the interactions between actors in the science, policy and practice domains, mainstreaming planning with rivers in integrated urban development plans, and strengthening cooperative and polycentric governance across administrative scales are key governance and institutional processes needed to address the trajectory of urban ecological degradation. Our paper sheds light on the fundamental role of strengthening governance and institutional processes for steering urban rivers toward sustainable paths for city resilience.

Invertebrates are often used as indicators of ecosystem health. In community ecology, the use of organism traits (e.g. behavioural, biological or ecological) can be of value in relation to impact d...

Microplastic pollution in freshwater ecosystems has garnered increasing attention due to its ecological risks and potential impacts on human health. While numerous studies have addressed microplastic prevalence in rivers, a critical gap remains in understanding their spatial distribution within the geomorphological and hydraulic structure of river channels. This study investigated the occurrence and variability of microplastics across hydraulic units in two urban river systems, the Buffalo and Swartkops Rivers, in the Eastern Cape Province of South Africa. Hydraulic units were categorised into flush (riffles and runs) and sink (pools and backwaters) hydraulic zones, based on in situ measurements of flow velocity, depth, and substrate composition. Flush zones were hypothesised to promote microplastic remobilisation due to higher flow energy, whereas sink zones were expected to favour microplastic deposition owing to reduced hydraulic energy. Samples of surface water (suspended microplastics) and sediment-water mixtures (settled, then resuspended microplastics) were collected across these units in both the wet/hot and dry/cold seasons. Settled microplastics were significantly more abundant in sink zones (1.82 ± 1.98 items/L) than flush zones (1.32 ± 1.49 items/L; p < 0.05), confirming their role as depositional environments. Suspended microplastics were more evenly distributed but slightly higher in flush zones (1.76 ± 1.44 items/L). Seasonal variation was evident, with higher abundances of both settled and suspended microplastics during the wet season, particularly in sink zones, indicating enhanced transport and deposition under high-flow conditions. Fibres and fragments were the dominant microplastic forms, and the smallest size class (0.063-0.5 mm) was most prevalent, especially in flush zones. Polyethylene (PE) and polypropylene (PP) were the most common polymers. Denser polymers such as polyamide, polycarbonate, and polyvinyl chloride occurred exclusively in sink zones, suggesting selective retention linked to particle density and hydraulic conditions. Polymer diversity was also higher in these zones. Effluent-impacted sites showed similar microplastic patterns to other locations, though upstream sites revealed localised variation. These findings underscore the role of hydraulic heterogeneity and seasonal hydrology in microplastic distribution and highlight the need for flow zone-based monitoring approaches in riverine microplastic assessments and management.

An increase in the incidence of Campylobacter species in rivers raises concerns on the safety of river water for humans who get exposed to river water. This study examines the spatiotemporal dynamics of Campylobacter species in the Bloukrans and Swartkops rivers, analysing patterns of its occurrence in relation to meteorological conditions, physicochemical parameters, seasons, and sampling sites. Physico-chemical parameters and meteorological conditions were measured during water sampling from various sites along the rivers over a year, while Polymerase Chain Reaction (PCR) was utilised to detect Campylobacter genus-specific genes and selected antibiotic-resistant genes. Campylobacter was detected in 66.67% (Bloukrans River) and 58.33% (Swartkops River). In the Bloukrans River, multi-drug resistance genes cmeA (20%), cmeB (65%), cmeC (10%), were detected while and tetO was detected at 70%. In the Swartkops River, the corresponding prevalence were 28%, 66.67%, 28.56%, and 76%. The study indicates that sampling season did not significantly impact Campylobacter prevalence. However, variation in Campylobacter occurrence exists among different sites along the rivers, reflecting the influence of site proximity to potential contamination sources. The study suggests that Campylobacter infection may be endemic in South Africa, with rivers serving as potential sources of exposure to humans, thereby contributing to the epidemiology of campylobacteriosis.

Contaminated rivers play a critical role in the transmission of Campylobacter and antibiotic-resistant genes (ARGs) in many parts of the world. South Africa is a water-scarce country which relies on its freshwater systems such as rivers for recreation, irrigation, and domestic activities. This study assesses the potential human exposure to Campylobacter and its ARGs from rivers through the ingestion route in two South African rivers. The concentration of viable Campylobacter and ARGs in selected rivers was determined using quantitative PCR. The concentrations were then used to estimate the number of gene copies a person could ingest after swimming in the contaminated water for 1 h (intake burden). The human intake burden of Campylobacter 16 S rRNA copies per 1-h swimming event ranged from 7.1 × 10⁵-3.7 × 10⁶ copies/h for the Bloukrans River, and 9.9 × 10¹-2.3 × 10⁵ copies/h for the Swartkops River. The intake burden of Campylobacter ARGs ranged from 1.64 × 10⁴-5.8 × 10⁵ copies/h for cmeB; 1.0 × 10³-5.7 × 10⁴ copies/h for tetO for the Bloukrans River, and 3.6 × 10²-1.551 × 10⁵ copies/h (cmeB) and 9.98 × 10²-5.7 × 10⁴ copies/h (tetO) for the Swartkops River. Ingestion of water from contaminated rivers during recreation, cultural, or religious activities may lead to human exposure to ARGs, posing a health risk. In many communities in the world, rivers play an important role in the social and cultural lives of people, and so it is important to monitor the quality of river water. Studies such as these will help prevent the spread of antibiotic-resistant genes and waterborne diseases caused by pathogens such as Campylobacter.