Known as the most harmful aquatic weed globally (Villamagna and Murphy 2010; Mbaka 2023), water hyacinth (Eichhornia crassipes) is native to South America and was introduced to various parts of the world mainly because of its attractive flowers (Yirefu et al. 2007). Studies have revealed that water hyacinth has invaded freshwater systems in over 50 countries worldwide (Jafari 2010). Climate change models have shown that its distribution might expand as global temperatures continue to increase (Villamagna and Murphy 2010; Villamagna et al. 2012). In Africa, water hyacinth was first recorded in the 1890s in the Nile River in Egypt and has since spread widely across freshwater bodies throughout the continent (Kanyamugenge 2018). Similarly, because of its high capacity to multiply beyond its native range, water hyacinth has spread to various East African water bodies, including those in Rwanda (Navarro and Phiri 2000). In Rwanda, water hyacinth was first publicly recorded in the Mukungwa River valley in 1987 and has since infested various lakes and wetlands, such as Akagera, Nyabarongo, Akanyaru, and the Rweru-Mugesera wetland complex (Gashamura 2009; Seburanga et al. 2014). However, the invasive nature of water hyacinth and the lack of sustainable management strategies have resulted in persistent environmental, social, and economic challenges nationwide (Seburanga et al. 2014), which are likely to worsen as climate variability, eutrophication, and increasing anthropogenic disturbances accelerate its expansion across African wetlands, highlighting the urgent need for sustainable management (Dersseh et al. 2019; Harun et al. 2021; IPCC 2023; Parida et al. 2023). These conditions collectively create a favorable environment for water hyacinth that accelerates its aggressive growth and dominance in aquatic ecosystems. Consequently, once water hyacinth establishes itself under these favorable conditions, its ecological impacts become increasingly pronounced. Its dense mats reduce light penetration and water circulation, lower phytoplankton productivity, decrease dissolved oxygen concentrations, increase sedimentation, and raise evapotranspiration (Dersseh et al. 2019; Parida et al. 2023). These mats also hinder sunlight from reaching submerged macrophytes, alter nutrient availability, and intensify competition among aquatic plants (Mengistu et al. 2017; Wang and Yan 2017). Beyond its ecological impacts, the socio-economic problems caused by water hyacinth are also severe, particularly for riparian communities that rely on water bodies for their livelihoods. Dense mats of water hyacinth reduce fish catchability, damage fishing equipment, thereby increasing operational costs, block waterways used for transport, and limit the availability of freshwater for domestic and agricultural use (Ndimele 2012; Dersseh et al. 2019). Water hyacinth also increases the siltation of dams and rivers, blocks irrigation channels, and decreases the economic value of riparian zones (Kenfack et al. 2019).

Despite its negative impacts, water hyacinth has been used in various economic activities, mainly because of its rapid growth and high biomass production. For many years, it has been used not only in bioremediation, the bioaccumulation of heavy metals, and biogas and biofuel production but also as animal feed and in compost production (Sayago and Rodríguez 2018; Ayanda et al. 2020; Parida et al. 2023). Various studies conducted across different parts of Africa have shown that the spread of water hyacinth seriously affects key livelihood resources, such as fisheries, crop production, and transportation (Hungwe et al. 2016; Kenfack et al. 2019; Enyew et al. 2020; Mbaka 2023).

Various studies conducted on water hyacinth in Rwanda have focused on different aspects of the issue. First, studies focused either on mapping its distribution using Landsat imagery (Mukarugwiro et al. 2019) or on assessing its occurrence and extent and selecting appropriate biological controls (Mukarugwiro 2020). Second, studies focused on its use to improve local livelihoods and restore ecosystems (Kanyamugenge 2018) and on local community perceptions of its control (Seburanga et al. 2014). Finally, other studies involved an assessment of biological control efforts for water hyacinth in the Kagera River headwaters of Rwanda (Williams et al. 2007). In the Rweru-Mugesera wetland complex, where water hyacinth infestation has expanded rapidly in recent years, there is limited empirical evidence not only on how local communities perceive the invasion but also on the extent to which their livelihoods have been affected. In addition, concerns remain about whether current management interventions adequately address local needs. This knowledge gap limits the development of sustainable management strategies for this invasive aquatic plant (Hill et al. 2016).

This study addresses this gap by investigating riparian community perceptions of water hyacinth infestation and evaluating its socio-economic impacts in the Rweru-Mugesera wetland complex, Eastern Rwanda. It integrates local ecological knowledge with quantitative socio-economic data collected from the surrounding communities experiencing different levels of water hyacinth infestation. By comparing areas with different water hyacinth invasion levels, the study provides a more comprehensive understanding of how invasion intensity influences community perceptions, livelihood outcomes, and local adaptation and management responses. Such an integrated socio-ecological approach is increasingly recognized as essential for developing effective invasive species management responses because successful interventions depend not only on ecological evidence but also on stakeholder participation and local acceptance (Reed 2008; IPBES 2023).

The findings of this study are expected to provide empirical evidence regarding the human dimensions of water hyacinth invasion in Rwanda, a context where socio-economic assessments are limited despite the increasing threat of invasive aquatic plants. In addition, they will inform policymakers, local government authorities, and conservationists at different levels in the development of participatory, evidence-based management strategies that incorporate local priorities and experiences. They will also support the implementation of Rwanda’s wetland conservation and restoration initiatives by identifying community-informed interventions that enhance livelihood resilience and ecosystem health (UNEP 2021; IPBES 2023; IPCC 2023).

The aim of this study was to assess local riparian community perceptions of water hyacinth infestation in the Rweru-Mugesera wetland complex and its socio-economic impacts. To achieve this aim, the study considered the following research questions:

The study found that the local riparian communities around the Rweru-Mugesera wetland complex were generally knowledgeable about water hyacinth, although knowledge levels varied across the three study sites. This variation reflects differences in infestation severity and the extent of community exposure to the invasive species. In areas where infestation was most severe, 92.5% of respondents reported being knowledgeable about the weed. This high awareness likely results from frequent interaction with water hyacinth, which directly affects fishing, water access, agriculture, and other livelihood activities. Communities facing persistent biological invasions tend to develop greater species recognition and practical knowledge due to daily exposure to the invasive species and its socio-economic consequences (Ligeve et al. 2012; Abba et al. 2025), whereas in the absence of visible infestation and associated impacts, community members are less likely to recognize invasive species as an environmental concern (Mwangi and Swallow 2005).

Neither gender nor education level had any influence on respondents’ knowledge of water hyacinth across the study sites, except in Ngoma District, where an association between education and knowledge was observed. This implies that awareness of water hyacinth proliferation is widespread through lived experiences rather than through formal education (Ndimele et al. 2011). This is in line with findings from a study conducted in a semi-arid area of Zimbabwe on farmers’ local knowledge, perceptions, and attitudes toward water hyacinth, where both educated and less-educated community members exhibited a similar understanding of water hyacinth ecology (Hungwe et al. 2016). Similarly, a study conducted by Gudina et al. (2024) in the Central Rift Valley of Ethiopia reported that the possession of local knowledge depends not only on formal education but also on direct experience and interaction with the environment.

With regard to the status of water hyacinth in the wetland complex, most respondents (62.9%) associated its increase with agricultural runoff, which increased nutrient enrichment in the wetland system. Such nutrient loading creates favorable conditions for rapid water hyacinth spread, as nutrients from fertilizers, livestock waste, and eroded soil often enter wetlands, creating eutrophic conditions that favor water hyacinth propagation (Villamagna and Murphy 2010; Harun et al. 2021). Poor land-use practices, such as unsustainable waste disposal, were also mentioned as contributing factors. A study by Ndimele et al. (2011) reported that agricultural runoff and urban wastewater inflows significantly fuel water hyacinth expansion by enriching aquatic environments with excess nutrients.

The perceived decline in water hyacinth coverage in the study area was mostly due to mechanical harvesting carried out by fishing cooperatives. Manual and mechanical water hyacinth removal efforts have the capacity to reduce its biomass in East African lakes for a period of time (Essl et al. 2011; Shackleton et al. 2017). In addition to mechanical removal, respondents mentioned the use of water hyacinth for animal feed and handicraft production as factors contributing to the reduction of water hyacinth spread. Water hyacinth is suitable for use as livestock feed due to its nutrient content, and its use is considered as one of the more effective and sustainable approaches to managing its growth (Gichuki et al. 2012; Moyo et al. 2013; Heuzé et al. 2015; Rajan et al. 2022).

Beyond its value as animal feed, water hyacinth was also used as a raw material for handicrafts such as mats, carpets, tissue boxes, trays, hats, sandals, shopping bags, and handbags (Rakotoarisoa et al. 2016; Mbaka 2023).

Fishing activities are vital to the livelihoods of riparian communities and were among the socio-economic activities severely affected by water hyacinth infestation in the Rweru-Mugesera wetland complex. This impact is particularly severe because the riparian community in the area depends on fishing as a primary source of income and livelihood. Despite its economic significance, the fishing sector encounters considerable challenges due to environmental degradation, especially the proliferation of aquatic invasive species such as water hyacinth, which disrupts fishing operations and reduces productivity (Harun et al. 2021; Mbaka 2023). Water hyacinth damages fishing hooks and nets, increases fish prices, and reduces fish weight and catchability (Mbula 2016). This weed affects fishing activities by reducing the quantities of fish caught, destroying fishing gear, causing the disappearance of some important fish species, limiting access to fishing sites, and reducing the size of some fishing areas (Mujingni 2012). For instance, a study conducted in the Wouri River Basin, Cameroon, by Kenfack et al. (2019) found that water hyacinth destroyed fishing gear and reduced open-water areas, leading to lower fish catches and higher fish prices. In Lake Victoria, Kateregga and Sterner (2009) reported that water hyacinth reduced fish stocks of tilapia and young Nile perch by limiting access to breeding, nursing, and feeding grounds. It has also been reported that fish catch rates decreased because water hyacinth mats blocked access to fishing grounds, delayed access to markets, and increased fishing costs.

Crop production is one of the rural livelihoods impacted by water hyacinth. The expansion of this weed on agricultural land causes a number of interrelated impacts, such as reductions in household crop production, especially for crops cultivated around the lake, and reduced crop costs. These effects are mainly due to the fact that water hyacinth promotes waterlogging in low-lying farmlands and interferes with land preparation and harvesting operations (Khotsa et al. 2025; Zewdie et al. 2025). In addition, it often forms dense floating mats that obstruct irrigation canals, drainage systems, and water flow, thereby reducing water availability for crops (Dersseh et al. 2019; Gosal et al. 2022). A study conducted in Lake Tana, Ethiopia, reported that water hyacinth reduced crop production by 75% and 100% in riparian agricultural systems (Enyew et al. 2020). Similarly, Damtie et al. (2022) found that household crop production, especially crops cultivated around the lake such as rice, was reduced due to the expansion of water hyacinth on agricultural land.

The most commonly reported impacts of water hyacinth infestation on transport in this study included longer travel times, reflecting how dense water hyacinth mats physically obstruct waterways and make navigation slower and riskier, forcing boat operators to take longer routes, travel at reduced speeds, or sometimes wait for the weed to be cleared (Kateregga and Sterner 2009; Tewabe et al. 2017). The reported increases in fuel use and reductions in income are consistent with higher operating costs and lost working hours because boat operators must spend more time cutting or avoiding water hyacinth, fuel consumption rises, and the number of profitable trips is reduced, which in turn leads to reduction in household revenues (Kenfack et al. 2019). In the Tano River and Tano Lagoon in Ghana, Honlah et al. (2019) reported that water hyacinth invasion increased the length of time farmers required to access their farms, mainly because they had to use their hands to remove water hyacinth from their designated routes to pave the way for their canoes. Similarly, in the Wouri River Basin in Douala, Cameroon, water hyacinth invasion significantly increased the time required to travel between villages, mainly because waterways were blocked by dense mats of the weed, making certain routes completely inaccessible. Therefore, the blockade of river transport led to a decline in passenger numbers, which contributed to reduced income for transport operators. Average monthly income from water transport fell sharply from approximately US$200 before the spread of water hyacinth to approximately US$50 after the spread of water hyacinth (Kenfack et al. 2019).

This study examined local riparian communities’ perceptions of water hyacinth and its socio-economic impacts in three districts surrounding the Rweru-Mugesera wetland complex in Eastern Rwanda. These communities showed extensive awareness of water hyacinth invasion, regardless of their gender, occupation, or educational background. Most respondents indicated that water hyacinth had increased over time, mainly due to fertilizer runoff from agricultural activities and increased temperatures associated with climate change. The common management strategies they highlighted included manual removal, utilization as animal feed, and production of handicrafts. The findings further indicate that water hyacinth has significantly disturbed local riparian livelihoods. This affected the fishing sector because fishing equipment was frequently damaged and access to fishing grounds became more difficult, leading to decreased fish production and rising fish prices. Agricultural activities were also negatively impacted due to reduced water availability for crops, decreased yields, and rising crop prices. Dense mats of water hyacinth slowed water transport, increased transportation costs, reduced transport-related income, and, in some cases, made boat operations impossible.

Although this study provides valuable insights into community perceptions of water hyacinth and its effects, the findings are primarily based on local perception data and are limited to three districts surrounding the Rweru-Mugesera wetland complex. Future research should incorporate long-term environmental monitoring, economic assessments, and scientific measurements to more accurately evaluate the severity of these impacts and determine the most effective management strategies over time. To address this challenge, a coordinated management plan for water hyacinth is required. National and local stakeholders, as well as community organizations, should work in close collaboration to reduce nutrient runoff by promoting improved agricultural practices, establish regular monitoring, and support manual removal efforts. Policy measures should also facilitate the conversion of harvested water hyacinth into value-added products such as handicrafts, compost, animal feed, and bioenergy through training, financial support, and market linkages. Such collaborative efforts can mitigate the spread of water hyacinth, enhance local incomes, strengthen wetland resilience, and support sustainable management of the Rweru-Mugesera wetland complex.