Use of water hyacinth (Eichhornia crassipes) in poor and remote regions – a case study from Lake Alaotra, Madagascar

The water hyacinth (Eichhornia crassipes) is one of the top ten most invasive aquatic plant species in the world. Due to its worldwide distribution, the plant has caused tremendous damage on ecosystems and human livelihoods alike. These negative impacts are especially problematic for developing countries such as Madagascar. Considering the weak economic situation of the country, using water hyacinth to generate economic profits remains the last option to manage the species. We investigated the use of water hyacinth at Lake Alaotra, the largest lake in the country. This lake and the surrounding area are of great ecological and economic relevance for Madagascar. However, the isolation of the region and poverty limit water hyacinth use only to alternatives suitable to the weak local infrastructure. The goal of this research is firstly to identify suitable water hyacinth use options according to the local conditions and to compare them with the locally used raw materials. The first part of this research identified drivers and barriers for using water hyacinth in the region according to the prevailing socioeconomic conditions. It identified especially the use of water hyacinth as raw material for fertilizers and handicrafts as suitable alternatives for Lake Alaotra. Within the second phase, water hyacinth handicrafts were produced and compared with the predominantly used traditional papyrus handicrafts regarding production path and related costs. It was found that assembling water hyacinth handicrafts was easier and faster and they could be sold at three times the sale prices of the traditional papyrus handicrafts. Within the last part, fertilizers based on water hyacinth (composts, green manure and ash) were locally produced and compared with the commonly used agricultural fertilizers NPK and cow dung. This was done by conducting a growth experiment with Chinese cabbage, a common fast-growing vegetable in the region. Additionally, the production and transportation costs of each type of fertilizer were also taken into account. The results showed high biomass gain of cabbage grown with water hyacinth composts which was also proved be cheaper than using NPK and cow dung. All in all, this research demonstrated the efficiency of water hyacinth use as compost and handicraft as a new source of income for the Alaotra region. However, the poverty and high vulnerability of the local population must be considered along the process for a successful implementation of water hyacinth use at Lake Alaotra. A participatory approach and by offering financial insurance to the farmers during the implementation phase could encourage them to test water hyacinth compost on their own fields. Due to the various external factors influencing the marketing of water hyacinth handicrafts, an intensive and sustained supervision should be provided to the craftswomen.