Lake Nokoué in Benin supports the livelihoods of more than 500.000 people through fish production and sand mining. However, its health is jeopardised by eutrophication and excessive growth of the invasive water hyacinth, which dies off and sink to sediment during dry seasons when the lake's salinity increases due to tidal intrusion. Water-hyacinth constitutes then a potential source of internal nutrient loading through the decomposition of detritus and therefore can exacerbate eutrophication problems. An important management question is whether the removal of water hyacinth before it dies would significantly reduce eutrophication problems through the removal of nutrients. To compare the amount of nutrients removed by water-hyacinth biomass to the amount of nutrients transported into the Lake, mass-balance approach has been taken. Nutrient concentrations, water hyacinth cover, and hydrological inflows were measured over a 12 month period from November 2016 to October 2017. Water-hyacinth biomass estimation was based on a calibrated NDVI and field measurement relationship. In total the hyacinth covered up to 18 km² (10%) of the lake, corresponding to 80,000 tonnes of dry weight which sink to the bottom each year when salinity rise. The potential internal nutrient loaded from hyacinth to the system was estimated to 1021 tonnes of nitrogen (8% of external input) and 231 tonnes of phosphorus (40% of external input). Considering that the tidal nutrient output compensates almost all the external nutrient inputs (about 70%), part of the nutrient available for eutrophication must come from internal sources, likely through the decomposition of sediment detritus.

贝宁的诺科埃湖通过鱼类生产和采砂为超过50万人的生计提供支持。但是，富营养化和侵入性风信子的过度生长会危害其健康，风信子在干旱季节会因潮汐入侵而增加盐分，从而死亡并沉入沉积物中。然后，风信子通过碎屑的分解构成内部养分负载的潜在来源，因此可能加剧富营养化问题。一个重要的管理问题是，风信子死前去除是否会通过去除养分来显着减少富营养化问题。为了比较通过水葫芦生物量去除的养分量与运输到湖泊中的养分量，采用了质量平衡法。在2016年11月至2017年10月的12个月内，对营养物浓度，水葫芦覆盖率和水文流入量进行了测量。水葫芦生物量估算基于校准的NDVI和田间测量关系。风信子总共覆盖了18公里湖泊中有^2个（10％），相当于每年80,000吨的干重，当盐度升高时，它们会沉入底部。从风信子到系统的潜在内部养分估计为1021吨氮（占外部输入的8％）和231吨磷（占外部输入的40％）。考虑到潮汐养分的输出几乎补偿了所有外部养分的输入（约70％），可用于富营养化的部分养分必须来自内部来源，可能是由于沉积物碎屑的分解所致。