Physico-chemical factors involved in rivers and lagoons invasion by water hyacinth, Côte d’Ivoire

Abstract

The invasion of freshwaters and coastal ecosystems by Eichhornia crassipes in tropical and subtropical countries causes serious economic and ecological problems. In the present work, the seasonal distribution of Eichhornia crassipes and abiotic factors that control its distribution in rivers and lagoons from Cote d’Ivoire were reported. Our data show that Eichhornia crassipes proliferation in lagoons was more related to freshwater discharges. By contrast, salinity inhibits its proliferation particularly during dry season when the influence of oceanic waters is significant. In rivers, Echhornia crassipes proliferation in rivers was completely different from one river to another. Higher proliferation of Echhornia crassipes in Comoe and Bia rivers was found during the wet season, while in Tanoe river the maximal proliferation was obtained in the dry season. Nutrient concentrations in rivers and lagoons were generally low due to their uptake accumulation of phosphorus in leaves, roots and rhizomes of Echhornia crassipes was different depending on aquatic systems. Higher phosphorus conditions (in rivers), Eichhornia crassipes accumulate more phosphorus in the rhizomes than in the other parts. By contrast, in the lower phosphorus conditions (in lagoons), Eichhornia crassipes accumulates more phosphorus in the leaves than in the other parts. Key words: Eichhornia crassipes, West Africa, coastal water, abiotic factors.