Contribution à la connaissance de l'écologie d'Eichhornia crassipes (Mart.) Solms-Laub. (Pontederiaceae) et de Pistia stratiotes L. (Araceae) dans la région maritime orientale du Togo

Abstract

The water plans of the Togolese East maritime region are all invaded by floating weeds. Phytosociological study of these ones show two communities: Lemno paucicoctatae-Pistietum stratioitis, a Myriophyllum spicatum community. Eichhornia crassipes is quite rare despite its presence on the Lomé lagoon and on the Mono river. Water chemical analysis show that values of conductivity, hydrotimetric title (TH), chloride ions and phosphate ions measured at a youthful stage of Pistia were lower than those measured with its death. The reverse phenomenon is observed for nitrate and ammonium ions. Feeble values of conductivity, TH and chlorides favourish nitrates and ammonium assimilation by floating species. Statistical analysis of the hydro-chemical parameters permit to classify these water biotopes in ponds, swamps, streams and lagoons. © 2005, Taylor & Francis Group, LLC.