IMPACTS OF Eichhornia crassipes (MART.) SOLMS ON THE DIVERSITY OF CLADOCERANS AT OVIA RIVER, BENIN CITY, EDO STATE.

ABSTRACT

Water hyacinth, Eichhornia crassipes is a common invasive aquatic plant which occurs in aquatic habitat of widely differing depth and nutrient level. It is listed as one of the most notorious weeds in the world with serious disadvantages. This study sought to examine the impacts of Eichhornia crassipes on the diversity and abundance of cladocerans in Ovia River, Edo State, Nigeria. Cladocerans were collected from four stations, comprising upstream without vegetation, litorral midstream with water hyacinth, limnetic midstream with macrophyte and downstream without macrophyte in Ovia River within a period of six months (April -September) during the dry and wet season. A total of 130 individuals comprising 17 taxa belonging to 7 families were identified. Among these, Sididae was predominant (56.92%). The most dominant species were Diaphanosoma sarsi (35%) and D. excisum (14%) respectively. The highest diversity and abundance were recorded at station 2, the littoral midstream station with water hyacinth. Taxa richness and abundance was highest in stations with water hyacinth (station 2 and 3) than stations without macrophyte (station 1 and 3). Also, species richness and abundance were higher in littoral station with vegetation than limnetic station with vegetation. It is interesting to note that Cladocera was not encountered during dry season. The highest number of Cladocera was recorded in July during the period of sampling. Shannon and Simpson diversity indices decreased in the following order stations 2< 3<1< 4. The results from this study suggests that the diversity and abundance of cladocerans seems to have been increased with the presence of water hyacinth in Ovia River.