Abiala creek is a typical aquatic weed infested creek in the Niger Delta Area of Nigeria. Examination of the aquatic vegetation revealed seven weed species dominated by Eichhornia crassipes (Mart.) Solm - Laub. The presence of these aquatic weeds negatively affected the plankton species diversity in the creek. The weed-free areas of the creek were qualitatively and quantitatively richer in plankton than the weed-infested areas. The aquatic weeds created an adverse environmental condition, which forced fish to migrate to the weed-free areas of the creek. The preponderance of male to female specimens and near absence of juvenile fishes was a reflection of the negative influence of the presence of the aquatic weeds on fish population structure. The predominating fish families - Polyteridae, Clariidae, Anabantidae and Channidae were discovered to have accessory respiratory organs.

Journal of Aquatic Sciences Volume 14, April 1999, pp. 61-65




KEY WORDS:

Eichhornia crassipes, aquatic weeds, plankton, diatom, Niger Delta, Nigeria.