Effects of sediment and water quality on the distribution and abundance of aquatic weeds of Jebba Lake, Nigeria

Abstract

Nutritional factors affecting the occurrence and distribution of aquatic weeds were monitored on Jebba Lake between June 1999 and May 2001. The result showed that bottom sediments quality and lake water chemistry impact the aquatic weed growth and development directly while shoreline chemical parameters impact more on the terrestrial vegetation. Chemical variables in bottom sediments, which directly affected abundance of aquatic weeds during the wet season include total nitrogen (r = 0.54), magnesium (r = 0.52), and ECEC (r = 0.45). However, during the dry season, aquatic weed occurrence and distribution were positively affected by total nitrogen (r = 0.65), organic matter and organic carbon (r = 0.64), potassium (r = 0.54), calcium (r = 0.53) and ECEC (r = 0.52) and pH of the sediment (r = 0.50). During the wet period, very low positive correlation existed between the aquatic weed abundance and the assayed physico-chemical parameters of water. During the dry season, weed abundance on the lake was principally affected by phosphorus and total nitrogen (r = 0.47) and to a lesser extent by sodium (r = 0.45) and calcium (r = 0.42).

Key words: Aquatic ecosystem, macrophyte/weed, ecological interaction, plant nutrient, sediment quality