Composition, distribution, and diversity of macrophytes and benthic macroinvertebrate communities in Eleyele Lake, southwestern Nigeria

Many human activities that have an effect on water quality and aquatic health are increasing along Eleyele Lake, which is a vital resource for domestic water supply and fishery in Ibadan, southwest Nigeria. This study provides information on the composition of macrophytes and benthic macroinvertebrates (which are bioindicators) in association with physicochemical parameters in Eleyele Lake. Water, macrophytes, and benthic macroinvertebrates were collected from four stations monthly from March to August 2021 and analysed using standard methods. The relationship between the measured physicochemical variables, macrophytes, and the abundance of benthic macroinvertebrate was explored using canonical correspondence analysis (CCA). The encountered macrophytes represented 19 species (11 emergent, six floating and two submerged) in 16 genera and 12 families. The most abundant species was Ipomea aquatica (25.83%) in station 2 and Sacciolepsis africana (19.19%) in station 1. A total of 282 benthic macroinvertebrate individuals belonging to three phyla, four classes, 11 genera, and 11 species were encountered. Pollution indicator species including Melanoides tuberculata, Biomphalaria pfeifferi and Chironomus larvae observed in all the sampling stations were the dominant species. The CCA indicated that the abundance of macrophytes correlated with depth and nutrient factors (mostly phosphate). The result of the CCA showed the abundance of Chironomus larvae being patterned by dissolved oxygen and nutrient factors (phosphate, nitrate, and sulphate). These further confirmed the polluted status of Eleyele Lake, especially by nutrient enrichment. The dominant macrophytes and benthic macroinvertebrates in Eleyele Lake are pollution-tolerant species and the lake has been impacted by nutrient enrichment.