COMPARATIVE ASSESSMENT OF TWO INLAND WATER BODIES IN BAYELSA STATE, NIGERIA

Abstract

Igbeba-Ago and OxBow Lakes are two inland water bodies in Bayelsa State, Nigeria. The water temperature, dissolved oxygen, pH, salinity, total dissolved solids and turbidity; nitrate and phosphate levels; plankton composition, abundance and diversity indices were evaluated, to provide comparative information on their community structure and ecological status. The values for the physicochemical parameters of the lakes indicated better variables for OxBow lake. Their turbidity values were higher than the <3NTU limit. The nitrate values ranged from 6.87±0.38 to 10.32±0.17 mg/L and phosphate ranged from 1.98±0.45 to 4.46±0.64 mg/L for Igbeba
Ago and OxBow lake respectively, which were close to the 10mg/L (nitrate) and 5mg/L (phosphate) limits. Bacillariophyceae, Cyanophyceae and Chlorophyceae were identified in both Lakes; Igbeba-Ago lake had 5 taxa (24 plankters) while OxBow lake had 10 taxa (877 plankters). Copepods and Cladocerans were identified in both Lakes. Igbeba-Ago Lake hosted fewer species (8) but exhibited a higher abundance of plankters (214), with Odonata being present—an observation not made in OxBow Lake, which had 10 species and 114 plankters. The diversity indices for phytoplankton and zooplankton suggested the effects of stress linked to nutrients load, inflow and anthropogenic influences. These implied moderate pollution in both Lakes, validated by the presence of ‘contaminant tolerant species’- Microcystis sp and Chlorella sp. There is need for regular monitoring of these water bodies to ensure that, the guidelines for water quality are maintained for their productivity and the ecosystem services that they provide.