ABSTRACT

The limnological characteristics of the Umudike reservoir in Ikwuano Local Government Area, Abia State, Nigeria was studied over a 12 month period (June, 2011 to May, 2012). The means and ranges of the physico-chemical parameters were recorded as follows: Temperature, air shade 29.52 (24.0 - 33.0°C); surface water 28.40 (24.0 - 34.0°C), and bottom water 26.67 (24.0 - 30.0°C), pH 5.76 (5.50 - 8.00), Depth 164.3 (131 - 198 cm), Transparency 72.3 (48 - 94 cm), Dissolved oxygen 6.57 (2.34 - 13.21 mg/l), Biochemical oxygen demand 2.97 (0.10 - 5.59 mg/1), Total hardness 23.7 (12 - 48 mg/l), Total alkalinity 6.29 (5.0 - 10 mg/I), Total Dissolved Solids (TDS) 591.2 (100 - 4300 mg/l), Total Suspended Solids 1432.3 (100 - 4000 mg/l) Turbidity 0.015 (0.00 - 0.08 NTU), Conductivity 68.34 (29.67 - 100.5 ps/cm). Magnesium 0.084 (0.00 - 0.69 mg/l), Potassium 3.19 (0.00 - 9. 40 mg/l), Sodium 1.25 (1.03 - 1.59 mg/l), Calcium 0.24 (0.00 - 0.66 mg/l), Iron 0.27 (0.008 - 1.567 mg/l), Sulphate 0.12 (0.008 - 0.681 mg/l), Nitrate 1.08 (0.00 - 4.41 mg/l) and Phosphate 0.68 (0.069 - 0.827 mg/l). All values except pH, Total dissolved solids and Total suspended solids fell within acceptable World Health Organization, European Economic Community and United States Environmental Protection Agency standards. Air shade temperature, Surface water temperature, pH, Dissolved oxygen, Percentage Saturation of Dissolved oxygen, Total hardness, Potassium, Sodium, Calcium and Iron showed significant difference monthly (P < 0.05), while among stations surface water temperature, pH, conductivity and turbidity showed significant differences (P<0.05). The commonest cationic order in the reservoir was K>Na>Ca>Mg in all stations. The PEASALLS INDEX ranged from 4.359 - 5.3256 mg/l in all stations while the Morphoedaphic index of the reservoir was 0.4159 mg/l. A checklist of phytoplankton revealed Species of Spirogyra (24.16%), Euglena (16.32%), Chlorella (14.40%), Micrasterias (12.96%), Cryptomonas (11.36%), Zygnema (10.72) % and Spirulina (10.08%). Based on the result and following standard criteria the reservoir could be said to be suitable for domestic, industrial and agricultural uses, however basic treatment can help improve the portability ofthe water.