Composition, Abundance and Diversity of Plankton in Hand-Dug Wells in Ikpe Community, Akwa Ibom State, Nigeria

Abstract

Groundwater is one of the cheapest sources of freshwater for most human activities in the developing countries. Groundwater is also home to some aquatic biota which has been poorly studied in Nigeria. The composition, abundance and distribution of plankton in 5 hand-dug wells were assessed in relation to some physicochemical parameters. The study was carried out between April and November 2022 in Ikpe Community, Akwa Ibom State, Nigeria using standard methods. The physicochemical results were: temperature (24.2-29.8 o C), pH (6.0-7.9), electrical conductivity (60.3-136.4µs/cm), total dissolved solids (42.2-95.5mg/l), nitrate (0.22-3.73mg/1), chloride (13.8-134.3mg/l) and phosphate (0.42-1.85mg/L). All the parameters were within acceptable limits except pH while nitrate, chloride and phosphate were significantly higher in wells 4 and 5. The phytoplankton recorded 17 species and 415 individuals/l in the uncovered wells while the zooplankton recorded 24 species and 958 individual/l in all the wells. The plankton assemblage was rich and comparable to some surface water environments. However, the presence and dominance of indicator groups (Baccillariophyceae and Rotifera) especially in the uncovered wells (2, 4 and 5) is an indication that the water quality was deteriorating. The low values of the biodiversity indices also point to the poor water quality. It can be concluded that the composition, abundance and distribution of the plankton in the wells was influenced by the physicochemical conditions of the wells, which in turn was influenced by the location, construction, human activities and the general environmental conditions of the wells.