Seasonal variation and plankton physico-chemical characteristics of Omeremaduche River, Abia state, Niger delta, Nigeria

Abstract

Omeremaduche river was surveyed for Physico-chemical and planktonic characteristics for a period of thirty-four (34) weeks. Three sections of the River were sampled and human activities were considered in the choice of sampling stations. Statistical analysis was done using the Analysis of Variance (ANOVA). The influence of Physico-chemical characteristics on plankton distribution were evaluated using Pearson’s Correlation. The mean values for pH, water-temperature, DO, BOD, phosphate and nitrate during the wet season were 6.91, 27.3, 5.86mg/l, 7.24mg/l, 0.38 and 4.18 respectively, while mean values of the same characteristics during the dry season were 6.68, 26.8, 7.22mg/l, 5.44mg/l, 0.25mg/l and 3.09mg/l. There was a significant difference in seasonal variation in DO, BOD, Nitrate and Phosphate, while there was no significant difference in pH and Water-temperature. The dry season variables were more favourable to plankton survival. Phytoplankton was characterized by four (4) phyla namely, Bacillariophyceae, Chlorophyceae, Euglenophyceae and Chrysophyceae while two (2) phyla Cladocera and Rhizopoda, represented the Zooplanktons. Bacillariophyceae recorded the highest number of individual species across the stations. The occurrence of plankton in Station 2, which is the point of dense anthropogenic activities, were less than what was obtained in the other sections. However, increased concentration of nutrients and dissolved oxygen were recorded in Station 3; this might have influenced the high plankton survival in the station. Changes in Physico-chemical characteristics of the River could be responsible for the varied plankton survival rate in the river. The seasonal variation may be attributed to varied rainfall patterns, while the partial variation may be due to the influence of various anthropogenic activities taking place around the river.