Assessing the Diversity and Abundance of Plankton Communities in River-Fed Earthen Fish Ponds in Relation to Productivity in Niger Delta (Ekpan Community), Nigeria

Fish health and productivity in the Niger Delta’s tropical aquaculture rely on good water quality, with river-fed ponds playing a key role in local fish production due to their nutrient-rich waters. This study evaluated seasonal variations in plankton communities in six river-fed earthen fish ponds in Ekpan Fishing Community, Niger Delta, Nigeria, from June to November. Phytoplankton diversity indicated primary productivity and nutrient status, with Cyanophyceae, Bacillariophyceae, Chlorophyceae, and Zygnemataceae as dominant families. Anabaena (450) and Oscillatoria (419) were the most abundant in June. Diatom Craticula (409) and green alga Coelastrum (319) also showed notable densities. High Cyanophyceae abundance suggests possible eutrophication, while Bacillariophyceae and Chlorophyceae levels reflect relatively balanced water conditions. Zooplankton also followed seasonal trends, with Rotifera and Copepoda dominating. Keratella spp. and Synchaeta spp. peaked at 244 and 214 individuals in October and November, respectively. Copepods such as Cyclops spp. (208 in September), Eucyclops spp. (230 in October), and Mesocyclops spp. (187 in November) were prominent, indicating stable conditions favourable for zooplankton and fish. Overall, the ponds exhibited nutrient-rich conditions that support plankton growth but pose a risk of eutrophication if not properly managed. The study recommends pond management strategies, including aeration, controlled feeding, and regular water exchange to maintain water quality and ecological balance. These findings offer valuable insights into the ecological dynamics of aquaculture ponds and inform sustainable fish farming practices in the Niger Delta.