Global Journal of Fisheries Science

Biotic systems rely on continuous energy inputs, mostly from sunlight through primary production, to maintain their structure and order. There is a paucity of information on the primary productivity of the Lower River Niger (LRN), hence, this study investigates the variation in the primary production of LRN across time and space. LRN was stratified into three zones (A1, A2, and A3) with two sampling sites each, according to their hydrological features. Sampling was carried out between April and December, covering wet and dry seasons. Water samples were collected using a Van Dorn bottle, poured into light and dark glass bottles, and analysed using the oxygen production rate in the bottles.  Data were analysed using standard statistics at α = 0.05. The primary productivity of LNR after the consumption of energy for respiration, Net Primary Productivity (NPP, g/O₂/m³/d), ranged from 0.25±0.05 in A1 to 0.75±0.28 in A3, with a spatial mean value of 0.45±0.23, and there was no significant difference spatially. The NPP mean value (0.58±0.06) was higher in the dry season than in the wet season (0.28±0.06); however, there was no significant difference seasonally. The primary productivity of the Lower River Niger of 0.75 g/O₂/m³/d was low compared to those of most inland water bodies in and outside Nigeria. This may portend negative implications for the fisheries of the river. There is, therefore, a need to pay attention to the environmental considerations of this important river.