Influence of physico-chemical characteristics on the primary productivity of Nworie River, Imo State, Nigeria

A twelve-month study was conducted to examine the influence of physico-chemical parameters on the primary production of Nworie River to assess its suitability for fish culture. Water samples were collected from three stations along the river course and examined for various parameters. Data collected were analyzed using multivariate analysis, stepwise linear regression and spearman correlation while Tukey’s honestly significant difference was used to separate the means. Results showed that water temperature was significantly different (p<0.05) at all stations and were within normal range for fish culture. Similar observation was made in, the levels of conductivity, total dissolved solids (TDS), nitrogen-nitrate, free carbon dioxide, depth, chlorine, hardness and primary productivity. The levels of dissolved oxygen (DO) and phosphate-phosphorus were not significant (p>0.05) but within normal range for fish culture. Alkalinity and pH showed significant differences (p<0.05) in all stations during the study. In Station 1, alkalinity and pH levels were 8.06±1.9mg/l and 5.4±0.3mg/l respectively. Heavy metal concentrations recorded revealed that the levels of Chromium (Cr), Cadmium (Cd), and Zinc (Zn) were significantly different (p<0.05) in all stations and were within permissible limit for fish culture while the level of lead (6.72±0.78 – 7.540.36mg/l) was not. The regression analysis revealed that variables in DO, TDS, free CO2, Cd, and depth influenced primary productivity and were both positively and negatively correlated at 5% and 1% probability levels respectively. The authors thus concluded that Nworie River may not support aquaculture development until some ecological situations are remedied. Keywords: Physico-chemical parameters, Aquaculture development, Nworie River, Fish culture