Comparative Analysis of Phytoplankton Communities in Newly Inundated Ponds Using Organic and Inorganic Fertilizers

A comparative study on the communities of phytoplankton in two newly inundated ponds was carried out from September 2023 to October 2023.The study was conducted in a completely random design experimental setup with two treatments, each replicated twice using organic (chicken manure) and inorganic fertilizer (di-a1mmonium phosphate fertilizer, (20:10:10) (2.5kg for each) fertilizers. Out of 1114 individuals of phytoplankton identified, 611 were from the organic fertilizer- treated tank, while 503 individuals were from the inorganic fertilizer- treated tank. The highest and the lowest phytoplankton species identified were Dactylococlopsis irregularis (79) > Phormidium tenue (53) > Ankistrodesmus falcatus (39) for the organic fertilized tank while the dominant species for the inorganic tank were Dactylococlopsis irregularis (45) > Ankistrodesmus falcatus (36), > Dinobryon bararicum (31). The least dominant species found in this current study for organic fertilizer were Closterium macilentum (7) > Amoeba polypodia (7) > Volvox aureus (3) > Raphidiopsis curvata (2) while the trend for inorganic fertilizer were Aphanizomenon flosaquae (7) > Spirulina subtilissima (4) > Nitzschia linearis (2). Physicochemical factors like Temperature, pH, Potassium, Total nitrogen, were found to be the important factors influencing the growth and distribution of phytoplankton and they exhibited significant positive correlation with phytoplankton in the PCA and CCA biplot. This present study revealed inter-tank differences in some of the physico-chemical parameters investigated. Potassium, phosphorus, nitrogen and dissolved oxygen (DO) were significantly different across the two treatments while temperature and pH were not statistically significant (P<0.05). The result from the analysis of all community parameters (Shannon-Wiener diversity, Evenness, Simpson and Margalef indices) showed slight variation. The highest in Shannon-Wiener diversity, Evenness, Simpson and Margalef indices were found in the inorganic fertilizer- treated tank (3.216, 0.8901, 0.956 and 4.34, respectively), while the lowest were found in the organic fertilize treated tank (3.141, 0.825, 0.948 and 4.209, respectively). This result indicates that the abundance and structure of phytoplankton communities were affected by the different fertilizer used and the tanks physicochemical conditions.