Effect of Commercial Inorganic Fertilizer on Abundance of Plankton in Pond Polyculture System

Abstract

The experiment was conducted to assess and compare the effect of micronutrient enrich commercial inorganic fertilizer and macronutrient enrich traditional inorganic fertilizer on plankton abundance in the manmade earthen ponds of Khulna University pond complex II for a period of three months from August to October 2017. There were three treatments each with three replications. Macro fertilizers (Urea 2.45 g m-1 week-1, TSP 2.45 g m-1 week-1 and molasses–yeast mixture 3.09 g m-1 week-1) were applied in treatment-1 (T1) while commercial inorganic fertilizer (4.5 g m-1 week-1) was applied in treatment-2 (T2) while no fertilizer was applied in treatment-3 (T3). Four different classes of phytoplankton namely Chlorophyceae, Cyanophyceae, Bacillariophyceae, and Euglenophycaea were found in this experiment in which Chlorophyceae (5304.25±223.78 cells L-1) was the dominant class in respect of abundance and number of genera. Additionally, four classes of zooplankton such as Copepoda, Cladocera, Rotifera, Ostracoda were observed in which Copepoda (1559.84±70.48 cells L-1) was the most dominant class in treatment T2 than other treatments. Mean abundance of different phytoplanktons were 8864.77±52.78, 11489.04±295.76, 5983.04±272.88 (cells L-1) in T1, T2 and T3 and mean abundance of zooplankton under treatments T1, T2 and T3 were 3997.65±126.78, 4621.64±45.67, 3017.66 ±137.67 (cells L-1) respectively. The results indicated that mean abundance of phytoplankton and zooplankton were significantly higher (P<0.05) in treatment T2 compared to other treatments. The total mean abundance of plankton was observed significantly higher (P<0.05) in treatment T2 than other treatments. Therefore, it is concluded that micro nutrient rich commercial inorganic fertilizer Bluemix was more effective on the primary production in polyculture ponds as well as increase the production of fish than traditional inorganic fertilizer.