Plankton Abundance and its Nexus with Climatic and Water Quality Parameters in the Nile Tilapia (Oreochromis niloticus) Broodfish Pond.

This study aimed to determine the relationship between the abundance of phytoplankton and zooplankton, climatic variables, and water quality parameters in a tilapia broodfish pond. Water quality parameters were daily collected while plankton abundance was monthly recorded. Daily climatic data were obtained from the local Meteorological Department of Bangladesh. Throughout the study period, fluctuations were detected in both climatic and water quality parameters. Phytoplankton abundance showed annual variations, with the highest value of 10x105/L recorded in June and the lowest value of 3.5x105/L in December. Similarly, zooplankton exhibited seasonal fluctuations, with the highest value of 10x105/L in October and the lowest value of 2.3x105/L in January. Among the phytoplankton composition, Chlorophyceae accounted for 52% of the total, followed by Bacillariophyceae, Cyanophyceae, and Euglenophyceae. On the other hand, Rotifera constituted 29% of the total zooplankton, followed by Cladocera, Copepoda, and Protozoa. The fluctuations in phytoplankton and zooplankton abundance were influenced by both climatic factors and water quality parameters. The canonical correlations between the pairs of canonical variates were estimated at 1.000 and 0.883, with significance probabilities of 0.054 and 0.631, respectively. The initial canonical function showed a strong correlation of 1.00 (100%) between climatic variables, water quality parameters, and plankton abundance. In addition, this study revealed a negative relationship between plankton abundance and factors, such as air temperature, rainfall, water temperature, pH, and ammonia levels, while a positive correlation was observed with dissolved oxygen (DO) levels. The second canonical function showed a significant correlation of 0.883 (88.3%) between climatic variables, water quality parameters, and plankton abundance. In this context, phytoplankton abundance exhibited a negative correlation with dissolved oxygen and solar intensity, while showing an opposite relationship with water transparency. Similarly, zooplankton abundance showed a positive relationship with water transparency, but an opposite relation with dissolved oxygen and solar intensity. [ABSTRACT FROM AUTHOR]