Seasonal variation in distribution and abundance of phytoplanktons in a fish pond of Madhepura District

Phytoplanktons are primary producers in an aquatic ecosystem. The distribution and abundance of phytoplanktons depends on physicochemical parameters of the water body and seasonal change. In the present study, distribution frequency and abundance of phytoplanktons were observed in summer season, rainy season and winter season. Physicochemical parameters of pond water was examined in each season (summer, rainy and winter). Temperature and pH were 32.60C and 8.1 respectively in summer season. The lowest value of temperature and pH was recorded in winter season (temperature- 17.30C and pH-6.9). E.C. was highest in summer (262.5?mhos/cm) and minimum in winter (160.3?mhos/cm). DO was highest in winter season (9.5mg/l) and lowest in rainy season (5.4mg/l). BOD was highest in rainy season (4.7mgl) and lowest in summer season (3.4mg/l). Phosphate was highest in summer season (1.93mg/l) and minimum in rainy season (1.83mg/l). Nitrate was highest in rainy season (1.25mg/l) and lowest in winter season (0.90mg/l). Seasonal variation in species of phytoplanktons were recorded which is mentioned in Table 02. Frequency of phytoplankton was examined. The highest frequency was recorded for Cladophoraglomerata (80%) in rainy season and winter season and 70% in summer season. Seasonal variation in abundance of phytoplanktons was studied. It was observed that the highest abundance occurred in rainy season (54600unit/ml) and lowest in winter season (33300unit/l).. KEYWORDS :Abundance, frequency, physicochemical parameters, phytoplanktons.