\cite{Kutkuhn}.
During the present study 73 species of phytoplankton (15 species of Myxophyceae, 30 species of Chlorophyceae, 23 species of Bacillariophyceae, 2 species of Euglenophyceae, 1 species of Dinophyceae, and 2 species of Xanthophyceae) were recorded from both the wetlands. Representation of Mougetia sp., Pediastrum sp. and Scenedesmus sp. was substantial to abundant in the plankton samples of the wetlands, especially from the closed ones, indicating their eutrophic nature (Hutchinson, 1987).
The zooplankton community, which is a vital link in the aquatic food chain, is influenced by many Physico-chemical and biological factors. Temperature is considered as one of the determining factors in the seasonal distribution of the zooplankton population (Byars, 1960). But in the present study, no such relationship was observed. Similar observations were made from the floodplain lakes of India (Singh, 2000). The seasonal variation of the zooplankton population closely followed that of phytoplankton. According to Wright (1961), the abundance of zooplankton is chiefly dependent on the abundance of phytoplankton. In the present study, the major peak was observed in December when the abundance of phytoplankton was not always the highest. Zooplankton population had an exceedingly high direct correlation with phytoplankton abundance (r=0.978) in the present study, which further corroborates the above facts. 
Apart from temperature and food availability, the zooplankton density is also related to the chemical properties of water (Unni, 1971). The present study revealed a poor population of zooplankton in Kole beel although phytoplankton was rich in this beel. Similar observations were made by Lahon (1983), Goswami (1985), Yadava, et al., (1987). However, Kole beel supported a considerably higher zooplankton population, contributing to 38.2 % of the total plankton population despite having a poor phytoplankton population. The zooplankton population derived a part of their food from the organic detritus in addition to phytoplankton in these heavy macrophytes-infested beels. 
The zooplankton community structure in Kole beel showed the dominance of copepods (Copepoda>Rotifera>Cladocera), which is a common feature in the beels s of Ganges Valley         On the other hand, the dominance of rotifers observed in Saguna beel (Rotifer>Copepoda>Protozoa> Cladocera) was agreeable with the trend reported from other closed beels of the lower Ganges Valley. A gradual decline was observed in the percentage contribution of copepods to the total plankton population from October onwards in Saguna beel, which may be related to the prediction pressure from the sizeable number of catla (Catla catla) fry stocked in these beels during September. 
Food of Juvenile catla (2-10 cm) overwhelmingly comprised crustaceans (80%) and in adults also they were the most dominant food group (45%). Copepods, though present throughout the year, did not show any regular periodicity. Chen (1965) and Yadava (1987a) reported the affinity of copepod populations towards warm water. Ganapati and Rao (1954) observed temperature to be the controlling factor in the seasonal variation of copepods. The irregular periodicity observed in the present study indicated no definite relationship with water temperature. Mathew (1975) and Singh (2000) observed that copepod production depended on the availability of food supply.
 Rotifers have a versatile capacity to survive in different environments as some of them feed on various phytoplanktons, some feed on detritus and bacteria, while some others have been described as raptorial predators (Singh, 2000). Such high adaptive nature of this group favored its dominance of the zooplankton community in Saguna beel. The predominance of rotifers is a common feature of Indian freshwaters (George, 1966; Michael, 1969; Lahon, 1983). The relative abundance of rotifers in the beels s under the present study may be attributed to the infestation of macrophytes and the high accumulation of organic nutrients due to their annual decomposition. Peak rotifer abundance occurred during November-December in the present study. George (1966) and Singh (2000) recorded maximum production of rotifers during the summer season. Among the rotifers, the loricate forms like Brachionus spp. and Keratella spp. were predominant. Michael (1966) and Singh (2000) have made similar observations. The peak biomass of protozoans was recorded during November-December in the present study. Thus, a temperature range of 23.5 to 26.1 °C seemed to favor their growth, which lies within the optimum temperature range for the growth of protozoans (Pennak, 1953).
 Various workers (Wright, 1961; Michael, 1966) have suggested that the density of cladocerans is primarily determined by the food supply. In the present study, their peak population coincided with periods of rich phytoplankton, which conforms with the above observation. 
5.4.1.3 Periphyton 
Periphyton assemblage is known to be controlled from the “top-down” by a fish grazer interaction, and/or from “bottom-up” by nutrient and light availability. Each lake is unique concerning the presence, type, abundance of fish, grazing invertebrates, periphyton, macrophytes, nutrients, and clarity of the water. Periphyton is composed of attached plants and animals embedded in a “mucopolysaccharide matrix”. But these organisms have a significant role in the food chain of an aquatic ecosystem. The abundance of periphyton in the wetlands was estimated at 390 nos/cm2 (Saguna) and 503 nos/cm2 (Kole).
The community structure of the periphytic organism in the wetlands of West Bengal was recorded as Bacillariophyceae > Myxophyceae > Chlorophyceae>Miscellaneous Algae>Protozoa>Rotifers.
ACKNOWLEDGEMENT
 
REFERENCES