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Introduction

The present observed pond is eutrophicated and keeps changing its physico– chemical and biotic complexes by virtue of seasonal changes and by incorporation of organic and man generated polluted matter like sewage, domestic discharges, municipal wastes, agrochemicals, grazing with other animal activities, surface run off, silt, clay, suspended inorganic and organic matter.

Present study reveals that how planktonic and biotic especially fishery lives get affected on account of alterations of abiotic factors in the Harchandpur pond.

Extensive work has been done by Indian limnologists on the ecology of Indian wetlands. How ever no sufficient work has been done on the ecology of wetlands of Distt. Etah.

The pond under study is getting deteriorated for pisci– culture and fishery management programmes due to lack of public attention, dis-management and infiltration of excess biogenic pollution. However people awareness could regenerate good conditions for production of living biota for commercial purposes. In this pond fishing is practisized by local contractors on behalf of Village Panchayat.

The Harchandpur pond is 9 Km. away from Etah city on Etah – Kanpur G.T. Road and located at about 0.25 Km. on eastern side of G.T. Road. The covering areas is around 10 hectares.

研究的目的是定性和做准备quantitative assessment of the abiotic and biotic conditions prevailing in the pond.

Material and Methods

Water samples were collected in clean glass bottles once in a month throughout the year (July 2005 to June 2006). Water temperature was recorded with centigrade thermometer.

Table -1: Variations of some physico-chemical parameters of observed pond during the year 2005 – 2006 Click here to view table

Transparency (penetration of light) was measured with Sacchi disc. pH was recorded with digital pH stick. Other physico-chemical parameters were estimated by standard methods of APHA (1998). Results were expressed in mg/l except pH, temperature and transparency. For plankton counting samples were collected from the water surface by filtering 5000ml. water through plankton net. Samples were preserved in 5% formalin and counting was done by haematocytometer and counter plate.

Results and Discussion

Four seasons were taken into account viz. Monsoon (July to Sept.), Post monsoon (Oct. to Nov.), winter season (Dec. to Feb) and summer season (march to June). Water temperature was more in summer and less in winter due to climato-geographical factors. Season wise fluctuation was due to heat gain from solar energy and transfer by conduction. (Chauhanet., 2006).Transparency was noticed high during winter and post winter times in which water becomes clear and transparent increasing penetration of light (low turbidity). Lower values were found in rainy season due to incoming surface run off with turbid rain waters.

Table - 2: Variations of No.of planktons during the year 2005 – 2006. Click here to view table

Alkalinity and Hardness were higher in summer probably by high growth of biota, more sewage, higher decomposition, domestic discharges and depletion of water level. Carbon-dioxide and bicarbonates concentrations got depleted in post monsoon and winter due to high rate of photosynthesis. pH kept more or less changing with alkalinity.

The D.O. concentration was suitable measure for aqua culture and fish management.D.O. was available in the pond by the direct diffusion from air and photosynthesis. (Dhakad and Chaudhary 2003). Dissolved oxygen (D.O.) was recorded maximum in winter due to high rate of photosynthesis and holding capacity of water. Its concentration was reduced during peak summer and monsoon due to more respiratory activities and decomposition by organisms. More pollution load also reduced D.O.

Phosphates and silicates had higher values in monsoon due to infiltration of agrochemicals, bony materials and other organic matter. Lower values were due to (in winter) more consumption by limnoplanktons (Mishraet al.,1998).

浮游植物s act as bridge between abiotic and biotic complexes in wetlands (Sahaetal.,2000). Chlorophyceae, Cyanophyceae,Bacillariophyceae were found as major groups of phytoplanktons while Rotifera, Cladocera and Copepoda were abundant Zooplanktons. Optimum presence of limnoplanktons leads to healthy production of macrofauna including fishes. No single factor could govern the production of limno-planktons. Infact variations in planktonic production attribute to many factors.

Two pulses of limnoplanktons were observed during present investigation. First one was recorded in winter and second one in summer (khanet al.,1974). Higher values of pH, D.O.andtransparency and low temperature, moderate values of alkalinity, phosphates and other vital minerals were probably responsible for winter pulse while Summer pulse was due to higher values of temperature, pH and alkalinity and moderate value of penetration of light.

Minimum growth of planktons was recorded during monsoon due to less D.O., minimum sunlight, less photosynthesis and transparency and load of turbid waters with organic pollution. These findings about limnoplanktons are similar to some extent to Jindal and Vasisht (1985).

The limnological evaluation of pond water described above shows certain fundamental features which promote moderate pisci-culture. Higher values of D.O., alkaline pH, higher values of total alkalinity and moderate presence of limnoplanktons are responsible for productive nature of pond.

References

1. Apha, Awwa, Wef - Standard methods for the examination of water and waste water 20^thedition, Washington. D.C.(1998).
2. Chauhan, R.P.S., Singh, M.P., Suraiya, A. and Singh, S.,Current world Environment., (2006) 1(1): 73- 75.
3. Dhakad, N.K. and Chaudhary, P., Nature Enviro. and poll. Tech., (2005) 4(2): 269-272.
4. Jindal, R. and Vasisht, H.S., Zoologica Orientalis, (1985) 2(1and 2) : 74 -83.
5. Mishra, A.P., Bora, B.K. and Sarma, M., J. fresh water Biol., (1998) 10(3-4):183-187.
6. Saha, S.B., Bhattacharya, S.B. and Chaudhary, A., J. Environ. Biol., (2000) 21(1): 9 - 14.
7. Vasisht, H.S. and Sharma, B.K., Indian J. Ecol., (1975) 2(1): 79 – 85.