VARIATION IN ZOOPLANKTON DIVERSITY AND ITS RELATIONSHIP WITH ABIOTIC ENVIRONMENT OF A VANDIYUR POND TAMILNADU INDIA

Ponds, Lakes and Reservoir are most significant water resources with multiple human utilization andecological relevance in which Zooplankton diversity is one of the most important ecological parameters in water quality assessment. It is good indicator of the changes in water quality because they are strongly affected by environmental conditions. In the present study an attempt has been made to study the seasonal variations in the Zooplankton community, its diversity and hydrological parameters of this water body. In the present study, a total of 24 species of Zooplankton were indentified from different classes during August 2014 to January 2015. Among the identified species, Zooplankton showed the complete dominance, especially, zooplankton belonging to four major groups i.e. 9 species of Rotifera, 6 species each of Cladocera, 4 Copepoda and five species of Ostracoda.


INTRODUCTION
Studies on fresh water bodies, natural or manmade have gained much importance in recent years mainly because of their multiple uses. Several workers have attempted to study the hydrobiological profile of varied water bodies with intent of assessing the quality of water zooplankton play a very important role in increasing photosynthesis in some algae which pass through their nutrient rich elementary canal in viable condition. Zooplankton acts as bio-indicator of water quality as well as quantification of primary energy transfer from producer to primary consumer (Dulic et al., 2006). Kolhe et al., 2013 also observed the zooplankton communities respond more quickly to environment variations. Therefore the water quality is a major factor in determining the welfare of the society (Dwivedi and Pathak, 2000). It also plays a vital role in governing the production of planktonic biomass. The management of any aquatic ecosystem is a means of conservation of fresh water habitat with an aim to maintain the water quality or to rehabilitate the physico-chemical and biological settling of water (Ravi Kumar et al., 2005). Based on the above mentioned facts, it is suggested to make an inventory of the physicochemical parameters and zooplankton diversity of vandiyur pond, located in Madurai.

Study Area
Vandiyur pond was selected for my research work actually; it is a small aquatic pond with a minimum depth of pond about 25 feet. It is located just east zone of Madurai town. In which possess the common fishes likeCatlacatla, Rohu and kendai. This pond water is used only for the agriculture and fish farm.

Sample Collection
The water sample was collected from the pond surface once in the early hours of the day from August 2014 to January 2015. The water samples were collected using one litre container for the estimation of water quality parameters. The collected samples were immediately taken to the laboratory for analysis. The estimation was done by using the standard book of Kumar and Kakrani (2000).

Biological Analysis
Zooplankton samples were collected by filtering 300 litres of water from the surface of the water body through plankton net (40 μm mesh size) and which was fixed immediately with 4% ormalin. The systematic identification of zooplankton was made by using standard keys of Dhanapathi (2000) (ppm) and Altaff (2004). The quantitative analysis of planktonic organisms was carried out using Sedgwick Rafter's plankton counting chamber.

RESULTS AND DISCUSSION
The seasonal fluctuations of pond water quality parameters have a markedinfluence on the numerical abundance of zooplankton. Jeppesenet al. (2002) has stated that the enormous and diversity of zooplankton vary according to limnological features and the trophic state of freshwater bodies.

Qualitative study of zooplankton in vandiyur pond
Rotifera-9, species Cladocera-6, species Copepoda -4 and species Ostracoda -5 species. In a pond system, a total of 24 species of zooplankton have been exposed that belongsto four major groups. They were included as follows,

Quantitative study of zooplankton in vandiyur pond
In the present work was assessed, B. calyciflorus was found to be more in number during the month of August 2014 and B. forficulain the month of November 2014 (3units/ml). The other species were recorded in low number. B. rubens was observed only during August 2014. The enormous of rotifers and their community characteristics are used as effective indicators of environmental changes, such as, acidity, food level and humidity etc. (Attayde and Bozelli, 1998). The number of cladocerans recorded was minimum during the study period. Ceriodaphnia cornuta was recorded during the entire period of study. Their presence indicates the health of the ecosystem, as it forms the basic food item for fishes. Mesocyclops aspericornis was observed maximum in the month of November 2014 (20 units/ml) and minimum in January 2015 (5 units/ml). Kumar (1999) reported that cyclopsserve as the most suitable pollution tolerant indicator. Heliodiaptomusviduuswas found in range from 2 units/ml in August 2014 to 10 units/ml in December 2014. Diaptomusnauplius showed variations from 3 units/ml in December to 10 units/ml in January 2015. The ostracod was represented by only one species, Stenocypris major was observed in all the months (1 unit/ml) except November 2014.
In the air temperature was ranged from 27 to 30 o C and water temperature from 25 to 29 o C. Kumar and Kakrani (2000) opined that the rise in temperature of water elevates the metabolic activity of an organisms. It also influences the growth and distribution of plankton. Welch (1952) has observed that smaller the water body, more quickly to react the changes in atmospheric temperature. The pH of the water body showed alkaline in nature ie. 7.2 to 8.0This range is good for growth of aquatic organisms (Lendhe and Yeragi, 2004). Bell (1971) has stated the pH ranges between 6.5 to 9.0 provides an adequate protection to the life of fresh water organisms. Jhingran (1991) reported that pH ranges between 6.0 to 8.5 indicates medium productivity, more than 8.5 highly productive and less than 6.0 low productive nature of water body. Total hardness ranged between 58 ppm in December 2014 and 142.27 ppm in August 2014. Fishes have been found to susceptible to diseases when hardness is below 20 ppm. If it ranged more than 300 ppm, it affects fish production due to more pH as reported by Das (1996). Dissolved oxygen content in the water sample ranged from 4.2 to 6.09 mg/l . Mustafa and Ahmad (1985) opined the partial of O2 dissolved in water depends upon the partial pressure of gas in the air close to water, rate of photosynthesis and oxygen holding capacity of water. Tarzwell (1957) reported that for supporting life, minimum of 3mg/l DO is required. Free Co2 ranged from 2.9 to 4.9 mg/l during the study period. In morning sample, there is an accumulation of free Co2 due to overnight community respiration. Salasker and Yeragi (2003) noted that slightly increased Co2 in winter season. Free Co2 is essential for photosynthesis and its concentration affects the aquatic fauna and its productivity. The total alkalinity was ranged from 89.17 to 212.16 ppm. In the water body, the alkalinity is imparted by number of bases viz., carbonates, bicarbonates, hydroxides, phosphates, nitrates, silicates, borates etc., (Kumar and Kakrani, 2000). The fluctuation in salinity is probably due to fluctuation in total solids (Boyd and Tucker, 1998).
The minimum value of chlorides (89.12 ppm) was found in the month of January 2015 and the maximum value of 131.00 ppm during the month of December 2014 was recorted. Chloride content above 250 ppm makes water salty in taste; however a level upto 1000 ppm is safe for human consumption (Kumar and Kakrani, 2000). The phosphatecontent of water sample showed 0.01 to 0.06 mg/l. It is an essential nutrient, play a vital role inbiological activities of aquatic organisms. Lendhe and Yeragi (2004) reported the range ofphosphates from 1.20 mg/l to 3.70mg/l in Phirangekharbav lake.

CONCLUSION
An inverse relationship was observed zooplankton abundance. The managed fish culture pond which wasperiodically limed, manured and fertilised showed greater zooplankton being the dominant group. Whereas theunmanaged village pond showed a less diverse and eutrophic condition,zooplankton being the dominant group. It implies that alarge amount of ecological niches are remaining void and unutilized in village ponds. Whereas all the available ecological niches are beingeffectively utilized by the stocked fishes and periodically replenishedby fertilization in the managed fish culture pond. Therefore selectivestocking with appropriate species at low densities and extensive fishculture practices in the village ponds has ample scope. Adoption andtransformation of such village ponds by scientific management practicesinto semi-intensive fish culture ponds may prove to be an ecologicallyefficient, financially feasible and socially viable venture.