MOLLUSCAN BIODIVERSITY AND ITS SEASONAL FLUCTUATIONS IN TEEKAR TAAL, HARYANA, INDIA

Freshwater molluscs are the integral part of every aquatic ecosystem and help not only in the ecosystem’s functioning but also enable the ecologists to judge the health of their abode. These shelled animals are used as the best biomonitoring tools worldwide. Gradually declining water quality of freshwater bodies owing to multiple factors, their biodiversity is also facing threat. Majority of the freshwater bodies near human vicinities are facing anthropogenic interventions, habitat destructions and overexploitation and the same is being reflected by the elimination of sensitive molluscan species and survival as well as abundance of other tolerant ones. The current study has been undertaken to understand the Malacofauna biodiversity in Morni hills, Panchkula, Haryana. During the study, total 359 gastropods both aquatic and land snails were collected. Premonsoon season witnessed greater molluscan abundance, 8.46 times, than post-monsoon. The molluscan biodiversity, 7 species, 7 Genera and 5 families, namely Filopaludina bengalensis, Melanoides tuberculata, Radix luteola, Gyraulus ladacensis, Indoplanorbis exustus, Ariophanta interrupta and Macrochlamys indica.Shannon-Weiner Index (H) and Simpson Diversity Index (D) for both seasons indicated higher species diversity during post monsoon season. Melanoides tuberculata was found to be dominant during pre-monsoon while Filopaludina bengalensis during post monsoon season.


Introduction
The Molluscs are soft bodied animals, with or without external shell showing great diversity and antiquity. These animals were found throughout the world in wide range of habitats including marine, freshwater and terrestrial. Factors like temperature, nature and abundance of vegetation, nature of substrate and chemical compositions of water as well as substrate play vital role in their occurrence, distribution and density. These important part of every aquatic ecosystem, many Http://www.granthaalayah.com ©International Journal of Research -GRANTHAALAYAH [170] species act as food sources to many animals as well as human beings (species like Filopaludina bengalensis, Pila globosa and Brotia costula). Other helps in nutrient cycle and are also used as bio indicator of their ecosystem's pollution, hence play a pivot role in ecological studies (Sharma et al., 2013;Kumar et al., 2018) of aquatic ecosystems.
The taxonomic study of molluscs started more than two centuries ago (Benson, 1832) in India and since then the taxonomic literature on Indian freshwater molluscs had been found scattered and scanty some of the worth mentioning ones are: Ray, 1951  The present study is the first attempt to identify the malaco-diversity in Teekar Taal along with understanding their diversity and abundance fluctuations in different seasons.

Study Area
Teekar Taal also known as Bhim Taal is a natural lake located in Morni hills of district Panchkula, Haryana ( Figure 1) with width of 550m and length 460m also a perfect tourist place surrounded by lush green hillocks. The water is also used for various other purposes like irrigation and animal bathing.

Sampling
Soil sampling, from littoral and sub littoral zone, was done during pre and post-monsoon seasons (2018) with the help of modified Dandy sampler. Shells were also hand-picked from the shoreline area too. The soil samples were brought to the laboratory, sieved through Standard Test Sieves of different mesh sizes (BSS 75mm, 44mm, 30mm, 10mm, and 4mm), shells were picked from sieves (75mm, 44mm and 30mm). The soft tissues were preserved in 5% formalin and empty shells were

Statistical Analysis
To understand the species richness/diversity and abundance of molluscan fauna, in Teekar Taal during pre and post monsoon season following indices were used: -

1) Shannon-Weiner Index (Shannon-Weiner, 1949)
This Index is used to characterize species richness/diversity in a community. It is calculated by using formula, H = -Σ pi ln pi pi= Proportion of individuals found of species i th in the sample.

2) Simpson's Diversity Index (Simpson, 1949)
This Index is a measure of diversity which takes into account the number of species present as well as the relative abundance of each species. It is calculated by using formula ] n = Total number of individuals of particular species N = Total number of individuals of all species

Results and Discussion
During the study, total of 359 specimens belonging to 7 species, 5 families and 7 genus of gastropods were collected (Table 1). Maximum numbers of specimens were collected during premonsoon while maximum variety during post-monsoon (Table 2).  Filopaludina bengalensis mandiensis (Lamarck, 1822) Figure 4 Shell, dextral, more conical than typica, medium sized, whorls 6 in number, more convex than typica, color yellowish brown, alternative broad and narrow dark spiral bands, bands regular; sutures less impressed than typica; body whorl, evenly convex; penultimate whorl, less broader than typica; spire with pointed apex, height almost equal to body whorl; aperture ovoid; umbilicus narrowly open; callus well eveloped; innner peristome, not distinct, thin, fused with body whorl, outer peristome thin.
Shell height Shell width Aperture height Aperture width Number of whorls 32mm 23mm 15mm 13mm 6
Shell height Shell width Aperture height Aperture width Number of whorls 12mm 8mm 7mm 5mm 3 ½ Melanoides tuberculata (Muller, 1774) Figure 6 Shell dextral, turreted, neither very slender nor much elongated, whorls 9 in numbers, planoconvex, color dark brown, dark red brown dots and flames either irregularly distributed or longitudinally arranged on the shell surface, sculptured with vertical ribs and spiral striae, striae distinct and raised on upper whorls but flater on lower ones; sutures moderaltely impressed ;body whorl lightly convex; length of spire twice or little less than twice the length of body whorl; aperture pear shaped; umbilicus closed; callus developed, translucent ; inner peristome fused with body whorl, shows thickening on the seaprtion from body whorl, outer peristome thin.

Shell height
Shell width Aperture height Aperture width Number of whorls 5mm 10mm 5.5mm 5mm 3 ½
Shell height Shell width Aperture height Aperture width Number of whorls 11.5mm 20mm 9mm 7mm 5