Faunal Studies of Krishnaraja Sagar Reservoir, Karnataka W.S.R. to Zooplankton,Aquatic Insects and Fishes

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Karnataka is one of the largest states in the country and bestowed with large number of lotic and lentic water resources comprising 5.60 lakh ha of which 2.93 lakh ha major and minor tanks, 2.67 lakh ha of reservoirs and about 5,800 km length of river systems making the state more productive in agriculture and fisheries. The drainage system of the state is conspicuous with rivers like Kalinadi, Netravati, Bediti, Aganashini, Chakra and Sharavati originated from western Ghats flowing in the west into the Arabian Sea and the major rivers systems like Tungabhadra, Cauveri, Krishna and two tributaries of Godavari viz. Manjira and Karanja flowing in the state and finally flowing in the cast into Bay of Bengal after passing through the state of Andhra Pradesh. The other tributaries are Bhiam, Ghataprabha, Malprabha and Tungabhadra. There are about 82 reservoirs (Veerappa Gowda, 2013) built across the rivers of Krishna, Godavari, Cauveri. All the cast-flowing drainages are mainly harnessed for irrigation, the west flowing streams are hold to tap their hydro-electric power potential and fisheries. The inland water resources offer enormous scope for development of fisheries in large scale in the state. The average estimated potential of these aquatic resources is around four lakh metric tonnes per annum. In addition to the fishery resources, the freshwater habitats: of the state are supporting rich faunal diversity including migratory and resident avian fauna.

The documentation on the faunal diversity of various freshwater habitats of the Karnataka: state is very limited. The studies on freshwater gastropods by Subba Rao, (1989), Ramakrishna et al. (2006), Punithavelu and Raghunathan (2007) are important. Recently Punithavelu and Raghunathan (2013) recorded about 29 species of mollusks with 7 forms; Biswas and Mandal (2013) listed 31 species of oligochaetes; 10 species of leeches by Mandal (2013). The studies on cladocera by Patil and Gouder (1982, 1985), Raghunathan (1988) and Raghunathan and Rane (2001) are important. Raghunathan (2013) reported 41 species of cladocera; Raghunahan and Valarmathi (2007) and Valarmathi and Raghnathan (2013) reported 20 species of freshwater shrimps, Srivastava (2013) reported 10 species of crabs, Society for Advancement of Aquaculture (2002) reported about 201 freshwater fishes, Gopi (2013) reported 28 species of fishes from Bhadra Wildlife Sanctuary and its reservoir area and Rema Devi et al. (2013) listed about 213 species of fishes from the freshwater habitats of Karnataka.

A perusal of literature shows that no major initiatives have been taken up to develop a database on biodiversity and ecosystem functions of the reservoirs of the state. Some studies were made on Tungabhadra reservoir by the Central Inland Fisheries Research Institute from 1963 to 1965, David et al (1969a), Govind (1963 and 1969), Krishnamoorthy (1966), Subba Rao and Govind (1964), Govind (1969) and Ramakrishniah (1994) on hydrology, plankton and benthic communities. In recent years, studies on zooplankton including cladocerans and rotifers of the freshwater bodies of Karnataka state have been made by Kiran et al. (2007), Padmanabha and Balagali (2007), Kudari and Kanamadi (2008), Koorosh et al (2009).