Lake 2010: Wetlands, Biodiversity and Climate Change MOLLUSCS OF PANGONG TSO, A HIGH ALTITUDE BRACKISH WATER LAKE IN LADAKH Boominathan, M and Ramachandra, T.V. Energy and Wetlands Research Group, Centre for Ecological Sciences, Indian Institute of Science, Bangalore. ABSTRACT In the course of ecological studies conducted during September 2010, at Pangong Tso, in Ladakh, we came across four species of Molluscs viz; Radix brevicauda, Radix lagotis, Valvata piscinalis, and Gyraulus sp. The molluscan species were collected in the form of empty shells, from a 10 m belt along the shoreline of the lake in the Merak village of Ladakh. The first three species have their global distribution confined to the colder countries of higher latitudes. In India they have been reported from the mountainous state of Jammu and Kashmir. Gyraulus, the species of which we have not been able to ascertain, is a cosmopolitan genus. The lake water having salinity of 10.69 ppt, at the time of our study, may be considered brackish. Although all the four molluscs have been reported from the water bodies of Jammu and Kashmir, it is the first report for Pangong Tso. Pangong Tso is a brackish lake; however, the molluscs reported from this lake are of freshwater origin. Initiating long-term study of molluscs will lead towards a breakthrough in documentation of mollusca and in preparing conservation strategies for the rare biodiversity of lakes such as Pangong Tso. Key words: Pangong Tso, Molluscs, Brackish lake, High altitude lake. INTRODUCTION Pangong Tso is a trans-boundary, high altitude, brackish water lake between India and China, at an elevation of 4300 m. It is a part of High Altitude Cold Desert Changthang Wildlife Sanctuary (yet to be declared by State Govt. Jammu and Kashmir). This lake has been proposed for Ramsar site (Chatterjee et al., 2002; Prasad et al., 2004) and the Ministry of Environment and Forest, Government of India has identified under the Wetland conservation Programme (Islam and Rahmani, 2008). Pangong Tso wetland harbours more than 300 species of birds, of which most of them are migratory; about 100 species are known to breed here (Namgail and Yom-Tov, 2009). It also acts as a foraging ground for these birds, especially on the marshes on the fringe (Chandan et al., 2005; Pfister, 2005). These foraging birds, especially summer breeders, feeding on molluscs, insects, and worms (Namgail and Yom-Tov, 2009). Even though, Pangong Tso wetland has international importance for biodiversity, the studies on invertebrates especially molluscs (which is one of the important food for many breeding birds) are sparse. Sharma (2000) found a fossil molluscs Radix auricularia (Syn: Lymnea auricularia), in the ancient lacustrine clay deposits above the present level of the lake and Godwin-Austen (1867) reported dead freshwater gastropod shells of Lymnaea and Planorbis, and bivalve Pisidium, along the shoreline. The other notable studies from Jammu and Kashmir are done by Sharma (2009), Dey and Mitra (2000), Dutta and Malhotra (1986), Kaul, et al., (1980), 22nd-24th December 2010 Page 1 Lake 2010: Wetlands, Biodiversity and Climate Change Rajagopal and Subba Rao (1968), Hora, et al., (1955), Prashad, (1928), Theobald (1878), and Woodward (1856). The aim of this study was to explore the molluscan diversity of Pangong Tso Lake. STUDY AREA Pangong Tso, is a trans-boundary brackish water lake between India and China, situated at 78.61°E, 33.79°N at an elevation of 4300 m. It is about 100 km away from Leh, towards east. The study was conducted in this lake region on September, 2010 near Merak village (Fig. 1). The Pangong Tso wetland is a results of tectonic movements (Williams, 1991), glaciation, and melt waters (Gujja et al., 2003). This lake receives water from numerous snow-fed streams (Negi, 2002). The lake, depending on the water input, alternates between saline and fresh water (Chang, 1987). The wetland area has 40 mm rainfall with 76 mm average annual precipitation. The precipitation season is from July to August. The temperature of this area vary from -40 degree C at night to +20 degree C at day time. The lake surface is covered by ~5 m thick mud and fine laminated sand (Pant et al., 2005), and the morain deposits at the western end of the lake (Trinkler, 1930). Fig 1: Pangong Lake and study site. Source: Googleearth, 2010. MATERIALS AND METHODS The empty molluscs shells were handpicked from a 10 m belt along the shoreline of Pangong Tso Lake, near Merak, Ladakh. The molluscs shells were stored in the plastic containers and brought to the lab for identification. The shells were identified up to the lower possible taxonomic level using Ramakrishna and Dey (2007). The pH was measured at the spot using EXTECH electrode (EC500). The chloride was analysed using Argentometric method (APHA, 1995) then the value was used to to find out the salinity level (Banerjee, 2005). RESULTS AND DISCUSSION The pH was 9.3 at Pangong Tso, such lakes with high salinity and pH were reported by William (1991). The 22nd-24th December 2010 Page 2 Lake 2010: Wetlands, Biodiversity and Climate Change salinity level of Pangong Tso Lake was 10.69 ppt, which was brackish (500 ppm salinity being upper limit for fresh water). The molluscs shells collected were freshwater gastropod species viz; Radix brevicauda (Fig 2a), Radix lagotis (Fig 2b), Valvata piscinalis (Fig 2c), and Gyraulus sp. (Fig 2d). The first three species have their global distribution confined to the colder countries. In India they have been reported from the mountainous state of Jammu and Kashmir. Gyraulus, the species of which we have not been able to ascertain, is a cosmopolitan genus. Although all the four molluscs have been reported from the water bodies of Jammu and Kashmir, it is the first report for Pangong Tso. Periostracum (outer thin organic layer) on the shell surface indicates that this organisms are recent ones. Since the lake alternates between saline and freshwater, freshwater molluscs are continue to live in this lake. Fig 2a. Radix brevicauda Fig 2b. Radix lagotis Fig 2c. Valvata piscinalis Fig 2d. Gyraulus sp. The length of Radix brevicauda, Radix lagotis, and Valvata piscinalis from anterior (apex) to posterior (bottom tip of aperture) were about 15 mm, 15 mm, and 5 mm respectively. Gyraulus was about 5 mm in diameter. CONCLUSION Pangong Tso is a brackish lake; however, the molluscs reported from this lake are of freshwater origin. Initiating long-term study of molluscs from this vast, under-studied, pristine Himalayan lake using suitably developed sampling methods, will lead towards a breakthrough in documentation of mollusca. Such studies will help in preparing conservation strategies for the rare biodiversity of lakes such as Pangong Tso. ACKNOWLEDGEMENTS We are thank full due to Tushar Prabhu, Rangarajan, Anshu Tomar, Lieutenant-General, and their team members for financial assistance, accommodation, and hospitality. And also we are great full to Harish, Durgha and Shankar Rao for accompanied in fieldwork. 22nd-24th December 2010 Page 3 Lake 2010: Wetlands, Biodiversity and Climate Change REFERENCES APHA. Standard Methods for the Examination of Water and Wastewater, 19th Edition. American Public Health Association, Washington DC; 1995. Banerjee PK. 2005. Oceanography for Beginners. 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