Status of biodiversity and limno-chemistry of Deepor Beel, a Ramsar site of international importance: Conservation needs and the way forward

Abstract

Deepor Beel is a prominent floodplain wetland and a Ramsar site of northeastern (NE) India (Ramsar site no. 1207) covering a 40.14 km² area and connected to River Brahmaputra. It provides numerous economic (e.g., livelihood and nutritional security) and ecological benefits (e.g. moderation of floods, groundwater recharge, repository of biodiversity) to the locality and its people. Deepor Beel was declared a Wildlife Sanctuary in 1989 and the area covered by the perennial water spread (10.1 km²) was subsequently designated as a Bird Sanctuary by the Government of Assam in 2009. The present paper provides an overview of the rich floral and faunal diversity of the wetland, including aquatic macrophytes (58 species), diatoms (65), zooplankton (171), bryozoans (5), molluscs (15), aquatic insects (55), prawns (3), crabs (2), finfish (68), amphibians (11), reptiles (33), birds (234) and mammals (24), in addition to the beel's limno-chemistry as well its conservation threats and suggested strategies. The wetland supports 18 globally threatened vertebrate species. Eleven bird species occurring in the wetland (Aythya baeri, A. nyroca, Leptoptilos dubius, L. javanicus, Ephippiorhynchus asiaticus, Gyps bengalensis, G. tenuirostris, Haliaeetus leucogaster, Pelecanus philippensis, Sarcogyps calvus, Threskiornis melanocephalus) have been included in the IUCN Red List of Threatened Species. Finfishes reported from the wetland declined from 67 species in 1999 to 64 between 2016 and 2018, which is a matter of concern. According to available information on limno-chemistry, the waters of the wetland have remained within the favorable range of water quality for fish production. Major threats faced by the wetland (e.g. pollution, encroachment, natural processes, etc.) and possible conservation strategies (e.g. control of aquatic pollution, prevention/ control of siltation, enacting and enforcing appropriate legislation, and other strategies) are outlined.