Wetland of Beels in Assam

BEELS OF ASSAM

Location: 1392 beets scattered in 17 districts of Assam state
Area: c.100,000 ha
Altitude: 30-100 m
Biogeographical province: 4.9.4
Wetland type:14

Description of site: Derelict and semi-derelict wetlands constituting a part of the Brahmaputra floodplain, the beets are a vitally important fishery resource of Assam.There are about 1392 beets in the state, the maximum number being in Nagaon district (289), followed by Cachar (263), North Lakhimpur (153), and Jorhat (131).Together the beets constitute over 80% of Assam’s lentic waters.Beels are of two types: lake-like
beets, which are wide, shallow, with an irregular shoreline and are connected to rivers through channels; and oxbow beets, which are mostly parts of abandoned river courses (although some may be connected to the main river system through channels),are relatively narrow, long, and have a curved or serpentine shape. Districts North Lakhimpur and Nagaon have the maximum number of oxbow beets while lower Assam, comprising Goalpara, Dhubri and Kokrajar, has batteries of large, lake-like beets with high fisheries potential. Some specific beets are: Tamaranga (57 ha, Goalpara district); Dhir (689 ha, Dhubri district); Dipor (4000 ha, Kamrup district - see entry on wetland site 70 ); Sareswar (1700 ha, Dhubri district - see entry on wetland site 69); Dighali, Dora, Chandubi, and Salsala (250 ha, 463 ha, 311 ha, and 21 ha, respectively, Kamrup district). Beet morphometry is affected by incursion of river water, degree of precipitation, and nature of catchment. The deposits of decaying weeds at the bottom contribute to richness of the bottom soils in beets. The pH ranges from 6.0 to 7.6; and water depth from lm to 5.3 m

Climatic conditions: Humid, tropical monsoon climate with a prolonged monsoon season from May to September. A relatively cool, dry winter and a pre-monsoon period from March to May with occasional storms. Temperatures range from 10.6°C to 32°C

Principal vegetation: The forms of many large beets have favoured extensive development of marginal and submerged vegetation dominated by macrophytes. With high values of light quality and quantity combined with appropriate temperature regime and total alkalinity, the submerged macrophytes play a major role in determining plankton productivity and primary productivity in beets. Owing to a high rate of accumulation of nutrients, macrophytes compete with phytoplankton and, under macrophyte-dominated conditions, phytoplankton do not get enough nutrients for their growth. As a result, phytoplankton, in general, is poor in beets. In Dhir beet, phytoplankton is dominated by Chlorophyceae (Pediastrum, Spirogyra, Eudorina Mongeotia) and Myxophyceae (Microcystis, Anabena, and Oscillatoria). Macrophytes include Hydrilla verticillata and Vallisneria spiralis.Other species are Salvinia, Lemna, Wolffia, Potamogeton, Najas, and Trapa. A conspicuous feature of the beels, is the unusually high proportion of detritus

Land tenure: Some are state-owned (Departments of Flood Control, Irrigation, Agriculture and Fisheries); others are privately owned Conservation measures proposed: At a workshop held on ,development of beel fishery in Assam in April 1987 under the auspices of Assam Agricultural University, Guwahati, it was recommended that the beels be managed for their vast fishery resources; that no part of any beel be reclaimed for agriculture, housing, and industrial purposes, and the wetland character should be maintained; that conservation measures banning capture of brood fish and juveniles of prime food be enforced with strict rigidity; and that pollution of beels by the release of domestic and industrial effluents be prevented

Land use: The beels are exploited for their fishery resources

Disturbances and threats: Infestation by water hyacinth is a problem. Reclamation for agriculture and urbanisation, over-exploitation of fishery resources, and pollution from domestic and industrial wastes and agricultural run-off are other problems. Various government departments involved in the development of beels are unable to coordinate their activities to formulate and implement a common strategy for beel management

Economic and social values: Valuable for their fishery resources. In contrast to an average annual fish production of c.6-7 kg per ha per year from Indian reservoirs, the overall fish production from Assam beels is more than 100 kg per hectare per year. Beel waters are also utilised for irrigation, domestic consumption, and bathing

Fauna: Not much information is available on the birds of Assam beels. Fish fauna, however, have been studied. In beels that maintain connection with the river, locally migratory fishes are of considerable significance. The Indian major carps, particularly catla and rohu, depict such forms with Labeo gonius also contributing significantly. Gravid fishes of these species enter the beel every year during the monsoon months for spawning. Eutropichthys vacha and Gudusia chapra migrate in large numbers to the beels during the monsoon and form a post-monsoon fishery of considerable magnitude. Both juveniles and adults of the long-range migrant, Hilsa ilisha are found in the beels (e.g. Dhir, Dora, and Son beels). The fishery of Dhir beel is dominated by Gudusia chapra and other miscellaneous species including minor carps followed by major carps, cat fishes, live fishes, and common carp. Dominant zooplankton in Dhir beel include Protozoans followed by Copepods, Rotifers and Cladocerans. Due to high decomposition of organic matter at the bottom, beels, in general, are rich in benthos. The macrobenthos in Dhir beel is dominated by Gastropods (68.14%) and Pelecypods (19%)

Special floral values: No information