By Dr. Maibam Dhanaraj Meitei (E-mail: [email protected])
Last century showed a remarkable loss in the area of Manipur’s central valley wetlands at an unpredicted high rate. Increase in indenting inhabitation, nutrient enrichment, construction inside the wetland, deterioration of water quality, microbial and heavy metal pollution, loss of biodiversity, high rate of siltation and garbage dumping is the present scenario of various wetlands of Manipur, including Loktak.
Population explosion and almost negligible increase in the net cultivated area led to tremendous rise in fertilizer usage throughout the Manipur river basin. Runoffs from agricultural fields find an easy way to Loktak and contribute significantly in the pollution of the wetland. Nutrient inflow to the wetland from the use of fertilizer is estimated between 100 to 200 kg ha-1. Imphal city alone accounts for 40% of the urban population of the basin, and generates nearly 126 metric tons of wastes/day, of which 40% remains untreated. In addition, loss of vegetation cover in the catchment hills due to jhum cultivation and construction of barrage upstream, particularly Ithai barrage have grieved the ecological condition. Constitution of Loktak Multipurpose Project for hydel and irrigation converted Loktak, a natural wetland with fluctuating water level into a reservoir with more or less constant water level. Of the 36 streams flowing into Loktak, Nambul river is infamous for its contribution in the wetland ecosystem degradation by loading nutrients and heavy metals in huge quantity. The consequences are loss of biodiversity, weed infestation, decreased fish production and proliferation of phoomdi.
Enormous growth of phoomdi has severe impact on the wetland ecosystem processes and functions. Phoomdi float mostly in suspended state and displaces water due to buoyancy. This affects the elevation-area-storage capacity relationship. The observed volume of water displaced by 1 cum of phoomdi is 0.75 cum of water and phoomdi occupies near to 107 km2 of the wetland surface. At present an estimated 45.96 Mcum of water is displaced by phoomdi. Therefore, increased phoomdi area will reduce the storage capacity of the wetland and eventually affect the water resources and wetland environment. The vast area of wetland covered by phoomdi (107 km2) is responsible for heavy loss of water through evapotranspiration. It has been estimated that water loss due to evaporation from the open water area of 73.5 km2 is 75.3 Mcum and the loss due to evapotranspiration from phoomdi covered area of 107 km2 is 136.4 Mcum. Presence of phoomdi in the channels and the channel mouth chokes and interferes with the flow regime. This results in prolonged stagnation and impoundment in the upstream courses and is one of the causative factors for flooding. As the phoomdi floats around the year, decaying of phoomdi plants and sinking in the wetland bottom has increased the eutrophication level of Loktak.
Mentioned factors led to the inclusion of Loktak in “Montreux records” by Ramsar Convention in 1993 (48 Wetlands in the list, out of 2171 identified Ramsar sites – by January 2013), highlighting the prior attention to be accorded to restoration of the wetland ecosystem. Government of Manipur responded with the establishment of Loktak Development Authority (LDA) for overall improvement and management of the wetland. Objective of LDA lies in checking the deteriorating condition of Loktak and to bring about improvement of the wetland with development in the fields of fisheries, agriculture, tourism and afforestation in consultation with the concerned departments of the state government.
With the unmanaged phoomdi in Loktak considered as potent factors for ecological succession of the wetland from open water to marshes and swamps. Initially, management of Loktak was mainly focused on removal of phoomdi, desiltation and availability of water to ensure sufficient generation of power. The master plan submitted by Water and Power Consultancy Services (India) Ltd (WAPCOS), a Delhi based Government of India’s consultancy organization focused mainly on development of fisheries, tourism and agriculture etc, with the construction of a 126 km long dyke encircling the wetland, dredging of a major portion of the wetland bottom, a large number of sluice gates, culverts, bridges and canals etc. with the removal of phoomdi by mechanical approach. The measures have not taken into account the problem of eutrophication, metal and organics pollution which is a physiological ailment of the wetland. This cannot be cured without understanding the ecosystem dynamics of the wetland which the authorities have failed to realize as relevant in their programme. Loktak development authority and WAPCOS while aiming at the enhancement of economic utility of the wetland and its beautification have ignored the problems of ecological health of the wetland. Dredging is meaningless if there is no adequate arrangement for the disposal of dredge spoils. Likewise, in depth baseline data need to be gathered before the removal of the phoomdi cover from the wetland. They failed to acknowledge the role of the phoomdi in maintaining a healthy and safe freshwater environment for the locals and the region, and the implications that will be caused to the freshwater wetland after phoomdi removal.
Phoomdi are reported to have a comprehensive capacity for nutrients and heavy metals accumulation from the wetland water column. Assessment of nutrients concentrations by several researchers showed accumulation of 478.6 metric tons of nitrogen (N) and 39.6 metric tons of phosphorous (P) annually by the phoomdi in the northern zone of Loktak. Phoomdi in the central and southern zone were reported to accumulate 729.0 and 419.2 metric tons of N and 60.3 and 36.1 metric tons of P from the eutrophic water. It was reported that that the nutrient concentrations in 8 dominant macrophytes of the phoomdi varied from 1.0-1.8% to 0.071-0.148% for N and P, respectively. Salvinia natans, Zizania latifolia, Echinochloa stagnina, Phragmites karka and Hedychium coronarium accumulated 1.8, 1.6, 1.0, 1.0 and 0.94% N and 0.084, 0.075, 0.054, 0.073 and 0.071% P from the eutrophic water of Loktak. It revealed an important role of phoomdi in phytoextraction of nutrients from the natural freshwater of Loktak. Thus, phoomdi helps in the restoration of the particular environment by acting as biological sink.
In addition, phoomdi plays an important role in the socio economy and traditional life of the local inhabitants. As phoomdi represents an entity constituted by more than 128 species of plants, presence of edible, medicinal, fodder, fuel, house making materials and plants useful in making handicrafts etc. are reported. For example; Locals normally have their meal with a vegetable prepared from phoomdi edibles. Local dishes, viz. iromba, kangsoi, kangsu, shak, singju and utti, thus form an important part of the traditional meal. Collection of the wild edibles from phoomdi is mainly done by womenfolk of the local communities. Alocasia cucullata, Centella asiatica, Hedychium coronarium, Neptunia oleracea, Oenanthe javanica, and Polygonum barbatum are commonly consumed. Phoomdi of Loktak provides luxuriant fodder for domestic animals. As a common practice, animals, viz. cows, buffaloes and goats are let free to graze in the phoomdi. Preferred fodders for the animals include Echinochloa stagnina, Enhydra fluctuans, Imperata cylindrica, Oenanthe javanica, and Zizania latifolia. Pigs are fed with cooked rice or fresh vegetables, viz. Alocasia cucullata or Alternanthera philoxeroides. Culms of Arundo donax, Narenga porphyrocoma and Phragmites karka, and shoots of Scirpus lacustris are commonly used as fuel in local households. As a commercial item, handicrafts made from S. lacustris are in great demand. Phak or mats, made by the womenfolks are sold at the rate of Rs. 200-300 per item. Handicrafts made from kouna helps in shaping the economy of many households devoted to the industry.
Above all, fish are attracted by phoomdi for shade, shelter, food and feeding grounds. The artisanal fishers around the lake has long ago understood the concept and they deftly devised a fish aggregating and capture method using the phoomdi in the form of circular floating island – called athaphoom. Loktak represents the largest fishery resource of Manipur, accounting for more than 50% of its fish producing area and near to >35% of its harvest from Loktak coming from athaphoom fishery. More than 19,000 tons of fish was harvested form Loktak and adjoining lake of Manipur during 2010-11, with 39% of the harvest from athaphoom fishing. Keibul Lamjao National Park (KLNP), a unique floating wildlife reserve in the world is composed of a continuous mass of floating phoomdi. It is the only natural habitat of the endangered species of Elds deer, Rucervus eldi eldi McClelland, with a population of near to < 200 heads in 2000. Loktak with its several islands located inside the wetland and surrounded by floating phoomdi of different geometrical shapes makes it a unique destination for tourism.
Proper management of the wetland requires an adequate understanding of the structure and dynamics of the whole ecosystem of the wetland in accordance with the science of limnology and wetland studies in place of ad-hoc methods practiced today by the organizations involved in the development of Loktak. At the conceptual level, the approach should be three pronged; comprising of dynamic conservation, sustainable development and equitable access to benefits of conservation. Dynamic conservation refers to setting up various means of an effective alternative for attaining the ecosystem condition of the wetland as it existed many decades ago. Sustainable development refers to the form of development that caters the need of the present generation without compromising with the needs of the future generations from the wetland. Likewise, the third aspect concentrates on ensuring equitable access to the benefits of the development to be implemented through the participation of various institutions and the local communities.
Removal of the floating island – phoomdi from Loktak need to reconsider the aspects mentioned, otherwise it will lead to ecological imbalance, disturbed socio economy of locals and ecosystem of the faunal members depending on phoomdi. It is the high time for the people of Manipur to decide and vote on whether they want to see the floating phoomdi as a blessing or a misfortune for Loktak, and act accordingly for the protection of the rapidly degrading Ramsar site before it dies.