Ecological Study of Rupa Lake, Pokhara Valley, Kaski, Nepal

Abstract

The present study was carried out in subtropical Rupa lake, wetland of Pokharavalley, from an ecological and management perspectives.Vegetationanalysis wasdone by quadrat method. Altogether 43 species of aquatic macrophytesrepresenting 26 family and 40 genera were recorded. By growth form, theemergents and the rooted floating leafed species recorded highest and lowestnumber of species respectively.Nelumbo nucifera,Trapa quadrispinosa,Trapabispinosa and Leersia hexandra recorded highest IVI value throughout theexperimental period. Physico-chemical parameters like: water temperature, DO,pH, total nitrogen andPO -Pwere analyzed.The water temperature varied from21.29°C to 23.39°C throughout the experimental period.Parameters like pHandDO recorded higher value in post monsoon period, while temperature, totalnitrogen andPO 4 4 -Precorded higher value in pre monsoon period.On the basis ofPO 4 -P, the lake can be categorized as eutrophic.Biomass ranges from 27.25 g/m to 389.25g/m 2 throughout the experimental period and the highest dry mass valueof 389.25g/m 2 wasobserved at the eastern side during the post monsoon period.Comparatively, higher dry mass value was recorded during the post monsoon period (171.1824.03g/m 2 ) than the pre monsoon (98.351.69g/m ). Amongthe growth form, the highest and lowest biomass was represented by emergents (251.1695.16g/m 2 ),free floating species (104.7628.02g/m 2 ) andsubmergedspecies (48.39  7.27g/m 2 ) respectively; which depicts the decrease inproductivity with the corresponding increase in depth contour. The reportedspeciesposses economic uses and ecological values including their role as a fishfood to human food and sheltering habitat to invertebrate and birds. The nuisanceof aquatic weeds has thwarted the lake to develop as a major ecotouristicdestination by impendingrecreationalandecological values. The principal threatsto the lake include; siltation, eutrophication, agricultural runoff and lake areaencroachment. Suggested management approaches include integrated land useplanning of the shoreline campaigning awareness among general public,demarcation of lake boundary and conservation through wise utilization ofaquatic plant resources. Key words: Siltation, Eutrophication, ConservationBiomass Species diversity, Limnology