Lake Phewa Research Articles

Implications on Lake Phewa and Kulekhani Reservoir of Chemical Fertiliser Application by Farmers

This study analysed factors influencing the decision to use chemical fertilisers by farmers at the household level, and it included a related assessment of nutrients in nearby water bodies. One focus group discussion was held at each site, and then a total of 198 and 58 households in Lake Phewa and Kulekhani Reservoir, respectively, were surveyed. The results reveal that 90% and 55% of households applied chemical fertilisers in Lake Phewa and Kulekhani Reservoir, respectively. A logistic regression model indicated that the two factors having a significant positive influence on the decision to use chemical fertilisers were higher vegetable yield and the amount of urea available to farmers Water sampling indicated that phosphorous concentrations were relatively high in both these water bodies compared to previous studies in other nearby lakes.

Hydrogeochemistry of Two Major Mid-hill Lentic Water Bodies for Irrigation of the Central Himalaya, Nepal

The concentration and composition of different salts in natural water bodies determine the water quality for various purposes. This study assesses the water quality of two mid-mountain lentic water bodies, Lake Phewa and Kulekhani Reservoir. For this purpose, selected physico-chemical parameters along with major ions such as HCO3-, SO42-, PO43-, NO3-, Cl-, Ca2+, Mg2+, Na+, K+, and NH4+ were analyzed. Major ions were analyzed using ion chromatography, anions by DX-600 and cations by Dionex ISC-2500 ion chromatographs. The sources of major ions were determined by using the Gibbs diagram, Piper plot, and Scatter plots. Dissolved oxygen, ammonia and phosphate showed seasonal variations in both lakes. The concentrations of cations are in the order of Ca2+ > Na+ > Mg2+ > K+ in both water bodies. However the trend of anions had small variations for Cl- and SO42- in Lake Phewa (HCO3- > Cl- > SO42- > NO3-) and Kulekhani Reservoir (HCO3- > SO42- > Cl- > NO3-). The Piper plot and equiline plots indicated that the water chemistry is dominantly controlled by the dissolution of carbonate minerals and to a limited extent by weathering of silicate minerals. This is further supported by the Gibbs plot showing bedrock geology as the main source of major ions. The overall study indicates that the hydrogeochemistry of these water bodies is controlled by local geology and is suitable for irrigation purposes.

Carlson's Trophic State Index for the Assessment of Trophic state of Phewa, Begnas and Rupa Lakes in Kaski district, Nepal

Eutrophication of wetlands has been considered as a global level environmental problem due to wide range of environmental impacts caused by it. All the lake bodies are subjected to natural eutrophication process but anthropogenic activities like excessive utilization of inorganic fertilizers containing phosphorus and nitrogen in the farmlands which ultimately reach to water bodies through runoff during rainfall further maximizes the eutrophication. The research was conducted to find the trophic state of Lake Phewa, Lake Begnas and Lake Rupa which are three major lakes of Lake Clusters of Pokhara Valley, a Ramsar listed wetland from mid-hills of Nepal. Trophic state of lakes were classified on the basis of Carlson’s Trophic State Index. This index was calculated with the measurement of Secchi depth, Chlorophyll-a, and Total Phosphorus using standard methods. Study revealed that all three lakes were mesotrophic in both pre-monsoon and monsoon season. Lake Rupa had the highest Carlson Trophic State Index (CTSI) and Lake Begnas had lowest CTSI in both the season. Development of lake from oligotrophic to eutrophic state is a natural and gradual process and hence these lakes have increased chances of being eutrophic naturally along with natural process being crucially altered by cultural eutrophication which shortens the life expectancy of the affected aquatic body. Suitable conservation measures are needed to reduce organic load from lake to prevent from being further degraded.

Microplastic pollution in urban Lake Phewa, Nepal: the first report on abundance and composition in surface water of lake in different seasons.

Microplastics are man-made pollutants which have been detected in surface water and groundwater. Research on microplastic concentration in aquatic environment is attracting scientists from developing countries, but in Nepal no information regarding microplastic in freshwater system is available. Therefore, this study investigates the presence and abundance of microplastic in lake surface water of Phewa Lake, the second largest lake in Nepal. The average concentration of microplastic for surface water was 2.96 ± 1.83 particles/L in winter (dry) season and 1.51 ± 0.62 particles/L in rainy (wet) season. Significant difference with t = 4.687 (p < 0.01) in microplastic concentration was observed in two different seasons. Fibers (93.04% for winter and 96.69% for rainy season) were the commonly found microplastic type in lake water and transparent as the dominant color for the two seasons. Almost all the detected microplastic were found to be < 1 mm in size. Due to the small size of microplastic and unavailability of micro-Fourier transform infrared spectroscopy (μ-FTIR) and Raman spectroscopy in Nepal, polymer identification was not done. The findings from this study can provide a valuable baseline data on microplastics for the first time in Nepal’s freshwater lake environment.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11356-021-18301-9.

Trophic Status of Lake Phewa and Kulekhani Reservoir, Nepal

Eutrophication is one of the growing environmental concerns and is affecting and compromising freshwater bodies across the world making the trophic status assessment of water bodies crucial for their restoration and sustainable use. This paper describes the trophic status of Lake Phewa and Kulekhani Reservoir from Nepal. Sampling was conducted during October 2017 (post-monsoon), April 2018 (Pre-monsoon), July 2018 (Monsoon) and February 2019 (Winter). Trophic State Index (TSI) as given by Carlson (1977) and Trophic State Index Deviation given by Carlson (1991) were estimated to assess trophic status and deviations between the Trophic State Indices. One-way analysis of variance showed significant seasonal variation (p &lt; 0.05) in Secchi depth, total phosphorus (TP), TSI in both the water bodies. Both the water bodies were classified as eutrophic during pre-monsoon and post-monsoon, and hypereutrophic during the monsoon indicating the increased flow of allochthonous inputs from their respective catchments. Non-algal turbidity was found to be the limiting factor for productivity. There is a need for sustainable watershed management in order to reduce the nutrients runoff and accumulation in the water bodies.

Trace elements and organochlorine pollutants in selected fish species from Lake Phewa, Nepal

ABSTRACTLake water and fish livers and gills of sahar (Tor putitora), spiny eel (Mastacembelus armatus), African magur (Clarias gariepinus), and tilapia (Oreochromis niloticus) from Lake Phewa, Nepal, were assessed for the concentrations of trace metals/elements and persistent organic pollutants. The lake water was neutral with low ionic and metallic concentrations as compared to high-altitude lakes of Nepal. The four elements Cu, Zn, Se, and Cd had highest concentrations in livers, indicating uptake from diet, whereas four other metallic elements Cr, Mn, Ni, and Pb had highest concentrations in gills, indicating uptake from lake water. O. niloticus tended to have most of trace metals in the liver at higher concentrations than the other species but significant differences among the different species were found only for Mn, Ni, and Zn in the gills. A pilot study on the concentrations of persistent organic pollutants in muscle revealed that dichlorodiphenyltrichloroethane and related compounds were the dominant organochlorine pesticides, having highest concentrations in C. gariepinus and lowest in O. niloticus.

Mercury and Selected Trace Elements from a Remote (Gosainkunda) and an Urban (Phewa) Lake Waters of Nepal

Two lakes, one from the remote high altitude on the southern slope of the Himalaya (Lake Gosainkunda) and another from the urban mid-hill area (Lake Phewa) were studied for evaluating anthropogenic inputs of the pollutants, particularly mercury (Hg) and other trace elements (TEs) (such as Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb). A total of 77 water samples, 24 from Lake Gosainkunda and 53 from Lake Phewa were collected from different depth profiles during October/November 2010. Concentrations of Hg were significantly higher in Lake Gosainkunda compared to Lake Phewa probably due to long-range transport of Hg and its deposition on high altitudes of the Himalayas, in addition to the probable natural geological sources. Some of the TEs (such as Al, V, Cr, Mn, Fe, and Co) show crustal origin in Lake Gosainkunda, whereas others such as Ni, Cu, Zn, Cd, and Pb indicate possible anthropogenic origin (enrichment factor (EF) > 4). On the other hand, Al, V, Cr, Ni, and Cu show crustal origin in Lake Phewa and the remaining TEs (Mn, Fe, Co, Zn, Cd, and Pb) showed high EF values relative to the crustal elements suggesting potential anthropogenic inputs of the pollutants. The study further indicates that two studied lakes have different potential sources for Mn, Fe, Co, Ni, and Cu regarding TE pollution. A high enrichment of Cd and Pb in high-altitude lake (with less anthropogenic activities) compared to the low-altitude lake (with high anthropogenic activities) indicates atmospheric long-range transportation of the pollutants in remote areas of the Himalayas which might be possible as air masses pass through the industrial areas and deposit in the high altitudes.

The risk of mercury exposure to the people consuming fish from Lake Phewa, Nepal.

The risk of mercury exposure through consumption of fish from Lake Phewa, Nepal was investigated. A total of 170 people were surveyed to know their fish consumption levels. The weekly mercury (Hg) intake in the form of methylmercury (MeHg) through fish was calculated by using the data on average MeHg concentrations in fish, the average consumption of fish per week, and an average body weight of the people. Hotel owners were consuming significantly high amounts of fish, followed by fishermen, in comparison to the government staff, army/police, locals and others (visitors). Some individuals exceeded the Provisional Tolerable Weekly Intake (PTWI) of 1.6 µg per kg body weight of MeHg (FAO/WHO). The minimum intake of MeHg (0.05 µg/kg/week) was found in the visitors (others) category, whereas the hotel owners had the maximum intake (3.71 µg/kg/week). In general, it was found that a person of 60 kg can consume at least 2 kg of fish per week without exceeding PTWI such that it does not pose any health risk associated with Hg poisoning at the present contamination level. Hg based PTWI values for Nepal has not been proposed yet in fishery resources so as to reduce health risk of the people.

Mercury Concentrations in Commercial Fish Species of Lake Phewa, Nepal

Mercury (Hg) concentrations in four commercial fish species (Tilapia Oreochromis niloticus, Spiny Eel Mastacembelus armatus, African catfish Clarias gariepinus, and Sahar Tor putitora), were investigated in Lake Phewa, Nepal. Mean values of total mercury (THg mg kg(-1), ww) in these fishes were 0.02, 0.07, 0.05, and 0.12 respectively. Methylmercury contributed 82 % of THg. The lowest value was detected in O. niloticus, an exclusive plant feeder. The biomagnification rate of Hg through the fish community was 0.041 per δ(15)N (‰). The present investigation produced an important baseline data of Hg pollution in the fish community in this region.

Abundance and nutrient limiting growth rate of heterotrophic bacterio‐plankton in Himalayan foot hill Lake Phewa, Nepal

We examined heterotrophic bacterial abundance, chlorophyll-a concentration and resources limiting bacterial growth from October 2004 to August 2005 in Lake Phewa. The lake has a large watershed that covers � 435 ha of water surface surrounded by � 23-time large catchment area that might receive up to 4850 mm annual precipitation. During the study, bacterial abundance ranged from 3.2 to 9.9 · 10 6 cells mL )1 , and chlorophyll-a varied from 2 to 32 l gL )1 . Bacterial abundance and chlorophyll-a weakly correlated (r = 0.40, n = 77, P < 0.1) in the lake. Experiments on resources, glucose (C), nitrogen (N), phosphorus (P) alone and in combination (CNP) limiting bacterial growth rate, were examined using dilution bioassays. Experimental bottles enriched with resources and controls without enrichment (in triplicate) were incubated in situ for 48 h at collection depth. Results showed that C, N and P in combination significantly (at 5% level) stimulated bacterial growth rate. Bioassays with single resource additions showed P as main nutrient limiting bacterial growth comparing with C and N, implying that rainfall received in the catchment might convey adequate resources causing increased P deficiency for bacterial growth in Himalayan foot hill Lake Phewa.

Phytoplankton primary production, chlorophyll‐aand nutrient concentrations in the water column of mountainous Lake Phewa, Nepal

The seasonal patterns of phytoplankton primary production, chlorophyll-a concentration, cell number and several other limnological variables in Lake Phewa, located in the active monsoon zone in Central Himalaya, Nepal, were studied for a year beginning in April 2001. During the study period, the gross primary production and chlorophyll-a concentrations were relatively low during the monsoon season. The phytoplankton cell number, represented by 24 genera, also fluctuated seasonally, but tended to increase in the pre- and post-monsoon period. These results suggest that the monsoon plays a crucial role in the primary production and phytoplankton dynamics for Lake Phewa. Among the phytoplankton species, Microcystis aeruginosa, a representative species for eutrophic lakes, was the dominant phytoplankton. At the same time, however, it is clear that the lake is not yet heavily eutrophic. The present study suggests that the exchange of lake water during the monsoon season contributes to maintaining the health of the lake against further degradation. Nevertheless, the silt carried in the monsoon rain run-off from the lake's catchment area suggests increasingly serious degradation problems for this small mountainous lake.

Evaluation of natural food for planktivorous fish in Lakes Phewa, Begnas, and Rupa in Pokhara Valley, Nepal

Six floating 4-m3 cages stocked with 40 silver carp per cage (three cages) and 40 bighead carp per cage (three cages) were placed in each of the three subtropical Lakes Phewa, Begnas, and Rupa. The fish were cultured, without supplying artificial feed, from August 1994 to December 1995. Fish growth was positively correlated with water temperature, and a slight loss in weight occurred in January when water temperature fell below 16°C in all the lakes. Fish growth was better in Lake Phewa than in Lakes Begnas and Rupa, where food might not have been sufficient or of a quality to sustain fish growth. The fish fed on mostly indigestible phytoplankton, Microcystis aeruginosa in Lake Begnas and on Tabellaria fenestrata and Microcystis aeruginosa in Lake Rupa, which can lead to poor fish growth. The maximum growth rate of silver carp (5.8 g day−1) and bighead carp (4.7 g day−1) occurred in Lake Phewa when Ceratium hirundinella and Peridinium spp. were abundant from August through October. The food particles found in the gut were mostly similar in silver and bighead carp, though Cladocerans (Bosmina longirostris) were observed sparsely in the gut contents of bighead carp only.

Limnological characteristics of subtropical Lakes Phewa, Begnas, and Rupa in Pokhara Valley, Nepal

Limnological characteristics were studied and analyzed in the subtropical Lakes Phewa, Begnas, and Rupa of Pokhara Valley, Nepal, from 1993 to 1997. The annual water temperature ranged from 12° to 29°C in all lakes. Lake Phewa and Lake Begnas were monomictic and anoxic in the hypolimnion during thermal stratification from April to September. Dissolved oxygen was drastically depleted in April and/or May in shallow Lake Rupa when the macrophyte community began to decompose. NH4 +-N accumulated below 5 m during March–September when dissolved oxygen was depleted in Lakes Phewa and Begnas. The PC : PP ratio was higher, but the PC : PN and PN : PP ratios were close to the Redfield ratio (106C : 16N : 1P) in Lakes Phewa and Begnas, denoting that P was limited. Annual net primary production showed that the lakes were productive but will tend to become heterotrophic in the future. The seasonal variation of chlorophyll a concentration was high, but its annual variation was low. Ceratium hirundinella and Peridinium spp. in Lake Phewa, Microcystis aeruginosa and Aulacoseira granulata in Lake Begnas, and Tabellaria fenestra in Lake Rupa were the dominant species. The zooplankton population and species varied irregularly. On the basis of chlorophyll a concentration in the euphotic zone and phytoplankton species composition, the lakes seem to be oligoeutrophic and to have some characteristics of temperate lakes rather than tropical lakes.

Use of a subsurface plankton layer to benefit a cage-culture fishery in Lake Phewa, Nepal

(1998). Use of a subsurface plankton layer to benefit a cage-culture fishery in Lake Phewa, Nepal. SIL Proceedings, 1922-2010: Vol. 26, No. 5, pp. 2220-2227.

Seasonality and Fecundity of Daphnia Lumholtzi Sars in Lake Phewa, Nepal

Monthly sampling of zooplankton in Lake Phewa, Nepal revealed 18 species of zooplankton excluding protozoans. The seasonality and fecundity of the largest common cladoceran Daphnia lumholtzi Sars was studied. Two distinct peaks of abundance were noted. No active stages were found during May and June. Egg ratio varied from zero to 0.88 in mature females. From the presence of only helmeted individuals of this species it is concluded that the predation pressure by fish was high.

Seasonal Variations of Zooplankton, Chlorophyll-A and Nutrients in Phewa Lake, Pokhara Valley, Nepal

In order to understand trophic status of lake Phewa, largest lake (535 ha) in Pokhara valley, seasonal pattern of zooplanktons, chlorophyll a and nutrients level in water column was examined from January to December 2005. Total zooplanktons density was highest in January and November, showed bimodal pattern in Lake Phewa. The sequence of dominant species of zooplankton was Nauplius &gt; Kerratella &gt; Cyclops &gt; Daphnia &gt; Eodiaptomus in this lake. Correlation between zooplankton species and nutrients level was established. The Chlorophyll- a as an indicator of phytoplankton biomass peaks in November and chlorophyll-a concentration was found lower in winter months. The NH4-N ranged between zero to 0.021 mg/l with mean of 0.003 mg/l. The annual concentration of nitrate+nitrite (NO3+NO2) was found upto 0.148 mg/l (mean= 0.013 mg/l), soluble reactive phosphate (PO4-P) ranged from zero to 0.003 mg/l (mean= 0.001 mg/l), and total phosphorous ranged upto 0.052 mg/l (mean= 0.009 mg/l) in lake Phewa in 2005. Based on nutrients and chlorophyll-a dynamics, the lake varied from mesotrophic to eutrophic in different seasons. The Phewa Lake fluctuated from oligo-mesotrophic in monsoon seasons to meso-eutrophic in dry periods. Key words: Zooplanktons, nutrients, chlorophyll. DOI: 10.3126/eco.v16i0.3473ECOPRINT 16: 51-57, 2009

Effect of Different Feed Ingredients on the Growth of Caged Common Carp

To know the effect of four different fish feed, nine months old common carp about 47 g size were stocked at the stocking density of 12 fish m-3 in the cages and cultured in Lake Phewa for 175 days. Four different feed ingredients used were fish meal + soybean + oil cake + rice bran + wheat flour, fish meal + oil cake + rice bran + wheat flour, soybean + oil cake + rice bran + wheat flour and commercial cattle feed. The crude protein ranges from 23 to 32.2%. 32.2% protein content feed containing ingredients of fish meal + soybean + oil cake + rice bran + wheat flour was better for the fish growth (0.30 g day-1) but was the lowest survival rate (65.4%) followed by 27.1% protein content feed containing fish meal + oil cake + rice bran + wheat flour (0.23 g day-1). 26.2% protein content feed containing soybean + oil cake + rice bran + wheat flour without animal protein was the poorest growth rate (0.17 g day-1) with the highest survival rate (95.7%) among the tested feed. It was observed that feed with higher protein level was better for the fish growth and the growth of the fish was different significantly among the treatments except the treatment fish meal + oil cake + rice bran + wheat flour and commercial cattle feed. The common carp fish cultured in cages through artificial feed was not satisfactory. It digs and burrows the pond embankments and sides in search of organic matter that makes pond turbid.Key words: Cage fish culture; Common carp; Feed ingredientsDOI: http://dx.doi.org/10.3126/narj.v4i0.4871Nepal Agriculture Research JournalVol. 4&amp;5, 2001/2002Page: 60-63Uploaded date: 9 June, 2011