Table of ContentsLand use and land coverWater qualityEcological assessment: macroinvertebrate assemblagesMactoinvertebrate speciesLand use and land coverStatistical analysis of land cover change in Mai Pokhari identifies three main land cover types, namely forest, agricultural land and grassland and observations of significant changes over a span of 10 years from 2000A.D. to 2010A.D. There has been a significant increase in agricultural land where forest has decreased significantly. The forest around Mai Pokhari was observed dense and increased over a 10-year interval, but decreased when moving outwards. This could be due to conservation practices managed by the Wetland Management Committee near the wetland. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get an original essay There is no collection of raw materials, including wood and fodder from the surroundings of a wetland, which contributed to the growth of a dense forest. Moving away from the wetlands, most of the forest was observed transformed into agricultural land. Dense community forests were also observed to the north and west of the wetlands, as well as scattered forests to the east and south, consisting mainly of residential areas. The population of the study area increased (CBS 2014) and most women were found involved in agricultural practices. Instead of traditional practices, large commercial agricultural farms were created. This could be the cause of the decrease in forest cover. Most residents near wetlands have established hotels and lodges as a major source of income. In such cases, people plant timber trees on their private lands for sale, which transforms scattered forest areas into residential areas. Forest depletion as well as massive construction have a direct impact on groundwater, causing a drop in water levels (Alam¹, Rashid, Bhat¹ and Sheikh, 2011). Roads near wetlands, house construction and heavy vehicle traffic could also add impacts to wetland conditions. . Most males from this region move to India for seasonal reasons. This current trend is replacing traditional occupation, including livestock and trade. Most grasslands become bare and overgrown. With less use of grasslands, they are slowly transforming into forest. Land conversion from one form to another has a huge negative impact on wetland resources (Alam, 2011) as well as local ecosystem services (Zhang, Zhao, Liu, Liu, & Li, 2015). Water quality Changes in physio-chemical parameters due to natural and human activities. Dissolution of bed materials, weather events are among the natural causes as well as climate change, although they are naturally influenced by human activities. The pH measured during both sampling seasons was found to be acidic. The measured pH is below water quality guidelines for the protection of aquatic life (6.5-9.0), which could be due to the acidic nature of the lake water due to deposition mass of fallen parts of Pinus roxburghii in the ground. There has been a significant deposition of organic matter in the lake and the decomposition of this organic matter releases carbon dioxide (CO2). The carbon dioxide thus produced combines with water andform of carbonic acid (H2CO3). Carbonic acid is also responsible for low pH. pH is positively correlated with ammonia and nitrate. The decomposition of organic sediments also releases nitrates and ammonium ions which enhance hydrogen ions (H+) making the water acidic (Adeogun & Fafione, 2011). The decomposition of organic matter forms acid-containing compounds and elevates hydrogen ions in water (Yimer and Mengistou, 2009). There could be a flow of NO3- and PO¬4- into wetlands from agricultural lands and grasslands. The optimal pH level for the survival of the organism varies from 5 to 9 and beyond this limit, species suffer (Mesner & Geiger, 2010). Water conductivity is always strongly influenced by the surrounding geology (Light, Licht, Bevilacqua, & Morash, 2005). Water conductivity was measured very low during both sampling periods, which was due to the presence of graphite rocks as bed and bank materials. Graphite is mainly composed of inert materials (Light et al., 2005). Dissolved oxygen is very reactive and changes rapidly in a very short time (Legesse, Giller and O'halloran, 2000). Dissolved oxygen is one of the main factors affecting the existence of aquatic species (Giller & Malmqvist, 1998). Community assemblages and distribution of aquatic organisms are directly linked to dissolved oxygen (Jackson & Myers, 2002). According to USEPA (2000) guidelines, a DO concentration greater than 5 mg/L is appropriate for the growth of most aquatic organisms and less than 3 mg/L. L is stressful for aquatic organisms. The measured DO is less than 3 mg/L, indicating a stressful environment. A similar result was displayed by Rai (2013) in his research. 5-8 mg/L DO for aquaculture and 80-100% DO saturation for a balanced aquatic ecosystem are guidelines set by the Nepal Water Quality Guidelines. The measured DO is below Nepal's water quality guidelines, which indicate unfavorable living conditions for aquatic organisms. The result showed a slight increase in DO concentration before the monsoon, but the overall concentration was also low. The major nutrients namely total phosphate and nitrate were found higher during post-monsoon and pre-monsoon season respectively. These nutrients have a major influence on the growth of algae and aquatic weeds (Wetzel 2001). The growth and decomposition of algae and macrophytes consume more dissolved oxygen and therefore decrease the dissolved oxygen concentration. Likewise, microbial organisms consume more dissolved oxygen to break down huge deposits of organic matter. These could be major factors in decreasing the concentration of dissolved oxygen in the lake. Low DO is a good indicator of poor lake water quality. Simply, alkalinity is an ability to resist change in pH. Generally, most lakes and reservoirs maintain a similar pH due to the presence of carbonates, one of the main components of alkalinity. Carbonate forms in water after the reaction of carbon dioxide with water. The addition and reduction of carbon dioxide are simultaneous processes in wetlands where the addition of carbon dioxide reduces the pH while the pH increases with the reduction of carbon dioxide. Water alkalinity is also associated with hardness. The higher the total alkalinity of the water, the harder the water will be. Total hardness is the sum of calcium hardness and magnesium hardness. The main cause of hardness ispresence of calcium and magnesium, often produced by the dissolution of limestone. In most of the samples, there were rocks that could release calcium and magnesium into the water. Bodies of water contain nutrients, but excess nutrients are harmful. Nitrogen, phosphorus and ammonia are the main nutrients in fresh water. These nutrients enter freshwater through a variety of sources, including substrate rocks, atmospheric deposition, surrounding vegetation, land use practices, and human activities. The overabundance of these nutrients makes the lake polluted because it encourages excessive algae growth. The growth and decomposition of algae reduces dissolved oxygen, making it difficult for aquatic organisms to survive. Some algae also produce toxins that can be harmful to aquatic organisms and humans if ingested. Nitrogen and its various forms are of great concern in the study of water analysis, as they are a major cause of environmental pollution. Various amounts of nitrogen enter water through natural and anthropogenic processes. Because nitrate is highly soluble in nature, it reaches water from terrestrial materials, organic matter, and fertilizers (Schmitt, Randall, & Malzer, 2001). Excess nitrate has a long-term and long-chain impact on the aquatic ecosystem. It promotes the growth of macrophytes and wild plants. The death of these plants adds organic matter and microorganisms for decomposition. The decomposition of organic matter by a microorganism consumes more oxygen and an oxygen deficit results in the death of the aquatic organism. Mai Pokhari is a rainfall-fed lake with a high organic matter content. Organic matter could be the main source of nitrate in the lake. Due to the gradual decline in water level, the lake water comes from the river water. River water moving toward the lake carries nutrients from external sources. Agricultural runoff, plant debris, and animal feces were sources of nitrate releasing into the river that was observed. The oxidation of ammonia also naturally forms nitrates. Nitrates were measured in the range of 0.07 mg/L to 3.2 mg/L and increased during the pre-monsoon season. Water quality guidelines and FAO have set a tolerable quality range of less than 300 mg/L for aquaculture. A concentration change of less than 15% from unimpacted local conditions is tolerable for the aquatic ecosystem according to Nepal's water quality guidelines. Ayers (1985) reported no impact on plants and aquatic organisms below the concentration of 5 mg/L. The nitrates measured were within the guideline range set by the water quality guidelines. The measured ammonia was between 0.18 mg/L and 2 mg/L above the range of water quality guidelines for the protection of the aquatic ecosystem (<0.007 mg/L) and for aquaculture (<0.03 mg/L). Unlike excessive nutrient enrichment. , excess ammonia in water bodies adds toxic substance or accumulation of toxic substance in the body of the aquatic organism and ultimately leads to death. Ammonia can enter Mai Pokhari through the breakdown of organic matter, nitrogenous animal feces and the nitrogen fixation process. Various forms of phosphorus come from various sources. Some major sources of phosphorus in Mai Pokhari could be the decomposition of organic matter and the release of phosphorus-containing minerals. Additionally, soil erosioncoming from the banks could contribute to the infiltration of phosphorus into the water. The water from Paha Khola also adds phosphorus to the lake water. The need for phosphorus is to improve the growth of aquatic organisms. Excess phosphorus promotes eutrophication. Eutrophication reduces the concentration of dissolved oxygen, making it difficult for aquatic organisms to survive. Total phosphate concentration was measured in the range of 0.25 mg/L to 4.1 mg/L. This measured value is higher than the recommendations for water quality for aquaculture (<0.6mg/L). For the protection of the aquatic ecosystem, a change in phosphorus concentration of less than 15% is allowed according to water quality guidelines. Ammonia, nitrate and total phosphate were found to correlate positively with each other (Table 7). Ammonia and nitrate are both forms of nitrogen and both are formed by the process of nitrogen fixation. In Mai Pokhari, organic matter was found to be a major stressor and releases nitrate, ammonium and total phosphate ions after decomposition. Additionally, animal feces, release of nutrient ions from minerals and rocks, and microbial releases also established a positive correlation between nutrients. Due to the higher concentration of nutrients, the DO is measured low. pH was measured to be positively correlated with nitrate and ammonia while it was negatively correlated with total phosphate. It reveals that acidic pH is the result of nitrogen ions in water (Yimer & Mengistou, 2009). When water is measured, it may be acidic because it contains fewer carbonate and magnesium ions, resulting in lower total water hardness. There is a measured negative correlation between pH and total hardness/total alkalinity. Total hardness and total alkalinity are positively correlated. The addition of calcium carbonate and magnesium carbonate from limestone and dolomite improves total hardness and total alkalinity.Ecological assessment: macroinvertebrate assemblagesBiological indicators are essential elements for assessment, management and conservation of water quality (Lewis, Jüttner, Reynolds, & Ormerod, 2007). Fish, macroinvertebrates and diatoms are major bioindicators of wildlife. The distribution of these species is determined by the stressor placed on the water, but most of the study reveals that poor habitat quality is also responsible for low species richness, composition and diversity. diversity (Griffith et al., 2005). Similar types of taxa were recorded during the post and pre-monsoon season. This could be due to almost similar climatic conditions, substrate type and nutrient concentration in a lake. The greatest number of taxa and ETO taxa were measured in L1. This was due to the mixed substrate type containing clay, silt, pebbles and freshly fallen plant parts. Site L1 was also observed to be more disturbed by human activities. Taxa richness was low in sites L4, L5 and L6 due to the clay substrate type. Diptera and oligochaetes were recorded as dominant taxa during both sampling periods. Three families of Diptera, namely Chironomidae, Tabanidae and Simuliidae, and two families of Oligochaetes, namely Tubificidae and Naididae, have been recorded. The high abundance of Chironomidae and Tubificidae was recorded in the littoral zone. The wide distribution of Chironomidae and Tubificidae could be their strength to exist in unstable substrates (Weatherhead & James, 2001). Generally unstable substrates have been.