Altitudinal trends in the diatoms, bryophytes, macroinvertebrates and fish of a Nepalese river system (original) (raw)
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Macroinvertebrate communities in streams in the Himalaya, Nepal
Freshwater Biology, 1993
1 Macroinvertebrates were sampled in the riffles of fifty-eight streams from three regions of the Himalaya (Anapurna, Langtang and Everest) in Nepal. A semi-quantitative method with identification to family level was used to describe communities on-site.2 Stream physicochemistry was assessed and the community structure of macroinvertebrates was related to chemistry, physiography (substratum composition, altitude and size), geographical location and the dominant land use in each catchment (terraced agriculture, forest or scrub). Community data were analysed by ordination (DECORANA) and classification (TWINSPAN).3 The concentration of cations in stream water decreased significantly with altitude. Chemistry also differed between regions; sites from Anapurna had a higher pH and conductivity than those in the other two areas.4 Communities were dominated by aquatic insect larvae, with Ephemeroptera, in particular the Baetidae, most numerous across sites.5 There were, nevertheless, differences in community structure between sites, which were related closely to stream physicochemistry. Ordination scores were strongly correlated with altitude, magnesium concentration and substratum composition. Classification was also linked to altitude and chemistry, differentiating high-altitude sites with low silica concentrations from others. Sites from the Anapurna and Everest regions, with their contrasting chemistry, were also separated.6 Community structure was also related to land use: streams draining catchments dominated by terraced agriculture had different communities from those in scrub or forest. This result was confounded, however, by the strong relationship between land use, altitude and chemistry; sites in terracing were at lower altitude, had higher concentrations of silica and a higher proportion of fine sediments than those in the other land-use types.7 Overall, our data indicate that natural features of the relief and geology in the Himalaya create strong gradients in their invertebrate faunas, but that activities of man may have an effect on stream structure and ecology through catchment management. Macroinvertebrates were sampled in the riffles of fifty-eight streams from three regions of the Himalaya (Anapurna, Langtang and Everest) in Nepal. A semi-quantitative method with identification to family level was used to describe communities on-site. Stream physicochemistry was assessed and the community structure of macroinvertebrates was related to chemistry, physiography (substratum composition, altitude and size), geographical location and the dominant land use in each catchment (terraced agriculture, forest or scrub). Community data were analysed by ordination (DECORANA) and classification (TWINSPAN). The concentration of cations in stream water decreased significantly with altitude. Chemistry also differed between regions; sites from Anapurna had a higher pH and conductivity than those in the other two areas. Communities were dominated by aquatic insect larvae, with Ephemeroptera, in particular the Baetidae, most numerous across sites. There were, nevertheless, differences in community structure between sites, which were related closely to stream physicochemistry. Ordination scores were strongly correlated with altitude, magnesium concentration and substratum composition. Classification was also linked to altitude and chemistry, differentiating high-altitude sites with low silica concentrations from others. Sites from the Anapurna and Everest regions, with their contrasting chemistry, were also separated. Community structure was also related to land use: streams draining catchments dominated by terraced agriculture had different communities from those in scrub or forest. This result was confounded, however, by the strong relationship between land use, altitude and chemistry; sites in terracing were at lower altitude, had higher concentrations of silica and a higher proportion of fine sediments than those in the other land-use types. Overall, our data indicate that natural features of the relief and geology in the Himalaya create strong gradients in their invertebrate faunas, but that activities of man may have an effect on stream structure and ecology through catchment management.
Macroinvertebrate communities of streams in western Nepal: effects of altitude and land use
Freshwater Biology, 1994
The influence of altitude and land-use changes on macroinverlebrate assemblages from riffles in forty-three streams in the Dolpo region of western Nepal were examined. Sampling sites ranged in altitude from 850 to 4250 m, and land-use patterns fell into five categories: alpine, forest, grassland, pasture and agricultural land. 2. TWINSPAN classification of physicochemical data separated streams into groups on the basis of climatic and physical factors. Streams from high, cold, alpine areas were separated from those in warmer, lower, agricultural areas. 3. In all, 138 macroinvertebrate taxa were collected from fifty-three insect families, Ephemeroptera were most common, especially Baetidae. 4. Taxonomic richness declined with increasing altitude. Ten insect families were significantly more abundant in lowland streams, and five were more common in alpine streams. 5. TWINSPAN and DECORANA revealed distinct invertebrate groupings of the fortythree streams surveyed. A high percentage of the variance (79.3%) in ordination space was explained by DECORANA axes 1 and 2. Altitude, temperature, stream width and land use were implicated in structuring invertebrate communities.
Spatial Distribution of Benthic Macroinvertebrate Fauna in Mountain Streams of Uttarakhand, India
Aquatic Ecosystem: Biodiversity, Ecology and Conservation, 2014
This is the pioneering attempt to study the spatial patterns in structure of lotic ecosystems that form the Ganga River system in the Himalaya. The diversity of source (glacier-fed [GF], snow-fed [SN] and springfed [SF]) and stream-size (both interrelated) across the altitudinal panorama, create numerous habitats that contribute to structural diversity. The spatial patterns in richness, density and taxonomic composition and distribution of benthic diatoms are less affected by source compared with macro-invertebrates but shows strong influence on the distribution of fish fauna that are poikiliotherms, because a glacier-fed river carries ice-cold water (usually <20 • C) in contrast to normal waters in spring-fed system (22 • C near snowline, 32 • C in foothills). The abundance patterns of biota of lower organisation grade (diatoms, macroinvertebrates) do not differ sharply even across distant river basins as they are more influenced by proximate factors; thus the sub-basins of the Alaknanda resemble more by virtue of one basin and there is notable resemblance between distant SF Bemunda (lower Ganga basin) and SF Gomti (East Rāmgangā basin) and even the farthest Yamuna and Rāmgangā. Fish are more sensitive to temperature and current velocities that are related to altitude and hence longitudinal rather than the spatial gradients in the mountains. The lotic ecosystem of Doon Valley harbour rich and diverse diatom flora, macroinvertebrate fauna and ichthyofauna. The examination of trophic, saprobic and ecological status shows that organic pollution, degradation and anthropogenic eutrophication are non-existent in the Lesser Himalayan rivers and streams, but the fragile Doon Valley is under severe anthropogenic stress. This and habitats fragmented by hydropower projects in the major rivers has threatened the iconic game fish Himalayan mahseer in the Ganga.
Nepal Journal of Environmental Science
While river macroinvertebrates are the most widely used form of bioindicators, their baseline information, although crucial, is scarce in Nepal. The main objective of this study was to assess the macroinvertebrate assemblages in mountain tributaries of the glacial-fed Tamor and rain-fed Kamala rivers. A total of eight sites were sampled during March 2015 (Spring), November 2015 (Autumn), January 2016 (Winter), and May 2016 (Summer). Altogether, 49 Families of macroinvertebrates belonging to 15 Orders were identified with 39 Families and 12 Orders in Tamor’s tributaries, and 33 Families and 10 Orders in Kamala’s tributaries. Non-metric multi-dimensional scaling (NMDS) revealed different assemblages between the two river systems. The most dominant Order in the Tamor was Ephemeroptera and it was Trichoptera in the Kamala. EPT (Ephemeroptera Plecoptera Trichoptera) assemblages were the most abundant in all four seasons for both the river systems and higher % EPT in Tamor’s tributaries i...
Ecoprint: An International Journal of Ecology, 2014
Present paper deals with the spatio-temporal variations in diversity and density of macro invertebratesin riffles and pools of the Mardi and the Vijayapur streams, Pokhara, Nepal. It was the pioneeringwork to study the biotic assemblage. Altogether 47 genera (32 from the riffles and 34 from the pools)belonging to 38 families and 12 orders were recorded during the study period. The taxa richness washigher (38 genera) in the Mardi stream than in the Vijayapur stream (30 genera). Total density at bothsites observed major peak and down fall in the spring and summer seasons, respectively. The averagetotal density during the spring peak was higher (967.42 m-2 in riffle and 652.10 m-2 in pool) at Site 1(Mardi stream) than at Site 2 (Vijaypur stream) (541.02 m-2 in riffle and 537.43 in pool). This peakwas mainly contributed by the order ephemeroptera. Ephemeroptera, diptera and trichoptera werefound predominant orders comprising 11, 8 and 8 genera, respectively. Heptagenidae, baetidae andle...
Biodiversity Data Journal, 2022
Benthic macroinvertebrates, encompassing large taxonomic groups of invertebrate organisms, are important components of aquatic ecosystems and play crucial roles in aquatic food webs. These organisms are also extensively used in water quality assessments as bioindicators for a range of stressors. Inter-basin water transfer (IBWT) is the transfer of water from a donor basin to a recipient basin and such transfers have both beneficial as well as adverse environmental and socio-economic impacts. This study attempts to generate baseline information on macroinvertebrates assemblages in glacial-fed (Bheri) and rain-fed (Babai) rivers of west Nepal, where Nepal’s first ever inter-basin transfer is in progress and the data can be used to assess the impact of inter-basin water transfer on water quality and aquatic biodiversity after completion. The dataset includes the records on the taxonomic diversity of macroinvertebrate in the Bheri and the Babai River systems. A total of 56 families of m...
Structure of Benthic Macroinvertebrate Communities in the Rivers of Western Himalaya, Nepal
Geosciences
According to River Continuum Concept (RCC), channel morphology, including sediment loads and channel width, river habitat, flow regimes and water quality, differs from the tributary to the downstream river’s mainstem, allowing shifts in faunal composition from dominance of shredders to collectors downstream, respectively. Tributaries are responsible for contributing organic carbons, nutrients and water. However, such knowledge is still limited in the monsoon-dominated river systems of the Himalaya. The study was conducted in the river’s mainstem and tributaries of the Karnali River Basin, which are glacier and spring-fed river systems, respectively, in the western Himalaya, Nepal. A total of 38 river stretches in the river’s mainstem and tributaries were sampled during post-monsoon and pre-monsoon seasons in the years 2018 and 2019. Water quality parameters, such as pH, temperature, electrical conductivity, total dissolved solids, dissolved oxygen, alkalinity and hardness, and the b...
Freshwater biodiversity in western Nepal: A review
Nepalese Journal of Zoology, 2021
Western Nepal is known for its rich freshwater resources that support diverse flora and fauna. Freshwater ecosystems of western Nepal provide multitudes of ecosystem goods, services (irrigation, hydroelectricity, drinking water) to humans, and provide breeding and feeding grounds for many wetland-dependent flora and fauna. But these wetlands are under tremendous pressure mainly due to anthropogenic activities. In this review, we provide a brief overview of the freshwater biodiversity, distributions of wetlands and their status in western Nepal. From this review, we found that western Nepal is rich in freshwater resources and supports diverse flora and fauna. The biologically significant Karnali River is the home of a globally endangered species, the South Asian river dolphin. We also discuss the conservation history of wetlands, identify the gaps, and further suggest priority hotspots for the formulation of future conservation strategies for these ecosystems.
Ecological Indicators, 2020
Aug 21-Aug 27 Nov 1-Nov 15 (2019) No. 577-578 Editorial Team: Prabhat Adhikari and Rejina Khanal For the 577-578 th issues of Headlines Himalaya, we reviewed journal articles from three sources and selected nine happenings from four countries. We selected six happenings from Nepal and three happenings from other Himalayan countries (India, Bhutan and Pakistan). The overall coverage of this issue is biodiversity, agriculture, wildlife, climate change and environment. Headlines Himalaya, a weekly research based information fact file is an attempt to keep our global readers abreast with the happenings in the Himalaya. Please share it with your colleagues and friends. Also, subscription is free. Enjoy!
Major stressors influencing the river ecosystems of Far and Mid Western Development Regions of Nepal
Current World Environment, 2019
Maintaining healthy river ecosystem is essential both from aquatic biodiversity conservation perspective as well as for the socio-cultural and economic development of nations all over the world. Many rivers in Nepal have largely been modified with the purpose of supplying drinking water, irrigating agricultural lands, producing hydro-electricity, and operating water mills. During the process, rivers are channelized and the river bed materials are removed. Such activities of river bed excavation have changed both the natural flow regimes and morphological characteristics of rivers. Studies on the impacts caused by such stressors on river ecosystems are lacking in the context of Nepalese river systems. Therefore we have assessed how these stressors might change the faunal composition of benthic macroinvertebrates in headwaters of the Western region of Nepal. The study was conducted in the headwaters of rivers of Mahakali and Karnali rivers. Habitat specific benthic macroinvertebrates ...