Papers by Rachna Nautiyal
Diatom : the Japanese journal of diatomology, 2004
New records of diatoms were observed from the River Alaknanda-Ganga, 32 from the Alaknanda and 26... more New records of diatoms were observed from the River Alaknanda-Ganga, 32 from the Alaknanda and 26 from the Ganga amounting to 58 taxa. The tally of diatom taxa from the Alaknanda-Ganga has risen from 193 reported earlier to 251. Recently, 77 new records of diatom taxa were found among 200 species, varieties and forms from the Mandakini basin drained by River Mandakini, a tributary of the Alaknanda, thus increasing the count to 328 of 30 genera in Garhwal Himalaya. Three of the new records were Cyclotella (centrales) and remaining 325 were pennales. The pennate flora was dominated by biraphids (210 taxa) represented by 18 genera. Navicula (50), Cymbella (39), Gomphonema (29) and Nitzschia (28), while Pinnularia (12) dominated among the rest 13 genera that represented 52 species, showing richness at generic level. The remaining components included 45 araphids of 6 genera, largely Synedra (19), Fragilaria (14) and Diatoma (9) and only 13 raphidioids (Eunotia 12 and Peronia 1). Notably,...
Variations in the Epilithic Diatom Community Structure Due to River Valleyprojects on the Ganga Between Rishikesh and Hardwar
Health Assessment of Loktak Lake Using Diatoms as Biological Indicators
Advances in Health and Environment Safety, 2017
Loktak Lake, characterized by floating vegetation ‘phumdi,’ is the only natural habitat of endang... more Loktak Lake, characterized by floating vegetation ‘phumdi,’ is the only natural habitat of endangered Sangai. The lake ecosystem is stressed by anthropogenic influences including commissioning of Ithai Barrage. Thus, a bio-assessment of ecosystem health was carried out using diatoms as indicator. The diatom samples were collected, integrated, processed, and mounted in Naphrax. Species count was made for 500 valves. Flora consisted of 114 diatom taxa. Species diversity and evenness are high. Van Dam ecologic categories depicted by 1–7 values, for pH, salinity, N2 uptake, O2 requirements, saprobity and trophic conditions of the Lake, were computed by OMNIDIA software. All categories (1–7) occurred only for trophic condition but the diatom community was dominated by eutraphentic forms, indicating eutrophication. Probably the barrage prevents flushing of nutrients accumulated from decaying phumdis. Leclercq Index indicates very high degradation, indicating vicious conditions in the lake. Restoration is essential to Loktak Lake.
Journal of Mountain Research
The purpose of the study is to examine the difference in diatom community, assemblages and their ... more The purpose of the study is to examine the difference in diatom community, assemblages and their diversity with respect to the natural and regulated section of montane river Tons (Yamuna basin) in Himalaya. Diatom samples were collected at 4 stations from upstream to downstream; TR1 to TR4 at regular monthly basis and preserved in 4% formaldehyde solution. The permanent mounts were prepared in naphrax and examined for recording the flora under the bright field using Nikon Japan 80i trinuclear research microscope. The number of diatom taxa decreased from natural to regulated section. The continuity was impaired in this stretch as only 42 of 116 species and 14 of 24 genera occurred at all the stations. The species richness was highest in the natural upstream section TR 1(96 from 21 genera). It declined at TR2 (59 species-18 genera) and increased mildly at TR3 (63 species-15 genera) and TR4 (69 species,15 genera). Four genera (Denticula, Hantzschia, Hippodonta and Adlafia) were totally...
Two new species of Gomphonema (Bacillariophyceae) from Doon Valley, Uttarakhand, India
This paper describes two new Gomphonema species from the lesser Himalayas, India, with their valv... more This paper describes two new Gomphonema species from the lesser Himalayas, India, with their valve morphology using light and scanning electron microscopy. The two species, Gomphonema juettnerii sp. nov. and G. doonensis sp. nov., were found in Nalota stream in Doon Valley of Uttarakhand State. Main features of G. juettnerii are valve outline, shape of the areolae and striae pattern and presence of stigma. Main features of G. doonensis are rounded headpole, striae made by doubly punctate striae and features in central area. A detailed discussion on doubly punctate striae in members of gomphonemoid diatoms is presented.
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Представлены результаты экспериментального исследования генерации импульсов фототока наносекундно... more Представлены результаты экспериментального исследования генерации импульсов фототока наносекундной длительности в серебро-палладиевых (Ag/Pd) резистивных пленках при возбуждении лазерными импульсами длительностью 120 fs на длине волны 795 nm. Фототок регистрировался в направлении, перпендикулярном плоскости падения луча на пленку. Исследуемые пленки толщиной 20 µm представляли собой пористый поликристаллический материал, преимущественно состоящий из наноразмерных кристаллитов PdO и твердого раствора Ag−Pd. Обнаружен фототок, направление которого зависит от знака циркулярной поляризации падающего излучения. Установлено, что обнаруженный фототок зависит от угла падения по нечетному закону и состоит из циркулярного и линейного вкладов, зависящего и не зависящего от знака циркулярной поляризации соответственно. Показано, что циркулярный фототок значительно превышает линейный. Установлено, что как для циркулярной, так и для линейной поляризации фототок прямопропорционален мощности возбуждающего излучения. При линейно поляризованном излучении лазера фототок зависит от угла поляризации по нечетному закону. Найденные закономерности находятся в согласии с механизмом генерации поперечного фототока при эффекте увлечения. Работа выполнена при финансовой поддержке РФФИ (проект № 13-08-01031) и Финской академии наук (грант N 288547).
Health Assessment of Loktak Lake Using Diatoms as Biological Indicators
Loktak Lake, characterized by floating vegetation ‘phumdi,’ is the only natural habitat of endang... more Loktak Lake, characterized by floating vegetation ‘phumdi,’ is the only natural habitat of endangered Sangai. The lake ecosystem is stressed by anthropogenic influences including commissioning of Ithai Barrage. Thus, a bio-assessment of ecosystem health was carried out using diatoms as indicator. The diatom samples were collected, integrated, processed, and mounted in Naphrax. Species count was made for 500 valves. Flora consisted of 114 diatom taxa. Species diversity and evenness are high. Van Dam ecologic categories depicted by 1–7 values, for pH, salinity, N2 uptake, O2 requirements, saprobity and trophic conditions of the Lake, were computed by OMNIDIA software. All categories (1–7) occurred only for trophic condition but the diatom community was dominated by eutraphentic forms, indicating eutrophication. Probably the barrage prevents flushing of nutrients accumulated from decaying phumdis. Leclercq Index indicates very high degradation, indicating vicious conditions in the lake...
Diatom Flora in Natural and Regulated Stretch of River Tons and Yamuna: Determining the Impacts of Hydropower Projects on the River Ecosystem
The impact of regulation was assessed on diatom flora of rivers, Tons and Yamuna, by recording di... more The impact of regulation was assessed on diatom flora of rivers, Tons and Yamuna, by recording diatom flora in the unregulated section upstream of dam (T1, Y1), in the regulated impounded section (T2, Y2), and in the regulated downstream section (T3, T4, Y3) in the Tons (T) and Yamuna (Y). The number of species declines from T1 to T4 but increases from Y1 to Y3. Hence, impacts differ. Four categories of flora distribution were observed; (i) highly tolerant to flow variation (ii) moderately tolerant (iii) sensitive to changes in flow ‘type-1’ and (iv) sensitive to changes in flow ‘type-2’. Some taxa were restricted to one location only. An exotic nuisance Didymosphenia found in impounded section of the Tons.
Aquatic Ecosystem Health & Management, 2013
This is the pioneering attempt to study the spatial patterns in structure of lotic ecosystems tha... more 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 spring-fed [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, macro-invertebrates) do not differ sharply even across distant river basins as they are more influenced by proximate factors; thus the sub-basins of the Alak...
Diatom : the Japanese journal of diatomology, 2004
New records of diatoms were observed from the River Alaknanda-Ganga, 32 from the Alaknanda and 26... more New records of diatoms were observed from the River Alaknanda-Ganga, 32 from the Alaknanda and 26 from the Ganga amounting to 58 taxa. The tally of diatom taxa from the Alaknanda-Ganga has risen from 193 reported earlier to 251. Recently, 77 new records of diatom taxa were found among 200 species, varieties and forms from the Mandakini basin drained by River Mandakini, a tributary of the Alaknanda, thus increasing the count to 328 of 30 genera in Garhwal Himalaya. Three of the new records were Cyclotella (centrales) and remaining 325 were pennales. The pennate flora was dominated by biraphids (210 taxa) represented by 18 genera. Navicula (50), Cymbella (39), Gomphonema (29) and Nitzschia (28), while Pinnularia (12) dominated among the rest 13 genera that represented 52 species, showing richness at generic level. The remaining components included 45 araphids of 6 genera, largely Synedra (19), Fragilaria (14) and Diatoma (9) and only 13 raphidioids (Eunotia 12 and Peronia 1). Notably,...
Achnanthidium chitrakootense spec. nov. from rivers of Northern and Central India
Polish Botanical Journal, 2010
The group of diatoms morphologically similar to Achnanthidium pyrenaicum (Hustedt) Kobayasi inclu... more The group of diatoms morphologically similar to Achnanthidium pyrenaicum (Hustedt) Kobayasi includes a number of ecologically important taxa. The restricted distribution patterns of some Achnanthidium Kutzing species have become more obvious after detailed studies of this relatively small group. It has been characterized as having terminal raphe fi ssures curved to the same side, slit-like external areola openings, and internal hymenate areola occlusions. Unlike the rest of Achnanthidium, the new species A. chitrakootense possesses areola occlusions of an unusual type. It is also characterized by a raphe with ter- minals externally curved towards the same side of the valve, crossing the hyaline rim between the valve face and valve mantle, and internally undulate raphe terminals. The new member of the Achnanthidium pyrenaicum group is described from rivers of northern and central India. The species is documented with LM and SEM micrographs, and the frustule morphology of this species...
Distribution patterns of diatoms in Doon Valley
Spatial Distribution of Benthic Macroinvertebrate Fauna in Mountain Streams of Uttarakhand, India
The group of diatoms morphologically similar to Achnanthidium pyrenaicum (Hustedt) Kobayasi inclu... more The group of diatoms morphologically similar to Achnanthidium pyrenaicum (Hustedt) Kobayasi includes a number of ecologically important taxa. The restricted distribution patterns of some Achnanthidium Kützing species have become more obvious after detailed studies of this relatively small group. It has been characterized as having terminal raphe fi ssures curved to the same side, slit-like external areola openings, and internal hymenate areola occlusions. Unlike the rest of Achnanthidium, the new species A. chitrakootense possesses areola occlusions of an unusual type. It is also characterized by a raphe with terminals externally curved towards the same side of the valve, crossing the hyaline rim between the valve face and valve mantle, and internally undulate raphe terminals. The new member of the Achnanthidium pyrenaicum group is described from rivers of northern and central India. The species is documented with LM and SEM micrographs, and the frustule morphology of this species and similar taxa is compared and briefl y discussed.
Species richness and diversity of epilithic diatom communities on different natural substrates in the coldwater river Alaknanda
Tropical Ecology, 2001
... One of us (Rachna Nautiyal) is thankful to the CSIR for providing financial assistance un-der... more ... One of us (Rachna Nautiyal) is thankful to the CSIR for providing financial assistance un-der Senior Research Fellowship Scheme. Dr. Prakash Nautiyal acknowledges the academic support and laboratory facilities provided by Prof. ... Environ-mental Publications, Karad (India). ...
Tropical Ecology, 2004
Variations in the density, composition and diversity of the benthic macroinvertebrates were studi... more Variations in the density, composition and diversity of the benthic macroinvertebrates were studied in the up and downstream sections of the impounded zones (Veerbhadra and Bhimgoda barrage) of the river Ganga in the foothills. In these sections differences in the benthic density were found to be insignificant (P<0.05). The sections differed in terms of composition and relative abundance of different taxa. The regulated stretch was found to harbour only Ephemerotera, Diptera, Trichoptera and Mollusca. Plecoterans were absent while Coleopterans were very rare in the regulated stretch as compared with the upstream pristine stretch studied earlier. The predominance of Heptageniidae and fragmented occurrence exhibited by other taxa are attributed to fluctuations in the flow regimes and loss of substrate diversity. The diversity of benthic community was lower in upstream sections being least in UVB (0.1348 -1.1319). However, the differences were not significant. Similarity index indicated lack of similarity in the community at impounded locations.
New records of diatoms were observed from the River Alaknanda-Ganga, 32 from the Alaknanda and 26... more New records of diatoms were observed from the River Alaknanda-Ganga, 32 from the Alaknanda and 26 from the Ganga amounting to 58 taxa. The tally of diatom taxa from the Alaknanda-Ganga has risen from 193 reported earlier to 251. Recently, 77 new records of diatom taxa were found among 200 species, varieties and forms from the Mandakini basin drained by River Mandakini, a tributary of the Alaknanda, thus increasing the count to 328 of 30 genera in Garhwal Himalaya. Three of the new records were Cyclotella (centrales) and remaining 325 were pennales. The pennate flora was dominated by biraphids (210 taxa) represented by 18 genera. Navicula (50), Cymbella (39), Gomphonema and Nitzschia (28), while Pinnularia (12) dominated among the rest 13 genera that represented 52 species, showing richness at generic level. The remaining components included 45 araphids of 6 genera, largely Synedra , Fragilaria and Diatoma (9) and only 13 raphidioids (Eunotia 12 and Peronia 1). Notably, 57 monoraphids belonged to just 3 genera. Achnanthes (49) dominated them. Navicula and Achnanthes were the most species rich genera. Achnanthes (33, 38) was species rich than Navicula (25, 28) in the Alaknanda-Ganga and Mandakini basin, respectively. There was an overall decrease in the raphidioids (12 to 2), monoraphids (45 to 34) and biraphids (115 to 103) from high (Mandakini basin) to low elevation (Ganga), while araphids (32), were comparably higher at mid elevations (Alaknanda).
Aquatic Ecosystem: Biodiversity, Ecology and Conservation, 2014
This is the pioneering attempt to study the spatial patterns in structure of lotic ecosystems tha... more 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.
Variations in the density, composition and diversity of the benthic macroinvertebrates were studi... more Variations in the density, composition and diversity of the benthic macroinvertebrates were studied in the up and downstream sections of the impounded zones (Veerbhadra and Bhimgoda barrage) of the river Ganga in the foothills. In these sections differences in the benthic density were found to be insignificant (P<0.05). The sections differed in terms of composition and relative abundance of different taxa. The regulated stretch was found to harbour only Ephemerotera, Diptera, Trichoptera and Mollusca. Plecoterans were absent while Coleopterans were very rare in the regulated stretch as compared with the upstream pristine stretch studied earlier. The predominance of Heptageniidae and fragmented occurrence exhibited by other taxa are attributed to fluctuations in the flow regimes and loss of substrate diversity. The diversity of benthic community was lower in upstream sections being least in UVB (0.1348 -1.1319). However, the differences were not significant. Similarity index indicated lack of similarity in the community at impounded locations.
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Papers by Rachna Nautiyal