Prakash Nautiyal

Genotoxicity and antioxidant enzyme activity induced by hexavalent chromium in Cyprinus carpio after in vivo exposure.

Abstract Fish, being an important native of the aquatic ecosystem, are exposed to multipollution states and are therefore considered as model organisms for ecotoxicological studies of aquatic pollutants, including metal toxicity. We investigated oxidative stress (OS) in liver, kidney and gill tissues through antioxidant enzyme activities and genotoxicity induced in whole blood and gill tissues through comet assay and micronucleus (MN) test in Cyprinus carpio after 96-hour in vivo static exposure to potassium dichromate at three sublethal (SL) test concentrations, including SL-I [93.95 mg/L, i.e. one quarter of half-maximal lethal concentration (LC50)], SL-II (187.9 mg/L, i.e. one half of LC50), and SL-III (281.85 mg/L, i.e. three quarters of LC50), along with a control. The 96-hour LC50 value for potassium dichromate was estimated to be 375.8 mg/L in a static system in the test species. Tissues samples were collected at 24, 48, 72 and 96 hours postexposure. Results indicated that the exposed fish experienced OS as characterized by significant (p < 0.05) variation in antioxidant enzyme activities, as compared to the control. Activities of superoxide dismutase and glutathione peroxidase increased, whereas activity of catalase decreased with the progression of the experiment. The mean percent DNA damage in comet tail and MN induction in gills and whole blood showed a concentration-dependent increase up to 96-hour exposure. The findings of this study would be helpful in organ-specific risk assessment of Cr(VI)-induced OS and genotoxicity in fishes.

Genotoxic and Mutagenic Assessment of Hexavalent Chromium in Fish Following In Vivo Chronic Exposure

ABSTRACT Chromium is a well-documented carcinogen. To evaluate the genotoxic potential of hexavalent chromium on an aquatic bio-system, freshwater murrel fish (Channa punctatus) were exposed to potassium dichromate. The 96-h LC50 for potassium dichromate was 61.80 mg/L for the test fish in a static system. On the basis of the 96-h LC50, fish were exposed to sublethal concentrations of the test chemical. Fish exposed to the test chemical were sampled on days 1, 7, 14, 21, and 28 post-exposure and blood and gill cells were collected. Significantly (p < .05) higher DNA damage in both lymphocyte and gillcells and micronuclei formation in whole blood was observed at different test concentrations and sampling times of the test chemical as compared to control fish. The mean% tail DNA in the comet tail assay showed a concentration-dependent increase and the maximum% tail DNA was observed on day 7 of exposure in both cells. A similar trend was also observed in micronuclei induction in blood with maximum induction on day 21. Hexavalent chromium showed genotoxic potential in chronic exposure of C. punctatus, and the micronucleus test and the comet assay are the methods for sensitive and rapid detection of the genetic effects.

Natural history of the Garhwal himalayan mahseerTor putitora (Hamilton) II. Breeding biology

The fish matured only after attaining an average length of 700 to 770 mm. The period between July to September was established to be its spawning season. Observations on the Gonado-Somatic Index (GSI) and relative condition factor confirmed this observation. The variation in the sex-ratio during the spawning season was considered to be a remarkable adaptation towards low fecundity. The paper also comments on the problems of the Garhwal Himalayan mahseer and precautionary methods awaiting implementation in this region.

Longitudinal Distribution of Benthic Macroinvertebrate Assemblages in a Central Highlands River, The Tons (Central India)

The median density of benthic macroinvertebrate assemblage declined longitudinally from headwater to mouth (except increase at T3) in the river Tons. Arthropoda was largest component followed by Mollusca and Annelida. The abundance of assemblages forming taxa Brachycentridae, Helidae and Leptophlebiidae declined at T2 and was replaced by Neoephemeridae and Glossocolecidae. Similarly, abundance of Baetidae and Caenidae decreased at T4 and was replaced by Chironomidae and Nephthydae at T4. The assemblages varied from the T1 to T4 but were dominated by Thiaridae at all stations except Neoephemeridae at T3. Principal component analysis revealed that Glossosomatidae, Glossocolecidae, Thiaridae and Neoephemeridae were the characteristic taxa at T1, T2–T4 and T3, respectively. Canonical correspondence analysis indicated that the substratum was an important factor for T1, T2 and T3, while water temperature for Chironomidae at T4. Rhyacophilidae, Neoephemeridae, Caenidae were associated with landuse and substratum, while current velocity was responsible for the abundance of Thiaridae. Thus, landuse, slope and substratum were the effective variables responsible for assemblage in the river Tons.

Catch-and-release angling as a management tool for freshwater fish conservation in India

Mahseer are popularly regarded by anglers as the king of freshwater fishes, and are valued across the Himalayan and South-east Asian regions. In India, mahseer are important game fish. Mahseer populations and their habitats face a range of anthropogenic threats, however, including unregulated fishing and habitat fragmentation as a result of hydro-development projects. Catch-and-release angling for mahseer attracts both national and international anglers and could provide information about rivers while generating revenue for regional economies. In this context, we evaluated catch-and-release angling records from rivers that flow within two Indian reserves (the Ramganga and Jia Bharali Rivers in Corbett and Nameri Tiger Reserves, respectively). Golden mahseer Tor putitora in the Ramganga and golden and chocolate mahseer Neolissochilus hexagonolepis in the Jia Bharali were the most frequently caught fish species. Catch data suggested these game fish populations are probably not negatively affected by angling activities. Interviews with stakeholders highlighted support for catch-and-release angling, mainly because of its perceived economic benefits. The data obtained in this research could potentially assist with both fish conservation and the protection of associated aquatic ecosystems.

Review of the Art and Science of Indian Mahseer (Game Fish) from Nineteenth to Twentieth Century: Road to Extinction or Conservation?

Mahseer species, the national heritage of India are globally acclaimed sport and table fish. Some mahseer species are now assessed as ‘endangered’, making it imperative to review historical and current state of knowledge on sport-related facets, taxonomy, fisheries ecology, biology, culture and conservation efforts. The review also examines the shortfalls in knowledge base and suggests issues that need to be addressed in future. The protection and conservation measures have fallen short of expectations as the pace of implementing mega-developmental projects exceeds natural recruitment rate of mahseers and lack of facilities for assisted propagation, at larger scale.

Genetic characterization of Clupisoma garua (Hamilton 1822) from six Indian populations using mtDNA cytochrome b gene.

Abstract Clupisoma garua (Hamilton, 1822) is a commercially important freshwater fish and a potential candidate species for aquaculture. This study investigates the genetic diversity and population structure of six Indian populations of C. garua using cytochrome b (cyt b) sequences of mitochondrial DNA (mtDNA). We sequenced cyt b gene of 64 individuals collected from five distant rivers: Ganga, Gomti, Betwa, Gandak and Brahmaputra. Sequencing of 1054 bp cyt b mtDNA fragment revealed the presence of 19 haplotypes with a haplotype diversity value of 1.000 and a nucleotide diversity value of 0.0258 ± 0.00164. The Gandak river fish population showed highest nucleotide diversity. The fixation index analysis indicated significant genetic divergence among populations from different geographical areas. Both the neighbor-joining tree and median-joining network analysis of the haplotype data showed distinct patterns of phylo-geographic structure. The hierarchical analysis of molecular variance revealed that intra-group variation among populations was highly significant. The results of this study suggest that C. garua populations, especially geographically isolated groups, have developed significant genetic structures within the population. In addition, tests of neutrality suggest that C. garua may have experienced a population expansion. The study results establish cyt b as polymorphic and a potential marker to determine the population structure of C. garua. Information of genetic variation and population structure generated from this study would be useful for planning effective strategies for the conservation and rehabilitation of Schilibid cat fishes.

Genetic divergence and molecular phylogenetics of Puntius spp. based on the mitochondrial cytochrome b gene

Puntius is an important genus of freshwater food and ornamental fish belonging to the family Cyprinidae. A total of 60 samples from twelve species of the genus Puntius were collected from eight sampling sites of eight Indian Rivers. Twelve species of Puntius (P. chola, P. sophore, P. filamentosus, P. fasciatus, P. vittatus, P. chelynoides, P. gonionotus, P. denisonii, P. ticto, P. gelius, P. conchonius and P. sarana) were investigated using 60 partial sequences of the mitochondrial cytochrome b (Cyt b, 1096 bp) gene to estimate genetic divergence and to establish the phylogenetic relationship. The average intraspecies diversity was estimated as 0.002, whereas the average interspecies diversity was estimated as 0.177. The sequence analysis of the Cyt b gene revealed four distinct groups, which are genetically distinct species and exhibited identical phylogenetic relationship. The present study validated the utility of the Cyt b gene in genetic diversity and phylogenetic studies.

The health of benthic diatom assemblages in lower stretch of a lesser Himalayan glacier-fed river, Mandakini

This study examines the ecological state of epilithic diatom assemblages along the lower stretch of Mandakini, a glacier-fed Himalayan river. The diatoms were sampled at four stations during winter and summer, only once in each season. Valve counts were obtained from Naphrax mounts prepared from each sample. Assemblages were recorded for each location. The software OMNIDIA Ver. 5.3 was used for computing the ecological values from the sample counts. Normally Achnanthidium spp. dominated the assemblages, except Nitzschia fonticola (Grunow) at S1 (Kund) and Encyonema minutum (Hilse in Rabh) at S4 (Rudraprayag), only during summer. The ecological values revealed that the assemblages were in β-mesosaprobic and mésotraphentic states. However, at S4, trophic state was observed to be eutraphentic. Louis Leclercq index indicated that organic pollution was nonexistent, while the anthropogenic eutrophication was low except at S2 (Tilwara) and S3 (Medanpur) in summer and was moderate at S4 in winter characterized by a lean flow. The most abundant indicator taxa for anthropogenic eutrophication are varied; Cymbella tumida (Brebisson-Van Heurck) at S1, Encyonema minutum at S2, S4 while Surirella aungusta (Kutzing) at S3. Ordination showed that the taxa indicating degradation and anthropogenic eutrophication figured as characteristic taxa at respective locations.

Ecosystem health indicators in the Ganga Basin (Uttarakhand, India): Biodiversity, spatial patterns in structure and distribution of benthic diatoms, macro-invertebrates and ichthyofauna

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 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.