The Ganga is a major riverine system of India providing ecosystem services to millions of households. However, this river is under stress due to various anthropogenic activities. River sediment harbours a variety of microorganisms which has a tremendous influence on river health. In the present study, metagenomic approach for microbial community characterization of three sediment samples collected from River Ganga at Farakka stretch was carried out. The sediment samples were sequenced using a high-throughput Next Generation Sequencing platform. Taxonomical classification study showed that the occurrence of bacteria is higher than other groups of microbes. The bacterial classes, such as Betaproteobacteria, Deltaproteobacteria, Gammaproteobacteria, and archaeal phylum, Thaumarchaeota, and Crenarchaeota were relatively higher than other communities. KEGG pathway analysis of three samples revealed that the number of genes associated with environmental information processing is higher in the Lalbag sample in comparison to Farakka barrage and Dhulian samples. The microbial community was categorized by functional classification using SEED analysis. Both COG and SEED analysis revealed that genes associated with carbohydrate metabolism are higher than other functional categories. The genus-level study confirms the higher occurrence of Pseudomonas, which corresponds to anthropogenic activities like mass bathing. The presence of bacterial genus Nitrospira and archaeal phylum Thaumarchaeota confirms a healthy nitrogen cycle in the environment. Moreover, the generated information would help in understanding the importance of microbial communities and their imperative function in maintaining the riverine ecosystem health.

The Godavari is the largest river of peninsular India and receives a significant quantity of pollutants from diverse sources, including many industries, urban developments and agricultural fields. Such pollution is more prominent in the upper stretch of the river. This work aimed to assess the water and sediment contaminations of River Godavari for the presence of trace metals Cd, Cr, Cu, Mn, Pb and Zn. Samples were collected from 10 sampling stations covering the entire stretch of the river. Sediment pollution characteristics and potential ecological risks were evaluated by calculating contamination factor, degree of contamination, pollution load index, geo-accumulation, and the potential ecological risk index. Pearson's correlation analysis and principal component analysis were used to predict the probable sources of heavy metals.

The concentrations of studied heavy metals in water were mostly observed below the detection limit using the flame mode of an Atomic Absorption Spectroscope and recorded safe for the biotic community. The mean concentrations of metals in the sediments were calculated and also recorded to be safe with respect to the guideline values of the United States Environmental Protection Agency (USEPA, 1999). However, the sampling site-specific calculated contamination factors indicated moderate contamination of some of the stretches as: S1 for the presence of Cu, Mn, Zn; S2 for Cu, Zn; S3 and S4 for Cu; S5 for the dominance of Mn. The rest of the sites were free from sediment metal contaminations. The degree of contamination values specified S2 as moderately contaminated. Pollution load index indicated sites S1 and S2 as contaminated. Both geo-accumulation and potential ecological risk index designated lower levels of pollution in the river owing to sediment metal contaminations. Furthermore, a comparison of the heavy metal concentrations with sediment quality guidelines signified that the heavy metal pollutions (Cu, Cr, Mn and Zn) tend to pose occasional harmful effects on the ecosystem. From Pearson's correlation analysis and principal component analysis, two main sources of metal pollution were predicted. The Cu, Cr and Zn contaminants were mainly derived from human activities and Mn from natural sources as well as human activities.

River connectivity is often described as a key requirement for maintaining the health and biodiversity of associated wetlands of rivers. A comparative study was undertaken to understand the influence of river connectivity on plankton diversity and abundance in an open (Chharaganga Beel) and a closed wetland (Kalobaur Beel) situated on the banks of River Ganga in West Bengal, India. During the present investigation, data revealed that the major groups of phytoplankton recorded were Cyanobacteria (33.12%), Bacillariophyta (29.07%), and Chlorophyta (22.34%) from the open wetland, and Bacillariophyta (47.40%), Euglenozoa (30.68%), and Chlorophyta (10.12%) from the closed one. Shannon diversity (H') and Margalef's species richness index indicate that phytoplankton diversity in the Chharaganga ecosystem was higher than in Kalobaur Beel. A one-way ANOVA showed significant station-wise difference for water turbidity (p<0.05) in both of the beels, and student t test revealed that differences in physico-chemical parameters between the studied beels was statistically significant (p<0.05) for depth, turbidity, conductivity, total hardness, nitrate, total N, phosphate-P, silicate, Ca²⁺, Mg²⁺and chlorophyll a,whereas abundance of phytoplankton groups was significantly different for Bacillariophyta (p<0.05) and Euglenozoa (p<0.05). The positive correlation of total N with Euglenozoa (r=0.496; p<0.05) might be the cause of favourable conditions for a higher abundance of Euglenozoa in the closed Kalobaur Beel,which is on the verge of partial eutrophication. The hydrological flushing by river water in the Chharaganga wetland maintains the ecological stability. Therefore, restoration of river connectivity is recommended to improve the health of the disconnected wetlands.

The understanding of patterns in fish assemblages is imperative for management and conservation plans. There is a dearth of information on the environmental factors affecting the fish community structure in the reservoirs built on the intermittent rivers of India. We hypothesized that the environmental factors most likely influenced the patterns in the structure of fish diversity at temporal and spatial scales in a subtropical reservoir of the Ganga River basin. The data was gathered seasonally from April 2017 to March 2018 from three sites each in the riverine, transitional, and lacustrine zones of the reservoir. About 16,220 fish specimens were captured that belonged to 7 orders, 14 families, 31 genera, and 40 species. The diversity indices showed the highest diversity in the riverine and the lowest in the lacustrine zones of the reservoir. At a temporal scale, the highest diversity was observed in the monsoon season and lowest during the summer season. The cluster analysis spatially separated the fish fauna into three groups, each group formed by sampling sites in the riverine, transitional and lacustrine regions of the reservoir and may have resulted from physico-chemical and anthropogenic influences. Our study suggests the need to consider the possible influence of altered environmental conditions on fish assemblage, and some recommendations were suggested for the improvement of the fisheries impacted by the construction of dams.

Floodplain wetlands located in Ganga-Brahmaputra basin are some of the major inland fisheries resources of India with substantial resource size of 554,213 ha. These resources are amenable to capture fisheries and fisheries enhancement. The Guwahati Regional Centre of Indian Council of Agricultural Research-Central Institute of Fisheries Research Institute, Barrackpore, West Bengal, India has developed protocols for scientific fish stock enhancement (through supplementary stocking) for floodplain wetlands (beels) of Assam. These enhancements aim to increase fish yield based on extensive field studies in the beels of the state during 2007–12. In order to assess the impact of fish stock enhancement following the Institute's guidelines, data on fish production of 183 beels under the administrative control of Assam Fisheries Development Corporation Ltd., Guwahati, India were collected and analysed for the period from 2007–08 to 2016–17. The data were analysed for two periods of 5 years each (2007–08 to 2011–12: period-I and 2012–13 to 2016–17: period-II) for unstocked beels (that are not subjected to supplementary stocking, thereby representing capture fisheries) and stocked beels (where supplementary stocking with Indian major and minor carps for fish stock enhancement is practised) in reference to different agro-climatic zones of Assam. The average fish yield from unstocked beels (96 no.) was 156.6 kg ha^-1yr^-1 during period-I, which increased to 206.4 kg ha^-1yr^-1 during period-II, showing an increase of 31.8% over the five-year period. As much as 47.5% of the beels (87 no.) of the state are now subjected to supplementary stocking for fish stock enhancement. The average fish yield rate of stocked beels was 258.5 kg ha^-1yr^-1 during period-I, which increased to 455.2 kg ha^-1yr^-1 during period-II. Thus, average fish yield rates increased as much as 76.1% over the five year periods in stocked beels showing that supplementary stocking resulted in significant enhancement of fish production from the beels of Assam after the Institute's intervention.

Deepor Beel is a prominent floodplain wetland and a Ramsar site of northeastern (NE) India (Ramsar site no. 1207) covering a 40.14 km² area and connected to River Brahmaputra. It provides numerous economic (e.g., livelihood and nutritional security) and ecological benefits (e.g. moderation of floods, groundwater recharge, repository of biodiversity) to the locality and its people. Deepor Beel was declared a Wildlife Sanctuary in 1989 and the area covered by the perennial water spread (10.1 km²) was subsequently designated as a Bird Sanctuary by the Government of Assam in 2009. The present paper provides an overview of the rich floral and faunal diversity of the wetland, including aquatic macrophytes (58 species), diatoms (65), zooplankton (171), bryozoans (5), molluscs (15), aquatic insects (55), prawns (3), crabs (2), finfish (68), amphibians (11), reptiles (33), birds (234) and mammals (24), in addition to the beel's limno-chemistry as well its conservation threats and suggested strategies. The wetland supports 18 globally threatened vertebrate species. Eleven bird species occurring in the wetland (Aythya baeri, A. nyroca, Leptoptilos dubius, L. javanicus, Ephippiorhynchus asiaticus, Gyps bengalensis, G. tenuirostris, Haliaeetus leucogaster, Pelecanus philippensis, Sarcogyps calvus, Threskiornis melanocephalus) have been included in the IUCN Red List of Threatened Species. Finfishes reported from the wetland declined from 67 species in 1999 to 64 between 2016 and 2018, which is a matter of concern. According to available information on limno-chemistry, the waters of the wetland have remained within the favorable range of water quality for fish production. Major threats faced by the wetland (e.g. pollution, encroachment, natural processes, etc.) and possible conservation strategies (e.g. control of aquatic pollution, prevention/control of siltation, enacting and enforcing appropriate legislation, and other strategies) are outlined.

The extremely severe cyclonic storm, Fani, the strongest tropical cyclone to hit India in 20 years, caused a landfall in the Bay of Bengal coast of Odisha, India in May 2019 and considerably impacted the lives and livelihoods of fisher families. The present study was based on primary data collected from 150 fishers' households located around Debi River, Mahanadi Estuary and Chilika Lagoon in Odisha. Twenty four per cent of the respondents reported severe damages to their kachha houses, while 43% respondent reported loss of fishing nets due to this extreme cyclonic event. Around 37% of the fishing boats were severely damaged. The household items and stored agricultural produce were also damaged. The damages were much less in Mahanadi Estuary and northern sector of Chilika Lagoon due to reduced intensity of the storm. The study further found that overall the resilience of the fisher households was poor. Six out of 12 indicators of resilience were in ‘crisis’ category while only four were in ‘desirable’ category. The Government needs to consider providing quick assistance to the fishers keeping in view the loss of livelihood; besides, special initiatives are necessary to be planned to enhance the resilience of the fisher households for such unforeseen events which have become regular occurrences in the east coast of Bay of Bengal.

Inland open-access fisheries of India are important resources that contribute significantly to the national economy while providing livelihood to millions. The majority of these resources are suitable for aquaculture, with a high potential for enhanced inland fish production. Enclosures (cages and pens) installed in such waters are useful for rearing fingerlings for enhancement programmes and table-fish production. Floating cages are most suitable for waterbodies vulnerable to occasional flooding, while pen enclosures installed in marginal areas of floodplain wetlands can be suitably reinforced to protect the fish during floods. Small indigenous fishes can be introduced into pens to increase their productivity. This paper reviews enclosure technologies in the inland open waters of India and discusses the socioeconomic benefits, ecological advantages, and climate resilience of these technologies. These factors may encourage their adoption and lead to an increase in fish production in the large inland waters of India.

Increased need for freshwater for human uses from the mid-1900s has severely impacted rivers and floodplain wetlands so that they are some of the most seriously degraded environments in the world. Research and monitoring in this area to date has focused on understanding ‘flow-ecology’ relationships, without investigating the mechanisms underlying them. The use of species traits offers a tool for defining mechanistic connections between biotic responses and environmental conditions. We examined nine macroinvertebrate trait categories in both wetlands and channels to determine whether their profiles responded to hydrology in the Gwydir River system in the northern Murray-Darling Basin, Australia. Trait responses were shown for the wetlands but not the river channels. Twelve traits showed positive relationships with the time the wetlands were connected to their river channels. It is unclear the reason(s) why the river channel invertebrate traits did not respond to hydrology. However, the use of environmental flows in the river systems may be important to other aspects of macroinvertebrate assemblages such as their role in food webs to support higher-order consumers.

Field observations and measurements of wetland plants have traditionally been used to monitor and evaluate wetland condition; however, there has been increasing use of remote sensing applications for rapid evaluations of wetland productivity and change. Combining key aspects of field- and remote sensing-based wetland evaluation methods can provide more efficient or improved biological indices. This exploratory study set out to develop a raster-based Wetland Vegetation Condition Indicator system that used airborne hyperspectral imagery-derived data to estimate plant-community quality (via wetland classification and Coefficient of Conservatism) and vegetation biomass (estimated using the Normalized Difference Vegetation Index). The Wetland Vegetation Condition Indicator system was developed for three Lake Ontario wetland areas and compared to a field-based floristic quality index and a dominant-plant based Floristic quality index_dom. The indicator system serves as a proof-of-concept that capitalized on the spatial and spectral attributes of high-resolution imagery to quantify and characterize the quality and quantity of wetland vegetation. A Pearson correlation analysis showed moderate r values of 0.59 and 0.62 for floristic quality index and floristic quality index_dom, respectively, compared to the indicator method. The differences are potentially due to the spatial resolution of the imagery and the indicator method only accounting for the dominant plants within each assessment unit (pixel), therefore disregarding understory plants or those with low abundance. However, the multi-metric Wetland Vegetation Condition Indicator approach shows promise as an indicator of wetland condition by using remotely sensed data, which could be useful for more efficient landscape-scale assessments of wetland health, resilience, and recovery.