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The rapid degradation, overexploitation, and encroachment of floodplain wetlands have led to considerable decline in fish diversity and production from these invaluable aquatic resources threatening livelihood of the dependent fishers. The climate change evident in the fast few decades has further aggravated the problem of eutrophication causing water stress and sedimentation leading to rampant macrophyte proliferation affecting ecological and economic functioning of these ecosystems. Macrophyte control and management needs serious attention for sustaining ecosystem services provided by these resources. In this direction, pen culture of grass carp Ctenopharyngodon idella as a biocontrol for macrophytes along with Indian major carps was implemented in a co-management mode in Beledanga, a typical floodplain wetland, a gradually shrinking, macrophyte dominated floodplain wetland in lower Ganga basin. Indian major carps Labeo catla (6.28±0.23g), Labeo rohita (5.1±0.12g), Cirrhinus mrigala (3.5±0.08g) were stocked in the ratio 4:3:3 at the rate of 20 Nos.m −2 in pens (0.1ha each) in triplicate. Grass carp (7.1±0.42g) was stocked in pen at the rate of 20Nos.m −2 in duplicate. The fishes were fed with pelleted feed twice a day at the rate of 2–3% of body weight. The seed was overwintered in pens for a period of 90 days from November 2019 to January 2020. Average weight recorded at the end of culture period was 25.13±1.70g, 18.11±0.63g, 14.53±0.87g, and 39.20±1.90g in L. catla , L. rohita , C. mrigala , and C. idella , respectively. The survival of fish ranged from 70 to 81%. Growth performance and feed utilization efficiency of grass carp were significantly higher ( p <0.05) compared to other carp species. The pen culture was found to be economically viable with a benefit cost ratio of 1.53. The fishes produced were released back into the open wetland as an additional input for culture-based fisheries. The intervention along with niche-based enhanced stocking led to 24% increase in the fish production from the wetland with grass carp contributing 20–22% of the total catch with 32% increase in revenue generated by the sale of fish within a short span of 1 year. The study successfully demonstrated technological suitability and economic feasibility of pen culture in this wetland and role of grass carp as a potential biocontrol species for macrophyte management. Grass carp stocked in open wetland grew to 0.8 to 1kg within 6 months and 2–2.3kg within a year and could utilize 40–45% of the submerged and emergent macrophytes. Integration and optimization of grass carp will not only aid in habitat management of macrophyte-choked wetlands but will also boost their small-scale fisheries by converting standing macrophyte biomass into protein-rich fish biomass. The enhanced production will also cater to nutritional and livelihood security of the dependent fishers.

The present study deals with the broader understanding of phytoplankton assemblage pattern and their ecohydrological interactions in two ecologically distinct floodplain wetlands of Teesta − Torsa basin, India. Analyses of data revealed significant seasonal variations ( p  ≤ 0.05) of ten water variables (temperature, transparency, pH, conductivity, total dissolved solids, dissolved oxygen, total hardness, total alkalinity, PO 4  − P, and SiO 4  − Si) in both the wetlands; however, no significant variation was observed among the sampling stations. In total, 128 species of phytoplankton were recorded (118 species belonging to 94 genera in seasonally open; 103 species belonging to 86 genera in closed wetland). Four algal groups, viz. Cyanophyceae, Coscinodiscophyceae, Bacillariophyceae, and Chlorophyceae, were the dominant quantitative component, remarkably influencing the total phytoplankton population in both the wetlands, contributing ~ 87% of total phytoplankton. Species Aulacoseira granulata alone contributed 12 − 41% and 8 − 34% to the total phytoplankton in the seasonally open and closed wetland, respectively, and indicated high organic load in both the wetlands. Altogether thirty-six and thirty-one phytoplankton taxa appeared as major indicators across the seasons for seasonally open and closed wetland, respectively. The indicator taxa ( Aulacoseira , Oscillatoria , Dolichospermum , Spirogyra , Synedra , Nitzschia , Navicula , Euglena , Phacus ) in both the wetlands hinted that the wetlands are under pollution pressure. The assemblage structure of phytoplankton was related to transparency, NO 3  − N, PO 4  − P, SiO 4  − Si, total dissolved solids, and temperature as evident from BIO − ENV. Furthermore, the marginal test also selected similar variables (depth, transparency, conductivity, PO 4  − P, SiO 4  − Si) for seasonally open and the variables such as depth, conductivity, total dissolved solids, total alkalinity, and NO 3  − N for the closed wetland. The study showed that the seasonal riverine connectivity greatly influences the variations in phytoplankton community in the seasonally open wetland.

The main aim of the present study is to assess the present ecological status of Bhomra wetland with respect to the fisheries and associated ecosystem services and to prescribe some climate-smart adaptation technologies in changing climate. The analysis showed increasing temperature (Kendall's tau = 0.60, p<0.05) and decreasing rainfall (Kendall's tau = −0.33, p<0.05) in the studied region over the last two decades. The wetland is dominated by Cypriniformes species followed by Perciformes species. The overall production of the fish (i.e., 32155 kg) from the wetland in 2020 is below the average production of the last 10 year (i.e., 54704 kg). Canonical correspondence analysis reviled a strong correlation (p<0.05) between the fish assemblage and ecological parameters (mainly total alkalinity and available nitrate) of the wetland. Though the species diversity was moderate along with the moderate species richness (i.e., Shannon-Weiner diversity index = 1.581±0.007), the evenness (Simpson evenness index = 0.995±0.001) was high throughout the wetland. The wetland was found suitable for carp culture, but the ecosystem's health has degraded over time. The communication further suggests several climate-resilient strategies for sustainable utilization of wetland ecosystem services and increasing adaptive capacity of the fishers.

The present study aims to understand the spatio-temporal dynamics in habitat ecology and fish assemblage and determine the relationship of habitat transition and fish distribution in a large riverine-reservoir cascade system (Sardar Sarovar Reservoir part in Madhya Pradesh). This study was carried out along a 125-km riverine-reservoir interface (RRI) during 2018–2020. The study showed presence of a total of 110 fish species (104 spp. in upstream main Narmada River stretch excluding reservoirs, 56 in RRI, and 39 in Sardar Sarovar reservoir). We recorded 50 species common in upstream riverine stretch of Narmada and the RRI while RRI uniquely harbored 3 native species ( Chitala chitala , Labeo boga , Salmostoma phulo ) not previously reported from Narmada River stretch upstream. The similarity percentage (SIMPER) analysis showed presence of S. phulo causing 27.91%, Schistura dayi (3.71%), and Rita pavimentata (3.41%) of dissimilarity among Maheshwar (S1), Rajghat (S2), Koteshwar (S3) non-confluence zone, and Kakrana (S4)-confluence zone. The analysis of data indicated disappearance of some species like deccan peninsular carp Labeo fimbriatus , Mahseer Tor khudree which was earlier reported but was absent in recent years. The statistical correlation of environmental variables with observed abundances of fish feeding guilds showed significant positive correlation with specific conductivity and total dissolved solid content of the water. The canonical correspondence analysis (CCA) indicated association among omnivorous fishes of the reservoir with water temperature; total dissolved solids; specific conductivity; total alkalinity; chlorophyll; and NO 3 -N. The herbivore fishes were found to be more associated with magnesium, dissolved oxygen, and phosphorus content of the water while insectivorous fishes were more associated with the silicate and transparency of the water. The abundance of omnivores species indicated dominance of generalist fish species rather than specialists in the interface region of reservoir showing conservation and ecological importance of the ecosystem. The baseline information generated on fish assemblage and ecological perspectives of the river reservoir interface and science-based management recommendations formulated in the study are critical for sustaining fish diversity, promoting fisheries enhancement, and management planning of tropical large reservoirs.

The degradation of peri-urban wetlands has been a significant consequence of urban development and climate change. The present study discovered the decadal changes in land cover and climate impact on Raja Wetland, revealing significant alterations from 2011 to 2021. The analysis indicates substantial reductions in agricultural land (36.36%), fallow land (30.90%), water spread areas (10.14%) and surrounding wetlands (18.06%). Conversely, settlements, terrestrial vegetation and aquatic macrophytes increased by 19.77%, 3.39% and 1.16%, respectively. The primary driver of wetland shrinkage was urban expansion leading to a decrease in wetland area from 43.39 ha in 2011 to 38.99 ha in 2021. Climate data from 1991 to 2020 show a decreasing trend in annual rainfall ( τ  = − 0.274, p  = 0.035) and an increasing trend in annual temperature ( τ  = 0.339, p  = 0.009), with significant warming particularly during the monsoon months. The wetland’s physicochemical attributes fluctuate seasonally, with eutrophic conditions prevailing (TSI range: 61.41–80.36). Notably, fish diversity is impacted by the dominance of the invasive species Oreochromis niloticus , which constitutes 89.31% of the catch. The established planktonic indicator genera of organic pollution were found to be abundant throughout the study period. These, combined with urban pollution and eutrophication, have led to a reduction in native fish species and overall aquatic health. The study highlights the urgent need for conservation measures to address the ecological imbalance and restore wetland resilience amidst ongoing climate and anthropogenic pressures. The communication also proposes various recommendations for the recovery and sustainable future use of wetland fisheries in the context of ongoing changes.

The floodplain wetlands in different regional settings vary with time and space in terms of function and geomorphological diversity. In recent decades, these eco-sensitive waterbodies have been exposed to a wide range of anthropogenic threats and climatic changes. Therefore, assessment of these ecological and environmental threats is prerequisite to understand the state of ecosystem and to develop a sustainable management strategy for conservation of wetland biodiversity and fisheries enhancement. This paper discusses the region-specific pattern of trophic state index (TSI) of the 27 floodplain wetlands in West Bengal, India. Carlson TSI and Lamparelli TSI methods were used to determine a better approach based on historical and continuous dataset and to delineate the interrelationship among historical climatic variability for sustainable management of the resources. The study revealed that agro-climatic divisions do not unveil any significant impact on the TSI calculated using Carlson TSI as well as Lamparelli TSI method. The TSI scores for the two methods were significantly different ( p  < 0.01) for different zones based on wetland habitat types. The TSI scores revealed most of the wetlands to be in mesotrophic state. Principal component analysis (PCA) indicated that TSI scores were having similar pattern of variation with rainfall and water temperature. The present study also conveys fundamental information on ecological status based on the trophic state, which will aid to develop region-specific strategies for sustainable fisheries enhancement.

Wetland fisheries are most vulnerable to climate and anthropogenic change, and therefore, vulnerability assessment is essential for the formulation of prudent management strategies. In the present study, vulnerability assessment was carried out in nine floodplain wetlands from three districts of West Bengal using stakeholder perception and ecological conditions. In absence of long-term time series data on ecology and fisheries of wetlands, stakeholder perception study was carried out to assess the vulnerability status to climate change. Phased interviews were conducted using structured questionnaires to study the stakeholder perception on climatic variability and changes in ecology and fisheries of wetlands over the past 15 years. Climate data used for climate trend analysis was procured from Indian Meteorological Department. Ecological parameters were studied from the wetlands seasonally from January 2018 to December 2018. Analysis of climatic variables for last three decades revealed a warming trend and decreasing rainfall in the study area. The temperature anomaly ranged from + 0.07 to + 0.31 °C while rainfall anomaly ranged from − 61.41 to − 372.62 mm. Respondents showed high level of consensus (75.3%) on climate change awareness. The respondents were aware of the fact that climate anomaly affects ecology and fisheries of wetlands in most of the cases with consensus ranging from 67.8 to 94.7%. The studied wetlands showed 2 to 81.28% reduction in depth, 21.52–61.29% reduction in species diversity, and 30–95% macrophyte infestation. The stakeholder perception-based vulnerability scores ranged from 18 to 31 and indicated 6 out of 9 wetlands (66.6%) as highly vulnerable and the rest as moderately vulnerable. The ecological vulnerability scores ranged from 17 to 21 and indicated 5 out of 9 wetlands (55.6%) as highly vulnerable and 4 wetlands in the moderately vulnerable range. Although both the approaches used in the present study categorized the studied wetlands as moderately to highly vulnerable, the category of some of the wetlands varied in both the approaches. This suggests that utilizing a single approach may not give precise vulnerability status of an ecosystem. Use of combined approaches for construction of a composite vulnerability index covering different aspects impacted by climate change might present a better picture of the vulnerability status and aid in formulation of effective mitigation/management plan.

Fish assemblage structure in Panchet, a large tropical reservoir along river Damodar, major tributary of river Ganga in India, was studied along the spatial gradient of the impoundment. Fish samples were collected bimonthly from October 2014 to September 2016. Fish community structure in terms of species composition, relative abundance, and trophic and conservation status was recorded. Spatial fish diversity was analyzed from riverine, transitional, and lacustrine zones. Sixty-two fish species were recorded wherein the family Cyprinidae dominated in number of species (26) followed by Bagridae (5). Shannon diversity index, evenness index, and species richness did not reveal significant variation ( p  > 0.05) across different zones. Relative abundance of individuals and species richness were maximum in the transitional zone and minimum in the lacustrine zone. Multi-dimensional scaling of fish assemblage revealed similar pattern in the riverine and transitional zones. Trophic guild of fishes indicated dominance of carnivorous species followed by planktivores. Conservation status (IUCN 2017 .3) showed 4 fish species in Near Threatened category. The study suggests conservation of fish habitats to maintain diversity and sustained production. The baseline information generated in the study will be beneficial for monitoring the alteration in fish assemblage, conservation of fish diversity, and management planning.

ICAR-CIFRI has been continuously working to develop wetland fisheries in a transdisciplinary knowledge-to-action mode to upscale the livelihood of vulnerable small-scale fishermen communities. The integrated development approach was initiated in different lower Gangetic floodplain wetlands of North 24 Parganas, West Bengal, India, to increase the fish production and socio-economic development of small-scale fishermen communities of the wetlands. Duma is one of the most extensive horseshoe-shaped wetlands in Asia. To augment the fish production from this wetland, the pen culture system was adopted by the fishers under the supervision of ICAR-CIFRI in 2021. Within a year, they received 15 tons of commercial fish, valued at around 30 lakhs apart from the small indigenous fish. It has recently been advised that auto-stocked, high-value minor carp in the wetland be adopted to improve income and conserve small indigenous species. In this article, SDG 14 (Life below water) addresses sustainable ecosystem management and livelihood enhancement for the wellbeing of the local people (SDG 3). Nutritional security of the local people is maintained through the small indigenous fish species which is crucial for addressing ‘No hunger’ as per SDG-2. The research also proves that women can play a crucial role in small-scale fisheries and they can economically stand alone, which is the main aim of SDG-5 (gender equality). However, significant issues such as lack of jurisdictional coordination, ecological changes, inequitable distribution of benefits, and income reduction persist in wetland management. The need for urgent reformation of policy and resource management systems is crucial to boost the economic efficiency of the SSF in the wetland. Training for more knowledge on fishing and fish farming, acquiring alternative livelihood and education on financial management should be brought to the fishermen’s communities. These could develop a resilient community that is more equipped to respond to future crises.

Reservoirs have been given priority as an important resource for fisheries enhancement in inland open waters. This paper described the spatial and temporal pattern of fish diversity using GIS platform, assemblage structure, and studied the influence of environmental parameters in these variables in a large tropical reservoir, Chandil, located in the eastern India using multiple approaches. Altogether, 42 fish species belonging to 30 genera were recorded from the reservoir, including two exotic species: pangas, Pangasianodon hypophthalmus , and Nile tilapia, Oreochromis niloticus . The diversity indices indicated lowest fish diversity in the lacustrine zone, but without distinct seasonal variation. The taxonomic distinctness was lower in the lacustrine zone as compared to other zones, and the summer season exhibited higher taxonomic distinctness, though the number of species was lowest. Most of the physicochemical parameters recorded are within the favorable range for fisheries enhancement. Among the environmental parameters, pH and nitrate significantly influenced the fish abundance. The study recommends suitable measures and interventions for conservation of the native fish diversity and sustainable fisheries development: closed season, protected/conservation area, introduction of fish aggregating device (FAD), and regulated fish culture in enclosures.