Emergence of toxic cyanobacterial species in the Ganga River, India, due to excessive nutrient loading

Dixit, Rakhi Bajpai; Patel, Akash; Toppo, Kiran; Nayaka, Sanjeeva

doi:10.1016/j.ecolind.2016.08.038

Cited by 26 publications

(17 citation statements)

References 41 publications

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“…Conflicting results in the literature did not solve this issue. In some rivers chlorophyll a concentration could directly be assessed confidently from P concentration (e.g., Basu and Pick, 1996;Dodds, 2006), whereas river flow conditions in other systems clearly constrained and determined the algal biomass (Biggs and Smith, 2002;Istvánovics et al, 2009). A few studies identified a combination of variables co-controlling phytoplankton blooms like the association of river flow conditions, water temperature and sunshine duration over the preceding days , flow and light intensity (Hardenbicker et al, 2014), and flow, temperature and nutrient availability (Van Vliet and Zwolsman, 2008).…”

Section: Introductionmentioning

confidence: 99%

QUAL-NET, a high temporal-resolution eutrophication model for large hydrographic networks

et al. 2018

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Abstract. To allow climate change impact assessment of water quality in river systems, the scientific community lacks efficient deterministic models able to simulate hydrological and biogeochemical processes in drainage networks at the regional scale, with high temporal resolution and water temperature explicitly determined. The model QUALity-NETwork (QUAL-NET) was developed and tested on the Middle Loire River Corridor, a sub-catchment of the Loire River in France, prone to eutrophication. Hourly variations computed efficiently by the model helped disentangle the complex interactions existing between hydrological and biological processes across different timescales. Phosphorus (P) availability was the most constraining factor for phytoplankton development in the Loire River, but simulating bacterial dynamics in QUAL-NET surprisingly evidenced large amounts of organic matter recycled within the water column through the microbial loop, which delivered significant fluxes of available P and enhanced phytoplankton growth. This explained why severe blooms still occur in the Loire River despite large P input reductions since 1990. QUAL-NET could be used to study past evolutions or predict future trajectories under climate change and land use scenarios.

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Section: Introductionmentioning

confidence: 99%

QUAL-NET, a high temporal-resolution eutrophication model for large hydrographic networks

et al. 2018

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“…[37]. Dixit et al [38] provided information on the detection by ELISA of microcystins produced by Oscillatoria sp. RBD01 and Leptolyngbya sp.…”

Section: Discussionmentioning

confidence: 99%

Limited Microcystin, Anatoxin and Cylindrospermopsin Production by Cyanobacteria from Microbial Mats in Cold Deserts

Khomutovska

Sandzewicz

Łach

et al. 2020

Toxins

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Toxic metabolites are produced by many cyanobacterial species. There are limited data on toxigenic benthic, mat-forming cyanobacteria, and information on toxic cyanobacteria from Central Asia is even more scarce. In the present study, we examined cyanobacterial diversity and community structure, the presence of genes involved in toxin production and the occurrence of cyanotoxins in cyanobacterial mats from small water bodies in a cold high-mountain desert of Eastern Pamir. Diversity was explored using amplicon-based sequencing targeting the V3-V4 region of the 16S rRNA gene, toxin potential using PCR-based methods (mcy, nda, ana, sxt), and toxins by enzyme-linked immunosorbent assays (ELISAs) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Molecular identification of cyanobacteria showed a high similarity of abundant taxa to Nostoc PCC-73102, Nostoc PCC-7524, Nodularia PCC-935 and Leptolyngbya CYN68. The PCRs revealed the presence of mcyE and/or ndaF genes in 11 samples and mcyD in six. The partial sequences of the mcyE gene showed high sequence similarity to Nostoc, Planktothrix and uncultured cyanobacteria. LC-MS/MS analysis identified six microcystin congeners in two samples and unknown peptides in one. These results suggest that, in this extreme environment, cyanobacteria do not commonly produce microcystins, anatoxins and cylindrospermopsins, despite the high diversity and widespread occurrence of potentially toxic taxa.

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“…Faecal coliform data is perhaps the most important water quality parameter in the current Indian context, as it has a direct link to human health, and Indian religious bathing customs (called Kumbh) bring people into contact with river water like nowhere else on Earth (Matta and Bisht, 2018). This routine regulatory data is now being augmented by the academic community in recent years, through the utilisation of 16S rRNA gene sequencing (Jani et al, 2018b;Jani et al, 2018a;Dixit et al, 2017;Zhang et al, 2018), but more of this in-depth bacterial research is urgently needed to better understand the composition of microbes in the Ganga and its tributaries. Despite the large phosphorus and nitrogen loadings to the Ganga River, from untreated urban wastewaters and agricultural practises, studies of the effects of eutrophication, particularly algal and cyanobacterial blooms, are also limited (Tare et al, 2003;Dixit et al, 2017;Yadav and Pandey, 2017b).…”

Section: Introductionmentioning

confidence: 99%

“…This routine regulatory data is now being augmented by the academic community in recent years, through the utilisation of 16S rRNA gene sequencing (Jani et al, 2018b;Jani et al, 2018a;Dixit et al, 2017;Zhang et al, 2018), but more of this in-depth bacterial research is urgently needed to better understand the composition of microbes in the Ganga and its tributaries. Despite the large phosphorus and nitrogen loadings to the Ganga River, from untreated urban wastewaters and agricultural practises, studies of the effects of eutrophication, particularly algal and cyanobacterial blooms, are also limited (Tare et al, 2003;Dixit et al, 2017;Yadav and Pandey, 2017b). Flow cytometry techniques have been developed in recent years to rapidly characterise phytoplankton communities and provide bacterial loadings in rivers (Read et al, 2014), and this could provide new insights into algal dynamics and bacterial pollution sources in the Ganga basin.…”

Section: Introductionmentioning

confidence: 99%

Nutrient and microbial water quality of the upper Ganga River, India: identification of pollution sources

Bowes

Read

Joshi

et al. 2020

Environ Monit Assess

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The Ganga River is facing mounting environmental pressures due to rapidly increasing human population, urbanisation, industrialisation and agricultural intensification, resulting in worsening water quality, ecological status, and impacts on human health. A combined inorganic chemical, algal and bacterial survey (using flow cytometry and 16S rRNA gene sequencing) along the upper and middle Ganga (from the Himalayan foothills to Kanpur) was conducted under pre-monsoon conditions. The upper Ganga had total phosphorus (TP) and total dissolved nitrogen concentrations of less than 100 µg l -1 and 1.0 mg l -1 , but water quality declined at Kannauj (TP = 420 µg l -1 ) due to major nutrient pollution inputs from human-impacted tributaries (principally the Ramganga and Kali Rivers).The phosphorus and nitrogen loads in these two tributaries and the Yamuna were dominated by soluble reactive phosphorus and ammonium, with high bacterial loads and large numbers of taxa indicative of pathogen and faecal organisms, strongly suggesting sewage pollution sources. The high nutrient concentrations, low flows, warm water and high solar radiation resulted in major algal blooms in the Kali and Ramganga, which greatly impacted the Ganga. Microbial communities were dominated by members of the Phylum Proteobacteria, Bacteriodetes and Cyanobacteria, with communities showing a clear upstream to downstream transition in community composition. To improve the water quality of the middle Ganga, and decrease ecological and human health risks, future mitigation must reduce urban wastewater inputs in the urbanised tributaries of the Ramganga, Kali and Yamuna Rivers.

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Emergence of toxic cyanobacterial species in the Ganga River, India, due to excessive nutrient loading

Cited by 26 publications

References 41 publications

QUAL-NET, a high temporal-resolution eutrophication model for large hydrographic networks

QUAL-NET, a high temporal-resolution eutrophication model for large hydrographic networks

Limited Microcystin, Anatoxin and Cylindrospermopsin Production by Cyanobacteria from Microbial Mats in Cold Deserts

Nutrient and microbial water quality of the upper Ganga River, India: identification of pollution sources

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