Community dynamics and activity of nirS-harboring denitrifiers in sediments of the Indus River Estuary

2020 ◽  
Vol 153 ◽  
pp. 110971 ◽  
Author(s):  
Fozia ◽  
Yanling Zheng ◽  
Lijun Hou ◽  
Zongxiao Zhang ◽  
Dengzhou Gao ◽  
...  
Keyword(s):  
Community Dynamics ◽  
River Estuary ◽  
Indus River

Optimization of salinity intrusion control through freshwater and tidal inlet modifications for the Indus River Estuary

2019 ◽  
Vol 224 ◽  
pp. 51-61 ◽  
Author(s):  
Muhammad Wajid Ijaz ◽  
Rasool Bux Mahar ◽  
Kamran Ansari ◽  
Altaf Ali Siyal
Keyword(s):  
River Estuary ◽  
Tidal Inlet ◽  
Salinity Intrusion ◽  
Indus River

scholarly journals Biotic vs. abiotic forcing on plankton assemblages varies with season and size class in a large temperate estuary

2020 ◽  
Vol 42 (2) ◽  
pp. 221-237 ◽  
Author(s):  
Gretchen Rollwagen-Bollens ◽  
Stephen Bollens ◽  
Eric Dexter ◽  
Jeffery Cordell
Keyword(s):  
Community Dynamics ◽  
Abiotic Factors ◽  
River Estuary ◽  
Multiple Time Scales ◽  
Nutrient Concentrations ◽  
Winter Period ◽  
Zooplankton Abundance ◽  
Multiple Time ◽  
P Availability ◽  
Lower Estuary

Abstract Large river estuaries experience multiple anthropogenic stressors. Understanding plankton community dynamics in these estuaries provides insights into the patterns of natural variability and effects of human activity. We undertook a 2-year study in the Columbia River Estuary to assess the potential impacts of abiotic and biotic factors on planktonic community structure over multiple time scales. We measured microplankton and zooplankton abundance, biomass and composition monthly, concurrent with measurements of chlorophyll a, nutrient concentrations, temperature and salinity, from a dock in the lower estuary. We then statistically assessed the associations among the abundances of planktonic groups and environmental and biological factors. During the late spring high flow period of both years, the lower estuary was dominated by freshwater and low salinity-adapted planktonic taxa, and zooplankton grazers were more strongly associated with the autotroph-dominated microplankton assemblage than abiotic factors. During the early winter period of higher salinity and lower flow, nutrient (P) availability exerted a strong influence on microplankton taxa, while only temperature and upwelling strength were associated with the zooplankton assemblage. Our results indicate that the relative influence of biotic (grazers) and abiotic (salinity, flow, nutrients and upwelling) factors varies seasonally and inter-annually, and among different size classes in the estuarine food web.

scholarly journals Vulnerability of the Indus River Delta of the North Arabian Sea, Pakistan

2016 ◽  
Vol 18 (3) ◽  
pp. 599-610 ◽  
Keyword(s):  
Seawater Intrusion ◽  
Social Impact ◽  
Sea Water ◽  
River Estuary ◽  
Weather Conditions ◽  
Ocean Model ◽  
Indus River ◽  
The North ◽  
Meteorological Observations ◽  
Coastal Ocean Model

<div> <p>Seawater intrusion has been a serious problem in the Indus River Estuary (IRE) for decades. The literature reviews, hydrological and meteorological observations were analyzed to examine and discuss the causes and consequences of seawater intrusion in the IRE. Both sea water intrusion and coastal erosion are having a devastating environmental and social impact and the whole ecosystem of the Indus Delta is facing serious threat. The Indus deltaic region is not only threatened by continuing activities upstream but also by the neighboring sea in the south, due to the impacts of local weather conditions. Observational results suggest that seawater intrusion reaches 84 km upstream in the IRE during the dry season. Extensive field investigations and a high resolution coastal ocean model are urgently needed for future study.</p> </div> <p>&nbsp;</p>

Rare unclassified 16S rRNA operational taxonomic units from the uncharted Engaño Bay (Argentinean Patagonia)

2018 ◽  
Vol 64 (1) ◽  
pp. 91-96
Author(s):  
Andrea Y. Calvo ◽  
Julieta M. Manrique ◽  
Leandro R. Jones
Keyword(s):  
16S Rrna ◽  
Community Dynamics ◽  
Sequence Data ◽  
River Estuary ◽  
Fragmented Habitats ◽  
Operational Taxonomic Units ◽  
Microbial Community Dynamics ◽  
Argentinean Patagonia ◽  
Culture Independent ◽  
Taxonomic Assignments

Rare microbes make up most of the diversity of marine microbiomes, and recent works have highlighted their importance for microbial community dynamics and in fragmented habitats. Rare taxa have been infrequently studied in comparison with abundant groups, and rare unclassified sequences are common in culture-independent studies. Here, we describe a detailed analysis of nonclassifiable sequences from the Chubut river estuary at the Argentinean Patagonia. Standard taxonomic assignments of environmental 16S rRNA sequences resulted in about 13% unclassified operational taxonomic units (OTUs). The potential affiliations of these OTUs could be narrowed by mapping the classification software assignments on a phylogeny obtained directly from our environmental sequence data. Customized BLAST analyses were remarkably consistent with these phylogenetic assignments, especially when the unclassified OTUs were blasted against sequences from cultured and type microorganisms. In addition, our BLAST analyses revealed significant similarities between several unclassified OTUs and a plethora of unclassified sequences from around the world. Further phylogenetic comparisons with 6194 carefully selected reference sequences showed that these unclassified sequences may correspond to 5 unnamed groups, possibly encompassing ranks from subclass to family inside the Alphaproteobacteria, and to an unknown Gracilibacteria lineage. Overall, these results demonstrate the value of straight phylogenetic analysis, customized BLAST searches, and comparisons with sequences from type material, for the systematic study of rare unclassified sequences.

scholarly journals Appraisal of hydro-ecology, geomorphology, and sediment behavior during low and high floods in the Lower Indus River Estuary

2022 ◽  
Author(s):  
Muhammad Waseem Boota ◽  
Chaode Yan ◽  
Shan-e-hyder Soomro ◽  
Ziwei Li ◽  
Muhammad Zohaib ◽  
...  
Keyword(s):  
Sediment Load ◽  
Morphological Changes ◽  
River Estuary ◽  
Field Measurements ◽  
River System ◽  
Water Area ◽  
Low Flow ◽  
Indus River ◽  
Peak Runoff ◽  
Bed Material

Abstract The riverine ecosystem is beholden by the freshwater; however, morphological changes and sediment load destabilize the natural river system which deteriorates the ecology and geomorphology of the river ecosystem. The Lower Indus River Estuary (LIRE) geomorphological response was synthesized using satellite imagery (1986–2020) and evaluated against the field measurements. The estuary sinuosity index has an increasing trend from 1.84 (1986) to 1.92 (2020) and the estuary water area is increased from 101.41 km2 (1986) to 110.24 km2 (2020). The sediment load investigation at Kotri barrage indicated that the median size of bed material samples during the low-flow period falls between 0.100 and 0.203 mm and the bed material after the high flow has clay and silt (&lt;0.0623 mm) ranging from 17–95% of the total weight of samples. The vegetated land loss on the banks is positively correlated with the peak runoff at Kotri barrage (r2=0.92). The bank erosion was computed with high precision (r2=0.84) based on an improved connection of the coefficient of erodibility and excess shear stress technique. This study will be helpful for policymakers to estimate the ecological health of LIRE, and sediment fluxes play an essential role in the mega-delta system and coastal management.

Numerical modelling study of seawater intrusion in Indus River Estuary, Pakistan

2019 ◽  
Vol 184 ◽  
pp. 74-84 ◽  
Author(s):  
Jun Wang ◽  
Li Li ◽  
Zhiguo He ◽  
Noor Ahmed Kalhoro ◽  
Dongfeng Xu
Keyword(s):  
Numerical Modelling ◽  
Seawater Intrusion ◽  
River Estuary ◽  
Indus River ◽  
Modelling Study

Integrated assessment of contemporary hydro-geomorphologic evolution of the Indus River Estuary, Pakistan in context to regulated fluvial regimes

2020 ◽  
Vol 236 ◽  
pp. 106657
Author(s):  
Muhammad Wajid Ijaz ◽  
Rasool Bux Mahar ◽  
Kamran Ansari ◽  
Altaf Ali Siyal ◽  
Muhammad Naveed Anjum
Keyword(s):  
Integrated Assessment ◽  
River Estuary ◽  
Indus River ◽  
Geomorphologic Evolution

scholarly journals Seasonal variation of oceanographic processes in Indus river estuary

MAUSAM ◽  
2021 ◽  
Vol 68 (4) ◽  
pp. 643-654
Author(s):  
NOOR AHMED KALHORO ◽  
ZHIGUO HE ◽  
DONGFENG XU ◽  
ASIF INAM ◽  
FAIZ MUHAMMAD ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
River Flow ◽  
River Estuary ◽  
Southwest Monsoon ◽  
Dry Season ◽  
Indus River ◽  
Wet Season ◽  
Salt Intrusion ◽  
Tidal Propagation ◽  
Significant Difference

Field investigations were conducted to study spatial and temporal (seasonal) variations in meteorological, hydrodynamic and hydrological variables in Indus River Estuary. The investigations were undertaken during wet, (moderate fluvial discharge), flood (highest fluvial discharge) and dry (zero fluvial discharge) seasons to obtain surface and near bed data during flood and ebb tides. Tides were semidiurnal, showing an asymmetric pattern with longer ebb tides and shorter flood tides. The hydrodynamic data revealed strong seasonal variation, the ebb velocities were significantly higher than flood current velocities during wet season, whereas a slight difference was found in current velocities during dry season, while the ebb phase lasted longer than flood during wet season; however no significant difference was observed during dry season. On the other hand during flood period the water currents were substantially higher and unidirectional related to the strong river flow. Turbidity values were considerably higher during flood season, than wet and dry seasons along the channel. However hydrological parameters such as temperature and dissolved Oxygen also revealed seasonal and spatial fluctuations, though they were within permissible range. The salinity distribution along the channel was related to the incoming river flow and tidal propagation. Higher salinity values were recorded in dry season, suggested that salinity variation at Estuary was due to salt intrusion from the North Arabian Sea, related to the absent of fluvial discharge form Indus River. Present study revealed substantial changes for hydrology and hydrodynamic conditions of the Indus River Estuary, related to the varying Indus River flow, as well as winds are another important atmospheric force in this region which enhanced the tidal forcing during southwest monsoon.

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