Mechanisms and Drivers of Soil Salinity in Coastal Bangladesh

Salehin, Mashfiqus; Chowdhury, Md Mahabub Arefin; Clarke, D.; Mondal, Shahjahan; Nowreen, Sara; Jahiruddin, M.; Haque, A.J.M. Emdadul

doi:10.1007/978-3-319-71093-8_18

Cited by 46 publications

(27 citation statements)

References 10 publications

(9 reference statements)

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“…Zebrafish, in particular, would benefit from the ability to detect and navigate NaCl gradients because the environments in which they likely evolved are characterized by dramatic changes in local salinity levels: the river basins that surround the Ganges River in India and Bangladesh, for example, 17,18 are characterized by soft, ion-poor water with NaCl concentrations as low as 1 part per trillion, which can increase locally by orders of magnitude during the dry season. 19 Importantly, such changes lead to elevated stress and cortisol levels and are ultimately lethal, [20][21][22] which makes neural mechanisms for detecting and avoiding salt gradients paramount for survival. Here, we show that zebrafish have evolved behavioral strategies to avoid highsalt environments and that this behavior is mediated by the olfactory system through a subset of olfactory sensory neurons that detect the combined presence of sodium and chloride.…”

Section: Introductionmentioning

confidence: 99%

Larval Zebrafish Use Olfactory Detection of Sodium and Chloride to Avoid Salt Water

et al. 2021

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Salinity levels constrain the habitable environment of all aquatic organisms. Zebrafish are freshwater fish that cannot tolerate high-salt environments and would therefore benefit from neural mechanisms that enable the navigation of salt gradients to avoid high salinity. Yet zebrafish lack epithelial sodium channels, the primary conduit land animals use to taste sodium. This suggests fish may possess novel, undescribed mechanisms for salt detection. In the present study, we show that zebrafish indeed respond to small temporal increases in salt by reorienting more frequently. Further, we use calcium imaging techniques to identify the olfactory system as the primary sense used for salt detection, and we find that a specific subset of olfactory receptor neurons encodes absolute salinity concentrations by detecting monovalent anions and cations. In summary, our study establishes that zebrafish larvae have the ability to navigate and thus detect salinity gradients and that this is achieved through previously undescribed sensory mechanisms for salt detection.

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Section: Introductionmentioning

confidence: 99%

Larval Zebrafish Use Olfactory Detection of Sodium and Chloride to Avoid Salt Water

et al. 2021

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“…Like all Asian deltas, the GBD is regularly impacted by tropical cyclone induced storm surges and coastal flooding. Since the 1970s, these natural hazards, coupled with reductions in upstream river flows, have been causing widespread increases in soil and water salinity in southwest Bangladesh (Salehin, et al, 2018). The actual location and geometry of the saltwater freshwater interface in coastal Bangladesh is unknown but likely to be highly variable because of the complex geological structure, varied submarine groundwater discharge rate (e.g., Werner et al 2013), and the impacts from storm inundation events and monsoonal flushing.…”

Section: Introductionmentioning

confidence: 99%

Impact of Climate Change and Land Use on Groundwater Salinization in Southern Bangladesh—Implications for Other Asian Deltas

Islam

Hoque

Ahmed

et al. 2019

Environmental Management

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Pervasive salinity in soil and water is affecting agricultural yield and the health of millions of delta dwellers in Asia. This is also being exacerbated by climate change through increases in sea-level and tropical storm surges. One consequence of this has been a widespread introduction of salt water shrimp farming. Here, we show, using field data and modeling, how changes in climate and land use are likely to result in increased salinization of shallow groundwater in SE Asian mega-deltas. We also explore possible adaptation options. We find that possible future increase of episodic inundation events, combined with salt water shrimp farming, will cause rapid salinization of groundwater in the region making it less suitable for drinking water and irrigation. However, modified land use and water management practices can mitigate the impacts on groundwater, as well as the overlying soil, from future salinization. The study therefore provides guidance for adaptation planning to reduce future salinization in Asian deltas.

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“…There is also a slope break of the delta near this extent that could also play a role in the sudden change of channel stability at this latitude 42 . The extent of saline groundwater 43,44 and the distance upstream that tidal influence can be felt in the water level have been analyzed for the GBMD 24,45 , but with this analysis, we can now understand where those extents have significant effect on channel movement and have a framework to examine how that extent evolves through time.…”

Section: Discussionmentioning

confidence: 99%

System wide channel network analysis reveals hotspots of morphological change in anthropogenically modified regions of the Ganges Delta

Jarriel

Isikdogan

Bovik

et al. 2020

Sci Rep

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the Ganges Brahmaputra Meghna Delta (GBMD) is a large and complex coastal system whose channel network is vulnerable to morphological changes caused by sea level rise, subsidence, anthropogenic modifications, and changes to water and sediment loads. Locating and characterizing change is particularly challenging because of the wide range of forcings acting on the GBMD and because of the large range of scales over which these forcings act. in this study, we examine the spatial variability of change in the GBMD channel network. We quantify the relative magnitudes and directions of change across multiple scales and relate the spatial distribution of change to the spatial distribution of a variety of known system forcings. We quantify how the channelization varies by computing the Channelized Response Variance (CRV) on 30 years of remotely sensed imagery of the entire delta extent. The CRV analysis reveals hotspots of morphological change across the delta. We find that the magnitude of these hotspots are related to the spatial distribution of the dominant physiographic forcings in the system (tidal and fluvial influence levels, channel connectivity, and anthropogenic interference levels). We find that the anthropogenically modified embanked regions have much higher levels of geomorphic change than the adjacent natural Sundarban forest and that this change is primarily due to channel infilling and increased rates of channel migration. Having a better understanding of how anthropogenic changes affect delta channel networks over human timescales will help to inform policy decisions affecting the human and ecological presences on deltas around the world. Many river deltas are large and complex systems whose channels evolve in response to changes in internal and external forcings. Changes to water inflow, sediment load, land use, subsidence, modern climate, and anthropogenic fluvial modification structures such as dams, levees, embankments, and dredging operations can all play a role in delta morphodynamics. With more than 500 million people living on river deltas around the world 1 , detecting the magnitudes of changes to deltas is critical for managing these systems, and it is especially important to detect the portions of the system that are changing the most. The goal of this study is to examine a large delta channel network to identify if change is occurring, where hotspots of change are occurring, what the rates of change are, and what may be causing the changes in certain areas to be higher than others. This information will help us better understand morphodynamic patterns in delta systems and make predictions to inform policy decisions affecting the human and ecological presences on deltas. Deltas are currently threatened by a variety of factors. As inflow conditions of water and sediment change, channel movement such as channel widening, narrowing, lateral migrations, meandering, and avulsions all act to rework delta landscapes. In addition to the natural morphological evolution of delta systems, changes can also be

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Mechanisms and Drivers of Soil Salinity in Coastal Bangladesh

Cited by 46 publications

References 10 publications

Larval Zebrafish Use Olfactory Detection of Sodium and Chloride to Avoid Salt Water

Larval Zebrafish Use Olfactory Detection of Sodium and Chloride to Avoid Salt Water

Impact of Climate Change and Land Use on Groundwater Salinization in Southern Bangladesh—Implications for Other Asian Deltas

System wide channel network analysis reveals hotspots of morphological change in anthropogenically modified regions of the Ganges Delta

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