Assessing artificial oxygenation in a riverine salt-wedge estuary with a three-dimensional finite-volume model

Huang, Peisheng; Kilminster, Kieryn; Larsen, Sarah

doi:10.1016/j.ecoleng.2018.04.020

Cited by 21 publications

(10 citation statements)

References 41 publications

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“…Hypoxic and anoxic conditions are common in some salt-wedge systems, such as the Swan River estuary in Australia [76], that limit vertical mixing of upper and lower layers producing stratified conditions. Here, reduced freshwater inflow promotes eutrophication and associated depleted oxygen levels, which can change biotic characteristics of fish [77] and zooplankton [58] communities.…”

Section: Threatsmentioning

confidence: 99%

Advancing the Science of Environmental Flow Management for Protection of Temporarily Closed Estuaries and Coastal Lagoons

Stein

Gee

Adams

et al. 2021

Water

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The science needed to inform management of environmental flows to temporarily closed estuaries and coastal lagoons is decades behind the state of knowledge for rivers and large embayments. These globally ubiquitous small systems, which are often seasonally closed to the ocean’s influence, are under particular threat associated with hydrologic alteration because of changes in atershed land use, water use practices, and climate change. Managing environmental flows in these systems is complicated by their tight coupling with watershed processes, variable states because of intermittently closing mouths, and reliance on regional scale sediment transport and littoral processes. Here we synthesize our current understanding of ecohydrology in temporarily closed estuaries (TCEs) and coastal lagoons and propose a prioritized research agenda aimed at advancing understanding of ecological responses to altered flow regimes in TCEs. Key research needs include agreeing on a consistent typology, improving models that couple watershed and ocean forcing at appropriate spatial and temporal scales, quantifying stress–response relationships associated with hydrologic alteration, improving tools to establish desired conditions that account for climate change and consider cultural/indigenous objectives, improving tools to measure ecosystem function and social/cultural values, and developing monitoring and adaptive management programs that can inform environmental flow management in consideration of other stressors and across different habitat types. Coordinated global efforts to address the identified research gaps can help guide management actions aimed at reducing or mitigating potential impacts of hydrologic alteration and climate change through informed management of freshwater inflows.

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Section: Threatsmentioning

confidence: 99%

Advancing the Science of Environmental Flow Management for Protection of Temporarily Closed Estuaries and Coastal Lagoons

Stein

Gee

Adams

et al. 2021

Water

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“…In recent decades, declining rainfall and river flows have reduced the frequency and scale of major flushing events (Silberstein et al ), encouraging increased water retention times and water column stratification (Hallett et al ). Hypoxia (i.e., dissolved O concentrations of <2 mgL −1 ) and harmful algal blooms are commonly associated with stratification events (Huang et al ) and are significant stressors of the system's ecology (Hallett, Valesini, Clarke et al ; Tweedley, Hallett et al ), periodically resulting in fish kills (Place et al ; Adolf et al ).…”

Section: Regional Context: Estuaries Of Southwestern Australiamentioning

confidence: 99%

“…This makes it difficult to identify the specific environmental pressures to which the estuarine condition (as reflected by the FCI) is responding, and is a critical gap preventing targeted, practical management interventions. However, a recently developed hydrological–biogeochemical model for the Swan Canning Estuary (Huang et al ) could help address this issue by providing modeled water quality data to fill key spatial gaps (e.g., in the shallows) and temporal gaps (predominantly night time). Work is currently underway to establish quantitative relationships between FCI results and modeled data on the dynamics of estuary hydrology, water quality, and algal blooms, and thus better characterize the drivers of ecological condition.…”

Section: Looking To the Future: Opportunities And Challengesmentioning

confidence: 99%

The Fish Community Index: A Practical Management Tool for Monitoring and Reporting Estuarine Ecological Condition

Hallett

Trayler²,

Valesini

2019

Integr Envir Assess & Manag

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Indicators of ecological health based on biological communities, including numerous multimetric indices, are used worldwide to assess and report the condition of aquatic ecosystems such as estuaries. Yet, these tools have rarely been applied to support estuary management in Australia. We present a case study of one such multimetric indicator, the Fish Community Index (FCI), which was developed and applied to quantify the ecological condition of estuaries in southwestern Australia (SWA). We outline the rationale, development, and implementation of the FCI for annual monitoring and reporting of the ecological condition of a highly urbanized estuary, highlighting the key research and management outcomes that it has delivered, and evaluating its potential future applications to support estuary management more broadly, both across Australia and internationally. The FCI is founded upon a conceptually simple and scientifically robust rationale and is sensitive to the ecological stressors that affect many estuaries across the region (e.g., hypoxia, algal blooms). Together with an accompanying annual fish monitoring regime, the FCI provides managers with a consistent, robust basis for quantifying and reporting spatiotemporal changes in estuary condition, with easily comprehensible outputs that facilitate communication with stakeholders, ranging from politicians to the general public. We attribute the successful implementation of this management tool to several characteristics, namely 1) support from a long‐term, collaborative partnership between managers and researchers; 2) comprehensive testing and validation of the index prior to implementation; 3) a robust, standardized monitoring regime; and 4) sustained resourcing from managers to implement the index as part of a reporting framework. The FCI has also been applied to other SWA estuaries and could provide a platform for more coordinated assessment and reporting of estuarine condition at the bioregional scale, thereby helping to improve the gap in reporting on the biotic integrity of Australian estuaries. Integr Environ Assess Manag 2019;15:726–738. © 2019 SETAC.

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“…In most cases, salt intrusion mediates lagoon salinity and drives a difference between the surface and bottom salinity (salinity stratification). In highly seasonal systems this effect leads to notable oxygen depletion and establishes hypoxia in the bottom boundary layer (Bruce et al, 2014;Cottingham et al, 2014;Huang et al, 2018). In Mediterranean climate regions, further concerns of hypersalinity through evaporation during the long dry summer and autumn months also exist (Potter et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Climate change overtakes coastal engineering as the dominant driver of hydrological change in a large shallow lagoon

Huang

Hennig

Kala

et al. 2020

Hydrol. Earth Syst. Sci.

Self Cite

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Abstract. Ecosystems in shallow micro-tidal lagoons are particularly sensitive to hydrologic changes. Lagoons are complex transitional ecosystems between land and sea, and the signals of direct human disturbance can be confounded by variability of the climate system, but from an effective estuary management perspective, the effects of climate versus direct human engineering interventions need to be identified separately. This study developed a 3D finite-volume hydrodynamic model to assess changes in hydrodynamics of the Peel–Harvey Estuary, a large shallow lagoon with restricted connection with ocean; this was done by considering how attributes such as water retention time, salinity and stratification have responded to a range of factors, focusing on the drying climate trend and the opening of a large artificial channel over the period from 1970 to 2016, and how they will evolve under current climate projections. The results show that the introduction of the artificial channel has fundamentally modified the flushing and mixing within the lagoon, and the drying climate has changed the hydrology by comparable magnitudes to that of the opening of the artificial channel. The results also highlight the complexity of their interacting impacts. Firstly, the artificial channel successfully improved the estuary flushing by reducing average water ages by 20–110 d, while in contrast the reduced precipitation and catchment inflow had a gradual opposite effect on the water ages; during the wet season this has almost counteracted the reduction brought about by the channel. Secondly, the drying climate caused an increase in the salinity of the lagoon by 10–30 PSU (Practical Salinity Unit); whilst the artificial channel increased the salinity during the wet season, it has reduced the likelihood of hypersalinity (>40 PSU) during the dry season in some areas. The opening of the artificial channel was also shown to increase the seawater fluxes and salinity stratification, while the drying climate acted to reduce the salinity stratification in the main body of the estuary. The impacts also varied spatially in this large lagoon. The southern estuary, which has the least connection with the ocean through the natural channel, is the most sensitive to climate change and the opening of the artificial channel. The projected future drying climate is shown to slightly increase the retention time and salinity in the lagoon and increase the hypersalinity risk in the rivers. The significance of these changes for nutrient retention and estuary ecology are discussed, highlighting the importance of these factors when setting up monitoring programmes, environmental flow strategies and nutrient load reduction targets.

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Assessing artificial oxygenation in a riverine salt-wedge estuary with a three-dimensional finite-volume model

Cited by 21 publications

References 41 publications

Advancing the Science of Environmental Flow Management for Protection of Temporarily Closed Estuaries and Coastal Lagoons

Advancing the Science of Environmental Flow Management for Protection of Temporarily Closed Estuaries and Coastal Lagoons

The Fish Community Index: A Practical Management Tool for Monitoring and Reporting Estuarine Ecological Condition

Climate change overtakes coastal engineering as the dominant driver of hydrological change in a large shallow lagoon

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