Flows and hypoxic blackwater events in managed ephemeral river channels

Hladyz, Sally; Watkins, Susanne C.; Whitworth, Kerry L.; Baldwin, Darren S.

doi:10.1016/j.jhydrol.2011.02.014

Cited by 95 publications

(88 citation statements)

References 25 publications

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“…This is probably important: for example, of an estimated 27 041 GL yr −1 of gauged runoff within the Murray-Darling Basin, just 4733 GL reach the ocean (CSIRO, 2008). Second, there is a chance that the typical DOC concentrations reported (and used here) have missed the initial surge of leaching and remineralisation which is likely to occur within the first few days of rainfall or flooding after an extended dry period (Glazebrook and Robertson, 1999;Hladyz et al, 2011). Third, remineralisation of DOC as water moves downstream along a river is not accounted for, and is probably important because the fraction of total organic carbon present as DOC can be highly variable (e.g.…”

Section: Riverine Transportmentioning

confidence: 99%

The Australian terrestrial carbon budget

et al. 2013

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Abstract. This paper reports a study of the full carbon (C-CO2) budget of the Australian continent, focussing on 1990–2011 in the context of estimates over two centuries. The work is a contribution to the RECCAP (REgional Carbon Cycle Assessment and Processes) project, as one of numerous regional studies. In constructing the budget, we estimate the following component carbon fluxes: net primary production (NPP); net ecosystem production (NEP); fire; land use change (LUC); riverine export; dust export; harvest (wood, crop and livestock) and fossil fuel emissions (both territorial and non-territorial). Major biospheric fluxes were derived using BIOS2 (Haverd et al., 2012), a fine-spatial-resolution (0.05°) offline modelling environment in which predictions of CABLE (Wang et al., 2011), a sophisticated land surface model with carbon cycle, are constrained by multiple observation types. The mean NEP reveals that climate variability and rising CO2 contributed 12 &pm; 24 (1σ error on mean) and 68 &pm; 15 TgC yr−1, respectively. However these gains were partially offset by fire and LUC (along with other minor fluxes), which caused net losses of 26 &pm; 4 TgC yr−1 and 18 &pm; 7 TgC yr−1, respectively. The resultant net biome production (NBP) is 36 &pm; 29 TgC yr−1, in which the largest contributions to uncertainty are NEP, fire and LUC. This NBP offset fossil fuel emissions (95 &pm; 6 TgC yr−1) by 38 &pm; 30%. The interannual variability (IAV) in the Australian carbon budget exceeds Australia's total carbon emissions by fossil fuel combustion and is dominated by IAV in NEP. Territorial fossil fuel emissions are significantly smaller than the rapidly growing fossil fuel exports: in 2009–2010, Australia exported 2.5 times more carbon in fossil fuels than it emitted by burning fossil fuels.

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Section: Riverine Transportmentioning

confidence: 99%

The Australian terrestrial carbon budget

et al. 2013

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“…Floodplains that are highly channelised (including anabranches) are more likely to contribute DOC to support riverine food webs (Hladyz et al 2011;McGinness and Arthur 2011). These channels serve to move water to and from the floodplain and can be filled either from overland flow from the catchment (Pathway 2) or from overbank flows.…”

Section: Characteristics Of Rivers and Floodplains That Determine Thementioning

confidence: 99%

“…both during small, medium and large events) and, hence, unlike other parts of the floodplain, may be flooded multiple times in the same year. Because they are low points in the landscape, litter, mostly from fringing vegetation, accumulates in the dry channel or any remnant pools (Hladyz et al 2011;McGinness and Arthur 2011).…”

Section: Characteristics Of Rivers and Floodplains That Determine Thementioning

confidence: 99%

Restoring dissolved organic carbon subsidies from floodplains to lowland river food webs: a role for environmental flows?

Baldwin

Colloff

Mitrovic

et al. 2016

Mar. Freshwater Res.

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Abstract. Environmental flows are managed events in river systems designed to enhance the ecological condition of aquatic ecosystems. Although not traditionally seen as important in lowland rivers, there is mounting evidence that terrestrial subsidies can be an important energy source in aquatic metazoan food webs. We argue that the apparent lack of importance of terrestrial subsidies to many lowland river food webs may reflect an artefact resulting from historical anthropogenic changes to lowland river-floodplain ecosystems, including the loss of lateral connectivity between rivers and their floodplains, changes in floodplain land use and carbon stores, and loss of sites of transformation within the main channel. The loss of floodplain subsidies to the main river channel can be partially redressed using environmental flows; however, this will require mimicking important aspects of natural high-flow events that have hitherto been overlooked when targeting environmental flows to a limited suite of biota. We suggest that key biotic targets for environmental flow releases may not be achievable unless river-floodplain subsidies are sufficiently restored. Environmental flows can go some way to addressing this shortfall, but only if floodplain subsidies to river channels are explicitly included in the design and management of environmental flows.

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“…This was recommended in the Murray-Darling Basin and specifically in the Lachlan River where a 44-67 GL year -1 increase in environmental allocations has been proposed (Murray-Darling Basin Authority 2010). However, environmental flows may also have a downside if the organic carbon is readily bioavailable, which may lead to hypoxia, fish deaths and other undesirable water-quality characteristics (Howitt et al 2007;Hladyz et al 2011). …”

Section: Introductionmentioning

confidence: 99%

Flow variability and longitudinal characteristics of organic carbon in the Lachlan River, Australia

Moran

Ganf

Wallace

et al. 2014

Mar. Freshwater Res.

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Abstract. Heterotrophic organic-carbon cycling is a major source of energy to aquatic food webs, yet there are few studies into patterns of heterotrophic productivity in large lowland rivers. The Lachlan River experienced a period of extreme flow variability from September 2010 to February 2011; for example, daily discharge (ML day À1) at one site reached .22 times its 10-year average. Heterotrophic cycling of dissolved organic carbon (DOC) and particulate organic carbon (POC) were assessed over this period at six sites on the Lachlan River. Concentrations of total organic carbon (TOC) ranged from 7 to 30 mg L À1 , of which the majority was in dissolved form. Concentration of DOC was positively correlated with daily discharge. Biochemical oxygen demand of TOC over 5 days (BOD 5 ) showed significant variability, ranging from 0.6 to 6.6 mg O 2 L À1 . BOD 5 did not appear related to discharge, but instead to a range of other factors, including regulation via weirs, lateral and longitudinal factors. Partitioning of DOC and POC showed that POC had an influence on BOD 5 comparable to DOC. This is relevant to environmental-flow management in the Lachlan River, the Murray-Darling Basin and rivers generally, by showing that flow variability influences a fundamental ecosystem characteristic, namely organic carbon.

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Flows and hypoxic blackwater events in managed ephemeral river channels

Cited by 95 publications

References 25 publications

The Australian terrestrial carbon budget

The Australian terrestrial carbon budget

Restoring dissolved organic carbon subsidies from floodplains to lowland river food webs: a role for environmental flows?

Flow variability and longitudinal characteristics of organic carbon in the Lachlan River, Australia

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