Managed floodplain inundation maintains ecological function in lowland rivers

Rees, Gavin N.; Cook, Robert A.; Ning, Nathan; McInerney, Paul; Petrie, Rochelle; Nielsen, Daryl L.

doi:10.1016/j.scitotenv.2020.138469

Cited by 15 publications

(14 citation statements)

References 58 publications

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“…Isotopic values of animals were within the ranges of values reported for the Ovens River (Hladyz et al 2012) and elsewhere (Rees et al 2020), although our δ 13 C values were generally lower (e.g., −35.11 ± 0.67‰ SE compared to − 30 ‰, Hladyz et al 2012). Low consumer δ 13 C values may be due to differences in taxonomic resolution (i.e., species vs. genus) or because we sampled during low flows, when groundwater contributions to the river channel are relatively higher.…”

Section: Discussionsupporting

confidence: 86%

“…Food webs represent an important facet of ecosystem function and describe the energy pathways between resources and animals (Hladyz et al 2012). Within freshwater ecosystems, research has focused on understanding the contribution and importance of terrestrially—and aquatically—derived carbon to food webs (e.g., Rees et al 2020). Less attention has been oriented towards determining the quality of food resources (e.g., Guo 2018) and the dominant pathways for energy to reach higher trophic levels.…”

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confidence: 99%

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Basal resource quality and energy sources in three habitats of a lowland river ecosystem

McInerney

Holt

Lester

et al. 2020

Limnology & Oceanography

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Understanding energy flow through ecosystems and among sub-habitats is critical for understanding patterns of biodiversity and ecosystem function. It can also be of considerable applied interest in situations where managing for connectivity among habitats is important for restoring degraded ecosystems. Here, we describe patterns of basal resource quality and identify primary basal energy sources in three habitats-river channels, anabranches and wetlands-of a lowland river floodplain in the Murray River catchment, Australia during a period of disconnected surface flow. We used a combination of stable isotope and fatty acid analyses to determine which basal resources were assimilated by the backswimmer Anisops thienemanni and the Eastern mosquitofish Gambusia holbrooki and assessed food quality across the three habitats. Seston was a primary basal resource for both animals in all three habitats, but was of higher quality within floodplain habitats than in the river channel. Although floodplain seston contained higher concentrations of essential fatty acids, fatty acid profiles of animals from different habitats remained similar. Our research suggests that inundation of floodplains and subsequent reconnection to the river could be valuable to afford riverine animals the opportunity to access high quality resources, but highlights a need to quantitatively assess the transfer of essential fatty acids between trophic levels to determine how much riverine animals are in fact limited by poorer quality food resources. We demonstrate the importance of estimating the quality of organic matter fluxes into food webs, and the potential role of targeted environmental flows to re-establish high quality energy pathways in riverine ecosystems. Food webs represent an important facet of ecosystem function and describe the energy pathways between resources and animals (Hladyz et al. 2012). Within freshwater ecosystems, research has focused on understanding the contribution and importance of terrestrially-and aquatically-derived carbon to food webs (e.g., Rees et al. 2020). Less attention has been oriented towards determining the quality of food resources (e.g., Guo 2018) and the dominant pathways for energy to reach higher trophic levels. Understanding which resources underpin food webs and factors influencing resource availability to animals is key to improving our capacity to gauge ecosystem health (Holland et al. 2020). Food quality, in its coarsest form, may be assessed by ecological stoichiometry (e.g., C : N) however, animals can be limited by availability of complex organic compounds such as amino acids (Dwyer et al. 2018), sterols and fatty acids (Twining et al. 2016). Within freshwater ecosystems, algae and, in particular, diatoms are considered high-quality food resources for herbivorous taxa due to their high concentration of inorganic nutrients (nitrogen and phosphorous) and longchain polyunsaturated fatty acids (e.g. Guo 2018). Some omega-3 (ω3) and omega-6 (ω6) polyunsaturated fatty acids, such as eicosapentaenoic (EPA;...

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Section: Discussionsupporting

confidence: 86%

mentioning

confidence: 99%

Basal resource quality and energy sources in three habitats of a lowland river ecosystem

McInerney

Holt

Lester

et al. 2020

Limnology & Oceanography

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“…5, 6). However, a lack of lateral connectivity between channels and wetlands represents a major opportunity cost to the protection and restoration of ecosystem functions by limiting the transfer of allochthonous carbon, nutrients and energy sources from the flood plain to the river channel (Baldwin et al 2016;Mitrovic and Baldwin 2016;Rees et al 2020). The 2018-19 annual watering priorities included, for the first time, the objective of improvement of flows from the channel out to the floodplain (Murray-Darling Basin Authority 2018a, p. 11).…”

Section: Environmental Water For Floodplain Wetlandsmentioning

confidence: 99%

“…We assessed the watering of floodplain wetlands rather than in-channel flows because of the many nationally and internationally significant wetlands in the Basin. Also, the flooding of wetlands generates bioavailable carbon and nutrients that return to the river channel downstream and drive within-channel aquatic food webs (Rees et al 2020). We evaluated whether environmental water could be considered to have been delivered efficiently and effectively by conducting interviews with staff from government agencies who are involved in policy and management of environmental flows.…”

Section: Introductionmentioning

confidence: 99%

A trickle, not a flood: environmental watering in the Murray–Darling Basin, Australia

Chen

Colloff

Lukasiewicz

et al. 2021

Mar. Freshwater Res.

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Environmental flows are an integral component for the conservation and management of rivers, flood plains and other wetlands in the Murray–Darling Basin. Under the Basin Plan, environmental water is managed by the Commonwealth Environmental Water Office (CEWO) and the states. We assessed CEWO environmental flows (2014–15 to 2018–19), compared our findings with expected outcomes for vegetation in the Basin-wide Environmental Watering Strategy (EWS) and interviewed water managers about the efficacy of environmental watering. Some 21% of CEWO water was delivered as flood events, to 9 of 19 river valleys, inundating 7% of wetland area in those valleys annually and 0.8% of major Basin wetlands. A consistent pattern was the watering of many small wetlands on the South Australian Murray with small volumes (median area 43ha, volume 125ML). Just 12% of the area of river red gum subject to EWS expected outcomes was flooded, and half these events were likely suboptimal to achieve ecological benefits. Wetlands have not received the water they need and vegetation outcomes cannot be met by completion of the Plan in 2024. Rules that constrain flooding of private land must be relaxed if the Plan is to achieve its statutory requirement of wetland conservation.

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“…Remote monitoring using drones (Tyler et al 2018) and underwater video can help our understanding of aspects such as spawning behaviour and habitat use (Butler and Rowland 2009;Ebner et al 2014). Other evolving options are worth exploring to further understand ecological processes, such as floodplain productivity (Rees et al 2020), including the use of bulk and compound-specific tracers, stable isotopes and fatty and amino acids to investigate productivity, food web resources, trophic requirements, fish condition and trophic ecology (e.g. Jardine et al 2020;Twining et al 2020).…”

Section: New Technologiesmentioning

confidence: 99%

A compendium of ecological knowledge for restoration of freshwater fishes in Australia

Koehn

Raymond

Stuart

et al. 2020

Mar. Freshwater Res.

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Many freshwater fishes are imperilled globally, and there is a need for easily accessible, contemporary ecological knowledge to guide management. This compendium contains knowledge collated from over 600 publications and 27 expert workshops to support the restoration of 9 priority native freshwater fish species, representative of the range of life-history strategies and values in south-eastern Australia’s Murray–Darling Basin. To help prioritise future research investment and restoration actions, ecological knowledge and threats were assessed for each species and life stage. There is considerable new knowledge (80% of publications used were from the past 20 years), but this varied among species and life stages, with most known about adults, then egg, juvenile and larval stages (in that order). The biggest knowledge gaps concerned early life stage requirements, survival, recruitment, growth rates, condition and movements. Key threats include reduced longitudinal and lateral connectivity, altered flows, loss of refugia, reductions in both flowing (lotic) and slackwater riverine habitats, degradation of wetland habitats, alien species interactions and loss of aquatic vegetation. Examples and case studies illustrating the application of this knowledge to underpin effective restoration management are provided. This extensive ecological evidence base for multiple species is presented in a tabular format to assist a range of readers.

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Managed floodplain inundation maintains ecological function in lowland rivers

Cited by 15 publications

References 58 publications

Basal resource quality and energy sources in three habitats of a lowland river ecosystem

Basal resource quality and energy sources in three habitats of a lowland river ecosystem

A trickle, not a flood: environmental watering in the Murray–Darling Basin, Australia

A compendium of ecological knowledge for restoration of freshwater fishes in Australia

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