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

Moran, Nicholas Patrick; Ganf, George G.; Wallace, Todd; Brookes, Justin D.

doi:10.1071/mf12297

Cited by 4 publications

(1 citation statement)

References 45 publications

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“…The assumption behind the spike in PR is that the floodplain is already well‐adapted to the extended period of dry conditions. This may even lead to anoxic water events (King et al., 2012; Moran et al., 2014) which occur when there is a high level of dissolved organic carbon which is consumed by microbes, rapidly leading to hypoxia. This creates a vulnerable condition for aquatic biota in the wetland.…”

Section: Discussionmentioning

confidence: 99%

Planktonic Metabolism and Microbial Carbon Substrate Utilization in Response to Inundation in Semi‐Arid Floodplain Wetlands

2021

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Ecosystem metabolism is a key process that is tied to trophic dynamics and biogeochemical cycles which include the formation and utilization of organic matter (DeAngelis, 2012). Planktonic metabolism is regarded as the balance between gross primary productivity of phytoplankton (GPP) and planktonic respiration (PR) (Hoellein et al., 2013). Together, planktonic and benthic metabolism comprise aquatic metabolism. The balance between GPP and PR determines whether an aquatic ecosystem is autotrophic, producing more carbon, or heterotrophic, consuming more carbon (Wetzel & Likens, 1991). Planktonic metabolism varies temporally as well as spatially (Caffrey, 2004), and is affected by various environmental factors including hydrology, geomorphology, light, temperature, nutrient availability and microbial communities (Belnap et al., 2005). Understanding the relationships between these factors is essential for developing effective management plans for wetlands (Bunn et al., 2006).Water allocations for the environment ("environmental flows") are an important part of the hydrology of many semi-arid rivers and floodplain wetlands, including the wetlands of national and international importance located in the 1 million km 2 catchment of the Murray-Darling Basin (MDB), Australia. They are often implemented to enhance or maintain ecological outcomes of a natural flow, fresh, or flood (OEH, 2012). However, apart from methanogenesis in sediments (Boon & Mitchell, 1995;Boon et al., 1997), little is known about the role of environmental flows for planktonic metabolism and microbial diversity in semi-arid floodplain wetlands. Some previous research has investigated planktonic metabolism during environmental flow conditions in one of the largest wetland systems in the MDB, the Macquarie Marshes (Kobayashi et al., 2009(Kobayashi et al., , 2013(Kobayashi et al., , 2014 showing that GPP and PR are highly variable and that hydro-geomorphological setting can be a critical factor determining the balance of GPP/PR. For example, within the water-column

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Section: Discussionmentioning

confidence: 99%

Planktonic Metabolism and Microbial Carbon Substrate Utilization in Response to Inundation in Semi‐Arid Floodplain Wetlands

2021

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Tributary Inflows to a Regulated River Influence Bacterial Communities and Increase Bacterial Carbon Assimilation

et al. 2023

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Inflows from unregulated tributaries change the physical, chemical, and biotic conditions in receiving regulated rivers, impacting microbial community structure and metabolic function. Understanding how tributary inflows affect bacterial carbon production (BCP) is integral to understanding energy transfer in riverine ecosystems. To investigate the role of tributary inflows on bacterial community composition and BCP, a ~90th percentile natural flow event was sampled over 5 days along the Lachlan River and its tributaries within the Murray-Darling Basin of eastern Australia. Increased tributary inflows after rainfall corresponded with a significantly different and more diverse bacterial community in the regulated mainstem. The major contributor to this difference was an increase in relative abundance of bacterial groups with a potential metabolic preference for humic substances (Burkholderiaceae Polynucleobacter, Alcaligenaceae GKS98 freshwater group, Saccharimonadia) and a significant decrease in Spirosomaceae Pseudarcicella, known to metabolise algal exudates. Increases in orthophosphate and river discharge explained 31% of community change, suggesting a combination of resource delivery and microbial community coalescence as major drivers. BCP initially decreased significantly with tributary inflows, but the total load of carbon assimilated by bacteria increased by up to 20 times with flow due to increased water volume. The significant drivers of BCP were dissolved organic carbon, water temperature, and conductivity. Notably, BCP was not correlated with bacterial diversity or community composition. Tributary inflows were shown to alter mainstem bacterial community structure and metabolic function to take advantage of fresh terrestrial dissolved organic material, resulting in substantial changes to riverine carbon assimilation over small times scales.

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On-farm gains and losses of soil organic carbon in terrestrial hydrological pathways: A review of empirical research

Nachimuthu

Hulugalle

2016

International Soil and Water Conservation Research

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

Cited by 4 publications

References 45 publications

Planktonic Metabolism and Microbial Carbon Substrate Utilization in Response to Inundation in Semi‐Arid Floodplain Wetlands

Planktonic Metabolism and Microbial Carbon Substrate Utilization in Response to Inundation in Semi‐Arid Floodplain Wetlands

Tributary Inflows to a Regulated River Influence Bacterial Communities and Increase Bacterial Carbon Assimilation

On-farm gains and losses of soil organic carbon in terrestrial hydrological pathways: A review of empirical research

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