Experimental drought changes ecosystem structure and function in a macrophyte-rich stream

Riis, Tenna; Levi, Peter; Baattrup‐Pedersen, Annette; Jeppesen, Knud; Leth, S. Rosenhøj

doi:10.1007/s00027-017-0536-1

Cited by 18 publications

(8 citation statements)

References 36 publications

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“…Many of the changes to river networks during drought are stressful to biota, for instance, low flows and network contraction can greatly reduce microbial metabolic rates (Amalfitano et al 2008;Fazi et al 2013;Timoner et al 2014). Low water volumes and groundwater inputs with drought lead to increasing stream and river temperature extremes (Mundahl 1990;Lake 2003;Riis et al 2017) and decreased flows reduce water oxygenation (Stanley et al 1997;Pardo and García 2016;Woelfle-Erskine et al 2017). Finally, fewer storms during drought means decreased inputs of terrestrial materials, including nutrients and allochthonous organic matter (Fazi et al 2013).…”

mentioning

confidence: 99%

Enhancement of primary production during drought in a temperate watershed is greater in larger rivers than headwater streams

Hosen

Aho

Appling

et al. 2019

Limnology & Oceanography

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Drought is common in rivers, yet how this disturbance regulates metabolic activity across network scales is largely unknown. Drought often lowers gross primary production (GPP) and ecosystem respiration (ER) in small headwaters but by contrast can enhance GPP and cause algal blooms in downstream estuaries. We estimated ecosystem metabolism across a nested network of 13 reaches from headwaters to the main stem of the Connecticut River from 2015 through 2017, which encompassed a pronounced drought. During drought, GPP and ER increased, but with greater enhancement in larger rivers. Responses of GPP and ER were partially due to warmer temperatures associated with drought, particularly in the larger rivers where temperatures during summer drought were > 10 C higher than typical summer baseflow. The larger rivers also had low canopy cover, which allowed primary producers to take advantage of lower turbidity and fewer cloudy days during drought. We conclude that GPP is enhanced by higher temperature, lower turbidity, and longer water residence times that are all a function of low discharge, but ecosystem response in temperate watersheds to these drivers depends on light availability regulated by riparian canopy cover. In larger rivers, GPP increased more than ER during drought, even leading to temporary autotrophy, an otherwise rare event in the typically light-limited heterotrophic Connecticut River main stem. With climate change, rivers and streams may become warmer and drought frequency and severity may increase. Such changes may increase autotrophy in rivers with broad implications for carbon cycling and water quality in aquatic ecosystems.Droughts are a disturbance to river ecosystems with farreaching effects on their structure and function. As freshwaters enter drought, the physical template (e.g., temperature, turbidity, conductivity, and pH) of stream and river ecosystems changes. These fundamental habitat alterations affect all components of the food web and the physicochemical environment (Stanley et al. 1997;Dahm et al. 2003). Many of the changes to river networks during drought are stressful to biota,

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mentioning

confidence: 99%

Enhancement of primary production during drought in a temperate watershed is greater in larger rivers than headwater streams

Hosen

Aho

Appling

et al. 2019

Limnology & Oceanography

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“…water volume, river discharge or flow velocities) are manipulated to represent ELFs either in isolation (e.g. Patel et al, 2021; Riis et al, 2017) or alongside other controlled parameters that covary with flow during ELFs, including dissolved oxygen (e.g. Calapez et al, 2018), fine sediment depositions (e.g.…”

Section: Research Paradigms Used To Examine Riverine Faunal Responses...mentioning

confidence: 99%

Extreme low‐flow effects on riverine fauna: A perspective on methodological assessments

et al. 2022

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River flow regimes face increasing pressure from human activities including water resource management operations and climate change. Consequently, extreme hydrological events are becoming more severe and commonplace, and there is a pressing need to understand and manage their ecological effects. Extreme low-flows (ELFs)those displaying significantly greater magnitudes and durations than typical low-flow conditionsare being increasingly experienced globally. Fish and macroinvertebrate responses to ELFs have been more widely researched relative to other organism groups in riverine environments, although such studies have employed variable methodological techniques. In this perspective piece, we identify field-based assessments and controlled experiments as two key research paradigms used to examine riverine faunal responses to ELFs. Field-based

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“…The CBOM stock did not respond to the interaction in any habitat, but FBOM increased in the wet channel, whereas SOM decreased. The increase in FBOM seems to be a consequence of enhanced deposition under reduced flows (Riis et al, 2017), which would be more noticeable in the polluted rivers, where suspended solids are more abundant (URA, 2016) (Supplementary Table S1). The decrease in SOM content is harder to explain but may be related to lower frequency of rewetting the dry sediments.…”

Section: Diversion-pollution Interactionmentioning

confidence: 99%

“…Water diversion affects river biota and processes. It reduces biofilm biomass and activity (Arroita et al, 2017), affects the storage of organic matter (OM) (Death et al, 2009;Arroita et al, 2015;Riis et al, 2017), reduces leaf-litter decomposition (Schlief and Mutz, 2009;Martínez et al, 2017), and modifies invertebrate (Dewson et al, 2007;Walters, 2011;González et al, 2018;González and Elosegi, 2021) and fish communities (Anderson et al, 2015;Benejam et al, 2016). These impacts probably are stronger during base flows, when a larger fraction of the water is diverted, but legacy effects from diversion periods can also affect the river during shutdown periods (Arroita et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Organic Matter Processing on Dry Riverbeds is More Reactive to Water Diversion and Pollution Than on Wet Channels

Pérez-Calpe

Guzmán

Larrañaga

et al. 2022

Front. Environ. Sci.

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Rivers are severely affected by human activities and many are simultaneously impacted by multiple stressors. Water diversion for hydropower generation affects ecosystem functioning of the bypassed reaches, which can alternate between periods with natural discharge and others with reduced flow that increase the surface of dry riverbeds. In parallel, urban pollution contributes a complex mixture of nutrients, organic matter, heavy metals, pesticides, and drugs, thus becoming an important stressor in rivers. However, there is little information on the interaction between both stressors on ecosystem functioning and, particularly, on organic matter processing, a key process linked to the input of energy to food webs. To assess the impact of water diversion and urban pollution on organic matter processing, we selected four rivers in a pollution gradient with a similar diversion scheme and compared reaches upstream and downstream from the diversion weirs. We measured leaf-litter decomposition and carbon dioxide (CO2) fluxes in both the wet channel and the dry riverbed. Water diversion and pollution in the wet channel did not affect CO2 fluxes but reduced microbial decomposition, whereas in the dry riverbed, their interaction reduced total and microbial decomposition and CO2 fluxes. Thus, both stressors affected organic matter processing stronger in dry riverbeds than in the wet channel. These results show that dry riverbeds must be taken into account to assess and manage the impacts of human activities on river ecosystems.

show abstract

Experimental drought changes ecosystem structure and function in a macrophyte-rich stream

Cited by 18 publications

References 36 publications

Enhancement of primary production during drought in a temperate watershed is greater in larger rivers than headwater streams

Enhancement of primary production during drought in a temperate watershed is greater in larger rivers than headwater streams

Extreme low‐flow effects on riverine fauna: A perspective on methodological assessments

Organic Matter Processing on Dry Riverbeds is More Reactive to Water Diversion and Pollution Than on Wet Channels

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