School of Ecosystem and Forest Sciences - Research Publications

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    Sediment Respiration Pulses in Intermittent Rivers and Ephemeral Streams
    von Schiller, D ; Datry, T ; Corti, R ; Foulquier, A ; Tockner, K ; Marce, R ; Garcia-Baquero, G ; Odriozola, I ; Obrador, B ; Elosegi, A ; Mendoza-Lera, C ; Gessner, MO ; Stubbington, R ; Albarino, R ; Allen, DC ; Altermatt, F ; Arce, M ; Arnon, S ; Banas, D ; Banegas-Medina, A ; Beller, E ; Blanchette, ML ; Blanco-Libreros, JF ; Blessing, J ; Boechat, IG ; Boersma, KS ; Bogan, MT ; Bonada, N ; Bond, NR ; Brintrup, K ; Bruder, A ; Burrows, RM ; Cancellario, T ; Carlson, SM ; Cauvy-Fraunie, S ; Cid, N ; Danger, M ; de Freitas Terra, B ; Dehedin, A ; De Girolamo, AM ; del Campo, R ; Diaz-Villanueva, V ; Duerdoth, CP ; Dyer, F ; Faye, E ; Febria, C ; Figueroa, R ; Four, B ; Gafny, S ; Gomez, R ; Gomez-Gener, L ; Graca, MAS ; Guareschi, S ; Gucker, B ; Hoppeler, F ; Hwan, JL ; Kubheka, S ; Laini, A ; Langhans, SD ; Leigh, C ; Little, CJ ; Lorenz, S ; Marshall, J ; Martin, EJ ; McIntosh, A ; Meyer, E ; Milisa, M ; Mlambo, MC ; Moleon, M ; Morais, M ; Negus, P ; Niyogi, D ; Papatheodoulou, A ; Pardo, I ; Paril, P ; Pesic, V ; Piscart, C ; Polasek, M ; Rodriguez-Lozano, P ; Rolls, RJ ; Sanchez-Montoya, MM ; Savic, A ; Shumilova, O ; Steward, A ; Taleb, A ; Uzan, A ; Vander Vorste, R ; Waltham, N ; Woelfle-Erskine, C ; Zak, D ; Zarfl, C ; Zoppini, A (AMER GEOPHYSICAL UNION, 2019-10-16)
    Intermittent rivers and ephemeral streams (IRES) may represent over half the global stream network, but their contribution to respiration and carbon dioxide (CO2) emissions is largely undetermined. In particular, little is known about the variability and drivers of respiration in IRES sediments upon rewetting, which could result in large pulses of CO2. We present a global study examining sediments from 200 dry IRES reaches spanning multiple biomes. Results from standardized assays show that mean respiration increased 32-fold to 66-fold upon sediment rewetting. Structural equation modeling indicates that this response was driven by sediment texture and organic matter quantity and quality, which, in turn, were influenced by climate, land use, and riparian plant cover. Our estimates suggest that respiration pulses resulting from rewetting of IRES sediments could contribute significantly to annual CO2 emissions from the global stream network, with a single respiration pulse potentially increasing emission by 0.2–0.7%. As the spatial and temporal extent of IRES increases globally, our results highlight the importance of recognizing the influence of wetting-drying cycles on respiration and CO2 emissions in stream networks.
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    Simulating rewetting events in intermittent rivers and ephemeral streams: A global analysis of leached nutrients and organic matter
    Shumilova, O ; Zak, D ; Datry, T ; von Schiller, D ; Corti, R ; Foulquier, A ; Obrador, B ; Tockner, K ; Allan, DC ; Altermatt, F ; Isabel Arce, M ; Arnon, S ; Banas, D ; Banegas-Medina, A ; Beller, E ; Blanchette, ML ; Blanco-Libreros, JF ; Blessing, J ; Boechat, IG ; Boersma, K ; Bogan, MT ; Bonada, N ; Bond, NR ; Brintrup, K ; Bruder, A ; Burrows, R ; Cancellario, T ; Carlson, SM ; Cauvy-Fraunie, S ; Cid, N ; Danger, M ; de Freitas Terra, B ; De Girolamo, AM ; del Campo, R ; Dyer, F ; Elosegi, A ; Faye, E ; Febria, C ; Figueroa, R ; Four, B ; Gessner, MO ; Gnohossou, P ; Cerezo, RG ; Gomez-Gener, L ; Graca, MAS ; Guareschi, S ; Guecker, B ; Hwan, JL ; Kubheka, S ; Langhans, SD ; Leigh, C ; Little, CJ ; Lorenz, S ; Marshall, J ; McIntosh, A ; Mendoza-Lera, C ; Meyer, EI ; Milisa, M ; Mlambo, MC ; Moleon, M ; Negus, P ; Niyogi, D ; Papatheodoulou, A ; Pardo, I ; Paril, P ; Pesic, V ; Rodriguez-Lozano, P ; Rolls, RJ ; Sanchez-Montoya, MM ; Savic, A ; Steward, A ; Stubbington, R ; Taleb, A ; Vander Vorste, R ; Waltham, N ; Zoppini, A ; Zarfl, C (WILEY, 2019-05-01)
    Climate change and human pressures are changing the global distribution and the extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico-chemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experimentally simulated, under standard laboratory conditions, rewetting of leaves, riverbed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative characteristics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dissolved substances during rewetting events (56%–98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contributed most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached OM. The opposite pattern was found in the arid zone. Environmental variables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached substances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying events.
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    High rates of organic carbon processing in the hyporheic zone of intermittent streams
    Burrows, RM ; Rutlidge, H ; Bond, NR ; Eberhard, SM ; Auhl, A ; Andersen, MS ; Valdez, DG ; Kennard, MJ (NATURE PUBLISHING GROUP, 2017-10-16)
    Organic carbon cycling is a fundamental process that underpins energy transfer through the biosphere. However, little is known about the rates of particulate organic carbon processing in the hyporheic zone of intermittent streams, which is often the only wetted environment remaining when surface flows cease. We used leaf litter and cotton decomposition assays, as well as rates of microbial respiration, to quantify rates of organic carbon processing in surface and hyporheic environments of intermittent and perennial streams under a range of substrate saturation conditions. Leaf litter processing was 48% greater, and cotton processing 124% greater, in the hyporheic zone compared to surface environments when calculated over multiple substrate saturation conditions. Processing was also greater in more saturated surface environments (i.e. pools). Further, rates of microbial respiration on incubated substrates in the hyporheic zone were similar to, or greater than, rates in surface environments. Our results highlight that intermittent streams are important locations for particulate organic carbon processing and that the hyporheic zone sustains this fundamental process even without surface flow. Not accounting for carbon processing in the hyporheic zone of intermittent streams may lead to an underestimation of its local ecological significance and collective contribution to landscape carbon processes.