The fate of C4 and C3 macrophyte carbon in central Amazon floodplain waters: Insights from a batch experiment

Mortillaro, Jean-Michel; Passarelli, Claire; Abril, Gwénaël; Hubas, Cédric; Albéric, Patrick; Artigas, Luis Felipe; Benedetti, Marc F.; Thiney, Najet; Pérez, M.; Vidal, Luciana O.; Méziane, Tarik

doi:10.1016/j.limno.2016.03.008

Cited by 16 publications

(10 citation statements)

References 51 publications

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“…What was confirmed by the highest GPP zmix value recorded in our study during the same period. Results from batch incubations with a variety of plant species present in Lake Janauacá, demonstrated the release of large amounts of nutrients during decomposition (Mortillaro et al, 2016). A similar release of nutrients and CO 2 presumably sustained the high levels of NCP zmix observed during this period.…”

Section: Plankton Metabolism and Its Influence On Co 2 Dynamicsmentioning

confidence: 83%

“…In lakes and other aquatic ecosystems along Amazonian floodplains, the DOC pool is a mixture of refractory organic matter and rapidly cycling labile C (Waichman, 1996;Mayorga et al, 2005). Evidence from isotopic measurements of respired CO 2 and fatty acids indicates that bacterial respiration along the central Amazon floodplain is sustained predominantly by DOC from C4 plants (Quay et al, 1992;Waichman, 1996;Mortillaro et al, 2016). Others, with less direct evidence, suggest that terrestrial C is also important (Ward et al, 2013(Ward et al, , 2016.…”

Section: Implications and Insights From Incubationsmentioning

confidence: 99%

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Influence of plankton metabolism and mixing depth on CO2 dynamics in an Amazon floodplain lake

Amaral

Borges

Mélack

et al. 2018

Science of The Total Environment

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We investigated plankton metabolism and its influence on carbon dioxide (CO) dynamics in a central Amazon floodplain lake (Janauacá, 3°23' S, 60°18' W) from September 2015 to May 2016, including a period with exceptional drought. We made diel measurements of CO emissions to the atmosphere with floating chambers and depth profiles of temperature and CO partial pressure (pCO) at two sites with differing wind exposure and proximity to vegetated habitats. Dissolved oxygen (DO) concentrations were monitored continuously during day and night in clear and dark chambers with autonomous optical sensors to evaluate plankton metabolism. Overnight community respiration (CR), and gross primary production (GPP) rates were higher in clear chambers and positively correlated with chlorophyll-a (Chl-a). CO air-water fluxes varied over 24-h periods with changes in thermal structure and metabolism. Most net daily CO fluxes during low water and mid-rising water at the wind exposed site were into the lake as a result of high rates of photosynthesis. All other measurements indicated net daily release to the atmosphere. Average GPP rates (6.8gCmd) were high compared with other studies in Amazon floodplain lakes. The growth of herbaceous plants on exposed sediment during an exceptional drought led to large carbon inputs when these areas were flooded, enhancing CR, pCO, and CO fluxes. During the period when the submerged herbaceous vegetation decayed phytoplankton abundance increased and photosynthetic uptake of CO occurred. While planktonic metabolism was often autotrophic (GPP:CR>1), CO out-gassing occurred during most periods investigated indicating other inputs of carbon such as sediments or soils and wetland plants.

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Section: Plankton Metabolism and Its Influence On Co 2 Dynamicsmentioning

confidence: 83%

Section: Implications and Insights From Incubationsmentioning

confidence: 99%

Influence of plankton metabolism and mixing depth on CO2 dynamics in an Amazon floodplain lake

Amaral

Borges

Mélack

et al. 2018

Science of The Total Environment

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“…b). These different extent of degradation to CH 4 between the two species may be attributable to different contents in refractory compounds, such as a high content in waxes for S. auriculata (Barthlott et al ; Mortillaro et al ) or a low content in structural compounds for N. indica (Esteves and Barbieri ).…”

Section: Discussionmentioning

confidence: 99%

“…Methanogenic potential of different OC types eutrophic lakes and reservoirs), are generally regarded as C sinks, because of frequent CO 2 undersaturation and/or high OC burial (Pacheco et al 2013;Anderson et al 2014), but if a significant part of the sedimenting OC is returned to the atmosphere as CH 4 , the CH 4 emissions could offset the C sink in terms of global warming potential Supporting Information). As most of CH 4 is released through ebullition and plant transport (Sch€ utz et al 1991;Wilkinson et al 2015), a challenge for future studies would to better quantify the fraction of CH 4 that is returned to the atmosphere through these two pathways.…”

Section: Grasset Et Almentioning

confidence: 99%

Large but variable methane production in anoxic freshwater sediment upon addition of allochthonous and autochthonous organic matter

Grasset

Mendonça

Saucedo

et al. 2018

Limnology & Oceanography

122

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An important question in the context of climate change is to understand how CH4 production is regulated in anoxic sediments of lakes and reservoirs. The type of organic carbon (OC) present in lakes is a key factor controlling CH4 production at anoxic conditions, but the studies investigating the methanogenic potential of the main OC types are fragmented. We incubated different types of allochthonous OC (alloOC; terrestrial plant leaves) and autochthonous OC (autoOC; phytoplankton and two aquatic plants species) in an anoxic sediment during 130 d. We tested if (1) the supply of fresh alloOC and autoOC to an anoxic refractory sediment would fuel CH4 production and if (2) autoOC would decompose faster than alloOC. The addition of fresh OC greatly increased CH4 production and the δ13C‐CH4 partitioning indicated that CH4 originated exclusively from the fresh OC. The large CH4 production in an anoxic sediment fueled by alloOC is a new finding which indicates that all systems with anoxic conditions and high sedimentation rates have the potential to be CH4 emitters. The autoOC decomposed faster than alloOC, but the total CH4 production was not higher for all autoOC types, one aquatic plant species having values as low as the terrestrial leaves, and the other one having values as high as phytoplankton. Our study is the first to report such variability, suggesting that the extent to which C fixed by aquatic plants is emitted as greenhouse gases or buried as OC in sediment could more generally differ between aquatic vegetation types.

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“…However, labile carbon derived from autochthonous sources was also shown to play an important role in the carbon dynamics of these systems (Mayorga et al ). Regarding Amazon floodplain lakes, there are apparently two distinct DOM pools: a large pool of more refractory DOM from C 3 allochthonous plants sources (terrestrial C from uplands, riverine inputs, leached from flooded forests and soils), and a small pool of labile DOM compounds derived from C 4 macrophytes and phytoplankton, which are consumed and rapidly turned over by heterotrophic bacteria (Waichman ; Melack and Forsberg ; Mortillaro et al ).…”

mentioning

confidence: 99%

Linking dissolved organic matter composition and bacterioplankton communities in an Amazon floodplain system

Melo

Kothawala

Bertilsson

et al. 2019

Limnology & Oceanography

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Dissolved organic matter (DOM) is the main substrate for aquatic prokaryotes, fuelling their metabolism and controlling community composition. Amazonian rivers transport and process large fluxes of terrestrial DOM, but little is known about the link between DOM composition and heterotrophic bacteria in the Amazon basin. The aims of this study were to characterize DOM composition and investigate the coupling between DOM and bacterial community composition (BCC) during a complete hydrological cycle in an Amazon floodplain system (lake Janauacá). Our study revealed a clear seasonal pattern in DOM composition through the flood pulse, which affected the amounts of autochthonous and allochthonous inputs and consequently the extent of humification, molecular weight, and aromaticity of the DOM. BCC was tightly coupled to DOM fluorescence, which was also driven by differences over the hydrological cycle, with distinct components and operational taxonomic units being simultaneously more abundant and correlating with a specific season. This coupling was particularly well reflected for three of the four identified fluorescence components, two terrestrial humic‐like components (C1 and C3) and an autochthonous component (C4). Despite clear changes in DOM composition, dissolved organic carbon concentrations tended to be relatively stable throughout the year. Overall, our results suggest that BCC shifts were associated with DOM quality but not with its quantity (that remains relatively constant throughout the year), and that bacteria preferably use labile and freshly produced DOM in lake Janauacá.

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The fate of C4 and C3 macrophyte carbon in central Amazon floodplain waters: Insights from a batch experiment

Cited by 16 publications

References 51 publications

Influence of plankton metabolism and mixing depth on CO2 dynamics in an Amazon floodplain lake

Influence of plankton metabolism and mixing depth on CO2 dynamics in an Amazon floodplain lake

Large but variable methane production in anoxic freshwater sediment upon addition of allochthonous and autochthonous organic matter

Linking dissolved organic matter composition and bacterioplankton communities in an Amazon floodplain system

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