Articles | Volume 22, issue 10
https://doi.org/10.5194/bg-22-2403-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-22-2403-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
27 May 2025
Research article |
| 27 May 2025
| 27 May 2025
Biogeochemical functioning of Lake Alaotra (Madagascar): a reset of aquatic carbon sources along the land–ocean aquatic continuum
Vao Fenotiana Razanamahandry
CORRESPONDING AUTHOR
Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
Alberto Vieira Borges
Chemical Oceanography Unit, University of Liège, Liège, Belgium
Liesa Brosens
Environmental Modeling Unit, Flemish Institute for Technological Research (VITO), Mol, Belgium
Cedric Morana
Chemical Oceanography Unit, University of Liège, Liège, Belgium
Tantely Razafimbelo
Laboratoire des Radio-Isotopes, University of Antananarivo, Antananarivo, Madagascar
Tovonarivo Rafolisy
Laboratoire des Radio-Isotopes, University of Antananarivo, Antananarivo, Madagascar
Gerard Govers
Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
Steven Bouillon
CORRESPONDING AUTHOR
Department of Earth and Environmental Sciences, KU Leuven, Leuven, Belgium
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Samuel T. Wilson, Hermann W. Bange, Damian L. Arévalo-Martínez, Jonathan Barnes, Alberto V. Borges, Ian Brown, John L. Bullister, Macarena Burgos, David W. Capelle, Michael Casso, Mercedes de la Paz, Laura Farías, Lindsay Fenwick, Sara Ferrón, Gerardo Garcia, Michael Glockzin, David M. Karl, Annette Kock, Sarah Laperriere, Cliff S. Law, Cara C. Manning, Andrew Marriner, Jukka-Pekka Myllykangas, John W. Pohlman, Andrew P. Rees, Alyson E. Santoro, Philippe D. Tortell, Robert C. Upstill-Goddard, David P. Wisegarver, Gui-Ling Zhang, and Gregor Rehder
Biogeosciences, 15, 5891–5907, https://doi.org/10.5194/bg-15-5891-2018, https://doi.org/10.5194/bg-15-5891-2018, 2018
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Trent R. Marwick, Fredrick Tamooh, Bernard Ogwoka, Alberto V. Borges, François Darchambeau, and Steven Bouillon
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Alberto V. Borges, Gwenaël Abril, and Steven Bouillon
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Gerard Govers, Roel Merckx, Bas van Wesemael, and Kristof Van Oost
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Naomi Geeraert, Fred O. Omengo, Fredrick Tamooh, Trent R. Marwick, Alberto V. Borges, Gerard Govers, and Steven Bouillon
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Marijn Van de Broek, Stijn Temmerman, Roel Merckx, and Gerard Govers
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Thibault Lambert, Steven Bouillon, François Darchambeau, Philippe Massicotte, and Alberto V. Borges
Biogeosciences, 13, 5405–5420, https://doi.org/10.5194/bg-13-5405-2016, https://doi.org/10.5194/bg-13-5405-2016, 2016
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Biogeosciences, 13, 4343–4357, https://doi.org/10.5194/bg-13-4343-2016, https://doi.org/10.5194/bg-13-4343-2016, 2016
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Fleur A. E. Roland, François Darchambeau, Cédric Morana, Sean A. Crowe, Bo Thamdrup, and Alberto V. Borges
Biogeosciences Discuss., https://doi.org/10.5194/bg-2016-300, https://doi.org/10.5194/bg-2016-300, 2016
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Thibault Lambert, Cristian R. Teodoru, Frank C. Nyoni, Steven Bouillon, François Darchambeau, Philippe Massicotte, and Alberto V. Borges
Biogeosciences, 13, 2727–2741, https://doi.org/10.5194/bg-13-2727-2016, https://doi.org/10.5194/bg-13-2727-2016, 2016
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This manuscript presents a detailed analysis of transport and transformation of dissolved organic matter along the Zambezi River and its largest tributary. A particular focus is put on the effects of floodplains/wetlands and reservoirs as well as low-flow vs. high-flow conditions on the longitudinal patterns in DOM concentration and composition. It is the first study to present such a detailed analysis for a whole, large river system, and in particular for a tropical river other than the Amazon.
N. Geeraert, F. O. Omengo, G. Govers, and S. Bouillon
Biogeosciences, 13, 517–525, https://doi.org/10.5194/bg-13-517-2016, https://doi.org/10.5194/bg-13-517-2016, 2016
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C. Morana, F. Darchambeau, F. A. E. Roland, A. V. Borges, F. Muvundja, Z. Kelemen, P. Masilya, J.-P. Descy, and S. Bouillon
Biogeosciences, 12, 4953–4963, https://doi.org/10.5194/bg-12-4953-2015, https://doi.org/10.5194/bg-12-4953-2015, 2015
C. R. Teodoru, F. C. Nyoni, A. V. Borges, F. Darchambeau, I. Nyambe, and S. Bouillon
Biogeosciences, 12, 2431–2453, https://doi.org/10.5194/bg-12-2431-2015, https://doi.org/10.5194/bg-12-2431-2015, 2015
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CO2 and CH4 concentrations and fluxes in the Zambezi River basin are well below the median/average values reported previously for tropical rivers, streams and reservoirs, and mainly controlled by the connectivity with floodplains and the presence of waterfalls and man-made reservoirs. The mass balance suggests that carbon transport to the ocean represents the major component (~60%) of the budget, while emissions to the atmosphere account for less than 40% of the total carbon yield.
C. Morana, A. V. Borges, F. A. E. Roland, F. Darchambeau, J.-P. Descy, and S. Bouillon
Biogeosciences, 12, 2077–2088, https://doi.org/10.5194/bg-12-2077-2015, https://doi.org/10.5194/bg-12-2077-2015, 2015
M. Hagens, C. P. Slomp, F. J. R. Meysman, D. Seitaj, J. Harlay, A. V. Borges, and J. J. Middelburg
Biogeosciences, 12, 1561–1583, https://doi.org/10.5194/bg-12-1561-2015, https://doi.org/10.5194/bg-12-1561-2015, 2015
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This study looks at the combined impacts of hypoxia and acidification, two major environmental stressors affecting coastal systems, in a seasonally stratified basin. Here, the surface water experiences less seasonality in pH than the bottom water despite higher process rates. This is due to a substantial reduction in the acid-base buffering capacity of the bottom water as it turns hypoxic in summer. This highlights the crucial role of the buffering capacity as a modulating factor in pH dynamics.
G. Abril, S. Bouillon, F. Darchambeau, C. R. Teodoru, T. R. Marwick, F. Tamooh, F. Ochieng Omengo, N. Geeraert, L. Deirmendjian, P. Polsenaere, and A. V. Borges
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We compared pCO2 data calculated from pH and alkalinity from those measured directly in a large array of temperate and tropical freshwaters. This revealed a large overestimation (up to 300%) of calculated pCO2 in the case of acidic and organic-rich waters, due to a contribution of organic acids anions to alkalinity and a lower buffering capacity of the carbonate system at acidic pH. Given the widespread distribution of acidic freshwaters, direct measurements of water pCO2 are encouraged.
P. Ciais, A. J. Dolman, A. Bombelli, R. Duren, A. Peregon, P. J. Rayner, C. Miller, N. Gobron, G. Kinderman, G. Marland, N. Gruber, F. Chevallier, R. J. Andres, G. Balsamo, L. Bopp, F.-M. Bréon, G. Broquet, R. Dargaville, T. J. Battin, A. Borges, H. Bovensmann, M. Buchwitz, J. Butler, J. G. Canadell, R. B. Cook, R. DeFries, R. Engelen, K. R. Gurney, C. Heinze, M. Heimann, A. Held, M. Henry, B. Law, S. Luyssaert, J. Miller, T. Moriyama, C. Moulin, R. B. Myneni, C. Nussli, M. Obersteiner, D. Ojima, Y. Pan, J.-D. Paris, S. L. Piao, B. Poulter, S. Plummer, S. Quegan, P. Raymond, M. Reichstein, L. Rivier, C. Sabine, D. Schimel, O. Tarasova, R. Valentini, R. Wang, G. van der Werf, D. Wickland, M. Williams, and C. Zehner
Biogeosciences, 11, 3547–3602, https://doi.org/10.5194/bg-11-3547-2014, https://doi.org/10.5194/bg-11-3547-2014, 2014
T. R. Marwick, F. Tamooh, B. Ogwoka, C. Teodoru, A. V. Borges, F. Darchambeau, and S. Bouillon
Biogeosciences, 11, 443–460, https://doi.org/10.5194/bg-11-443-2014, https://doi.org/10.5194/bg-11-443-2014, 2014
F. Tamooh, A. V. Borges, F. J. R. Meysman, K. Van Den Meersche, F. Dehairs, R. Merckx, and S. Bouillon
Biogeosciences, 10, 6911–6928, https://doi.org/10.5194/bg-10-6911-2013, https://doi.org/10.5194/bg-10-6911-2013, 2013
Related subject area
Biogeochemistry: Limnology
Diatom shifts and limnological changes in a Siberian boreal lake: a multiproxy perspective on climate warming and anthropogenic air pollution
Tracing rate and extent of human-induced hypoxia during the last 200 years in the mesotrophic lake, Tiefer See (NE Germany)
Thermal stratification and meromixis in four dilute temperate zone lakes
Mercury records covering the past 90 000 years from lakes Prespa and Ohrid, SE Europe
Temporary stratification promotes large greenhouse gas emissions in a shallow eutrophic lake
The influence of carbon cycling on oxygen depletion in north-temperate lakes
Conceptual models of dissolved carbon fluxes in a two-layer stratified lake: interannual typhoon responses under extreme climates
Soil-biodegradable plastic films do not decompose in a lake sediment over 9 months of incubation
Anthropogenic activities significantly increase annual greenhouse gas (GHG) fluxes from temperate headwater streams in Germany
Role of formation and decay of seston organic matter in the fate of methylmercury within the water column of a eutrophic lake
Contrasting activation energies of litter-associated respiration and P uptake drive lower cumulative P uptake at higher temperatures
Rapidly increasing sulfate concentration: a hidden promoter of eutrophication in shallow lakes
The dominant role of sunlight in degrading winter dissolved organic matter from a thermokarst lake in a subarctic peatland
Dissolved organic matter signatures in urban surface waters: spatio-temporal patterns and drivers
Towards a history of Holocene P dynamics for the Northern Hemisphere using lake sediment geochemical records
Methane in the Danube Delta: the importance of spatial patterns and diel cycles for atmospheric emission estimates
Methane oxidation in the waters of a humic-rich boreal lake stimulated by photosynthesis, nitrite, Fe(III) and humics
Porewater δ13CDOC indicates variable extent of degradation in different talik layers of coastal Alaskan thermokarst lakes
Holocene phototrophic community and anoxia dynamics in meromictic Lake Jaczno (NE Poland) using high-resolution hyperspectral imaging and HPLC data
Changing sources and processes sustaining surface CO2 and CH4 fluxes along a tropical river to reservoir system
The relative importance of photodegradation and biodegradation of terrestrially derived dissolved organic carbon across four lakes of differing trophic status
The influences of historic lake trophy and mixing regime changes on long-term phosphorus fraction retention in sediments of deep eutrophic lakes: a case study from Lake Burgäschi, Switzerland
Ice formation on lake surfaces in winter causes warm-season bias of lacustrine brGDGT temperature estimates
Drivers of diffusive CH4 emissions from shallow subarctic lakes on daily to multi-year timescales
High organic carbon burial but high potential for methane ebullition in the sediments of an Amazonian hydroelectric reservoir
Direct O2 control on the partitioning between denitrification and dissimilatory nitrate reduction to ammonium in lake sediments
Spatial distribution of environmental indicators in surface sediments of Lake Bolshoe Toko, Yakutia, Russia
Ostracods as ecological and isotopic indicators of lake water salinity changes: the Lake Van example
Reviews and syntheses: Dams, water quality and tropical reservoir stratification
Nitrogen cycling in Sandusky Bay, Lake Erie: oscillations between strong and weak export and implications for harmful algal blooms
Distinctive effects of allochthonous and autochthonous organic matter on CDOM spectra in a tropical lake
High-frequency productivity estimates for a lake from free-water CO2 concentration measurements
Nitrification and ammonium dynamics in Taihu Lake, China: seasonal competition for ammonium between nitrifiers and cyanobacteria
Quality transformation of dissolved organic carbon during water transit through lakes: contrasting controls by photochemical and biological processes
Continuous measurement of air–water gas exchange by underwater eddy covariance
Capturing temporal and spatial variability in the chemistry of shallow permafrost ponds
Organic carbon mass accumulation rate regulates the flux of reduced substances from the sediments of deep lakes
Cyanobacterial carbon concentrating mechanisms facilitate sustained CO2 depletion in eutrophic lakes
New insights on resource stoichiometry: assessing availability of carbon, nitrogen, and phosphorus to bacterioplankton
Spatio-seasonal variability of chromophoric dissolved organic matter absorption and responses to photobleaching in a large shallow temperate lake
Isotopic composition of nitrate and particulate organic matter in a pristine dam reservoir of western India: implications for biogeochemical processes
Bacterial production in subarctic peatland lakes enriched by thawing permafrost
Photochemical mineralisation in a boreal brown water lake: considerable temporal variability and minor contribution to carbon dioxide production
Are flood-driven turbidity currents hot spots for priming effect in lakes?
Organic carbon burial efficiency in a subtropical hydroelectric reservoir
Importance of within-lake processes in affecting the dynamics of dissolved organic carbon and dissolved organic and inorganic nitrogen in an Adirondack forested lake/watershed
Temperature dependence of the relationship between pCO2 and dissolved organic carbon in lakes
The nature of organic carbon in density-fractionated sediments in the Sacramento-San Joaquin River Delta (California)
Microbial nutrient limitation in Arctic lakes in a permafrost landscape of southwest Greenland
Phototrophic pigment diversity and picophytoplankton in permafrost thaw lakes
Amelie Stieg, Boris K. Biskaborn, Ulrike Herzschuh, Andreas Marent, Jens Strauss, Dorothee Wilhelms-Dick, Luidmila A. Pestryakova, and Hanno Meyer
Biogeosciences, 22, 2327–2350, https://doi.org/10.5194/bg-22-2327-2025, https://doi.org/10.5194/bg-22-2327-2025, 2025
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Globally, lake ecosystems have undergone significant shifts since the 1950s due to human activities. This study presents a unique ~220-year sediment record from a remote Siberian boreal lake, providing a multiproxy perspective on climate warming and anthropogenic air pollution. Analyses of diatom assemblages, diatom silicon isotopes, and carbon and nitrogen sediment proxies reveal complex biogeochemical interactions, highlighting anthropogenic influences even on remote water resources.
Ido Sirota, Rik Tjallingii, Sylvia Pinkerneil, Birgit Schroeder, Marlen Albert, Rebecca Kearney, Oliver Heiri, Simona Breu, and Achim Brauer
Biogeosciences, 21, 4317–4339, https://doi.org/10.5194/bg-21-4317-2024, https://doi.org/10.5194/bg-21-4317-2024, 2024
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Hypoxia has spread in Tiefer See (NE Germany) due to increased human activity. The onset of hypoxia indicated by varve preservation is dated to ~1920 at the lake’s depocenter, which responds faster and more severely to the reduction in oxygen level. The spread of hypoxic conditions is a gradual process that has lasted nearly 100 years, and the chemistry of the sediments shows that the depletion of oxygen in the lake started several decades before the onset of varve preservation.
Elizabeth D. Swanner, Chris Harding, Sajjad A. Akam, Ioan Lascu, Gabrielle Ledesma, Pratik Poudel, Heeyeon Sun, Samuel Duncanson, Karly Bandy, Alex Branham, Liza Bryant-Tapper, Tanner Conwell, Omri Jamison, and Lauren Netz
Biogeosciences, 21, 1549–1562, https://doi.org/10.5194/bg-21-1549-2024, https://doi.org/10.5194/bg-21-1549-2024, 2024
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Four lakes were thought to be permanently stratified. Years’ worth of data indicate only one lake is permanently stratified. Strong temperature gradients keep it stratified – unusual for a lake in a temperate climate. The lake has elevated oxygen concentrations within the temperature gradient. Rapid development of the gradient in the spring traps oxygen, and oxygen production by photosynthetic organisms during the summer adds more.
Alice R. Paine, Isabel M. Fendley, Joost Frieling, Tamsin A. Mather, Jack H. Lacey, Bernd Wagner, Stuart A. Robinson, David M. Pyle, Alexander Francke, Theodore R. Them II, and Konstantinos Panagiotopoulos
Biogeosciences, 21, 531–556, https://doi.org/10.5194/bg-21-531-2024, https://doi.org/10.5194/bg-21-531-2024, 2024
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Many important processes within the global mercury (Hg) cycle operate over thousands of years. Here, we explore the timing, magnitude, and expression of Hg signals retained in sediments of lakes Prespa and Ohrid over the past ∼90 000 years. Divergent signals suggest that local differences in sediment composition, lake structure, and water balance influence the local Hg cycle and determine the extent to which sedimentary Hg signals reflect local- or global-scale environmental changes.
Thomas A. Davidson, Martin Søndergaard, Joachim Audet, Eti Levi, Chiara Esposito, Tuba Bucak, and Anders Nielsen
Biogeosciences, 21, 93–107, https://doi.org/10.5194/bg-21-93-2024, https://doi.org/10.5194/bg-21-93-2024, 2024
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Shallow lakes and ponds undergo frequent stratification in summer months. Here we studied how this affects greenhouse gas (GHG) emissions. We found that stratification caused anoxia in the bottom waters, driving increased GHG emissions, in particular methane released as bubbles. In addition, methane and carbon dioxide accumulated in the bottom waters during stratification, leading to large emissions when the lake mixed again.
Austin Delany, Robert Ladwig, Cal Buelo, Ellen Albright, and Paul C. Hanson
Biogeosciences, 20, 5211–5228, https://doi.org/10.5194/bg-20-5211-2023, https://doi.org/10.5194/bg-20-5211-2023, 2023
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Internal and external sources of organic carbon (OC) in lakes can contribute to oxygen depletion, but their relative contributions remain in question. To study this, we built a two-layer model to recreate processes relevant to carbon for six Wisconsin lakes. We found that internal OC was more important than external OC in depleting oxygen. This shows that it is important to consider both the fast-paced cycling of internally produced OC and the slower cycling of external OC when studying lakes.
Hao-Chi Lin, Keisuke Nakayama, Jeng-Wei Tsai, and Chih-Yu Chiu
Biogeosciences, 20, 4359–4376, https://doi.org/10.5194/bg-20-4359-2023, https://doi.org/10.5194/bg-20-4359-2023, 2023
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We successfully developed conceptual models to examine how dissolved carbon distributions change with climate within a small subtropical lake, considering both physical and biochemical processes. Typhoons controlled the seasonal and interannual variation in C fluxes due to large amounts of carbon loading and rapid mixing within the whole lake, resulting in the net primary production being 3.14 times higher in typhoon years than in non-typhoon years in Yuan‒Yang Lake.
Sigrid van Grinsven and Carsten Schubert
Biogeosciences, 20, 4213–4220, https://doi.org/10.5194/bg-20-4213-2023, https://doi.org/10.5194/bg-20-4213-2023, 2023
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Agriculture relies heavily on plastic mulch films, which may be transported to aquatic environments. We investigated the breakdown of soil-biodegradable agricultural mulch films in lake sediments. After 40 weeks, films were intact, and no significant CO2 or CH4 was produced from the biodegradable mulch films. We conclude that the mulch films we used have a low biodegradability in lake sediments. The sediment lacks the microbes needed to break down the biodegradable plastics that were used here.
Ricky Mwangada Mwanake, Gretchen Maria Gettel, Elizabeth Gachibu Wangari, Clarissa Glaser, Tobias Houska, Lutz Breuer, Klaus Butterbach-Bahl, and Ralf Kiese
Biogeosciences, 20, 3395–3422, https://doi.org/10.5194/bg-20-3395-2023, https://doi.org/10.5194/bg-20-3395-2023, 2023
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Despite occupying <1 %; of the globe, streams are significant sources of greenhouse gas (GHG) emissions. In this study, we determined anthropogenic effects on GHG emissions from streams. We found that anthropogenic-influenced streams had up to 20 times more annual GHG emissions than natural ones and were also responsible for seasonal peaks. Anthropogenic influences also altered declining GHG flux trends with stream size, with potential impacts on stream-size-based spatial upscaling techniques.
Laura Balzer, Carluvy Baptista-Salazar, Sofi Jonsson, and Harald Biester
Biogeosciences, 20, 1459–1472, https://doi.org/10.5194/bg-20-1459-2023, https://doi.org/10.5194/bg-20-1459-2023, 2023
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Toxic methylmercury (MeHg) in lakes can be enriched in fish and is harmful for humans. Phytoplankton is the entry point for MeHg into the aquatic food chain. We investigated seasonal MeHg concentrations in plankton of a productive lake. Our results show that high amounts of MeHg occur in algae and suspended matter in lakes and that productive lakes are hot spots of MeHg formation, which is mainly controlled by decomposition of algae organic matter and water-phase redox conditions.
Nathan J. Tomczyk, Amy D. Rosemond, Anna Kaz, and Jonathan P. Benstead
Biogeosciences, 20, 191–204, https://doi.org/10.5194/bg-20-191-2023, https://doi.org/10.5194/bg-20-191-2023, 2023
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Warming is expected to increase rates of microbial metabolism, but the effect of warming on nutrient demand is unclear. Our experiments demonstrate that microbial nutrient uptake increases less with temperature than metabolism, particularly when environmental nutrient concentrations are low. However, our simulation models suggest that warming may actually lead to declines in ecosystem-scale nutrient uptake as warming accelerates the depletion of carbon substrates required for microbial growth.
Chuanqiao Zhou, Yu Peng, Li Chen, Miaotong Yu, Muchun Zhou, Runze Xu, Lanqing Zhang, Siyuan Zhang, Xiaoguang Xu, Limin Zhang, and Guoxiang Wang
Biogeosciences, 19, 4351–4360, https://doi.org/10.5194/bg-19-4351-2022, https://doi.org/10.5194/bg-19-4351-2022, 2022
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The dramatical increase in SO42- concentration up to 100 mg L-1 in eutrophic lakes has aroused great attention. It enhanced the sulfate reduction to release a large amount of ΣS2- during cyanobacteria decomposition. The Fe2+ released from the iron reduction process is captured by ΣS2-, and finally the combination of iron and P was reduced, promoting the release of endogenous P. Therefore, increasing sulfate concentrations are shown to be a hidden promoter of eutrophication in shallow lakes.
Flora Mazoyer, Isabelle Laurion, and Milla Rautio
Biogeosciences, 19, 3959–3977, https://doi.org/10.5194/bg-19-3959-2022, https://doi.org/10.5194/bg-19-3959-2022, 2022
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Dissolved organic matter collected at the end of winter from a peatland thermokarst lake was highly transformed and degraded by sunlight, leading to bacterial stimulation and CO2 production, but a fraction was also potentially lost by photoflocculation. Over 18 days, 18 % of the incubated dissolved organic matter was lost under sunlight, while dark bacterial degradation was negligible. Sunlight could have a marked effect on carbon cycling in organic-rich thermokarst lakes after ice-off.
Clara Romero González-Quijano, Sonia Herrero Ortega, Peter Casper, Mark O. Gessner, and Gabriel A. Singer
Biogeosciences, 19, 2841–2853, https://doi.org/10.5194/bg-19-2841-2022, https://doi.org/10.5194/bg-19-2841-2022, 2022
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Despite today's diversity of methods to measure dissolved organic matter (DOM), its potential to give ecological information about urban surface waters has been underused. We found DOM from urban lakes and ponds to differ greatly from that of urban streams and rivers in composition as well as temporal turnover. Urban land use (the percentage of green space), nutrient supply and point source pollution were the principal drivers of DOM. We suggest including DOM composition in regular monitoring.
Madeleine Moyle, John F. Boyle, and Richard C. Chiverrell
Biogeosciences, 18, 5609–5638, https://doi.org/10.5194/bg-18-5609-2021, https://doi.org/10.5194/bg-18-5609-2021, 2021
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We reconstruct Holocene landscape P yield and lake water TP concentration for 24 sites across the Northern Hemisphere by applying a process model to published lake sediment geochemical records. We find sites with the same landscape development history show similar geochemical profiles depending on climate, human impact, and other local factors. Our reconstructions can be used to understand present-day terrestrial P cycling, lake water nutrient status, and export of terrestrial P to the oceans.
Anna Canning, Bernhard Wehrli, and Arne Körtzinger
Biogeosciences, 18, 3961–3979, https://doi.org/10.5194/bg-18-3961-2021, https://doi.org/10.5194/bg-18-3961-2021, 2021
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Inland waters are usually not well restrained in terms of greenhouse gas measurements. One of these regions is the Danube Delta, Romania. Therefore, we measured continuously with sensors to collect high-resolution data for CH4 and O2 throughout the Delta. We found significant variation for all concentrations over the day and night and between regions, as well as large spatial variation throughout all regions, with large CH4 concentrations flowing in from the reed beds to the lakes.
Sigrid van Grinsven, Kirsten Oswald, Bernhard Wehrli, Corinne Jegge, Jakob Zopfi, Moritz F. Lehmann, and Carsten J. Schubert
Biogeosciences, 18, 3087–3101, https://doi.org/10.5194/bg-18-3087-2021, https://doi.org/10.5194/bg-18-3087-2021, 2021
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Lake Lovojärvi is a nutrient-rich lake with high amounts of methane at the bottom, but little near the top. Methane comes from the sediment and rises up through the water but is consumed by microorganisms along the way. They use oxygen if available, but in deeper water layers, no oxygen was present. There, nitrite, iron and humic substances were used, besides a collaboration between photosynthetic organisms and methane consumers, in which the first produced oxygen for the latter.
Ove H. Meisel, Joshua F. Dean, Jorien E. Vonk, Lukas Wacker, Gert-Jan Reichart, and Han Dolman
Biogeosciences, 18, 2241–2258, https://doi.org/10.5194/bg-18-2241-2021, https://doi.org/10.5194/bg-18-2241-2021, 2021
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Arctic permafrost lakes form thaw bulbs of unfrozen soil (taliks) beneath them where carbon degradation and greenhouse gas production are increased. We analyzed the stable carbon isotopes of Alaskan talik sediments and their porewater dissolved organic carbon and found that the top layers of these taliks are likely more actively degraded than the deeper layers. This in turn implies that these top layers are likely also more potent greenhouse gas producers than the underlying deeper layers.
Stamatina Makri, Andrea Lami, Luyao Tu, Wojciech Tylmann, Hendrik Vogel, and Martin Grosjean
Biogeosciences, 18, 1839–1856, https://doi.org/10.5194/bg-18-1839-2021, https://doi.org/10.5194/bg-18-1839-2021, 2021
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Anoxia in lakes is a major growing concern. In this study we applied a multiproxy approach combining high-resolution hyperspectral imaging (HSI) pigment data with specific HPLC data to examine the Holocene evolution and main drivers of lake anoxia and trophic state changes. We find that when human impact was low, these changes were driven by climate and natural lake-catchment evolution. In the last 500 years, increasing human impact has promoted lake eutrophication and permanent anoxia.
Cynthia Soued and Yves T. Prairie
Biogeosciences, 18, 1333–1350, https://doi.org/10.5194/bg-18-1333-2021, https://doi.org/10.5194/bg-18-1333-2021, 2021
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Freshwater reservoirs emit greenhouse gases (GHGs, CO2 and CH4) to the atmosphere; however, the sources underlying these emissions are numerous, and their magnitude is not well known. This study quantifies surface CO2 and CH4 emissions and all their potential sources in a tropical reservoir. Results highlight the changes in GHG sources along the river–reservoir continuum, with internal metabolism being a key component but highly uncertain and challenging to estimate at an ecosystem scale.
Christopher M. Dempsey, Jennifer A. Brentrup, Sarah Magyan, Lesley B. Knoll, Hilary M. Swain, Evelyn E. Gaiser, Donald P. Morris, Michael T. Ganger, and Craig E. Williamson
Biogeosciences, 17, 6327–6340, https://doi.org/10.5194/bg-17-6327-2020, https://doi.org/10.5194/bg-17-6327-2020, 2020
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We looked at how terrestrial dissolved organic carbon (DOC) from the watersheds of four different lakes responded to both biodegradation (i.e., microbes) and photodegradation (i.e., sunlight). The traditional paradigm is that biodegradation is more important than photodegradation. Our research shows that, on short timescales (i.e., 7 d), sunlight is more important than microbes in degrading DOC. Interestingly, the lakes had different responses to sunlight based on their trophic status.
Luyao Tu, Paul Zander, Sönke Szidat, Ronald Lloren, and Martin Grosjean
Biogeosciences, 17, 2715–2729, https://doi.org/10.5194/bg-17-2715-2020, https://doi.org/10.5194/bg-17-2715-2020, 2020
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In a small, deep lake on the Swiss Plateau, net fluxes of labile P fractions in sediments that can be released to surface waters have been predominately controlled by past hypolimnetic anoxic conditions since the early 1900s. More than 40 years of hypolimnetic withdrawal can effectively reduce net P fluxes in sediments and internal P loads but not effectively decrease eutrophication. These findings should likely serve the management of deep eutrophic lakes in temperate zones.
Jiantao Cao, Zhiguo Rao, Fuxi Shi, and Guodong Jia
Biogeosciences, 17, 2521–2536, https://doi.org/10.5194/bg-17-2521-2020, https://doi.org/10.5194/bg-17-2521-2020, 2020
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BrGDGT distribution in Gonghai Lake is different from surrounding soils, and its derived temperature reflects a mean annual lake water temperature (LWT) that is higher than the mean annual air temperature (AT). The higher mean annual LWT is due to ice formation in winter that prevents thermal exchange between lake water and air.
Joachim Jansen, Brett F. Thornton, Alicia Cortés, Jo Snöälv, Martin Wik, Sally MacIntyre, and Patrick M. Crill
Biogeosciences, 17, 1911–1932, https://doi.org/10.5194/bg-17-1911-2020, https://doi.org/10.5194/bg-17-1911-2020, 2020
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Lakes are important emitters of the greenhouse gas methane. We use field observations and a model to evaluate the importance of known drivers of methane production and release. Fast and slow changes of the diffusive flux were governed by wind speed and sediment temperature, respectively. Increased turbulence enhanced release, but storms depleted the lakes of gas and limited emissions. Our findings may inform model studies on the effects of weather and climate change on lake methane emissions.
Gabrielle R. Quadra, Sebastian Sobek, José R. Paranaíba, Anastasija Isidorova, Fábio Roland, Roseilson do Vale, and Raquel Mendonça
Biogeosciences, 17, 1495–1505, https://doi.org/10.5194/bg-17-1495-2020, https://doi.org/10.5194/bg-17-1495-2020, 2020
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Hydropower is expanding in the Amazon Basin, but the potential effects of river damming on carbon fluxes cannot be gauged due to a lack of studies. We quantified, for the first time in an Amazonian reservoir, both organic carbon burial and the concentrations of methane in the sediments. We found that the dual role of sediments as both a carbon sink and methane source may be particularly pronounced in this Amazonian reservoir.
Adeline N. Y. Cojean, Jakob Zopfi, Alan Gerster, Claudia Frey, Fabio Lepori, and Moritz F. Lehmann
Biogeosciences, 16, 4705–4718, https://doi.org/10.5194/bg-16-4705-2019, https://doi.org/10.5194/bg-16-4705-2019, 2019
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Our results demonstrate the importance of oxygen in regulating the fate of nitrogen (N) in the sediments of Lake Lugano south basin, Switzerland. Hence, our study suggests that, by changing oxygen concentration in bottom waters, the seasonal water column turnover may significantly regulate the partitioning between N removal and N recycling in surface sediments, and it is likely that a similar pattern can be expected in a wide range of environments.
Boris K. Biskaborn, Larisa Nazarova, Lyudmila A. Pestryakova, Liudmila Syrykh, Kim Funck, Hanno Meyer, Bernhard Chapligin, Stuart Vyse, Ruslan Gorodnichev, Evgenii Zakharov, Rong Wang, Georg Schwamborn, Hannah L. Bailey, and Bernhard Diekmann
Biogeosciences, 16, 4023–4049, https://doi.org/10.5194/bg-16-4023-2019, https://doi.org/10.5194/bg-16-4023-2019, 2019
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To better understand time-series data in lake sediment cores in times of rapidly changing climate, we study within-lake spatial variabilities of environmental indicator data in 38 sediment surface samples along spatial habitat gradients in the boreal deep Lake Bolshoe Toko (Russia). Our methods comprise physicochemical as well as diatom and chironomid analyses. Species diversities vary according to benthic niches, while abiotic proxies depend on river input, water depth, and catchment lithology.
Jeremy McCormack, Finn Viehberg, Derya Akdemir, Adrian Immenhauser, and Ola Kwiecien
Biogeosciences, 16, 2095–2114, https://doi.org/10.5194/bg-16-2095-2019, https://doi.org/10.5194/bg-16-2095-2019, 2019
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We juxtapose changes in ostracod taxonomy, morphology (noding) and oxygen (δ18O) and carbon (δ13C) isotopic composition for the last 150 kyr with independent low-resolution salinity proxies. We demonstrate that for Lake Van, salinity is the most important factor influencing the composition of the ostracod assemblage and the formation of nodes on the valves of limnocytherinae species. Ostracod δ18O shows a higher sensibility towards climatic and hydrological variations than the bulk isotopy.
Robert Scott Winton, Elisa Calamita, and Bernhard Wehrli
Biogeosciences, 16, 1657–1671, https://doi.org/10.5194/bg-16-1657-2019, https://doi.org/10.5194/bg-16-1657-2019, 2019
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A global boom in dam construction throughout the world’s tropics motivated us to review and synthesize information on the water quality impacts of dams with a focus on low-latitude contexts and scope for mitigation. Sediment trapping and reservoir stratification are key process driving chemical and ecological impacts on tropical rivers. We analyze the 54 most-voluminous low-latitude reservoirs and find that stratification seems to be a ubiquitous phenomenon.
Kateri R. Salk, George S. Bullerjahn, Robert Michael L. McKay, Justin D. Chaffin, and Nathaniel E. Ostrom
Biogeosciences, 15, 2891–2907, https://doi.org/10.5194/bg-15-2891-2018, https://doi.org/10.5194/bg-15-2891-2018, 2018
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This paper highlights dynamic nitrogen cycling in a freshwater estuary, with implications for harmful algal blooms and downstream nitrogen loading. Phytoplankton and microbes actively consumed nitrogen in this system, contributing to recycling of nitrogen within the system and permanent nitrogen removal, respectively. However, delivery of nitrogen from the river and fixation of atmospheric nitrogen by phytoplankton outweighed nitrogen uptake, resulting in variable downstream nitrogen delivery.
Luciana Pena Mello Brandão, Ludmila Silva Brighenti, Peter Anton Staehr, Eero Asmala, Philippe Massicotte, Denise Tonetta, Francisco Antônio Rodrigues Barbosa, Diego Pujoni, and José Fernandes Bezerra-Neto
Biogeosciences, 15, 2931–2943, https://doi.org/10.5194/bg-15-2931-2018, https://doi.org/10.5194/bg-15-2931-2018, 2018
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Using mesocosms we investigated the effect of the increase in the allochthonous and autochthonous sources of DOM in a tropical lake, in order to simulate its effects on the characteristics of lakes caused by anthropogenic impacts. The seasonal allochthonous input has much larger effects on the lake and, in addition to increasing nutrients, alters the transparency of water and consequently controls the seasonal dynamics of phytoplankton (autochthonous source) and lake ecology.
Maria Provenzale, Anne Ojala, Jouni Heiskanen, Kukka-Maaria Erkkilä, Ivan Mammarella, Pertti Hari, and Timo Vesala
Biogeosciences, 15, 2021–2032, https://doi.org/10.5194/bg-15-2021-2018, https://doi.org/10.5194/bg-15-2021-2018, 2018
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We extensively tested and refined a direct, high-frequency free-water CO2 measurement method to study the lake net ecosystem productivity. The method was first proposed in 2008, but neglected ever since.
With high-frequency direct methods, we can calculate the lake productivity more precisely, and parameterise its dependency on environmental variables. This helps us expand our knowledge on the carbon cycle in the water, and leads to a better integration of water bodies in carbon budgets.
Justyna J. Hampel, Mark J. McCarthy, Wayne S. Gardner, Lu Zhang, Hai Xu, Guangwei Zhu, and Silvia E. Newell
Biogeosciences, 15, 733–748, https://doi.org/10.5194/bg-15-733-2018, https://doi.org/10.5194/bg-15-733-2018, 2018
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Our paper highlights the importance of dual-nutrient management: nitrogen (N) and phosphorus (P) in lakes with cyanobacterial harmful algal blooms.
Taihu Lake (China) experiences seasonal blooms due to increased input of N and P from field runoff. The main process investigated in our study, nitrification,
is important for N removal through denitrification. We show that nitrification is less efficient during the blooms, due to competition for nutrients between
N microbes and cyanobacteria.
Martin Berggren, Marcus Klaus, Balathandayuthabani Panneer Selvam, Lena Ström, Hjalmar Laudon, Mats Jansson, and Jan Karlsson
Biogeosciences, 15, 457–470, https://doi.org/10.5194/bg-15-457-2018, https://doi.org/10.5194/bg-15-457-2018, 2018
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The quality of dissolved organic carbon (DOC), especially its color, is a defining feature of freshwater ecosystems. We found that colored DOC fractions are surprisingly resistant to natural degradation during water transit through many brown-water lakes. This is explained by the dominance of microbial processes that appear to selectively remove noncolored DOC. However, in lakes where sunlight degradation plays a relatively larger role, significant DOC bleaching occurs.
Peter Berg and Michael L. Pace
Biogeosciences, 14, 5595–5606, https://doi.org/10.5194/bg-14-5595-2017, https://doi.org/10.5194/bg-14-5595-2017, 2017
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We use the aquatic eddy covariance technique – developed first for benthic O2 flux measurements – right below the air–water interface (~ 4 cm) to determine gas exchange rates and coefficients. This use of the technique is particularly useful in studies of gas exchange and its dynamics and controls. The approach can thus help reduce the recognized problem of large uncertainties linked to gas exchange estimates in traditional aquatic ecosystem studies.
Matthew Q. Morison, Merrin L. Macrae, Richard M. Petrone, and LeeAnn Fishback
Biogeosciences, 14, 5471–5485, https://doi.org/10.5194/bg-14-5471-2017, https://doi.org/10.5194/bg-14-5471-2017, 2017
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Shallow ponds and lakes are common features in permafrost systems. We show that the chemistry of these water bodies can be dynamic, although the changes are consistent through time between ponds. This synchrony in some water chemistry appears to be related to water level variations. Because hydrological conditions can vary greatly over the course of the year and during a storm, this work underscores the importance of interpreting water samples from these systems within their hydrologic context.
Thomas Steinsberger, Martin Schmid, Alfred Wüest, Robert Schwefel, Bernhard Wehrli, and Beat Müller
Biogeosciences, 14, 3275–3285, https://doi.org/10.5194/bg-14-3275-2017, https://doi.org/10.5194/bg-14-3275-2017, 2017
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Based on a broad dataset of lake sediment analysis and porewater measurements from various Swiss lakes, this paper argues that the accumulation of organic carbon in the sediment is one of the main driving forces for the generation of reduced substances such as methane and ammonia. These substances significantly contribute to the hypolimnetic oxygen consumption. The relationships presented help to evaluate the scale of the flux of reduced substances where no direct measurements are available.
Ana M. Morales-Williams, Alan D. Wanamaker Jr., and John A. Downing
Biogeosciences, 14, 2865–2875, https://doi.org/10.5194/bg-14-2865-2017, https://doi.org/10.5194/bg-14-2865-2017, 2017
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Our study investigated the mechanisms sustaining cyanobacteria blooms when CO2 is depleted in lake surface waters. We found that when lake CO2 concentrations drop below those of the atmosphere, cyanobacteria switch on carbon concentrating mechanisms (CCMs), allowing them to actively take up bicarbonate. This may provide bloom-forming cyanobacteria with a competitive advantage over other algae. These results provide insight into the timing and duration of blooms in high-nutrient lakes.
Ana R. A. Soares, Ann-Kristin Bergström, Ryan A. Sponseller, Joanna M. Moberg, Reiner Giesler, Emma S. Kritzberg, Mats Jansson, and Martin Berggren
Biogeosciences, 14, 1527–1539, https://doi.org/10.5194/bg-14-1527-2017, https://doi.org/10.5194/bg-14-1527-2017, 2017
María Encina Aulló-Maestro, Peter Hunter, Evangelos Spyrakos, Pierre Mercatoris, Attila Kovács, Hajnalka Horváth, Tom Preston, Mátyás Présing, Jesús Torres Palenzuela, and Andrew Tyler
Biogeosciences, 14, 1215–1233, https://doi.org/10.5194/bg-14-1215-2017, https://doi.org/10.5194/bg-14-1215-2017, 2017
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As first study within my PhD with the general objective to improve and adapt remote sensing algorithms for the estimation of coloured dissolved organic matter (CDOM) content in lakes in a global scale, we carried out this set of measurements and experiments.
This study gives us a better understanding of sources and variability in the optical properties of CDOM in lakes and how photobleaching controls and affects them.
Pratirupa Bardhan, Syed Wajih Ahmad Naqvi, Supriya G. Karapurkar, Damodar M. Shenoy, Siby Kurian, and Hema Naik
Biogeosciences, 14, 767–779, https://doi.org/10.5194/bg-14-767-2017, https://doi.org/10.5194/bg-14-767-2017, 2017
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Although India has the third highest number of dams globally, there is a knowledge gap on the cycling of bioessential elements in such systems. This study (first of its kind) investigates the stable isotopes of nitrate and particulate organic matter in a pristine Indian reservoir. Nitrogen transformations in the anaerobic bottom waters were isotopically characterised. Overall, solar intensity, water depth and redox conditions are the major controls on the biogeochemical cycling in this system.
Bethany N. Deshpande, Sophie Crevecoeur, Alex Matveev, and Warwick F. Vincent
Biogeosciences, 13, 4411–4427, https://doi.org/10.5194/bg-13-4411-2016, https://doi.org/10.5194/bg-13-4411-2016, 2016
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Subarctic lakes are changing in size as a result of permafrost thawing, resulting in mobilization of soil materials. Our study characterizes the carbon and nutrient regime of a set of thaw lakes and their adjacent permafrost soils in a rapidly degrading landscape, showing how these materials create favorable conditions for aquatic bacterial communities. We discuss the controls over the bacterial community, and demonstrate that gain processes are not a primary control.
Marloes Groeneveld, Lars Tranvik, Sivakiruthika Natchimuthu, and Birgit Koehler
Biogeosciences, 13, 3931–3943, https://doi.org/10.5194/bg-13-3931-2016, https://doi.org/10.5194/bg-13-3931-2016, 2016
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Temporal variability in the apparent quantum yield of photochemical CDOM mineralisation in a boreal brown water lake was severalfold smaller than previously reported across different lakes. Simulated DIC photoproduction (2012–2014) averaged 2.0 ± 0.1 to 10.3 ± 0.7 g C m−2 yr−1 using the least and most reactive sample, which represented 1 to 8 % of the total mean CO2 emissions. Thus, direct CDOM photomineralisation makes only a minor contribution to mean CO2 emissions from Swedish brown water lakes.
Damien Bouffard and Marie-Elodie Perga
Biogeosciences, 13, 3573–3584, https://doi.org/10.5194/bg-13-3573-2016, https://doi.org/10.5194/bg-13-3573-2016, 2016
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This survey of an exceptional flood over Lake Geneva challenges the long-standing hypothesis that dense, particle-loaded and oxygenated rivers plunging into lakes necessarily contribute to deep-oxygen replenishment. We identified some river intrusions as hot spots for oxygen consumption, where inputs of fresh river-borne organic matter reactivate the respiration of more refractory lacustrine organic matter in a process referred to as "priming effect".
Raquel Mendonça, Sarian Kosten, Sebastian Sobek, Simone Jaqueline Cardoso, Marcos Paulo Figueiredo-Barros, Carlos Henrique Duque Estrada, and Fábio Roland
Biogeosciences, 13, 3331–3342, https://doi.org/10.5194/bg-13-3331-2016, https://doi.org/10.5194/bg-13-3331-2016, 2016
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Hydroelectric reservoirs in the tropics emit greenhouse gases but also bury carbon in their sediments. We investigated the efficiency of organic carbon (OC) burial in a large tropical reservoir, using spatially resolved measurements of sediment accumulation, and found that more than half (~ 57 %) of the OC deposited onto the sediment is buried. This high efficiency in OC burial indicates that tropical reservoirs may bury OC more efficiently than natural lakes.
Phil-Goo Kang, Myron J. Mitchell, Patrick J. McHale, Charles T. Driscoll, Shreeram Inamdar, and Ji-Hyung Park
Biogeosciences, 13, 2787–2801, https://doi.org/10.5194/bg-13-2787-2016, https://doi.org/10.5194/bg-13-2787-2016, 2016
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Lakes play important roles in controlling organic matter derived from watersheds and within-lake production. The organic matter is normally measured by elemental quantities, such as carbon(C) and nitrogen(N), because the two elements are essential for aquatic ecosystems. We observed an decrease of C, but an increase of N in organic matters in a lake. The reason of the different pattern might be that inorganic N in the lake appeared to be recycled to produce organic N due to within-lake processes.
L. Pinho, C. M. Duarte, H. Marotta, and A. Enrich-Prast
Biogeosciences, 13, 865–871, https://doi.org/10.5194/bg-13-865-2016, https://doi.org/10.5194/bg-13-865-2016, 2016
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Unlike the positive relationship reported before between partial pression of carbon dioxide and dissolved organic carbon for lake waters, we found no significant relationship in our low-latitude lakes, despite very broad ranges in both variables. The strength of this relationship declines with increasing water temperature, suggesting substantial differences in carbon cycling in warm lakes, which must be considered when upscaling limnetic carbon cycling to global scales.
S. G. Wakeham and E. A. Canuel
Biogeosciences, 13, 567–582, https://doi.org/10.5194/bg-13-567-2016, https://doi.org/10.5194/bg-13-567-2016, 2016
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Bed sediments from the Sacramento-San Joaquin River Delta (CA) were fractionated according to density and analyzed for sediment mass distribution, elemental (C and N) composition, mineral surface area, and stable carbon and radiocarbon isotope compositions of organic carbon (OC) and fatty acids to evaluate the nature of organic carbon in river sediments. These data demonstrate the complex source and age distributions within river sediments.
B. Burpee, J. E. Saros, R. M. Northington, and K. S. Simon
Biogeosciences, 13, 365–374, https://doi.org/10.5194/bg-13-365-2016, https://doi.org/10.5194/bg-13-365-2016, 2016
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This study investigates microbial nutrient limitation patterns across a region of southwest Greenland in relation to environmental factors. Using microbial enzyme activities to infer nutrient limitation patterns, we determined that most lakes are P-limited. Further, P limitation was tightly controlled by lake dissolved organic carbon (DOC) concentration.
A. Przytulska, J. Comte, S. Crevecoeur, C. Lovejoy, I. Laurion, and W. F. Vincent
Biogeosciences, 13, 13–26, https://doi.org/10.5194/bg-13-13-2016, https://doi.org/10.5194/bg-13-13-2016, 2016
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Permafrost thaw lakes are a subject of increasing research interest given their abundance across the northern landscape. Our aim in the present study was to characterize the photosynthetic communities in a range of subarctic thaw lakes using a combination of HPLC analysis of algal and bacterial pigments, flow cytometry and molecular analysis. Our results showed that the thaw lakes contain diverse phototrophic communities and are a previously unrecognized habitat for abundant picophotoautotrophs.
Cited articles
An, S., Zheng, F., Zhang, F., Van Pelt, S., Hamer, U., and Makeschin, F.: Soil quality degradation processes along a deforestation chronosequence in the Ziwuling area, China, CATENA, 75, 248–256, https://doi.org/10.1016/j.catena.2008.07.003, 2008.
Andrianandrasana, H. T., Randriamahefasoa, J., Durbin, J., Lewis, R. E., and Ratsimbazafy, J. H.: Participatory ecological monitoring of the Alaotra wetlands in Madagascar, Biodivers. Conserv., 14, 2757–2774, https://doi.org/10.1007/s10531-005-8413-y, 2005.
Aufdenkampe, A. K., Mayorga, E., Raymond, P. A., Melack, J. M., Doney, S. C., Alin, S. R., Aalto, R. E., and Yoo, K.: Riverine coupling of biogeochemical cycles between land, oceans, and atmosphere, Front. Ecol. Environ., 9, 53–60, https://doi.org/10.1890/100014, 2011.
Bade, D. L., Pace, M. L., Cole, J. J., and Carpenter, S. R.: Can algal photosynthetic inorganic carbon isotope fractionation be predicted in lakes using existing models?, Aquat. Sci., 68, 142–153, https://doi.org/10.1007/s00027-006-0818-5, 2006.
Bakoariniaina, L. N., Kusky, T., and Raharimahefa, T.: Disappearing Lake Alaotra: Monitoring catastrophic erosion, waterway silting, and land degradation hazards in Madagascar using Landsat imagery, J. African Earth Sci., 44, 241–252, https://doi.org/10.1016/j.jafrearsci.2005.10.013, 2006.
Borges, A. V, Darchambeau, F., Teodoru, C. R., Marwick, T. R., Tamooh, F., Geeraert, N., Omengo, F. O., Guérin, F., Lambert, T., Morana, C., Okuku, E., and Bouillon, S.: Globally significant greenhouse-gas emissions from African inland waters, Nat. Geosci., 8, 637–642, https://doi.org/10.1038/ngeo2486, 2015.
Borges, A. V., Darchambeau, F., Lambert, T., Morana, C., Allen, G. H., Tambwe, E., Toengaho Sembaito, A., Mambo, T., Nlandu Wabakhangazi, J., Descy, J.-P., Teodoru, C. R., and Bouillon, S.: Variations in dissolved greenhouse gases (CO2, CH4, N2O) in the Congo River network overwhelmingly driven by fluvial-wetland connectivity, Biogeosciences, 16, 3801–3834, https://doi.org/10.5194/bg-16-3801-2019, 2019.
Borges, A. V., Deirmendjian, L., Bouillon, S., Okello, W., Lambert, T., Roland, F. A. E., Razanamahandry, V. F., Voarintsoa, N. R. G., Darchambeau, F., Kimirei, I. A., Descy, J. P., Allen, G. H., and Morana, C.: Greenhouse gas emissions from African lakes are no longer a blind spot, Sci. Adv., 8, eabi8716, https://doi.org/10.1126/sciadv.abi8716, 2022.
Bouchez, J., Galy, V., Hilton, R. G., Gaillardet, J., Moreira-Turcq, P., Pérez, M. A., France-Lanord, C., and Maurice, L.: Source, transport and fluxes of Amazon River particulate organic carbon: Insights from river sediment depth-profiles, Geochim. Cosmochim. Ac., 133, 280–298, 2014.
Broothaerts, N., Razanamahandry, V. F., Brosens, L., Campforts, B., Jacobs, L., Razafimbelo, T., Rafolisy, T., Verstraeten, G., Bouillon, S., and Govers, G.: Vegetation changes and sediment dynamics in the Lake Alaotra region, central Madagascar, Holocene, 33, 459–470, https://doi.org/10.1177/09596836221145376, 2022.
Brosens, L., Broothaerts, N., Campforts, B., Jacobs, L., Razanamahandry, V. F., Van Moerbeke, Q., Bouillon, S., Razafimbelo, T., Rafolisy, T., and Govers, G.: Under pressure: Rapid lavaka erosion and floodplain sedimentation in central Madagascar, Sci. Total Environ., 806, 150483, https://doi.org/10.1016/j.scitotenv.2021.150483, 2022.
Burkhardt, S., Riebesell, U., and Zondervan, I.: Effect of growth rate, CO2 concentration, and cell size on the stable carbon isotope fractionation in marine phytoplankton, Geochim. Cosmochim. Ac., 63, 3729–3741, 1999.
Chaperon, P., Danloux, J., and Ferry, L.: Fleuves et rivières de Madagascar, Editions d., ORSTOM, Paris, 1993.
Chiriboga, G., Bouillon, S., and Borges, A. V.: Dissolved greenhouse gas (CO2, CH4, N2O) emissions from highland lakes of the Andes cordillera in Northern Ecuador, Aquat. Sci., 86, 1–24, https://doi.org/10.1007/s00027-023-01039-6, 2024.
Cifuentes, L. A., Sharp, J. H., and Fogel, M. L.: Stable carbon and nitrogen isotope biogeochemistry in the Delaware estuary, Limnol. Oceanogr., 33, 1102–1115, https://doi.org/10.4319/lo.1988.33.5.1102, 1988.
Cole, J. J., Caraco, N. F., Kling, G. W., and Kratz, T. K.: Carbon dioxide supersaturation in the surface waters of lakes, Science, 265, 1568–1570, https://doi.org/10.1126/science.265.5178.1568, 1994.
Cole, J. J., Prairie, Y. T., Caraco, N. F., McDowell, W. H., Tranvik, L. J., Striegl, R. G., Duarte, C. M., Kortelainen, P., Downing, J. A., Middelburg, J. J., and Melack, J.: Plumbing the global carbon cycle: Integrating inland waters into the terrestrial carbon budget, Ecosystems, 10, 171–184, https://doi.org/10.1007/s10021-006-9013-8, 2007.
Copsey, J., Rajaonarison, L., Randriamihamina, R., and Rakotoniaina, L.: Voices from the marsh: Livelihood concerns of fishers and rice cultivators in the Alaotra wetland, Madagascar Conserv. Dev., 4, 25–30, https://doi.org/10.4314/mcd.v4i1.44008, 2009.
Cox, R., Bierman, P., Jungers, M. C., and Rakotondrazafy, A. F. M.: Erosion Rates and Sediment Sources in Madagascar Inferred from 10Be Analysis of Lavaka, Slope, and River Sediment, J. Geol., 117, 363–376, https://doi.org/10.1086/598945, 2009.
Cox, R., Zentner, D. B., Rakotondrazafy, A. F. M., and Rasoazanamparany, C. F.: Shakedown in Madagascar: Occurrence of lavakas (erosional gullies) associated with seismic activity, Geology, 38, 179–182, https://doi.org/10.1130/G30670.1, 2010.
Cox, R., Carrère, A., Rakotondrazafy, A. F. M., and Voarintsoa, N. R.: Lavaka (erosional gullies) provide productive patch environments for flora and farming in Madagascar's grassy highlands, Plants People Planet, 6 287–303, https://doi.org/10.1002/ppp3.10440, 2023.
CREAM (Centre de recherche, d'études et d'appui à l'analayse economique à Madagascar): Monographie – Région Alaotra Mangoro, 1–233, 2013.
Cuevas-Lara, D., Alcocer, J., Cortés-Guzmán, D., Soria-Reinoso, I. F., García-Oliva, F., Sánchez-Carrillo, S., and Oseguera, L. A.: Particulate organic carbon in the tropical Usumacinta river, southeast Mexico: concentration, flux, and sources, Water, 13, 1561, https://doi.org/10.3390/w13111561, 2021.
Darchambeau, F., Sarmento, H., and Descy, J.-P.: Primary production in a tropical large lake: The role of phytoplankton composition, Sci. Total Environ., 473–474, 178–188, https://doi.org/10.1016/j.scitotenv.2013.12.036, 2014.
Dauchez, S., Legendre, L., and Fortier, L.: Assessment of simultaneous uptake of nitrogenous nutrients (15N) and inorganic carbon (13C) by natural phytoplankton populations, Mar. Biol., 123, 651–666, https://doi.org/10.1007/BF00349108, 1995.
Deirmendjian, L., Lambert, T., Morana, C., Bouillon, S., William, J. D., and Alberto, O.: Dissolved organic matter composition and reactivity in Lake Victoria, the world's largest tropical lake, Biogeochemistry, 150, 61–83, https://doi.org/10.1007/s10533-020-00687-2, 2020.
de Kluijver, A., Schoon, P. L., Downing, J. A., Schouten, S., and Middelburg, J. J.: Stable carbon isotope biogeochemistry of lakes along a trophic gradient, Biogeosciences, 11, 6265–6276, https://doi.org/10.5194/bg-11-6265-2014, 2014.
Del Giorgio, P. A. and Peters, R. H.: Balance between Phytoplankton Production and Plankton Respiration in Lakes, Can. J. Fish. Aquat. Sci., 50, 282–289, https://doi.org/10.1139/f93-032, 1993.
Del Giorgio, P. A. and Peters, R. H.: Patterns in planktonic P:R ratios in lakes: Influence of lake trophy and dissolved organic carbon, Limnol. Oceanogr., 39, 772–787, https://doi.org/10.4319/lo.1994.39.4.0772, 1994.
Del Giorgio, P. A., Cole, J. J., Caraco, N. F., and Peters, R. H.: Linking planktonic biomass and metabolism to net gas fluxes in northern temperate lakes, Ecology, 80, 1422–1431, https://doi.org/10.2307/177085, 1999.
Dosseur, H. and Ibiza, D.: Etudes Hydrologiques sur l'Alaotra – Modélisation du bassin, ORSTOM, Paris, 1982.
Duarte, C. M. and Prairie, Y. T.: Prevalence of heterotrophy and atmospheric CO2 emissions from aquatic ecosystems, Ecosystems, 8, 862–870, https://doi.org/10.1007/s10021-005-0177-4, 2005.
Ferry, L., Mietton, M., Robison, L., and Erismann, J.: Alaotra Lake (Madagascar): past, present and future, Zeitschrift für Geomorphol., 53, 299–318, https://doi.org/10.1127/0372-8854/2009/0053-0299, 2009.
Ferry, L., Mietton, M., Touchart, L., and Hamerlynck, O.: Lake Alaotra (Madagascar) is not about to disappear. Hydrological and sediment dynamics of an environmentally and socio-economically vital wetland, Dynamiques environnementales-Journal Int. des Geosci. l'environnement, 32, 105–122, 2013.
Gawade, L., Krishna, M. S., Sarma, V. V. S. S., Hemalatha, K. P. J., and Venkateshwara Rao, Y.: Spatio-temporal variability in the sources of particulate organic carbon and nitrogen in a tropical Godavari estuary, Estuar. Coast. Shelf Sci., 215, 20–29, https://doi.org/10.1016/j.ecss.2018.10.004, 2018.
Geeraert, N., Omengo, F. O., Govers, G., and Bouillon, S.: Dissolved organic carbon lability and stable isotope shifts during microbial decomposition in a tropical river system, Biogeosciences, 13, 517–525, https://doi.org/10.5194/bg-13-517-2016, 2016.
Gillikin, D. P. and Bouillon, S.: Determination of δ18O of water and δ13C of dissolved inorganic carbon using a simple modification of an elemental analyser-isotope ratio mass spectrometer: an evaluation, Rapid Commun. Mass Spectrom., 21, 1475–1478, https://doi.org/10.1002/rcm.2968, 2007.
Gran, G.: Determination of the equivalence point in potentiometric titrations of seawater with hydrochloric acid, Oceanol. Acta, 5, 209–218, 1952.
Hanson, P. C., Hamilton, D. P., Stanley, E. H., Preston, N., Langman, O. C., and Kara, E. L.: Fate of Allochthonous Dissolved Organic Carbon in Lakes: A Quantitative Approach, edited by: Evens, T., PLOS One, 6, 1–12, https://doi.org/10.1371/journal.pone.0021884, 2011.
Jacoby, H. G. and Minten, B.: Is land titling in Sub-Saharan Africa cost-effective? Evidence from Madagascar, World Bank Econ. Rev., 21, 461–485, https://doi.org/10.1093/wber/lhm011, 2007.
Jenkins, A. P., Jupiter, S. D., Qauqau, I., and Atherton, J.: The importance of ecosystem-based management for conserving aquatic migratory pathways on tropical high islands: a case study from Fiji, Aquat. Conserv. Mar. Freshw. Ecosyst., 20, 224–238, https://doi.org/10.1002/aqc.1086, 2010.
Johnson, M. S., Matthews, E., Du, J., Genovese, V., and Bastviken, D., Methane emission from global lakes: new spatiotemporal data and observation-driven modeling of methane dynamics indicates lower emissions, J. Geophys. Res.-Biogeo., 127, e2022JG006793, https://doi.org/10.1029/2022JG006793, 2022.
Kirk, J. T. O.: Light and photosynthesis in aquatic ecosystems, Cambridge University Press, New York, 1994.
Kull, C. A.: Madagascar's Burning Issue: The Persistent Conflict over Fire, Environ. Sci. Policy Sustain. Dev., 44, 8–19, https://doi.org/10.1080/00139150209605604, 2002.
Lammers, J. M., Reichart, G. J., and Middelburg, J. J.: Seasonal variability in phytoplankton stable carbon isotope ratios and bacterial carbon sources in a shallow Dutch lake, Limnol. Oceanogr., 62, 2773–2787, https://doi.org/10.1002/lno.10605, 2017a.
Lammers, P. L., Richter, T., Waeber, P. O., and Mantilla-Contreras, J.: Lake Alaotra wetlands: how long can Madagascar's most important rice and fish production region withstand the anthropogenic pressure?, Madagascar Conserv. Dev., 10, 116–127, https://doi.org/10.4314/mcd.v10i3.4, 2015.
Lammers, P. L., Richter, T., Lux, M., Ratsimbazafy, J., and Mantilla-Contreras, J.: The challenges of community-based conservation in developing countries – A case study from Lake Alaotra, Madagascar, J. Nat. Conserv., 40, 100–112, https://doi.org/10.1016/j.jnc.2017.08.003, 2017b.
Lauster, G. H., Hanson, P. C., and Kratz, T. K.: Gross primary production and respiration differences among littoral and pelagic habitats in northern Wisconsin lakes, Can. J. Fish. Aquat. Sci., 63, 1130–1141, https://doi.org/10.1139/f06-018, 2006.
Legendre, L. and Gosselin, M.: Estimation of N or C uptake rates by phytoplankton using 15N or 13C: revisiting the usual computation formulae, J. Plankton Res., 19, 263–271, https://doi.org/10.1093/plankt/19.2.263, 1997.
Lewis, E. and Wallace, D.: Program developed for CO2 system calculations, Environmental System Science Data Infrastructure for a Virtual Ecosystem (ESS-DIVE), United States, 1998.
Lewis, W. M.: Biogeochemistry of tropical lakes, SIL Proceedings, 1922–2010, 30, 1595–1603, https://doi.org/10.1080/03680770.2009.11902383, 2010.
López-Sandoval, D. C., Rodríguez-Ramos, T., Cermeño, P., Sobrino, C., and Marañón, E.: Photosynthesis and respiration in marine phytoplankton: Relationship with cell size, taxonomic affiliation, and growth phase, J. Exp. Mar. Bio. Ecol., 457, 151–159, https://doi.org/10.1016/j.jembe.2014.04.013, 2014.
Marwick, T. R., Borges, A. V., Van Acker, K., Darchambeau, F., and Bouillon, S.: Disproportionate contribution of riparian inputs to organic carbon pools in freshwater systems, Ecosystems, 17, 974–989, https://doi.org/10.1007/s10021-014-9772-6, 2014.
McClain, M. E., Boyer, E. W., Dent, C. L., Gergel, S. E., Grimm, N. B., Groffman, P. M., Hart, S. C., Harvey, J. W., Johnston, C. A., Mayorga, E., McDowell, W. H., and Pinay, G.: Hot spots and hot moments at the interface of terrestrial and aquatic ecosystems, Ecosystems, 6, 301–312, 2003.
Mietton, M., Gunnell, Y., Nicoud, G., Ferry, L., Razafimahefa, R., and Grandjean, P.: Lake Alaotra, Madagascar: A late Quaternary wetland regulated by the tectonic regime, CATENA, 165, 22–41, https://doi.org/10.1016/j.catena.2018.01.021, 2018.
Montgomery, D. R.: Soil erosion and agricultural sustainability, P. Natl. Acad. Sci. USA, 104, 13268–13272, https://doi.org/10.1073/pnas.0611508104, 2007.
Morana, C., Sarmento, H., Descy, J. P., Gasol, J. M., Borges, A. V., Bouillon, S., and Darchambeau, F.: Production of dissolved organic matter by phytoplankton and its uptake by heterotrophic prokaryotes in large tropical lakes, Limnol. Oceanogr., 59, 1364–1375, https://doi.org/10.4319/lo.2014.59.4.1364, 2014.
Morana, C., Darchambeau, F., Roland, F. A. E., Borges, A. V., Muvundja, F., Kelemen, Z., Masilya, P., Descy, J.-P., and Bouillon, S.: Biogeochemistry of a large and deep tropical lake (Lake Kivu, East Africa: insights from a stable isotope study covering an annual cycle, Biogeosciences, 12, 4953–4963, https://doi.org/10.5194/bg-12-4953-2015, 2015.
Morana, C., Borges, A. V., Deirmendjian, L., Okello, W., Sarmento, H., Descy, J.-P., Kimerei, I. A., and Bouillon, S.: Prevalence of autotrophy in African tropical lakes, Ecosystems, 26, 627–642, https://doi.org/10.1007/s10021-022-00783-4, 2022.
Moreau, J.: Le Lac Alaotra à Madagascar: cinquante ans d'aménagement des pêches, OROSTOM, hydrobiol., XIII, 171–179, 1980.
Pattanayak, S. K. and Wendland, K. J.: Nature's care: diarrhea, watershed protection, and biodiversity conservation in Flores, Indonesia, Biodivers. Conserv., 16, 2801–2819, https://doi.org/10.1007/s10531-007-9215-1, 2007.
Penot, E., Rakotoarimanana, A., and Scopel, E.: Conservation agriculture adoption and local farmers' strategies in Lake Alaotra, Madagascar, 3rd International Conference on Conservation Agriculture in Southeast Asia, 10–15 December 2012, Hanoi, Vietnam, 2012.
Penot, E., Fevre, V., Flodrops, P., and Razafimahatratra, H. M.: Conservation Agriculture to buffer and alleviate the impact of climatic variations in Madagascar: farmers' perception, Cah. Agric., 27, 25003, https://doi.org/10.1051/cagri/2018009, 2018.
Peterson, B. J. and Fry, B.: Stable isotopes in ecosystem studies., Annu. Rev. Ecol. Syst., 18, 293–320, https://doi.org/10.1146/annurev.es.18.110187.001453, 1987.
Ralison, O. H., Borges, A. V., Dehairs, F., Middelburg, J. J., and Bouillon, S.: Carbon biogeochemistry of the Betsiboka estuary (north-western Madagascar), Org. Geochem., 39, 1649–1658, https://doi.org/10.1016/j.orggeochem.2008.01.010, 2008.
Ranarijaona, H.: Concept de Modèle Ecologique pour la Zone Humide Alaotra, Madagascar Conserv. Dev., 2, 2016–2020, https://doi.org/10.4314/mcd.v2i1.44128, 2009.
Razanamahandry, V. F., Dewaele, M., Govers, G., Brosens, L., Campforts, B., Jacobs, L., Razafimbelo, T., Rafolisy, T., and Bouillon, S.: Stable isotope profiles of soil organic carbon in forested and grassland landscapes in the Lake Alaotra basin (Madagascar): insights in past vegetation changes, Biogeosciences, 19, 3825–3841, https://doi.org/10.5194/bg-19-3825-2022, 2022.
Repasch, M., Scheingross, J. S., Hovius, N., Vieth-Hillebrandt, A., Mueller, C. W., Höschen, C., Szupiany, R. N., and Sachse, D.: River organic carbon fluxes modulated by hydrodynamic sorting of particulate organic matter, Geophys. Res. Lett., 49, e2021GL096343, https://doi.org/10.1029/2021GL096343, 2022.
Reynolds, C. S.: The Ecology of Phytoplankton, Cambridge University Press, Cambridge, https://doi.org/10.1017/CBO9780511542145, 2006.
Richey, J., Melack, J., Aufdenkampe, A., Ballester, V., and Hess, L.: Outgassing from Amazonian rivers and wetlands as a large tropical source of atmospheric CO2, Nature, 416, 617–620, https://doi.org/10.1038/416617a, 2002.
Richey, J. E., Spencer, R. G. M., Drake, T. W., and Ward, N. D.: Fluvial Carbon Dynamics across the Land to Ocean Continuum of Great Tropical Rivers: The Amazon and Congo, in: Congo Basin Hydrology, Climate, and Biogeochemistry: A Foundation for the Future, edited by: Tshimanga, R. M., Moukandi N'kaya, G. D., and Alsdorf, D., Geophysical Monograph Series, Wiley, 391–412, https://doi.org/10.1002/9781119657002.ch20, 2022.
Sobek, S., Söderbäck, B., Karlsson, S., Andersson, E., and Brunberg, A. K.: A carbon budget of a small humic lake: An example of the importance of lakes for organic matter cycling in boreal catchments, Ambio, 35, 469–475, https://doi.org/10.1579/0044-7447(2006)35[469:ACBOAS]2.0.CO;2, 2006.
Staehr, P. A., Baastrup-Spohr, L., Sand-Jensen, K., and Stedmon, C.: Lake metabolism scales with lake morphometry and catchment conditions, Aquat. Sci., 74, 155–169, https://doi.org/10.1007/s00027-011-0207-6, 2012.
Teodoru, C. R., Nyoni, F. C., Borges, A. V., Darchambeau, F., Nyambe, I., and Bouillon, S.: Dynamics of greenhouse gases (CO2, CH4, N2O) along the Zambezi River and major tributaries, and their importance in the riverine carbon budget, Biogeosciences, 12, 2431–2453, https://doi.org/10.5194/bg-12-2431-2015, 2015.
Toming, K., Kotta, J., Uuemaa, E., Sobek, S., Kutser, T., and Tranvik, L. J.: Predicting lake dissolved organic carbon at a global scale, Sci. Rep., 10, 8471, https://doi.org/10.1038/s41598-020-65010-3, 2020.
Tranvik, L. J., Downing, J. A., Cotner, J. B., Loiselle, S. A., Striegl, R. G., Ballatore, T. J., Dillon, P., Finlay, K., Fortino, K., Knoll, L. B., Kortelainen, P. L., Kutser, T., Larsen, S., Laurion, I., Leech, D. M., Leigh McCallister, S., McKnight, D. M., Melack, J. M., Overholt, E., Porter, J. A., Prairie, Y., Renwick, W. H., Roland, F., Sherman, B. S., Schindler, D. W., Sobek, S., Tremblay, A., Vanni, M. J., Verschoor, A. M., Von Wachenfeldt, E., and Weyhenmeyer, G. A.: Lakes and reservoirs as regulators of carbon cycling and climate, Limnol. Oceanogr., 54, 2298–2314, https://doi.org/10.4319/lo.2009.54.6_part_2.2298, 2009.
Tranvik, L. J., Cole, J. J., and Prairie, Y. T.: The study of carbon in inland waters – from isolated ecosystems to players in the global carbon cycle, Limnol. Oceanogr. Lett., 3, 41–48, https://doi.org/10.1002/lol2.10068, 2018.
Vollenweider, R. A.: Calculation models of photosynthesis-depth curves and some implications regarding day rate estimates in primary production measurements, in: Primary Productivity in Aquatic Environments, edited by: Goldman, C. R., 425–458, University of California Press, 1966.
Weiss, R. F.: Determinations of carbon dioxide and methane by dual catalyst flame ionization chromatography and nitrous oxide by electron capture chromatography, J. Chromatogr. Sci., 19, 611–616, https://doi.org/10.1093/chromsci/19.12.611, 1981.
Wetzel, R. G.: Dissolved organic carbon: detrital energetics, metabolic regulators, and drivers of ecosystem stability of aquatic ecosystems, 455–477, in: Aquatic ecosystems, interactivity of organic matter, edited by: Findlay, S. E. G. and Sinsabaugh, R. L., Academic Press, https://doi.org/10.1016/B978-012256371-3/50020-2, 2003.
Wright, S., Jeffrey, S., Mantoura, R., Llewellyn, C., Bjornland, T., Repeta, D., and Welschmeyer, N.: Improved HPLC method for the analysis of chlorophylls and carotenoids from marine phytoplankton, Mar. Ecol. Prog. Ser., 77, 183–196, https://doi.org/10.3354/meps077183, 1991.
Zheng, F., He, X., Gao, X., Zhang, C.-E., and Tang, K.: Effects of erosion patterns on nutrient loss following deforestation on the Loess Plateau of China, Agric. Ecosyst. Environ., 108, 85–97, https://doi.org/10.1016/j.agee.2004.12.009, 2005.
Short summary
A comprehensive survey of the biogeochemistry of the Lake Alaotra system showed that the lake and surrounding wetlands acted as a substantial source of new organic carbon (OC), which was exported downstream. Marsh vegetation was the main source of dissolved OC, while phytoplankton contributed to the particulate OC pool. The biogeochemical functioning of Lake Alaotra differs from most East African lakes studied, likely due to its large surface area, shallow water depth, and surrounding wetlands.
A comprehensive survey of the biogeochemistry of the Lake Alaotra system showed that the lake...
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