Prevalence of Heterotrophy and Atmospheric CO2 Emissions from Aquatic Ecosystems

Duarte, Carlos M.; Prairie, Yves T.

doi:10.1007/s10021-005-0177-4

Cited by 339 publications

(281 citation statements)

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“…It is widely accepted that lakes are typically supersaturated with CO 2 relative to the overlying atmosphere (Kling et al, 1991;Cole et al, 1994;Duarte and Prairie, 2005). This net heterotrophic condition is believed to predominate as ecosystem respiration frequently exceeds ecosystem primary production in lakes due to the input of allochthonous organic matter from their catchments (Del Giorgio et al, 1999;Pace et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Diurnal sampling reveals significant variation in CO2 emission from a tropical productive lake

Reis

Barbosa

2014

Braz. J. Biol.

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It is well accepted in the literature that lakes are generally net heterotrophic and supersaturated with CO 2 because they receive allochthonous carbon inputs. However, autotrophy and CO 2 undersaturation may happen for at least part of the time, especially in productive lakes. Since diurnal scale is particularly important to tropical lakes dynamics, we evaluated diurnal changes in pCO 2 and CO 2 flux across the air-water interface in a tropical productive lake in southeastern Brazil (Lake Carioca) over two consecutive days. Both pCO 2 and CO 2 flux were significantly different between day (9:00 to 17:00) and night (21:00 to 5:00) confirming the importance of this scale for CO 2 dynamics in tropical lakes. Net heterotrophy and CO 2 outgassing from the lake were registered only at night, while significant CO 2 emission did not happen during the day. Dissolved oxygen concentration and temperature trends over the diurnal cycle indicated the dependence of CO 2 dynamics on lake metabolism (respiration and photosynthesis). This study indicates the importance of considering the diurnal scale when examining CO 2 emissions from tropical lakes.Keywords: pCO 2 , CO 2 flux, diurnal variations, tropical productive lake.Amostragem diurna demonstra variação significativa na emissão de CO 2 em um lago tropical produtivo Resumo É amplamente aceito na literatura que lagos são em geral heterotróficos e supersaturados com CO 2 já que recebem carbono alóctone. Porém, autotrofia e insaturação de CO 2 podem ocorrer em pelo menos parte do tempo, especialmente em lagos produtivos. Como a escala diurna é particularmente importante para a dinâmica de lagos tropicais, variações diurnas na pCO 2 e no fluxo de CO 2 através da interface ar-água foram avaliadas num lago tropical produtivo do sudeste do Brasil (Lagoa Carioca) durante dois dias consecutivos. Tanto a pCO 2 quanto o fluxo de CO 2 foram significativamente diferentes entre o dia (9:00 às 17:00) e a noite (21:00 às 5:00), confirmando a influência desta escala na dinâmica do CO 2 na Lagoa Carioca. Foram registradas heterotrofia e emissão de CO 2 pela lagoa apenas durante a noite, enquanto durante o dia não houve emissão significativa. Variações na concentração de oxigênio dissolvido e na temperatura ao longo do dia indicaram a dependência da dinâmica do CO 2 no metabolismo (respiração e fotossíntese) deste lago. Este estudo indica a importância de se considerar a escala diurna na avaliação da emissão de CO 2 por lagos tropicais.Palavras-chave: pCO 2 , fluxo de CO 2 , variações diurnas, lago tropical produtivo.

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Section: Introductionmentioning

confidence: 99%

Diurnal sampling reveals significant variation in CO2 emission from a tropical productive lake

Reis

Barbosa

2014

Braz. J. Biol.

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“…Because organic C inputs can be co-equal or larger than aquatic GPP, respiration, export, or storage can also be significantly larger than aquatic GPP, a condition very rarely met on land (Polis and Power 2004). Lakes, for example, are commonly net sources of CO 2 to the atmosphere while simultaneously burying organic C in their sediments (Dillon and Molot 1997;Kortelainen and others 2004;Duarte and Prairie 2005;Pace and Prairie 2005;Rantakari and Kortelainen 2005;Sobek et al 2005). In lakes, R often exceeds GPP (that is, NEP is negative) because a portion of the organic C imported from land is respired (del Giorgio and Peters 1994;Prairie and others 2002).…”

Section: Formulating Integrated C Budgetsmentioning

confidence: 99%

Plumbing the Global Carbon Cycle: Integrating Inland Waters into the Terrestrial Carbon Budget

et al. 2007

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Because freshwater covers such a small fraction of the Earth's surface area, inland freshwater ecosystems (particularly lakes, rivers, and reservoirs) have rarely been considered as potentially important quantitative components of the carbon cycle at either global or regional scales. By taking published estimates of gas exchange, sediment accumulation, and carbon transport for a variety of aquatic systems, we have constructed a budget for the role of inland water ecosystems in the global carbon cycle. Our analysis conservatively estimates that inland waters annually receive, from a combination of background and anthropogenically altered sources, on the order of 1.9 Pg C y )1 from the terrestrial landscape, of which about 0.2 is buried in aquatic sediments, at least 0.8 (possibly much more) is returned to the atmosphere as gas exchange while the remaining 0.9 Pg y )1 is delivered to the oceans, roughly equally as inorganic and organic carbon. Thus, roughly twice as much C enters inland aquatic systems from land as is exported from land to the sea. Over prolonged time net carbon fluxes in aquatic systems tend to be greater per unit area than in much of the surrounding land. Although their area is small, these freshwater aquatic systems can affect regional C balances. Further, the inclusion of inland, freshwater ecosystems provides useful insight about the storage, oxidation and transport of terrestrial C, and may warrant a revision of how the modern net C sink on land is described.

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“…In terms of carbon cycling within a lake, supersaturation generally indicates net heterotrophy, where organic carbon from external sources (allochthonous) or from pools of stored carbon (i.e. sediment organic matter or DOC accumulated in the water column) is respired and released to the atmosphere at a greater rate than autochthonous carbon uptake and storage (Carpenter et al 2005;Cole et al 2000Cole et al , 2002del Giorgio and Peters 1993;Duarte and Prairie 2005;Lennon and Pfaff 2005). Undersaturation indicates net autotrophy where more autochthonously generated carbon is stored in the sediments, or water column, than is respired and released to the atmosphere (Flanagan et al 2006;Hanson et al 2004;Schindler et al 1997).…”

Section: Introductionmentioning

confidence: 99%

Experimental warming increases CO2 saturation in a shallow prairie pond

Flanagan¹,

McCauley

2010

Aquat Ecol

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There is an urgent need to understand the effect of climate warming on the carbon dynamics of lakes and ponds in order to assess contributions to global carbon budgets. Currently, we are unable to predict how the exchange of carbon gases (i.e. CO 2 ) across the air-water boundary and organic carbon storage in the sediments will be altered with realistic warming scenarios downscaled from climatic models. Given the prevalence of shallow systems and tight atmospheric coupling, we conducted a mesocosm experiment to test the impacts of warming on CO 2 saturation in a shallow prairie pond. We outline and test three possible scenarios for the effect of warming on the CO 2 saturation of ponds, resulting in either an increase, decrease or no net effect for CO 2 saturation. We show that with approximately a two-degree (8C) increase in average water temperature, the pCO 2 of the warmed mesocosms was nine times greater than the ambient temperature mesocosms by the end of the 5-week experiment. Changes in water colour (a measure of dissolved organic carbon) in warmed systems indicate that decomposition of organic matter in the sediments and water column was the main contributor to the increase in pCO 2 in the warmed mesocosms. Our results show that with warming, the release of CO 2 from shallow ponds to the atmosphere will increase and carbon storage in the sediments will decrease, altering the current functioning of shallow prairie ponds and influencing the contribution of ponds to the global carbon cycle.

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Prevalence of Heterotrophy and Atmospheric CO2 Emissions from Aquatic Ecosystems

Cited by 339 publications

References 52 publications

Diurnal sampling reveals significant variation in CO2 emission from a tropical productive lake

Diurnal sampling reveals significant variation in CO2 emission from a tropical productive lake

Plumbing the Global Carbon Cycle: Integrating Inland Waters into the Terrestrial Carbon Budget

Experimental warming increases CO2 saturation in a shallow prairie pond

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