Drivers of metabolism and net heterotrophy in contrasting lakes

Stæhr, Peter A.; Sand‐Jensen, Kaj; Raun, Ane Løvendahl; Nilsson, Bertel; Kidmose, Jacob

doi:10.4319/lo.2009.55.2.0817

Cited by 46 publications

(35 citation statements)

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“…Even though tropical lakes have been pointed out to act as important CO 2 sources to the atmosphere (Marotta et al, 2009), our findings demonstrate the importance of meteorological variables driving limnological conditions. Consequently, shifts in aquatic metabolism along the year are found, as has been recorded in other subtropical (Carmouze et al, 1991;Thomaz et al, 2001) and temperate lakes (Staehr et al, 2010).…”

Section: Discussionmentioning

confidence: 54%

“…Variations in irradiance, temperature, and organic matter affect aquatic organisms and their metabolisms, driving the net ecosystem production and shifting between autotrophic and heterotrophic phases during the course of a day or year (Staehr et al, 2010;Marotta et al, 2010). However, the intensity of these metabolic processes can vary between temperate and tropical/ subtropical lakes (Amado et al, 2013), both daily and seasonally, since temperature and light are highly variable in boreal and temperate regions compared to tropical areas (Barbosa, 1997).…”

Section: Introductionmentioning

confidence: 99%

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Determining the high variability of pCO2 and pO2 in the littoral zone of a subtropical coastal lake

2014

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Abstract:The aquatic metabolism comprises production and mineralization of organic matter through biological processes, such as primary production and respiration that can be estimated by gases concentration in the water column. Aim: The study aimed to assess the temporal variability of pCO 2 and pO 2 in the littoral zone of a subtropical coastal lake. Our hypotheses are i) high variability in meteorological conditions, such as temperature and light, drive the high variability in pCO 2 and pO 2 , and ii) the lake is permanently heterotrophic due to the low phosphorus concentration. Methods: We estimated pCO 2 from pH-alkalinity method, and pO 2 from dissolved oxygen concentration and water temperature measured in free-water during 24 hours in the autumn, winter, spring and summer. Results: Our findings showed that limnological variables had low temporal variability, while the meteorological variables and pCO 2 presented a high coefficient of variation, which is representative of each climatic season. In autumn and winter, it was recorded that the lake was supersaturated in CO 2 relative to the atmosphere, while in spring and summer CO 2 concentration was below the concentration found in the atmosphere. Over 24 hours, pCO 2 also showed high variability, with autumn presenting higher concentration during the night when compared to daytime. Water temperature and chlorophyll a were negatively correlated with pCO 2 , while pO 2 was positively correlated with wind and light. Conclusion: Agreeing with our first hypothesis, pCO 2 showed an expressive temporal variation in a subtropical lake associated to the high variability in meteorological conditions. On the other hand, our second hypothesis was not confirmed, since Peri Lake exported CO 2 to the atmosphere in some periods and in others, CO 2 was removed from the atmosphere.Keywords: subtropical, temporal variation, aquatic metabolism, meteorological conditions, seasonality.Resumo: O metabolismo aquático envolve os processos de produção e mineralização da matéria orgânica através de processos biológicos, tais como produção primária e respiração, que podem ser estimados através da concentração de gases na coluna d'água. Objetivo: O objetivo do presente estudo foi determinar a variabilidade temporal da pCO 2 e da pO 2 na zona litorânea de uma lagoa costeira subtropical, tendo como hipótese que i) a alta variabilidade nas condições meteorológicas, tais como temperatura e luz, direcionam a elevada variabilidade na pCO 2 e pO 2 e que ii) o ambiente é permanentemente heterotrófico devido à baixa concentração de fósforo. Métodos: Nós estimamos a pCO 2 através do método pH-alcalinidade, e a pO 2 a partir da concentração de oxigênio dissolvido e temperatura da água, medidos em água livre, durante 24 horas, no outono, inverno, primavera e verão. Resultados: Nossos resultados mostraram que as variáveis limnológicas amostradas apresentaram baixa variabilidade temporal, porém as variáveis meteorológicas e a pCO 2 apresentaram elevado coeficiente de variação, refletindo a variação...

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Section: Discussionmentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Determining the high variability of pCO2 and pO2 in the littoral zone of a subtropical coastal lake

2014

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“…Ecosystem metabolism, the biological assimilation and release of carbon, is central to the function of aquatic ecosystems (Hanson et al ; Staehr et al , b ). Photosynthesis stores light energy in the form of organic compounds, and gross carbon assimilation (known as gross primary production or GPP) provides metabolic energy and structural material to primary producers, higher trophic levels, and detrital food webs (Del Giorgio et al ; Carpenter et al ; Chapin et al ).…”

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confidence: 99%

Time‐varying responses of lake metabolism to light and temperature

Phillips

2019

Limnology & Oceanography

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Light is a primary driver of lake ecosystem metabolism, and the dependence of primary production on light is often quantified as a photosynthesis‐irradiance or “P‐I” curve. The parameters of the P‐I curve (e.g., the maximum primary production when light is in excess) can change through time due to a variety of biological factors (e.g., changes in biomass or community composition), which themselves are subject to external drivers (e.g., herbivory or nutrient availability). However, the relative contribution of variation in the P‐I curve to overall ecosystem metabolism is largely unknown. I developed a statistical model of ecosystem metabolism with time‐varying parameters governing the P‐I curve, while also accounting for the influence of temperature. I parameterized the model with dissolved oxygen time series spanning six summers from Lake Mývatn, a shallow eutrophic lake in northern Iceland with large temporal variability in ecosystem metabolism. All of the estimated parameters of the P‐I curve varied substantially through time. The sensitivity of primary production to light under light‐limiting conditions was particularly variable (>15‐fold) and had a compensatory relationship with ambient light levels. However, the 3.5‐fold variation in the maximum potential primary production made the largest contribution to variation in ecosystem metabolism, accounting for around 90% of the variance in net ecosystem production. Much of the variation in maximum primary production was attributable to cyanobacterial blooms, which occur in some but not all years in Mývatn. Overall, these results illustrate how changes in the P‐I curve contribute substantially to temporal variation in lake ecosystem metabolism.

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“…Given that Lake Kariba acts as an efficient trap for allochthonous particles and OC, we hypothesized that it is a net heterotrophic system [ Staehr et al , 2010; Tranvik et al , 2009], i.e., that respiration exceeds gross primary production, and as a result water column concentrations of OC mineralization products, CO 2 and CH 4 , accumulate beyond saturated levels [ Sobek et al , 2005]. Net heterotrophic systems are net sources of CO 2 (and potentially CH 4 ) to the atmosphere [ Cole et al , 1994].…”

Section: Discussionmentioning

confidence: 99%

Sediment accumulation and carbon, nitrogen, and phosphorus deposition in the large tropical reservoir Lake Kariba (Zambia/Zimbabwe)

et al. 2011

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[1] Large dams affect the aquatic continuum from land to ocean by accumulating particles and nutrients in their reservoirs. We examined sediment cores to quantify sediment, organic carbon (OC), nitrogen (N), and phosphorous (P) accumulation, and to examine historic changes and spatial variability in the sedimentation pattern in Lake Kariba, the largest hydropower reservoir in the Zambezi River Basin (ZRB). Sediment characteristics (concentrations of OC, N, P; d 13 C and d 15 N; wet bulk density) showed large variability both with sediment depth and between cores. While organic matter (OM) in river deltas was primarily allochthonous in origin, OM characteristics (d 13 C, C:N) in lacustrine sediments suggest that autochthonous sources account for >45% of the OM that accumulates over large areas of the lake. At the same time, the relative contribution of allochthonous material within individual layers of lacustrine cores varied considerably with depth due to discrete flood deposits. The overall sediment accumulation rate in Lake Kariba is on the order of 4 × 10 6 t yr −1 , and the estimated OC accumulation of 120 × 10 3 t C yr −1 accounts for ∼1‰ of globally buried OC in reservoirs. In addition, mass balance calculations revealed that approximately 70% and 90% of incoming total N and P, respectively, are eliminated from the water column by sedimentation (N, P) and denitrification (N). Since Lake Kariba attenuates flow from ∼50% of the ZRB, these OC, N, and P removals represent a drastic reduction in nutrient loadings to downstream riparian ecosystems and to the coastal Indian Ocean.

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Drivers of metabolism and net heterotrophy in contrasting lakes

Cited by 46 publications

References 0 publications

Determining the high variability of pCO2 and pO2 in the littoral zone of a subtropical coastal lake

Determining the high variability of pCO2 and pO2 in the littoral zone of a subtropical coastal lake

Time‐varying responses of lake metabolism to light and temperature

Sediment accumulation and carbon, nitrogen, and phosphorus deposition in the large tropical reservoir Lake Kariba (Zambia/Zimbabwe)

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