The Importance of Allochthonous Particulate Carbon Pathways in a Subalpine Lake

1977 ◽  
Vol 34 (9) ◽  
pp. 1410-1418 ◽  
Author(s):  
R. C. Wissmar ◽  
J. E. Richey ◽  
D. E. Spyridakis
Keyword(s):  
Carbon Budget ◽  
Particulate Carbon ◽  
Allochthonous Inputs ◽  
Allochthonous Carbon ◽  
Subalpine Lake ◽  
Lake Washington ◽  
Autochthonous Production ◽  
Carbon Losses ◽  
Zooplankton Production ◽  
Carbon Pathways

Particulate carbon pathways in subalpine Findley Lake, Washington, were examined to assess the dependence of invertebrate consumer production upon allochthonous and autochthonous carbon. Results suggest that allochthonous carbon provides a food base for insect production (6.5 kg C∙ha−1) and autochthonous production of carbon appears to maintain zooplankton production (5.0 kg C∙ha−1). Annual inputs of allochthonous carbon from snow, fluvial, and litterfall sources amounted to 75 kg C∙ha−1. Autochthonous production totaled 51 kg C∙ha−1. Most of the allochthonous inputs were lost through sedimentation (63 kg C∙ha−1) and fluvial output (15 kg C∙ha−1). In contrast, most of the autochthonous carbon losses through grazing and respiration were retained in the water column. Total allochthonous and autochthonous inputs were 126 kg C∙ha−1∙yr−1 and outputs were 114 kg C∙ha−1∙yr−1. A pelagic carbon budget did not balance by 12 kg C∙ha−1∙yr−1, a number well within the propagated variation of 26 and 21% for input and outputs, respectively. Key words: allochthonous, carbon, subalpine, lake

Carbon-13/Carbon-12 Variation in Subalpine Lake Aquatic Insects: Food Source Implications

1980 ◽  
Vol 37 (4) ◽  
pp. 742-746 ◽  
Author(s):  
Greg H. Rau
Keyword(s):  
Aquatic Insects ◽  
Carbon Sources ◽  
Aquatic Insect ◽  
Insect Emergence ◽  
Subalpine Lake ◽  
Adult Insect ◽  
Organic Carbon Sources ◽  
Lake Washington ◽  
Conifer Tree ◽  
Insect Biomass

Relative 13C concentrations were found to be significantly different among the three primary organic carbon sources for aquatic insect production within Findley Lake, Washington, USA. These three carbon sources were conifer tree detritus (mean δ18C = −27.3 per mil), periphyton (−34.6 per mil), and plankton (−45.9 per mil). Correspondingly, the δ18C of the adults of assumed autochthonous carbon feeders, Paraleptophlebia sp. (Ephemeroptera: Leptophlebiidae) and Chaoborus trivittatus (Diptera: Chaoboridae), well approximated the δ13C of periphyton and plankton, respectively. The remainder of the adult insect emergence, mostly Limnelphilidae and Chironomidae, exhibited δ13C values intermediate between the terrestrial and periphyton carbon. Approximately 38% of the 51 kg C of insect biomass annually emerging from this lake was conservatively estimated to originate from terrestrial plant sources.Key words: carbon-13, carbon pathways, lake, aquatic insects, feeding ecology, insect emergence, terrestrial detritus

scholarly journals Comparison of uncertainties in land-use change fluxes from bookkeeping model parameterization

2021 ◽  
Author(s):  
Ana Bastos ◽  
Kerstin Hartung ◽  
Tobias B. Nützel ◽  
Julia E. M. S. Nabel ◽  
Richard A. Houghton ◽  
...  
Keyword(s):  
Land Use ◽  
Carbon Budget ◽  
Management Practices ◽  
Multiple Sources ◽  
Global Carbon Budget ◽  
Model Parameterization ◽  
Natural Land ◽  
Spatio Temporal ◽  
Land Use And Management ◽  
Carbon Losses

Abstract. Fluxes from deforestation, changes in land-cover, land-use and management practices (FLUC for simplicity) contributed to circa 14 % of anthropogenic CO2 emissions in 2009–2018. Estimating FLUC accurately in space and in time remains, however, challenging, due to multiple sources of uncertainty in the calculation of these fluxes. This uncertainty, in turn, is propagated to global and regional carbon budget estimates, hindering the compilation of a consistent carbon budget and preventing us from constraining other terms, such as the natural land sink. Uncertainties in FLUC estimates arise from many different sources, including differences in model structure (e.g., process- based vs. bookkeeping) and model parameterization. Quantifying the uncertainties from each source requires controlled simulations to separate their effects. Here we analyze differences between the two bookkeeping models used regularly in the global carbon budget estimates since 2017: the model by Hansis et al. (Hansis et al., 2015) (BLUE) and that by Houghton and Nassikas (Houghton and Nassikas, 2017) (HN2017). The two models have a very similar structure and philosophy, but differ significantly both with respect to FLUC intensity and spatio-temporal variability. This is due to differences in the land-use forcing, but also in the model parameterization. We find that the larger emissions in BLUE compared to HN2017 are largely due to differences in C densities between natural and managed vegetation or primary and secondary vegetation, and higher allocation of cleared and harvested material to fast turnover pools in BLUE than in HN2017. Beside parameterization and the use of different forcing, other model assumptions cause differences, in particular that BLUE represents gross transitions which leads to overall higher carbon losses that are also more quickly realized than HN2017.

scholarly journals Stable carbon isotope biogeochemistry of lakes along a trophic gradient

2014 ◽  
Vol 11 (5) ◽  
pp. 6615-6646 ◽  
Author(s):  
A. de Kluijver ◽  
P. L. Schoon ◽  
J. A. Downing ◽  
S. Schouten ◽  
J. J. Middelburg
Keyword(s):  
Organic Carbon ◽  
Carbon Isotope ◽  
Phytoplankton Biomass ◽  
Stable Carbon Isotope ◽  
Carbon Isotope Ratio ◽  
Stable Carbon ◽  
Eutrophic Lakes ◽  
Organic C ◽  
Allochthonous Carbon ◽  
Autochthonous Production

Abstract. The stable carbon (C) isotope variability of dissolved inorganic and organic C (DIC and DOC), particulate organic carbon (POC), glucose and polar-lipid derived fatty acids (PLFA) were studied in a survey of 22 North American oligotrophic to eutrophic lakes. The δ13C of different PLFA were used as proxy for phytoplankton producers and bacterial consumers. Lake pCO2 was primarily determined by autochthonous production (phytoplankton biomass), especially in eutrophic lakes, and governed the δ13C of DIC. All organic-carbon pools showed larger isotopic variability in eutrophic lakes compared to oligo-mesotrophic lakes because of the high variability in δ13C at the base of the food web (both autochthonous and allochthonous carbon). Phytoplankton δ13C was negatively related to lake pCO2 over all lakes and positively related to phytoplankton biomass in eutrophic lakes, which was also reflected in a large range in photosynthetic isotope fractionation (ϵCO2-phyto, 8–25 ‰). The carbon isotope ratio of allochthonous carbon in oligo-mesotrophic lakes was rather constant, while it varied in eutrophic lakes because of maize cultivation in the watershed.

scholarly journals Carbon dynamics at the river-estuarine transition: a comparison among tributaries of Chesapeake Bay

2021 ◽  
Author(s):  
Paul Bukaveckas
Keyword(s):  
Mass Balance ◽  
Transport Processes ◽  
Phytoplankton Production ◽  
Organic C ◽  
Allochthonous Inputs ◽  
Net Flux ◽  
River Estuarine ◽  
Autochthonous Production ◽  
Internal Cycling

Abstract. Sources and transformation of C were quantified using mass balance and ecosystem metabolism data for the upper segments of the James, Pamunkey and Mattaponi Estuaries. The goal was to assess the role of external (river inputs & tidal exchange) vs. internal (metabolism) drivers in influencing the forms and fluxes of C. C forms and their response to river discharge differed among the estuaries based on their physiographic setting. The James, which receives the bulk of inputs from upland areas (Piedmont and Mountain), exhibited a higher ratio of inorganic to organic C, and larger inputs of POC. The Pamunkey and Mattaponi receive a greater proportion of inputs from lowland (Coastal Plain) areas, which were characterized by low DIC and POC, and elevated DOC. We anticipated that transport processes would dominate during colder months when discharge is elevated and metabolism is low, and that biological processes would predominate in summer, leading to attenuation of C through-puts via de-gassing of CO2. Contrary to expectations, highest retention of OC occurred during periods of high through-put, as elevated discharge resulted in greater loading and retention of POC. In summer, internal cycling of C via production and respiration was large in comparison to external forcing despite the large riverine influence in these upper estuarine segments. The estuaries were found to be net heterotrophic based on retention of OC, export of DIC, low GPP relative to ER, and a net flux of CO2 to the atmosphere. In the James, greater contributions from phytoplankton production resulted in a closer balance between GPP and ER, with autochthonous production exceeding allochthonous inputs. Combining the mass balance and metabolism data with bioenergetics provided a basis for estimating the proportion of C inputs utilized by the dominant metazoan. The findings suggest that invasive catfish utilize 15 % of total OM inputs and up to 40 % of allochthonous inputs to the James.

scholarly journals Stable carbon isotope biogeochemistry of lakes along a trophic gradient

2014 ◽  
Vol 11 (22) ◽  
pp. 6265-6276 ◽  
Author(s):  
A. de Kluijver ◽  
P. L. Schoon ◽  
J. A. Downing ◽  
S. Schouten ◽  
J. J. Middelburg
Keyword(s):  
Organic Carbon ◽  
Carbon Isotope ◽  
Phytoplankton Biomass ◽  
Stable Carbon Isotope ◽  
Carbon Isotope Ratio ◽  
Stable Carbon ◽  
Eutrophic Lakes ◽  
Organic C ◽  
Allochthonous Carbon ◽  
Autochthonous Production

Abstract. The stable carbon (C) isotope variability of dissolved inorganic and organic C (DIC and DOC), particulate organic carbon (POC), glucose and polar-lipid derived fatty acids (PLFAs) was studied in a survey of 22 North American oligotrophic to eutrophic lakes. The δ13C of different PLFAs were used as proxy for phytoplankton producers and bacterial consumers. Lake pCO2 was primarily determined by autochthonous production (phytoplankton biomass), especially in eutrophic lakes, and governed the δ13C of DIC. All organic-carbon pools showed overall higher isotopic variability in eutrophic lakes (n = 11) compared to oligo-mesotrophic lakes (n = 11) because of the high variability in δ13C at the base of the food web (both autochthonous and allochthonous carbon). Phytoplankton δ13C was negatively related to lake pCO2 over all lakes and positively related to phytoplankton biomass in eutrophic lakes, which was also reflected in a large range in photosynthetic isotope fractionation (ϵCO2-phyto, 8–25‰). The carbon isotope ratio of allochthonous carbon in oligo-mesotrophic lakes was rather constant, while it varied in eutrophic lakes because of maize cultivation in the watershed.

scholarly journals From sink to source: high inter-annual variability in the carbon budget of a Southern African wetland

2021 ◽  
Vol 380 (2215) ◽  
Author(s):  
Carole Helfter ◽  
Mangaliso Gondwe ◽  
Michael Murray-Hudson ◽  
Anastacia Makati ◽  
Ute Skiba
Keyword(s):  
Carbon Dioxide ◽  
Primary Productivity ◽  
Continuous Monitoring ◽  
Carbon Budget ◽  
Sharp Decrease ◽  
Okavango Delta ◽  
Vegetation Types ◽  
Effects Of Drought ◽  
The Individual ◽  
Carbon Losses

We report on three years of continuous monitoring of carbon dioxide (CO 2 ) and methane (CH 4 ) emissions in two contrasting wetland areas of the Okavango Delta, Botswana: a perennial swamp and a seasonal floodplain. The hydrographic zones of the Okavango Delta possess distinct attributes (e.g. vegetation zonation, hydrology) which dictate their respective greenhouse gas (GHG) temporal emission patterns and magnitude. The perennial swamp was a net source of carbon (expressed in CO 2 -eq units), while the seasonal swamp was a sink in 2018. Despite differences in vegetation types and lifecycles, the net CO 2 uptake was comparable at the two sites studied in 2018/2020 (−894.2 ± 127.4 g m −2  yr −1 at the perennial swamp, average of the 2018 and 2020 budgets, and −1024.5 ± 134.7 g m −2  yr −1 at the seasonal floodplain). The annual budgets of CH 4 were however a factor of three larger at the permanent swamp in 2018 compared to the seasonal floodplain. Both ecosystems were sensitive to drought, which switched these sinks of atmospheric CO 2 into sources in 2019. This phenomenon was particularly strong at the seasonal floodplain (net annual loss of CO 2 of 1572.4 ± 158.1 g m −2 ), due to a sharp decrease in gross primary productivity. Similarly, drought caused CH 4 emissions at the seasonal floodplain to decrease by a factor of 4 in 2019 compared to the previous year, but emissions from the perennial swamp were unaffected. Our study demonstrates that complex and divergent processes can coexist within the same landscape, and that meteorological anomalies can significantly perturb the balance of the individual terms of the GHG budget. Seasonal floodplains are particularly sensitive to drought, which exacerbate carbon losses to the atmosphere, and it is crucial to improve our understanding of the role played by such wetlands in order to better forecast how their emissions might evolve in a changing climate. Studying such hydro-ecosystems, particularly in the data-poor tropics, and how natural stressors such as drought affect them, can also inform on the potential impacts of man-made perturbations (e.g. construction of hydro-electric dams) and how these might be mitigated. Given the contrasting effects of drought on the CO 2 and CH 4 flux terms, it is crucial to evaluate an ecosystem's complete carbon budget instead of treating these GHGs in isolation. This article is part of a discussion meeting issue ‘Rising methane: is warming feeding warming? (part 2)’.

scholarly journals Phytoplankton, not allochthonous carbon, sustains herbivorous zooplankton production

2009 ◽  
Vol 106 (50) ◽  
pp. 21197-21201 ◽  
Author(s):  
Michael T. Brett ◽  
Martin J. Kainz ◽  
Sami J. Taipale ◽  
Hari Seshan
Keyword(s):  
Herbivorous Zooplankton ◽  
Allochthonous Carbon ◽  
Zooplankton Production

Small-Scale Variability of New Production and Particulate Fluxes in the Ocean

1987 ◽  
Vol 44 (1) ◽  
pp. 198-205 ◽  
Author(s):  
Alain F. Vézina ◽  
Trevor Platt
Keyword(s):  
Empirical Support ◽  
Euphotic Zone ◽  
Nonlinear Process ◽  
Small Scale ◽  
Particulate Carbon ◽  
Short Term ◽  
New Production ◽  
Plankton Biomass ◽  
External Sources ◽  
Carbon Losses

Particulate carbon losses from the surface waters of the ocean can be estimated from short-term ([Formula: see text]) determinations of the contribution of nitrate to total nitrogen uptake (f(t)), under the assumption that the nitrate flux represents the supply of N from external sources. We used numerical modeling of the euphotic food web to explore the relationship between short-term variability in f(t) and the long-term export normalized to production, [Formula: see text]. We found that modeling sedimentation as a nonlinear process was necessary to simulate variability in f(t). The resulting model generated nonlinear relationships of f(t) to Pt and f(t) to [NO3] that, to date, have only been empirically described. The shape of the f ratio curves depends on an exponent n that expresses a power law dependence of the sedimentation rate on the concentration of suspended material in the euphotic zone, for which there is increasing empirical support. Simulations of the model with a temporally variable NO3 supply show that particulate losses can amount to 30–40% of production in seasonal oligotrophic systems. The model suggests that [Formula: see text] in N-limited ocean provinces depends on the variance of the nutrient field and on the sensitivity of the loss rate to variations in the plankton biomass in the euphotic zone.

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