scholarly journals Element budgets in an Arctic mesocosm CO<sub>2</sub> perturbation study

2012 ◽  
Vol 9 (8) ◽  
pp. 11885-11924 ◽  
Author(s):  
J. Czerny ◽  
K. G. Schulz ◽  
T. Boxhammer ◽  
R. G. J. Bellerby ◽  
J. Büdenbender ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Ocean Acidification ◽  
Nutrient Dynamics ◽  
Temporal Dynamics ◽  
Nitrogen And Phosphorus ◽  
Nutrient Pools ◽  
Dissolved Organics ◽  
Elemental Stoichiometry ◽  
Element Budgets ◽  
Wall Growth

Abstract. Recent studies on the impacts of ocean acidification on pelagic communities have identified changes in carbon to nutrient dynamics with related shifts in elemental stoichiometry. In principle, mesocosm experiments provide the opportunity of determining the temporal dynamics of all relevant carbon and nutrient pools and, thus, calculating elemental budgets. In practice, attempts to budget mesocosm enclosures are often hampered by uncertainties in some of the measured pools and fluxes, in particular due to uncertainties in constraining air/sea gas exchange, particle sinking, and wall growth. In an Arctic mesocosm study on ocean acidification using KOSMOS (Kiel Off-Shore Mesocosms for future Ocean Simulation) all relevant element pools and fluxes of carbon, nitrogen and phosphorus were measured, using an improved experimental design intended to narrow down some of the mentioned uncertainties. Water column concentrations of particulate and dissolved organic and inorganic constituents were determined daily. New approaches for quantitative estimates of material sinking to the bottom of the mesocosms and gas exchange in 48 h temporal resolution, as well as estimates of wall growth were developed to close the gaps in element budgets. Future elevated pCO2 was found to enhance net autotrophic community carbon uptake in 2 of the 3 experimental phases but did not significantly affect particle elemental composition. Enhanced carbon consumption appears to result in accumulation of dissolved organic compounds under nutrient recycling summer conditions. This carbon over-consumption effect becomes evident from budget calculations, but was too small to be resolved by direct measurements of dissolved organics. The out-competing of large diatoms by comparatively small algae in nutrient uptake caused reduced production rates under future ocean CO2 conditions in the end of the experiment. This CO2 induced shift away from diatoms towards smaller phytoplankton and enhanced cycling of dissolved organics was pushing the system towards a retention type food chain with overall negative effects on export potential.

scholarly journals Implications of elevated CO<sub>2</sub> on pelagic carbon fluxes in an Arctic mesocosm study – an elemental mass balance approach

2013 ◽  
Vol 10 (5) ◽  
pp. 3109-3125 ◽  
Author(s):  
J. Czerny ◽  
K. G. Schulz ◽  
T. Boxhammer ◽  
R. G. J. Bellerby ◽  
J. Büdenbender ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Ocean Acidification ◽  
Mass Balance ◽  
Nutrient Dynamics ◽  
Temporal Dynamics ◽  
Elemental Stoichiometry ◽  
Wall Growth

Abstract. Recent studies on the impacts of ocean acidification on pelagic communities have identified changes in carbon to nutrient dynamics with related shifts in elemental stoichiometry. In principle, mesocosm experiments provide the opportunity of determining temporal dynamics of all relevant carbon and nutrient pools and, thus, calculating elemental budgets. In practice, attempts to budget mesocosm enclosures are often hampered by uncertainties in some of the measured pools and fluxes, in particular due to uncertainties in constraining air–sea gas exchange, particle sinking, and wall growth. In an Arctic mesocosm study on ocean acidification applying KOSMOS (Kiel Off-Shore Mesocosms for future Ocean Simulation), all relevant element pools and fluxes of carbon, nitrogen and phosphorus were measured, using an improved experimental design intended to narrow down the mentioned uncertainties. Water-column concentrations of particulate and dissolved organic and inorganic matter were determined daily. New approaches for quantitative estimates of material sinking to the bottom of the mesocosms and gas exchange in 48 h temporal resolution as well as estimates of wall growth were developed to close the gaps in element budgets. However, losses elements from the budgets into a sum of insufficiently determined pools were detected, and are principally unavoidable in mesocosm investigation. The comparison of variability patterns of all single measured datasets revealed analytic precision to be the main issue in determination of budgets. Uncertainties in dissolved organic carbon (DOC), nitrogen (DON) and particulate organic phosphorus (POP) were much higher than the summed error in determination of the same elements in all other pools. With estimates provided for all other major elemental pools, mass balance calculations could be used to infer the temporal development of DOC, DON and POP pools. Future elevated pCO2 was found to enhance net autotrophic community carbon uptake in two of the three experimental phases but did not significantly affect particle elemental composition. Enhanced carbon consumption appears to result in accumulation of dissolved organic carbon under nutrient-recycling summer conditions. This carbon over-consumption effect becomes evident from mass balance calculations, but was too small to be resolved by direct measurements of dissolved organic matter. Faster nutrient uptake by comparatively small algae at high CO2 after nutrient addition resulted in reduced production rates under future ocean CO2 conditions at the end of the experiment. This CO2 mediated shift towards smaller phytoplankton and enhanced cycling of dissolved matter restricted the development of larger phytoplankton, thus pushing the system towards a retention type food chain with overall negative effects on export potential.

Carbon, nitrogen and phosphorus elemental stoichiometry in aquacultured and wild-caught fish and consequences for pelagic nutrient dynamics

2011 ◽  
Vol 158 (12) ◽  
pp. 2847-2862 ◽  
Author(s):  
Marie Czamanski ◽  
Adi Nugraha ◽  
Philippe Pondaven ◽  
Marine Lasbleiz ◽  
Annick Masson ◽  
...  
Keyword(s):  
Nutrient Dynamics ◽  
Nitrogen And Phosphorus ◽  
Elemental Stoichiometry

Effects of herbivore-induced nutrient stress on correlates of fitness and on nutrient resorption in scrub oak (Quercusilicifolia)

1995 ◽  
Vol 25 (11) ◽  
pp. 1858-1864 ◽  
Author(s):  
Jeffrey D. May ◽  
Keith T. Killingbeck
Keyword(s):  
Nutrient Dynamics ◽  
Plant Fitness ◽  
Nitrogen And Phosphorus ◽  
Acorn Production ◽  
Nutrient Pools ◽  
Scrub Oak ◽  
Copper And Zinc ◽  
Copper Manganese ◽  
Foliar Nutrient ◽  
Nitrogen Phosphorus

We investigated effects of defoliation by gypsy moth (Lymantriadispar L.) larvae on plant fitness and on foliar nutrient dynamics in scrub oak (Quercusilicifolia Wangenh.). Complete defoliation of treatment plants in 1986 and 1987 resulted in the production of a second flush of leaves (secondary leaves) in each of those years. Insecticide effectively protected controls from herbivory. Mean radial stem growth in 1987–1988 and acorn production in 1988–1989 in plants defoliated by L. dispar were 49% and 88% less than in controls, respectively. Defoliation had little effect on the content of nitrogen, phosphorus, copper, manganese, and zinc in green leaves. However, there was significantly less nitrogen, copper, and zinc in senesced secondary leaves of treatment plants than in the primary leaves of controls. Reduced levels of copper and zinc were also evident in senesced primary leaves of defoliated plants in 1988, when no defoliation occurred. Resorption efficiencies for copper and zinc averaged, respectively, 29% and 117% higher in defoliated plants than in controls for all three years, supporting the hypothesis that resorption may be plastic in response to changes in the magnitude of internal nutrient pools. The lack of such a response in resorption of nitrogen and phosphorus may have been due to biochemical and (or) physiological limitations that prevented increased resorption, since resorption efficiencies of these elements were already high (72% and 75%, respectively).

scholarly journals Alterations in microbial community composition with increasing <i>f</i>CO<sub>2</sub>: a mesocosm study in the eastern Baltic Sea

2017 ◽  
Vol 14 (16) ◽  
pp. 3831-3849 ◽  
Author(s):  
Katharine J. Crawfurd ◽  
Santiago Alvarez-Fernandez ◽  
Kristina D. A. Mojica ◽  
Ulf Riebesell ◽  
Corina P. D. Brussaard
Keyword(s):  
Microbial Community ◽  
Ocean Acidification ◽  
Baltic Sea ◽  
Community Dynamics ◽  
Inorganic Nitrogen ◽  
Microbial Community Composition ◽  
Cell Diameter ◽  
Viral Lysis ◽  
Nitrogen And Phosphorus ◽  
Eastern Baltic

Abstract. Ocean acidification resulting from the uptake of anthropogenic carbon dioxide (CO2) by the ocean is considered a major threat to marine ecosystems. Here we examined the effects of ocean acidification on microbial community dynamics in the eastern Baltic Sea during the summer of 2012 when inorganic nitrogen and phosphorus were strongly depleted. Large-volume in situ mesocosms were employed to mimic present, future and far future CO2 scenarios. All six groups of phytoplankton enumerated by flow cytometry ( <  20 µm cell diameter) showed distinct trends in net growth and abundance with CO2 enrichment. The picoeukaryotic phytoplankton groups Pico-I and Pico-II displayed enhanced abundances, whilst Pico-III, Synechococcus and the nanoeukaryotic phytoplankton groups were negatively affected by elevated fugacity of CO2 (fCO2). Specifically, the numerically dominant eukaryote, Pico-I, demonstrated increases in gross growth rate with increasing fCO2 sufficient to double its abundance. The dynamics of the prokaryote community closely followed trends in total algal biomass despite differential effects of fCO2 on algal groups. Similarly, viral abundances corresponded to prokaryotic host population dynamics. Viral lysis and grazing were both important in controlling microbial abundances. Overall our results point to a shift, with increasing fCO2, towards a more regenerative system with production dominated by small picoeukaryotic phytoplankton.

Nitrogen and Phosphorus Availability and the Role of Fire in Heathlands at Wilsons Promontory

1994 ◽  
Vol 42 (3) ◽  
pp. 269 ◽  
Author(s):  
MA Adams ◽  
J Iser ◽  
AD Keleher ◽  
DC Cheal
Keyword(s):  
Phosphatase Activity ◽  
C:N Ratio ◽  
Soil Nutrient ◽  
Fire Frequency ◽  
P Availability ◽  
Native Plant ◽  
Nitrogen And Phosphorus ◽  
Nutrient Pools ◽  
Inorganic P ◽  
Eucalypt Forests

Analyses of carbon, nitrogen and phosphorus in heathland soils at Wilsons Promontory and on Snake Island show that the effects of fire, including repeated fires, are confined to the surface 2 cm. The uppermost soil in long-unburnt heathlands is rich in these elements and usually has a smaller C:N ratio compared with the soil below. Indices of N and P availability (C:N ratios, concentrations of potentially mineralisable N and extractable inorganic P, phosphatase activity) are similar to those in highly productive eucalypt forests-a finding in conflict with past assessments of nutrient availability in heathlands. Phosphatase activity and concentrations of carbon, nitrogen and potentially mineralisable N were less in soils from repeatedly burnt heathlands than in soils from long unburnt heathlands whereas there was a greater concentration of extractable inorganic P in soils from repeatedly burnt heathlands. The balance between nitrogen input and loss is dependent on fire frequency and present-day management of heathland (and other native plant communities with low nutrient capitals) should recognise that over- or under-use of fire will significantly alter soil nutrient pools and availability and that these changes may alter community species composition and productivity.

scholarly journals Spatial and Temporal Variations of Nitrogen and Phosphorus in Surface Water and Groundwater of Mudong River Watershed in Huixian Karst Wetland, Southwest China

2021 ◽  
Vol 13 (19) ◽  
pp. 10740
Author(s):  
Linyan Pan ◽  
Junfeng Dai ◽  
Zhiqiang Wu ◽  
Liangliang Huang ◽  
Zupeng Wan ◽  
...  
Keyword(s):  
Surface Water ◽  
Temporal Dynamics ◽  
Flow Direction ◽  
Influencing Factor ◽  
Shallow Groundwater ◽  
Temporal Variations ◽  
Field Investigation ◽  
Spatial And Temporal Variation ◽  
Nitrogen And Phosphorus ◽  
River Watershed

When considering the factors affecting the spatial and temporal variation of nitrogen and phosphorus in karst watersheds, the unique karst hydrogeology as an internal influencing factor cannot be ignored, as well as natural factors such as meteorological hydrology and external factors such as human activities. A watershed-scale field investigation was completed to statistically analyze spatial and temporal dynamics of nitrogen and phosphorus through the regular monitoring and collection of surface water and shallow groundwater in the agricultural-dominated Mudong River watershed in the Huixian Karst Wetland over one year (May 2020 to April 2021). Our research found that non-point source pollution of nitrogen (84.5% of 239 samples TN > 1.0 mg/L) was more serious than phosphorus (7.5% of 239 samples TP > 0.2 mg/L) in the study area, and shallow groundwater nitrogen pollution (98.3% of 118 samples TN > 1.0 mg/L) was more serious than surface water (68.6% of 121 samples TN > 1.0 mg/L). In the three regions with different hydrodynamic features, the TN concentration was higher and dominated by NO3−-N in the river in the northern recharge area, while the concentrations of TN and TP were the highest in shallow groundwater wells in the central wetland core area and increased along the surface water flow direction in the western discharge area. This research will help improve the knowledge about the influence of karst hydrodynamic features on the spatial patterns of nitrogen and phosphorus in water, paying attention to the quality protection and security of water in karst areas with a fragile water ecological environment.

scholarly journals Extreme Levels of Ocean Acidification Restructure the Plankton Community and Biogeochemistry of a Temperate Coastal Ecosystem: A Mesocosm Study

2021 ◽  
Vol 7 ◽  
Author(s):  
Carsten Spisla ◽  
Jan Taucher ◽  
Lennart T. Bach ◽  
Mathias Haunost ◽  
Tim Boxhammer ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Fish Larvae ◽  
Plankton Community ◽  
Trophic Levels ◽  
Coastal Regions ◽  
Mesozooplankton Community ◽  
Planktonic Food ◽  
Elemental Stoichiometry ◽  
Secondary Consumers ◽  
Induced Changes

The oceans’ uptake of anthropogenic carbon dioxide (CO2) decreases seawater pH and alters the inorganic carbon speciation – summarized in the term ocean acidification (OA). Already today, coastal regions experience episodic pH events during which surface layer pH drops below values projected for the surface ocean at the end of the century. Future OA is expected to further enhance the intensity of these coastal extreme pH events. To evaluate the influence of such episodic OA events in coastal regions, we deployed eight pelagic mesocosms for 53 days in Raunefjord, Norway, and enclosed 56–61 m3 of local seawater containing a natural plankton community under nutrient limited post-bloom conditions. Four mesocosms were enriched with CO2 to simulate extreme pCO2 levels of 1978 – 2069 μatm while the other four served as untreated controls. Here, we present results from multivariate analyses on OA-induced changes in the phyto-, micro-, and mesozooplankton community structure. Pronounced differences in the plankton community emerged early in the experiment, and were amplified by enhanced top-down control throughout the study period. The plankton groups responding most profoundly to high CO2 conditions were cyanobacteria (negative), chlorophyceae (negative), auto- and heterotrophic microzooplankton (negative), and a variety of mesozooplanktonic taxa, including copepoda (mixed), appendicularia (positive), hydrozoa (positive), fish larvae (positive), and gastropoda (negative). The restructuring of the community coincided with significant changes in the concentration and elemental stoichiometry of particulate organic matter. Results imply that extreme CO2 events can lead to a substantial reorganization of the planktonic food web, affecting multiple trophic levels from phytoplankton to primary and secondary consumers.

Gas-Exchange Rates in a Small Lake as Determined by the Radon Method

1973 ◽  
Vol 30 (10) ◽  
pp. 1475-1484 ◽  
Author(s):  
Steve Emerson ◽  
Wallace Broecker ◽  
D. W. Schindler
Keyword(s):  
Exchange Rate ◽  
Gas Exchange ◽  
Exchange Rates ◽  
Partial Pressure ◽  
Lake Water ◽  
Radon Concentration ◽  
Natural Waters ◽  
Carbon Dioxide Partial Pressure ◽  
Nitrogen And Phosphorus ◽  
Gas Exchange Rate

The radon method, used previously in ocean-atmosphere systems, is used here to determine the gas-exchange rate between the atmosphere and lake 227 of the Experimental Lakes Area. Fertilization of the lake with nitrogen and phosphorus caused the carbon dioxide partial pressure in the lake water to drop well below atmospheric levels; hence, in order to better understand the carbon budget of the lake, an estimate of the CO2 gas-exchange rate was necessary.To determine gas-exchange rates by measuring radon evasion to the atmosphere the source of radon in the lake water must be dissolved radium. Since the radon concentration in lakes derives not only from the decay of dissolved radium but also from the inflow of radon-rich groundwaters, radium was added to the lake to increase the radon concentration well above this fluctuating background level. Although this procedure was complicated by algal uptake of the radium in the lake (Emerson and Hesslein 1973), we were able to place limits on the gas-exchange rate.Our results indicate that the "stagnant boundary layer" thickness is approximately 300 μ. This value is among the largest observed in natural waters. Using this value and the partial pressure of CO2 in the lake water we have calculated an invasion rate of 17 ± 8 mmoles CO2/m2 day.

Soil Organic Matter and Nutrient Dynamics of Shortgrass Steppe Ecosystems

2008 ◽  
Author(s):  
Ingrid C. Burke ◽  
Arvin R. Mosier
Keyword(s):  
Nutrient Dynamics ◽  
Natural Disturbance ◽  
Temporal Patterns ◽  
Controlling Factors ◽  
Shortgrass Steppe ◽  
Spatial And Temporal Patterns ◽  
Nutrient Pools ◽  
Steppe Ecosystems ◽  
C And N Cycling ◽  
Major Factors

Since the days of the IBP, there has been a strong emphasis on research about the biogeochemistry of shortgrass steppe ecosystems (e.g., Clark, 1977; Woodmansee, 1978). A major theme has been seeking to understand spatial and temporal patterns and controls of biogeochemical pools and fluxes at scales that span from several centimeters to hundreds of kilometers, and from hours to millennia. The synthesis of this work has resulted in a conceptual framework regarding the biogeochemical dynamics of the shortgrass steppe, with two key components:… 1. Spatial and temporal patterns are controlled by five 1. major factors: climate, physiography, natural disturbance, human use, and biotic interactions. Plants are the most important biotic component. The interaction of these factors as they change in time and space determines the distribution and size of biogeochemical pools and the rates of biogeochemical processes. 2. Carbon (C), nitrogen (N), and other associated biologically active elements are overwhelmingly located belowground, with more than 90% found in soils (Burke et al., 1997a). This distribution determines the biogeochemical sensitivity of the shortgrass steppe to perturbations…. These ideas have been synthesized in the development of the CENTURY ecosystem simulation model, originally developed for grasslands and agroecosystems in the shortgrass steppe region of the western Great Plains (Parton et al., 1987, and chapter 15, this volume). The model represents complex interactions among the five controlling factors to simulate C and N cycling, and has served as an organizing framework for developing hypotheses and for evaluating questions that are dif. cult to address in the field (Parton et al., chapter 15, this volume). The objectives of this chapter are to describe how nutrient pools and fluxes are distributed in the shortgrass steppe, to characterize how the five controlling factors interact to create spatial and temporal patterns, and to evaluate the potential future changes to which the biogeochemistry of the shortgrass steppe may be particularly vulnerable.

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