Growth, photosynthesis, and extracellular organic release in colonized and axenic Myriophyllum spicatum

1989 ◽  
Vol 67 (12) ◽  
pp. 3429-3438 ◽  
Author(s):  
H. Godmaire ◽  
C. Nalewajko
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Myriophyllum Spicatum ◽  
Distribution Patterns ◽  
Release Rates ◽  
Lower Growth ◽  
Bicarbonate Uptake ◽  
Algal Photosynthesis ◽  
Major Nutrients ◽  
Carbon Concentrations

Growth and photosynthesis of axenic and colonized Myriophyllum were compared to test the validity of using axenic plants as controls in the quantification of extracellular organic carbon (EOC) release. Axenic plants were characterized by lower growth rates that could be attributed to the unavailability of some major nutrients other than N, P, or C and (or) micronutrients in the culture medium. Vmax, the maximum rate of bicarbonate uptake, and Pmax, the maximum light-saturated rate of photosynthesis, of nonaxenic Myriophyllum were significantly higher than those of axenic plants. These differences could be attributed to epiphytic algal photosynthesis. At subsaturating dissolved inorganic carbon concentrations (below 15 mg C ∙ L−1), both plants achieved similar rates of photosynthesis but differed in the kinetics of EOC release. In short-term incubation (2–6 h), 14C-EOC accounted for 0.2–0.4% of photosynthesis, and total EOC amounted to 1.3–3.8%. 14C-EOC consisted primarily (≥ 60%) of low molecular weight products (≤ 1500). No differences were apparent in size distribution patterns of 14C-EOC from axenic and nonaxenic Myriophyllum and at different dissolved inorganic carbon concentrations. Axenic plants generally showed lower rates of EOC release (in absolute values). On colonized Myriophyllum, the contribution of the epiphytes to the EOC release pool was found to be low (≤ 20% of 14C-EOC) and could partly explain the greater EOC release rates of nonaxenic plants. However, our results are not totally conclusive because the lower growth rate of axenic plants could also be responsible for the lower photosynthetic and EOC release rates of these plants.

scholarly journals Transient tracer distributions in the Fram Strait in 2012 and inferred anthropogenic carbon content and transport

Ocean Science ◽  
2016 ◽  
Vol 12 (1) ◽  
pp. 319-333 ◽  
Author(s):  
Tim Stöven ◽  
Toste Tanhua ◽  
Mario Hoppema ◽  
Wilken-Jon von Appen
Keyword(s):  
Surface Water ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Atlantic Water ◽  
Fram Strait ◽  
Polar Surface ◽  
Anthropogenic Carbon ◽  
Tracer Age ◽  
Transient Tracer ◽  
Carbon Concentrations

Abstract. The storage of anthropogenic carbon in the ocean's interior is an important process which modulates the increasing carbon dioxide concentrations in the atmosphere. The polar regions are expected to be net sinks for anthropogenic carbon. Transport estimates of dissolved inorganic carbon and the anthropogenic offset can thus provide information about the magnitude of the corresponding storage processes. Here we present a transient tracer, dissolved inorganic carbon (DIC) and total alkalinity (TA) data set along 78°50′ N sampled in the Fram Strait in 2012. A theory on tracer relationships is introduced, which allows for an application of the inverse-Gaussian–transit-time distribution (IG-TTD) at high latitudes and the estimation of anthropogenic carbon concentrations. Mean current velocity measurements along the same section from 2002–2010 were used to estimate the net flux of DIC and anthropogenic carbon by the boundary currents above 840 m through the Fram Strait. The new theory explains the differences between the theoretical (IG-TTD-based) tracer age relationship and the specific tracer age relationship of the field data, by saturation effects during water mass formation and/or the deliberate release experiment of SF6 in the Greenland Sea in 1996, rather than by different mixing or ventilation processes. Based on this assumption, a maximum SF6 excess of 0.5–0.8 fmol kg−1 was determined in the Fram Strait at intermediate depths (500–1600 m). The anthropogenic carbon concentrations are 50–55 µmol kg−1 in the Atlantic Water/Recirculating Atlantic Water, 40–45 µmol kg−1 in the Polar Surface Water/warm Polar Surface Water and between 10 and 35 µmol kg−1 in the deeper water layers, with lowest concentrations in the bottom layer. The net fluxes through the Fram Strait indicate a net outflow of  ∼  0.4 DIC and  ∼  0.01 PgC yr−1 anthropogenic carbon from the Arctic Ocean into the North Atlantic, albeit with high uncertainties.

Inorganic carbon acquisition by the chrysophyte alga Mallomonas papillosa

2005 ◽  
Vol 83 (7) ◽  
pp. 891-897 ◽  
Author(s):  
Shabana Bhatti ◽  
Brian Colman
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Photosynthetic Oxygen Evolution ◽  
Intracellular Accumulation ◽  
Oxygen Evolution Rate ◽  
Internal Ph ◽  
Bicarbonate Uptake ◽  
Photosynthetic Oxygen ◽  
Ph Range ◽  
External Ph

Photosynthetic characteristics of the chrysophyte alga Mallomonas papillosa Harris et Bradley were investigated to determine whether this species has some form of CO2-concentrating mechanism. The effect of external pH on the photosynthetic oxygen evolution rate of air-grown cells demonstrated an optimum in the pH range 5.0–7.0. This species lacked external carbonic anhydrase, and the cells had no capacity for direct bicarbonate uptake and had a low affinity for dissolved inorganic carbon. Measurement of the fluxes of CO2 and O2 in photosynthesizing cells at pH 7.0, using mass spectrometry, displayed no rapid uptake but only a slow depletion of CO2 from the medium upon illumination. Furthermore, CO2 uptake and O2 evolution by M. papillosa was greatly reduced by iodoacetamide, an inhibitor of CO2 fixation. The overall internal pH of M. papillosa was determined by distribution of 14C-benzoic acid over the pH range 5.5–6.0 and [2-14C]-5,5-dimethyloxazolidine-2,4-dione over the pH range 6.5–7.0 between the cells and medium. As the external pH was lowered from 7.0 to 5.5, there was a decrease in the internal pH of M. papillosa cells from 8.31 to 7.75. The ΔpH was great enough to allow the intracellular accumulation of inorganic carbon by the diffusive uptake of CO2.Key words: bicarbonate uptake, chrysophyte, CO2 uptake, internal pH, Mallomonas papillosa.

scholarly journals B/Ca in coccoliths and relationship to calcification vesicle pH and dissolved inorganic carbon concentrations

2012 ◽  
Vol 80 ◽  
pp. 143-157 ◽  
Author(s):  
Heather Stoll ◽  
Gerald Langer ◽  
Nobumichi Shimizu ◽  
Kinuyo Kanamaru
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Carbon Concentrations

scholarly journals Cyanobacterial carbon concentrating mechanisms facilitate sustained CO<sub>2</sub> depletion in eutrophic lakes

2017 ◽  
Vol 14 (11) ◽  
pp. 2865-2875 ◽  
Author(s):  
Ana M. Morales-Williams ◽  
Alan D. Wanamaker Jr. ◽  
John A. Downing
Keyword(s):  
Inorganic Carbon ◽  
Phytoplankton Bloom ◽  
Dissolved Inorganic Carbon ◽  
Negative Relationship ◽  
Anthropogenic Pressure ◽  
Phytoplankton Blooms ◽  
Eutrophic Lakes ◽  
Bicarbonate Uptake ◽  
Carbon Concentrating Mechanisms ◽  
Photosynthetic Fractionation

Abstract. Phytoplankton blooms are increasing in frequency, intensity, and duration in aquatic ecosystems worldwide. In many eutrophic lakes, these high levels of primary productivity correspond to periods of CO2 depletion in surface waters. Cyanobacteria and other groups of phytoplankton have the ability to actively transport bicarbonate (HCO3−) across their cell membrane when CO2 concentrations are limiting, possibly giving them a competitive advantage over algae not using carbon concentrating mechanisms (CCMs). To investigate whether CCMs can maintain phytoplankton bloom biomass under CO2 depletion, we measured the δ13C signatures of dissolved inorganic carbon (δ13CDIC) and phytoplankton particulate organic carbon (δ13Cphyto) in 16 mesotrophic to hypereutrophic lakes during the ice-free season of 2012. We used mass–balance relationships to determine the dominant inorganic carbon species used by phytoplankton under CO2 stress. We found a significant positive relationship between phytoplankton biomass and phytoplankton δ13C signatures as well as a significant nonlinear negative relationship between water column ρCO2 and isotopic composition of phytoplankton, indicating a shift from diffusive uptake to active uptake by phytoplankton of CO2 or HCO3− during blooms. Calculated photosynthetic fractionation factors indicated that this shift occurs specifically when surface water CO2 drops below atmospheric equilibrium. Our results indicate that active HCO3− uptake via CCMs may be an important mechanism in maintaining phytoplankton blooms when CO2 is depleted. Further increases in anthropogenic pressure, eutrophication, and cyanobacteria blooms are therefore expected to contribute to increased bicarbonate uptake to sustain primary production.

Isotopic Composition of Dissolved Inorganic Carbon in the Great Lakes

1978 ◽  
Vol 35 (4) ◽  
pp. 422-430 ◽  
Author(s):  
R. R. Weiler ◽  
J. O. Nriagu
Keyword(s):  
Organic Matter ◽  
Great Lakes ◽  
Lake Erie ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Total Inorganic Carbon ◽  
Upper Great Lakes ◽  
Industrial Sewage ◽  
Carbon Concentrations ◽  
Isotopic Effects

Values for the δ13C of the dissolved total inorganic carbon in the Great Lakes are presented. The surface values are about two parts per thousand more negative than the values to be expected assuming equilibrium with the atmospheric CO2 reservoir. In the hypolimnion of Lake Erie, the values become more negative as the summer progresses due to the increasing amounts of CO2 from decaying organic matter. Although Lakes Erie and Ontario receive considerably larger amounts of organic carbon as domestic and industrial sewage effluents than the upper Great Lakes, their higher inorganic carbon concentrations evidently mask any isotopic effects from the decay of the organic pollutants. Models to explain the variation in the δ13C in the hypolimnion and epilimnion of a lake are presented. The agreement between predicted and observed δ13C trends for the hypolimnion model is reasonable, suggesting that the flux rates assumed in the model are reasonable for the processes occurring in the lakes. Key words: carbon isotopes, Great Lakes, inorganic carbon, models

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