Net Photosynthesis and Respiration of Cladonia ecmocyna (Ach.) Nyl. from the Rocky Mountains and Comparison with Three Eastern Alpine Lichens

1973 ◽  
Vol 89 (1) ◽  
pp. 58 ◽  
Author(s):  
William G. Eickmeier ◽  
Michael S. Adams
Keyword(s):  
Rocky Mountains ◽  
Net Photosynthesis ◽  
Photosynthesis And Respiration

Inhibition of Metabolic Hydrogen Ion Flux Resulting from Cadmium Stress in Aquatic Microecosystems

1987 ◽  
Vol 19 (11) ◽  
pp. 85-94
Author(s):  
William D. Nicholas ◽  
A. Ray Abernathy
Keyword(s):  
Net Photosynthesis ◽  
Cadmium Stress ◽  
Effective Concentration ◽  
Hydrogen Ion ◽  
Ph Change ◽  
Control Data ◽  
Data Set ◽  
Analysis Techniques ◽  
Photosynthesis And Respiration ◽  
Periodic Changes

Periodic changes in pH were monitored at 30 s intervals in naturally-derived, aquatic microeco-systems. The pH of the system was controlled between two setpoints with a microcomputer. When the upper setpoint was reached a light bank was turned off until the pH dropped to the lower setpoint and the light was again turned on. The cycling of the pH in the microcosms was analyzed using time series analysis techniques. Each experiment resulted in a 24 hour control data set and a 24 hour experimental data set that began with the addition of an inhibitor or toxicant. EC50 values (effective concentration for 50% inhibition) of net photosynthesis and respiration of the community were calculated from slopes of the periodic response to cadmium and compared to literature values. The EC50 for dark induced pH change was 3.8 ppm while the EC50 for light induced pH change was 0.51 ppm. Increasing cadmium concentrations caused dominant peaks in the variance periodograms to be shifted to longer periods.

The ecology of Rhizocarpon superficial. II. The seasonal response of net photosynthesis and respiration to temperature, moisture, and light

1983 ◽  
Vol 61 (12) ◽  
pp. 3019-3030 ◽  
Author(s):  
D. S. Coxson ◽  
K. A. Kershaw
Keyword(s):  
Photosynthetic Capacity ◽  
Net Photosynthesis ◽  
Response Matrix ◽  
Operating Environment ◽  
Capacity Change ◽  
Response To Temperature ◽  
Random Fluctuations ◽  
Photosynthesis And Respiration ◽  
Resistance To Heat ◽  
Photosynthetic Adaptation

The seasonal gas-exchange response matrix for the crustaceous lichen Rhizocarpon superficiale (Schaer.) Vain, is presented. Maximum rates for net photosynthesis of ca. 1 mg CO2 g−1 h_1 are generated at 900 μE m−2 s−1 illumination between 50 and 60% relative thallus moisture content and at thallus temperatures of 14 °C down to 1 °C, during all seasons of the year. This broad response to temperature as well as the apparently high resistance to heat stress in Rhizocarpon is discussed in relation to the special characteristics of its boundary-layer habitat. The absence of any seasonal photosynthetic capacity change is discussed in terms of the constraint imposed by the random fluctuations in the thermal operating environment of the lichen. We postulate that the predictability of the operating environment largely determines the extent and the level of any photosynthetic adaptation.

Photosynthetic response to growth temperature and CO2 enrichment in two species of C4 grasses

1985 ◽  
Vol 63 (3) ◽  
pp. 483-487 ◽  
Author(s):  
Catherine Potvin ◽  
Boyd R. Strain
Keyword(s):  
North Carolina ◽  
Growth Temperature ◽  
Dark Respiration ◽  
Co2 Enrichment ◽  
Net Photosynthesis ◽  
C4 Grasses ◽  
Eleusine Indica ◽  
Respiration Rates ◽  
Acclimation Potential ◽  
Photosynthesis And Respiration

Plants of Echinochloa crus-galli from Québec, North Carolina, and Mississippi and of Eleusine indica from Mississippi were grown under three thermoperiods (28:22, 24:18, 21:15 °C) and two atmospheric CO2 concentrations (350 and 675 μL ∙ L−1). CO2 enrichment induced an increase in net photosynthesis and in dark respiration for all populations. Neither conductance, transpiration, nor the transpiration/photosynthesis ratio were affected by CO2 enrichment. Plants showed higher photosynthetic and dark respiration rates when grown in warm regimes. Stomatal conductance did not vary with growth temperature. Cool-adapted plants from Québec maintained the overall highest net photosynthesis and respiration. Plants originating from warm areas had a weaker acclimation potential to low temperature than those from cool environments.

scholarly journals Photosynthesis and respiration of the soft coral Xenia umbellata respond to warming but not to organic carbon eutrophication

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11663
Author(s):  
Susana Marcela Simancas-Giraldo ◽  
Nan Xiang ◽  
Meghan Moger Kennedy ◽  
Rassil Nafeh ◽  
Edoardo Zelli ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Coral Reefs ◽  
Soft Coral ◽  
Net Photosynthesis ◽  
Ocean Warming ◽  
Soft Corals ◽  
Negative Effects ◽  
Gross Photosynthesis ◽  
Significant Difference ◽  
Photosynthesis And Respiration

Eutrophication with dissolved organic carbon (DOC) as a far under-investigated stressor, and ocean warming, can strongly affect coral reefs and hard corals as major reefs ecosystem engineers. However, no previous studies have investigated the metabolic responses of soft corals to DOC eutrophication, or its interaction with ocean warming. Thus, we investigated respiration and photosynthesis response of Xenia umbellata, a common mixotrophic soft coral from the Indo-pacific, to (1) three levels of DOC eutrophication simulated by glucose addition over the first 21 days of experiment and (2) ocean warming scenarios where the temperature was gradually increased from 26 °C (control condition) to 32 °C over another 24 days in an aquarium experiment. We found no significant difference in response to DOC treatments and all corals survived regardless of the DOC concentrations, whilst subsequent exposure to simulated ocean warming significantly decreased gross photosynthesis by approximately 50% at 30 °C, and 65% at 32 °C, net photosynthesis by 75% at 30 °C and 79% at 32 °C, and respiration by a maximum of 75% at 30 °C; with a slight increase at 32 °C of 25%. The ratio between gross photosynthesis and respiration decreased by the end of the warming period but remained similar between controls and colonies previously exposed to DOC. Our findings suggest that soft corals may be more resistant than hard corals to DOC eutrophication and in consequence, may potentially experiment in less magnitude the negative effects of increased temperature or subsequently both stressors. The results of this study may contribute to explain the successful role of soft corals in phase shifts as reported from many coral reefs. Where predicted declines in reef ecosystems health due to increased eutrophication levels can be exacerbated by future warming.

Theoretical and Experimental Analysis of the 14C Technique and Its Use in Studies of Primary Production

1976 ◽  
Vol 33 (8) ◽  
pp. 1715-1721 ◽  
Author(s):  
Louis A. Hobson ◽  
W. James Morris ◽  
Kathleen T. Pirquet
Keyword(s):  
Environmental Conditions ◽  
Experimental Analysis ◽  
Rate Constants ◽  
Net Photosynthesis ◽  
Field Studies ◽  
Marine Phytoplankton ◽  
Theoretical Studies ◽  
Continuous Irradiation ◽  
Gross Photosynthesis ◽  
Photosynthesis And Respiration

Theoretical and experimental field studies of 14C uptake by marine phytoplankton were carried out to determine environmental conditions required for the technique to measure net photosynthesis. Results of theoretical studies indicate that rapidly metabolizing populations (rate constants for gross photosynthesis and respiration of 0.1 h−1 and 0.007 h−1 respectively) may saturate with 14C after about 30 h of continuous irradiation. Results of field studies indicate that a minimum of 24 h are required for net photosynthesis to be measured when daily irradiations exceed 20 cal cm−2 and nutrient limitation of photosynthesis does not occur. Additional measurements that may be made to aid in interpreting results obtained by the 14C technique are briefly discussed.

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