Algal Photosynthesis and Physiology

Author(s):  
John Raven ◽  
John Beardall
Keyword(s):  
1993 ◽  
Vol 50 (2) ◽  
pp. 282-289 ◽  
Author(s):  
Paul A. del Giorgio ◽  
Robert H. Peters

We analyzed published rates of algal photosynthesis and plankton community respiration to test the hypothesis that the ratio of planktonic primary production to community (P/R) varies systematically with lake trophy. Regression analyses show that algal production and plankton respiration are closely related to chlorophyll concentrations for lakes spanning a wide trophic range. More surprisingly, plankton respiration exceeds algal photosynthesis in oligotrophic lakes, and P/R rises above unity only when chlorophyll concentrations are above 17 mg∙m−3. A simple allometric model based on the predicted biomasses of the different planktonic component yield rates of community respiration that are in good agreement with measured values. Moreover, the model suggest that in oligotrophic lakes, microbial respiration may greatly exceed the current estimates based on bacterial production data and that heterotrophs contribute proportionately more to total plankton metabolism than they do in eutrophic lakes. Because such high respiration rates require external energy subsidies, these results; challenge the view that pelagial communities of most lakes are even approximately self-supporting.


Author(s):  
A. E. Douglas

Of a wide range of algae tested, juvenile Convoluta roscoffensis ingested only Platymonas convolutae, the natural symbiont; related species of the genera Platymonas, Prasinocladus and Tetraselmis; and Chlamydomonas coccoides. Platymonas convolutae was not ingested to a greater extent than Prasinocladus marinus, Tetraselmis tetrathele and Tetraselmis verrucosa, or taken up in preference to T. verrucosa when animals were exposed to a choice between the two species. Convoluta ingested fewer cells of C. coccoides than P. convolutae and related species. Uptake of P. convolutae was not affected by pretreatment of the cells with lectins or proteases, incubation in media of pH 5·0–9·0 or inhibition of algal photosynthesis, but was substantially reduced if the algae were killed.Cells of P. convolutae, Pr. marinus, T. tetrathele and T. verrucosa persisted and divided in juvenile Convoluta. The algal population in the worms started to increase 2–3 d after ingestion and within 15–20 d the animals were uniformly green. These algae formed a viable symbiosis with Convoluta and promoted the growth of the animals. In contrast, C. coccoides cells did not persist in Convoluta for more than 12–24 h a nd were probably disrupted.P. convolutae cells lost their thecae within a few days of ingestion and before migration from the central to sub-epidermal region of the animal. Animal vacuoles surrounded recently ingested thecate algae. Structural studies of the adult symbiosis suggest that the algae were also intracellular and enclosed in vacuoles.It is proposed that Convoluta discriminates against algae unrelated to P. convolutae on initial contact and in the central region of the host. The nature of the recognition mechanism(s) has not been established.


2015 ◽  
Vol 12 ◽  
pp. 43-51 ◽  
Author(s):  
C. Vejrazka ◽  
M. Streefland ◽  
R.H. Wijffels ◽  
M. Janssen
Keyword(s):  

2015 ◽  
Vol 12 (11) ◽  
pp. 8429-8465 ◽  
Author(s):  
H. B. DeJong ◽  
R. B. Dunbar ◽  
D. A. Mucciarone ◽  
D. A. Koweek

Abstract. Predicting when surface waters of the Ross Sea and Southern Ocean will become undersaturated with respect to biogenic carbonate minerals is challenging in part due to the lack of baseline high resolution carbon system data. Here we present ~ 1700 surface total alkalinity measurements from the Ross Sea and along a transect between the Ross Sea and southern Chile from the austral autumn (February–March 2013). We calculate the saturation state of aragonite (ΩAr) and calcite (ΩCa) using measured total alkalinity and pCO2. In the Ross Sea and south of the Polar Front, variability in carbonate saturation state (Ω) is mainly driven by algal photosynthesis. Freshwater dilution and calcification have minimal influence on Ω variability. We estimate an early spring surface water ΩAr value of ~ 1.2 for the Ross Sea using a total alkalinity–salinity relationship and historical pCO2 measurements. Our results suggest that the Ross Sea is not likely to become undersaturated with respect to aragonite until the year 2070.


2019 ◽  
Vol 143 (3) ◽  
pp. 287-299 ◽  
Author(s):  
Marie-Claire ten Veldhuis ◽  
Gennady Ananyev ◽  
G. Charles Dismukes

AbstractLichens are a symbiosis between a fungus and one or more photosynthetic microorganisms that enables the symbionts to thrive in places and conditions they could not compete independently. Exchanges of water and sugars between the symbionts are the established mechanisms that support lichen symbiosis. Herein, we present a new linkage between algal photosynthesis and fungal respiration in lichen Flavoparmelia caperata that extends the physiological nature of symbiotic co-dependent metabolisms, mutually boosting energy conversion rates in both symbionts. Measurements of electron transport by oximetry show that photosynthetic O2 is consumed internally by fungal respiration. At low light intensity, very low levels of O2 are released, while photosynthetic electron transport from water oxidation is normal as shown by intrinsic chlorophyll variable fluorescence yield (period-4 oscillations in flash-induced Fv/Fm). The rate of algal O2 production increases following consecutive series of illumination periods, at low and with limited saturation at high light intensities, in contrast to light saturation in free-living algae. We attribute this effect to arise from the availability of more CO2 produced by fungal respiration of photosynthetically generated sugars. We conclude that the lichen symbionts are metabolically coupled by energy conversion through exchange of terminal electron donors and acceptors used in both photosynthesis and fungal respiration. Algal sugars and O2 are consumed by the fungal symbiont, while fungal delivered CO2 is consumed by the alga.


2018 ◽  
Vol 142 ◽  
pp. 65-74 ◽  
Author(s):  
Meng Wang ◽  
Karl A. Payne ◽  
Shuang Tong ◽  
Sarina J. Ergas

Weed Science ◽  
1972 ◽  
Vol 20 (5) ◽  
pp. 492-497 ◽  
Author(s):  
Claude E. Boyd

Bacterial production of CO2from sucrose substrate increased growth of seven species of algae in CO2-limited laboratory cultures. Decomposition of organic matter in pond water also supplied enough CO2to support good algal growth in cultures deprived of other sources of CO2. Estimates of CO2production from decay of dissolved organic matter in six pond waters ranged from 0.32 to 3.53 mg/L per 24 hr. The carbonate-bicarbonate equilibrium system is a major source of CO2for algal photosynthesis. However, in waters of low or extremely high alkalinity, this system will not support high rates of photosynthesis. In such waters CO2from decomposition will stimulate photosynthesis. Decomposable organic compounds must be considered with nitrogen and phosphorus as factors responsible for accelerated eutrophication and nuisance algal blooms.


Chemosphere ◽  
2019 ◽  
Vol 224 ◽  
pp. 333-342 ◽  
Author(s):  
Kentaro Misaki ◽  
Yuhei Morita ◽  
Kentaro Kobayashi ◽  
Yuichi Sugawara ◽  
Yoshihisa Shimizu ◽  
...  

2005 ◽  
Vol 51 (12) ◽  
pp. 153-161 ◽  
Author(s):  
R.J. Davies-Colley ◽  
R.J. Craggs ◽  
J. Park ◽  
J.W. Nagels

The optical character of waste stabilization ponds (WSPs) is of concern for several reasons. Algal photosynthesis, which produces oxygen for waste oxidation in WSPs, is influenced by attenuation of sunlight in ponds. Disinfection in WSPs is influenced by optical characteristics because solar UV exposure usually dominates inactivation. The optical nature of WSPs effluent also affects assimilation by receiving waters. Despite the importance of light behaviour in WSPs, few studies have been made of their optical characteristics. We discuss simple optical measures suitable for routine monitoring of WSPs (including at sites remote from laboratories): optical density of filtrates – an index of dissolved coloured organic (humic) matter, visual clarity – to provide an estimate of the beam attenuation coefficient (a fundamental quantity needed for optical modelling) colour (hue) – as an indicator of general WSP ‘condition’ and irradiance attenuation quantifying depth of light penetration. The value of optical characterisation of WSPs is illustrated with reference to optical data for WSPs in NZ (including high-rate algal ponds) treating dairy cattle wastewater versus domestic sewage. We encourage increased research on optical characteristics of WSPs and the incorporation of optical measures in monitoring and modelling of WSP performance


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