Photosynthetic performance of surface-associated algae below sea ice as measured with a pulse-amplitude-modulated (PAM) fluorometer and O-2 microsensors

The photosynthetic performance of sea ice microalgae, benthic microalgae, coralline red algae (Phymatolithon foecundum) and brown macroalgae (Laminaria saccharina, Fucus evanescens and Desmarestia aculeata) in an ice-covered high-Arctic fjord (Young Sound, NE Greenland) was studied with in situ inst...

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Bibliographic Details
Published in:Marine Ecology Progress Series
Main Authors: Kuhl, M, Glud, Ronnie, Borum, J, Roberts, R, Rysgaard, S
Format: Article in Journal/Newspaper
Language:English
Published: 2001
Subjects:
Marine & Freshwater Biology
Oceanography
EUKARYOTIC ALGAE
Ecology
QUANTUM YIELD
CHLOROPHYLL FLUORESCENCE
IN-SITU
YOUNG SOUND
NORTHEAST GREENLAND
DEPTH DISTRIBUTION
PRIMARY PRODUCTIVITY
ELECTRON-TRANSPORT
BENTHIC MICROALGAE
Arctic
Greenland
Sea ice
Online Access:https://pure.uhi.ac.uk/en/publications/2d5fa6c6-31cf-405b-85f3-332df448bc57
https://doi.org/10.3354/meps223001
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Summary:The photosynthetic performance of sea ice microalgae, benthic microalgae, coralline red algae (Phymatolithon foecundum) and brown macroalgae (Laminaria saccharina, Fucus evanescens and Desmarestia aculeata) in an ice-covered high-Arctic fjord (Young Sound, NE Greenland) was studied with in situ instruments for oxygen microprofiling and active chlorophyll fluorescence measurements. In situ measurements of the effective quantum yield of Photosystem II (PSII) under ambient low irradiance ranged between 0.3 and 0.7. Net oxygen production of benthic microalgae and sea ice microalgae was measured in situ at low irradiance of similar to2 to 30 mumol photons m(-2) s(-1). The compensation irradiance determined in the laboratory for coralline algae arid brown macroalgae was 1.6 and 1.9 mumol photons m(-2) s(-1) respectively., The same experiments showed irradiances at onset of saturation, E-k, for coralline red algae and brown macroalgae of 17 and 12.8 mumol photons m(-2) s(-1) respectively. In situ measurements of rapid light curves, measured over 1 to 2 min by the saturation pulse method, enabled snap shots of the in situ adaptation of the photosynthetic apparatus in the different phototrophs under ambient irradiance conditions. These measurements showed Ek values for PSII related electron transport (relative ETR) at 7.9 (sea ice microalgae), 4.6 (benthic microalgae), 11 (coralline red algae) and 4.4 to 7.3 (brown macroalgae) mumol photons m(-2) s(-1). At higher irradiance levels, relative ETR decreased, indicating inhibition and/or downregulation of photosynthesis. When light curves were measured with longer application of the different actinic light levels, a less pronounced or zero decrease of relative ETR was found at higher irradiance, and Ek values were shifted to higher irradiance, i.e. 6.9 mumol photons m(-2) s(-1) (benthic microalgae) and 11.5 to 16.1 mumol photons m(-2) s(-1) (brown macroalgae). This apparent short-term acclimation to increasing irradiance reversed to the initial characteristics of the light ...

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