Photosynthetic performance of surface-associated algae below sea ice as measured with a pulse-amplitude-modulated (PAM) fluorometer and O2 microsensors

Michael Kühl; Ronnie N. Glud; Jens Borum; Rodney Roberts; Søren Rysgaard

doi:10.3354/meps223001

Photosynthetic performance of surface-associated algae below sea ice as measured with a pulse-amplitude-modulated (PAM) fluorometer and O² microsensors

Michael Kühl^*, Ronnie N. Glud, Jens Borum, Rodney Roberts, Søren Rysgaard

^*Corresponding author af dette arbejde

129 Citationer (Scopus)

Abstract

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 -2 to 30 μmol photons m^-2 s^-1. The compensation irradiance determined in the laboratory for coralline algae and brown macroalgae was 1.6 and 1.9 μmol 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 μmol 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 E_k 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) μmol 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 E_k values were shifted to higher irradiance, i.e. 6.9 μmol photons m^-2 s^-1 (benthic microalgae) and 11.5 to 16.1 μmol photons m^-2 s^-1 (brown macroalgae). This apparent short-term acclimation to increasing irradiance reversed to the initial characteristics of the light curve within 15 to 20 min after irradiance returned to ambient intensity. Our measurements add to the small database on in situ photosynthetic performance of surface-associated algae below ice cover. All phototrophs were well adapted to low irradiance under the ice, and active fluorescence measurements indicated that the phototrophs are able to adapt reversibly within minutes to moderate changes in irradiance levels.

Originalsprog	Engelsk
Tidsskrift	Marine Ecology Progress Series
Vol/bind	223
Sider (fra-til)	1-14
Antal sider	14
ISSN	0171-8630
DOI	https://doi.org/10.3354/meps223001
Status	Udgivet - 28 nov. 2001

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10.3354/meps223001

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@article{e1e75b3b2d304103a7b0e58c7e273484,

title = "Photosynthetic performance of surface-associated algae below sea ice as measured with a pulse-amplitude-modulated (PAM) fluorometer and O2 microsensors",

abstract = "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 -2 to 30 μmol photons m-2 s-1. The compensation irradiance determined in the laboratory for coralline algae and brown macroalgae was 1.6 and 1.9 μmol photons m-2 s-1 respectively. The same experiments showed irradiances at onset of saturation, Ek, for coralline red algae and brown macroalgae of 17 and 12.8 μmol 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) μmol 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 μmol photons m-2 s-1 (benthic microalgae) and 11.5 to 16.1 μmol photons m-2 s-1 (brown macroalgae). This apparent short-term acclimation to increasing irradiance reversed to the initial characteristics of the light curve within 15 to 20 min after irradiance returned to ambient intensity. Our measurements add to the small database on in situ photosynthetic performance of surface-associated algae below ice cover. All phototrophs were well adapted to low irradiance under the ice, and active fluorescence measurements indicated that the phototrophs are able to adapt reversibly within minutes to moderate changes in irradiance levels.",

keywords = "Arctic, Fluorescence, Macroalgae, Microalgae, Microsensor, Oxygen, Photosynthesis, Sea ice",

author = "Michael K{\"u}hl and Glud, {Ronnie N.} and Jens Borum and Rodney Roberts and S{\o}ren Rysgaard",

year = "2001",

month = nov,

day = "28",

doi = "10.3354/meps223001",

language = "English",

volume = "223",

pages = "1--14",

journal = "Marine Ecology - Progress Series",

issn = "0171-8630",

publisher = "Inter-Research",

}

TY - JOUR

T1 - Photosynthetic performance of surface-associated algae below sea ice as measured with a pulse-amplitude-modulated (PAM) fluorometer and O2 microsensors

AU - Kühl, Michael

AU - Glud, Ronnie N.

AU - Borum, Jens

AU - Roberts, Rodney

AU - Rysgaard, Søren

PY - 2001/11/28

Y1 - 2001/11/28

N2 - 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 -2 to 30 μmol photons m-2 s-1. The compensation irradiance determined in the laboratory for coralline algae and brown macroalgae was 1.6 and 1.9 μmol photons m-2 s-1 respectively. The same experiments showed irradiances at onset of saturation, Ek, for coralline red algae and brown macroalgae of 17 and 12.8 μmol 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) μmol 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 μmol photons m-2 s-1 (benthic microalgae) and 11.5 to 16.1 μmol photons m-2 s-1 (brown macroalgae). This apparent short-term acclimation to increasing irradiance reversed to the initial characteristics of the light curve within 15 to 20 min after irradiance returned to ambient intensity. Our measurements add to the small database on in situ photosynthetic performance of surface-associated algae below ice cover. All phototrophs were well adapted to low irradiance under the ice, and active fluorescence measurements indicated that the phototrophs are able to adapt reversibly within minutes to moderate changes in irradiance levels.

AB - 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 -2 to 30 μmol photons m-2 s-1. The compensation irradiance determined in the laboratory for coralline algae and brown macroalgae was 1.6 and 1.9 μmol photons m-2 s-1 respectively. The same experiments showed irradiances at onset of saturation, Ek, for coralline red algae and brown macroalgae of 17 and 12.8 μmol 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) μmol 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 μmol photons m-2 s-1 (benthic microalgae) and 11.5 to 16.1 μmol photons m-2 s-1 (brown macroalgae). This apparent short-term acclimation to increasing irradiance reversed to the initial characteristics of the light curve within 15 to 20 min after irradiance returned to ambient intensity. Our measurements add to the small database on in situ photosynthetic performance of surface-associated algae below ice cover. All phototrophs were well adapted to low irradiance under the ice, and active fluorescence measurements indicated that the phototrophs are able to adapt reversibly within minutes to moderate changes in irradiance levels.

KW - Arctic

KW - Fluorescence

KW - Macroalgae

KW - Microalgae

KW - Microsensor

KW - Oxygen

KW - Photosynthesis

KW - Sea ice

UR - http://www.scopus.com/inward/record.url?scp=0035965843&partnerID=8YFLogxK

U2 - 10.3354/meps223001

DO - 10.3354/meps223001

M3 - Journal article

AN - SCOPUS:0035965843

SN - 0171-8630

VL - 223

SP - 1

EP - 14

JO - Marine Ecology - Progress Series

JF - Marine Ecology - Progress Series

ER -