Hostname: page-component-586b7cd67f-gb8f7 Total loading time: 0 Render date: 2024-11-28T04:00:21.830Z Has data issue: false hasContentIssue false
  • English
  • Français

Photosynthetic rates of Ulva (Chlorophyta) measured by pulse amplitude modulated (PAM) fluorometry

Published online by Cambridge University Press:  01 February 2000

SVEN BEER ,
CHRISTER LARSSON ,
ORNA PORYAN  and
LENNART AXELSSON
SVEN BEER
Affiliation:
Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel
CHRISTER LARSSON
Affiliation:
Kristineberg Marine Research Station, S-450 34 Fiskebäckskil, Sweden
ORNA PORYAN
Affiliation:
Department of Plant Sciences, Tel Aviv University, Tel Aviv 69978, Israel
LENNART AXELSSON
Affiliation:
Kristineberg Marine Research Station, S-450 34 Fiskebäckskil, Sweden
Get access

Abstract

In this work, we attempt to quantify pulse amplitude modulated (PAM) chlorophyll fluorescence measurements in marine macroalgae in terms of photosynthetic rates. For this, the effective electron transfer quantum yield of photosystem II measured for two Ulva species, at various irradiances and inorganic carbon (Ci) concentrations, was multiplied by the estimated flux of photons absorbed by the photosynthetic pigments associated with this photosystem. The rates of electron transport (ETR) calculated in this way were then compared with rates of photosynthetic O2 evolution as measured in association with the fluorescence measurements. It was found that the calculated ETRs correlated linearly with rates of ‘gross’ O2 evolution (net O2 exchange corrected for dark respiration as measured immediately after turning off each irradiance level) within the range of irradiances applied (up to 608 μmol photons m−2 s−1). The average molar O2/ETR ratio was 0·238 for Ulva lactuca and 0·261 for Ulva fasciata, which is close to the theoretical maximal value of 0·25. Rates of O2 evolution at various concentrations of Ci also showed linear correlations with ETR, and the average molar O2/ETR ratio was 0·249. These results show that PAM fluorometry can be used as a practical tool for quantifying photosynthetic rates at least under moderate irradiances in thin-bladed macroalgae such as Ulva possessing a CO2-concentrating system. A comparison between the PAM-101 (which was used in Sweden for the light- and Ci-response measurements of Ulva lactuca) and the newly developed portable Diving-PAM (used for Ulva fasciata in Israel) showed that such fluorescence-based photosynthetic rate measurements can also be carried out in situ.

Keywords

oxygen evolutionPAM fluorometryphotosynthesisUlva
Type
Research Article
Information
European Journal of Phycology , Volume 35 , Issue 1 , February 2000 , pp. 69 - 74
Copyright
© 2000 British Phycological Society

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)