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AB 22:195-212 (2014)  -  DOI:

Continuous monitoring of in vivo chlorophyll a fluorescence in Ulva rigida (Chlorophyta) submitted to different CO2, nutrient and temperature regimes

F. L. Figueroa1,*, R. Conde-Álvarez1, J. Bonomi Barufi2, P. S. M. Celis-Plá1, P. Flores1, E. J. Malta3, D. B. Stengel4, O. Meyerhoff5, A. Pérez-Ruzafa6

1Department of Ecology, Faculty of Sciences, University of Malaga, 29071 Malaga, Spain
2Departamento de Botânica, Universidade Federal de Santa Catarina, 88040-970 Trindade, Florianópolis, SC, Brazil
3Centro IFAPA Agua del Pino, Crtra. El Rompido Punta Umbría, 21459 Cartaya (Huelva), Spain
4Botany and Plant Science, School of Natural Sciences, Ryan Institute for Environmental Marine and Energy Research, National University of Ireland Galway, Galway, Ireland
5Heinz Walz GmbH, Eichenring 6, 91090 Effeltrich, Germany
6Department of Ecology and Hydrology, Faculty of Biology, Regional Campus of International Excellence ‘Campus Mare Nostrum’, University of Murcia, 30100 Murcia, Spain
*Corresponding author:

ABSTRACT: A Monitoring-PAM fluorometer with high temporal resolution (every 5 min) was used to assess the effects on photosynthesis in Ulva rigida (Chlorophyta) during exposure to 2 different CO2 conditions: current (‘LC’, 390 ppm), and the predicted level for the year 2100 (‘HC’, 700 ppm) in a crossed combination with 2 different daily pulsed nitrate concentrations (‘LN’, 5 µM and ‘HN’, 50 µM) and 2 temperature regimes (ambient and ambient +4°C). Effective quantum yield (ΔF/Fm’) in the afternoon was lower under HCLN conditions than under the other treatments. The decrease in ΔF/Fm’ from noon to the afternoon was significantly lower under +4°C compared to ambient temperature. Maximal quantum yield (Fv/Fm) decreased during the night with a transient increase 1 to 3 h after sunset, whereas a transient increase in ΔF/Fm’ was observed after sunrise. These transient increases have been related to activation/deactivation of the electron transport rate and the relaxation of non-photochemical quenching. Relative electron transport rate was higher under the LC and +4°C treatment, but the differences were not significant due to high variability in daily irradiances. Redundancy analysis on the data matrix for the light periods indicates that photosynthetically active radiation through the day is the main variable determining the physiological responses. The effects of nutrient levels (mainly carbon) and experimental increase of temperature were low but significant. During the night, the effect of nutrient availability is of special importance with an opposite effect of nitrogen compared to carbon increase. The application of the Monitoring-PAM to evaluate the effects of environmental conditions by simulating climate change variations under outdoor-controlled, semi-controlled conditions is discussed.

KEY WORDS: Climate change · In vivo chlorophyll fluorescence · Monitoring-PAM · Nitrate · Ocean acidification · Temperature · Ulva rigida

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Cite this article as: Figueroa FL, Conde-Álvarez R, Bonomi Barufi J, Celis-Plá PSM and others (2014) Continuous monitoring of in vivo chlorophyll a fluorescence in Ulva rigida (Chlorophyta) submitted to different CO2, nutrient and temperature regimes. Aquat Biol 22:195-212.

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