Pulse amplitude modulated fluorescence in the green macrophytes,Codium adherens,Enteromorpha muscoides,Ulva gigantea and Ulva rigida,from the Atlantic coast of Southern Spain |
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| Institution: | 1. Departamento de Biología, Área de Ecología, Facultad de Ciencias del Mar y Ambientales, Universidad de Cádiz, 11510, Puerto Real, Cádiz, Spain;2. Dipartimento di Scienze della terra, dell''ambiente e della vita (DISTAV), Università degli Studi di Genova, Corso Europa, 26 16132, Genova, Italy;3. GEOMAR Helmholtz Centre for Ocean Research Kiel, Experimental Ecology (Foodwebs), Düsternbrooker Weg 20, D-24105 Kiel, Germany;1. Intelligent Automotive Systems Group, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft, The Netherlands;2. Integrated Vehicle Safety Department, The Netherlands Organization for Applied Scientific Research (TNO), Automotive Campus 30, 5708 JZ Helmond, The Netherlands;3. Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Via Ponzio 34/5, 20133 Milano, Italy;4. SKF Automotive Division, Nieuwegein 3430 DT, The Netherlands;1. Physics Department, Faculty of Science (Girl''s Branch), Al Azhar University, Nasr City, Cairo, Egypt;2. Physics Department, Faculty of Science, Al-Azhar University, Nasr City, 11884 Cairo, Egypt |
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| Abstract: | The effect of ambient and enhanced solar radiation on the photosynthetic apparatus in four marine green macroalgae on the Southern coast of Spain (Strait of Gibraltar) was investigated using pulse amplitude modulation (PAM) fluorescence. The dependence of the fluorescence parameters on the irradiance of the actinic light was determined for all four species. It showed that maximal fluorescence after light adaptation (Fm′), photochemical quenching (qP) and the photosynthetic quantum yield decreased in Enteromorpha muscoides with irradiance while non-photochemical quenching (qN) rose continuously. In Ulva rigida the photosynthetic quantum yield dropped at irradiances above 4 W m?2 but qP did not decrease with increasing light. qN quenching rose sharply above 37 W m?2, and maximal fluorescence dropped above 1 W m?2. In Ulva gigantea the yield dropped to zero at irradiances of 37 W m?2, as did qP at 53 W m?2. qN started from an intermediate level and increased to a maximum at the highest irradiances. In Codium adherens, the yield and qP behaved similarly as in U. rigida, while qN rose at much lower irradiances. All investigated algae suffered from photoinhibition even at their natural sites of growth when the sun is at high angles. The hypothesis that algae with flat thalli suffer more than those with massive ones was confirmed. Photoinhibition was less pronounced in U. rigida and C. adherens than in the other two species. After 1 h of exposure to solar radiation at the surface, the photosynthetic quantum yield decreased substantially in the surface algae E. muscoides and U. rigida. In both macroalgae, recovery of the photosynthetic quantum yield was almost complete after 2–3 h in the shade. Two other green algae from shaded habitats (U. gigantea and C. adherens) did not show complete recovery of the yield from photoinhibition. This confirms the second hypothesis that sun-adapted algae recover faster from photoinhibition than those adapted to shaded sites. |
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