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Photosynthetic traits of freshwater lichens are consistent with the submersion conditions of their habitat

Coste, C. and Chauvet, Eric and Grieu, Philippe and Lamaze, Thierry Photosynthetic traits of freshwater lichens are consistent with the submersion conditions of their habitat. (2016) Annales de Limnologie - International Journal of Limnology, vol. 52. pp. 235-242. ISSN 0003-4088

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Official URL: http://dx.doi.org/10.1051/limn/2016009

Abstract

In this study, we compared the photosynthetic performance of epilithic freshwater lichens on siliceous stream rock submerged for: more than 9 (hyper-), 6–9 (meso-) or 3–6 months (sub-hydrophilic lichens). In the dry state, neither variable fluorescence nor respiration activity could be detected. In the wet state, rates of dark respiration (O2 uptake and CO2 production for immerged and in-air samples) were in the lower range of that reported for non-aquatic lichens. With 200 (under water) or 500 mmol.mx2.sx1 photosyntheticallly active photon flux density (PPFD) (aerial), photosynthesis was positive but rates were lower than that published for non-aquatic species. Under intense PPFD (2000 mmol.mx2.sx1, aerial), photo- synthesis increased in sub- but became negative in hyper-hydrophilic species. After hydration, dry samples increased photosystem II (PSII) efficiency, which reached near steady state in <6–7 min. Hyper-hydrophilic lichen took longer than sub-hydrophilic species. A long period of desiccation (4 months) had a negative effect on subsequent PSII photochemistry of hyper- but not of sub-hydrophilic hydrated lichens. When thalli were allowed to dehydrate, all types of lichens lost PSII activity after about 15–20 min. Deactivation was faster in the hyper- than in the sub-hydrophilic species. The metabolic traits presented here are thus consistent with the ecological amplitude of the freshwater lichens studied.

Item Type:Article
Additional Information:Thanks to EDP Sciences editor. The definitive version is available at http://www.limnology-journal.org/articles/limn/abs/2016/01/limn150062/limn150062.html
HAL Id:hal-01336658
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National des Etudes Spatiales - CNES (FRANCE)
French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
French research institutions > Institut National de la Recherche Agronomique - INRA (FRANCE)
French research institutions > Institut de Recherche pour le Développement - IRD (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
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Deposited By: Eric Chauvet
Deposited On:23 Jun 2016 13:02

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