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Effets de la limitation en sels nutritifs, de la température et de leurs interactions sur la réponse de cinq espèces phytoplanctoniques : Approche multifactorielle expérimentale en monoculture et en communauté

Abstract : The effects of nitrogen and phosphorus depletion, temperature and their interaction were studied on five microalgae which differ in terms of phenology and size. By a multifactorial experimental approach, we demonstrated that nutrient effects override temperature effects, and that species from a same classical functional group could show different responses. Our results suggest that size matters for the responses of microalgae in our different conditions. Indeed, an interactive effect of temperature and nutrients was observed leading to decrease of photosynthetic activity of the small sized algae. These species also showed a high variability in their responses compared to larger ones. Furthermore, particular and dissolved carbohydrates per cell was positively influenced by nutrient limitation, temperature or their interaction, independently of cell size but rather in a specific way. Lastly, in order to highlight the relationship between productivity and diversity three experimental communities were done under nitrogen or phosphorus depletion. Our results demonstrated a better efficiency of nutrient and light absorption of communities compared to monocultures. However these communities were overall less productive than monocultures in terms of carbohydrate and biomass formation. No clear trend between diversity and productivity was shown in our study. Our results provide useful information about the responses of phytoplankton to environmental gradients and consequently of several ecosystem processes taking into accounts the modifications expected through global change.
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https://tel.archives-ouvertes.fr/tel-01128344
Contributor : Fabien Dufossé <>
Submitted on : Monday, March 9, 2015 - 3:30:48 PM
Last modification on : Thursday, January 7, 2021 - 3:01:01 AM
Long-term archiving on: : Wednesday, June 10, 2015 - 4:15:40 PM

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  • HAL Id : tel-01128344, version 1

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Fabien Dufossé. Effets de la limitation en sels nutritifs, de la température et de leurs interactions sur la réponse de cinq espèces phytoplanctoniques : Approche multifactorielle expérimentale en monoculture et en communauté. Biodiversité et Ecologie. Université des sciences et technologies de Lille 1, 2014. Français. ⟨tel-01128344v1⟩

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