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Spatial analysis if prodution by macrophytes, phytoplankton and epiphyton in a large river system under different water-level conditions

Vis, C. et Hudon, C. et Carignan, R. et Gagnon, P. (2007). Spatial analysis if prodution by macrophytes, phytoplankton and epiphyton in a large river system under different water-level conditions. Ecosystems , 10 (2). p. 293-310. DOI: 10.1007/s10021-007-9021-3.

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Résumé

Relative contributions by macrophytes, epiphyton and phytoplankton to total primary production was estimated in a large (~300 km2) widening of the St. Lawrence River (Canada), over a 2-year period with contrasting flows and water levels. Spatially-explicit estimates of whole-system production were obtained by combining field measurements with remotely sensed data and empirical models using GIS. Primary production and relative contributions of each producer type differed markedly between open-water and wetland habitats. Spatial differences within each habitat arose from interactions between physical factors including light, water depth, water transit times and wind stress. At the whole-system level, annual primary production represented 105 gC m-2 y-1, divided roughly equally among phytoplankton (34 %), submerged macrophytes (27 %), emergent macrophytes (23 %) and epiphyton (16 %). A 10% decrease in annual flows and 1-m decline in water levels between 2000 and 2001 resulted in a 50 % loss of marsh habitat, a 60 % increase in phytoplankton production in the open-water zone, and in the appearance of conspicuous filamentous algal mats. Low water levels induced substantial shifts in the spatial configuration and relative importance of primary producers although total river primary production remained stable between years.

Type de document: Article scientifique
Statut du texte intégral: Autre
Mots-clés libres: Large rivers, Fluvial lake, Primary production, Phytoplankton, Epiphyton, Macrophytes, Low water levels
Sujets: 3. Végétation, milieux humides
Date de dépôt: 25 août 2016 15:20
Dernière modification: 25 août 2016 15:20
URI: http://belsp.uqtr.ca/id/eprint/574

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Concepteur de la BELSP : André Barabé, Ph. D.