Linking phosphorus pools of water, sediment and macrophytes in running waters

University of Metz, UFR Sci. F.A., UPRES EBSE, Equipe de Phytoécologie, Campus Bridoux, Avenue du Général Delestraint, F-57070 Metz, France.

Corresponding author: thiebaut@sciences.univ-metz.fr

Abstract

The aim of our paper was to study the space and time variations of phosphorus contents in the sediment, water and tissue of aquatic plants. Tissue Total Phosphorus of six aquatic plants (Callitriche platycarpa, C. hamulata, C. obtusangula, Elodea nuttallii, E. canadensis and Ranunculus peltatus) was analysed alongside the sediment Total Phosphorus (TP) and Soluble Reactive Phosphorus concentrations (SRP) in water, at the same site. Twelve sites were selected, and, samples were collected to test the seasonal and the annual patterns of phosphorus variation in 3 compartments. Streams ranged from oligotrophic to eutrophic waters. The sediments varied from mesotrophic to eutrophic states. A highly significant site effect was shown for water and for sediment. Water SRP varied with time (season, year), whereas no significant time effect was established for the sediment TP. Tissue TP varied according to year and season in Callitriche platycarpa, C. hamulata and E. nuttallii. The tissue phosphorus storage depended on the trophic level of sediment and water and varied according to species. The rank order of tissue TP content was C. obtusangula > R. peltatus ≥ E. nuttallii ≥ E. canadensis > C. platycarpa > C. hamulata. Removal of aquatic plants biomass with its accumulated phosphorus could be an alternative technique to other eutrophication control strategies. Further work is needed to improve our knowledge to estimate the ecological risk of harvesting on biodiversity and on ecosystem function.