title: Measuring the trophic status of ponds: relationships between summer rate of periphytic net primary productivity and water physico-chemistry.
abstract: The monitoring of the water quality is a major environmental concern and specific method of assessment needs to be addressed for ponds. Among threats on freshwater, eutrophication remains an important and widespread problem. To assess if the trophic state of ponds can be significantly predicted by physico-chemical surrogates, parallel measurements of water physico-chemistry and of summer rates of periphytic net primary productivity (NPP) were performed on a set of nine lowland Swiss ponds representing the whole spectrum of trophic states. The developed methods to measure periphytic NPP on artificial substrates give similar values between the pseudo-replicates and are functional for ponds. The winter concentration of total nitrogen (TN) in the water is a significant predictor of the average summer rates of NPP while in submerged macrophyte beds total phosphorus (TP) is a better predictor. Rates of NPP measured in open water were most often higher and water transparency lower than in macrophyte beds, highlighting the positive influence of macrophytes on water quality and a possible co-occurrence in a pond of contrasting conditions when submerged species are present. This emphasizes the importance of maintaining or restoring submerged macrophyte stands in ponds to improve the water quality.
authors.affiliation: Laboratory of Ecology and Aquatic Biology (LEBA), University of Geneva, Chemin des Clochettes 18, CH-1206 Geneva, Switzerland. lionel.sager@unige.ch
authors.forename: Lionel
authors.initials: L
authors.lastname: Sager
mesh_terms: D000383:Agriculture; D000818:Animals; D004784:Environmental Monitoring; D005399:Fishes; D005618:Fresh Water / Q000032:analysis* / Q000737:chemistry; D005843:Geography; D019015:Geologic Sediments / Q000032:analysis; D006801:Humans; D009584:Nitrogen / Q000032:analysis; D012621:Seasons; D012996:Solutions; D013557:Switzerland; D014874:Water Pollutants, Chemical / Q000032:analysis
chemical_list: D012996:Solutions; D014874:Water Pollutants, Chemical; D009584:Nitrogen