title: Seasonal patterns of nitrogen and phosphorus limitation in four German lakes and the predictability of limitation status from ambient nutrient concentrations.
abstract: To identify the seasonal pattern of nitrogen (N) and phosphorus (P) limitation of phytoplankton in four different lakes, biweekly experiments were conducted from the end of March to September 2011. Lake water samples were enriched with N, P or both nutrients and incubated under two different light intensities. Chlorophyll a fluorescence (Chla) was measured and a model selection procedure was used to assign bioassay outcomes to different limitation categories. N and P were both limiting at some point. For the shallow lakes there was a trend from P limitation in spring to N or light limitation later in the year, while the deep lake remained predominantly P limited. To determine the ability of in-lake N:P ratios to predict the relative strength of N vs. P limitation, three separate regression models were fit with the log-transformed ratio of Chla of the P and N treatments (Response ratio = RR) as the response variable and those of ambient total phosphorus:total nitrogen (TN:TP), dissolved inorganic nitrogen:soluble reactive phosphorus (DIN:SRP), TN:SRP and DIN:TP mass ratios as predictors. All four N:P ratios had significant positive relationships with RR, such that high N:P ratios were associated with P limitation and low N:P ratios with N limitation. The TN:TP and DIN:TP ratios performed better than the DIN:SRP and TN:SRP in terms of misclassification rate and the DIN:TP ratio had the highest R₂ value. Nitrogen limitation was predictable, frequent and persistent, suggesting that nitrogen reduction could play a role in water quality management. However, there is still uncertainty about the efficacy of N restriction to control populations of N₂ fixing cyanobacteria.
authors.affiliation: Brandenburg University of Technology Cottbus - Senftenberg, Department of Freshwater Conservation, Bad Saarow, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Kolzau
authors.affiliation: Brandenburg University of Technology Cottbus - Senftenberg, Department of Freshwater Conservation, Bad Saarow, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Wiedner
authors.affiliation: Brandenburg University of Technology Cottbus - Senftenberg, Department of Freshwater Conservation, Bad Saarow, Germany.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Rücker
authors.affiliation: Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Köhler
authors.affiliation: Berlin Senate - Department for Urban Development and the Environment, Berlin, Germany.
authors.forename: Antje
authors.initials: A
authors.lastname: Köhler
authors.affiliation: Brandenburg University of Technology Cottbus - Senftenberg, Department of Freshwater Conservation, Bad Saarow, Germany.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Dolman
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D000458:Cyanobacteria / Q000378:metabolism; D005858:Germany; D060106:Lakes / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry* / Q000378:metabolism; D010758:Phosphorus / Q000737:chemistry* / Q000378:metabolism; D010839:Phytoplankton / Q000378:metabolism; D012621:Seasons
chemical_list: D002734:Chlorophyll; D010758:Phosphorus; D009584:Nitrogen; D000077194:Chlorophyll A
references.citation: Science. 1977 Jan 21;195(4275):260-2
references.pmid: 17787798
references.citation: Sci Prog. 1960;11:150-70
references.pmid: 24545739
references.citation: Nature. 2004 May 13;429(6988):171-4
references.pmid: 15141209
references.citation: Ecol Lett. 2011 Sep;14(9):852-62
references.pmid: 21749598
references.citation: Environ Sci Technol. 2011 Dec 15;45(24):10300-5
references.pmid: 22070635
references.citation: PLoS One. 2011 Mar 31;6(3):e18508
references.pmid: 21483809
references.citation: PLoS One. 2012;7(6):e38757
references.pmid: 22719937
references.citation: Environ Sci Pollut Res Int. 2003;10(2):126-39
references.pmid: 12729046
references.citation: Ecol Lett. 2007 Dec;10(12):1135-42
references.pmid: 17922835
references.citation: Proc Biol Sci. 2012 Nov 7;279(1746):4322-33
references.pmid: 22915669
references.citation: Oecologia. 2007 Jun;152(3):473-84
references.pmid: 17375336
references.citation: Ecol Appl. 2010 Sep;20(6):1542-55
references.pmid: 20945758
references.citation: Water Res. 2009 Apr;43(6):1788-800
references.pmid: 19232667
references.citation: J Environ Qual. 2010 Feb 19;39(2):725-33
references.pmid: 20176845
references.citation: Proc Natl Acad Sci U S A. 2008 Aug 12;105(32):11254-8
references.pmid: 18667696