SHALLOW LAKE ECOSYSTEMS Review Paper Nitrogen, macrophytes, shallow lakes and nutrient limitation: resolution of a current controversy? Brian Moss • Erik Jeppesen • Martin Søndergaard • Torben L. Lauridsen • Zhengwen Liu Received: 29 July 2011 / Accepted: 12 February 2012 / Published online: 6 March 2012 Ó Springer Science+Business Media B.V. 2012 Abstract Phosphorus (P) is conventionally thought to limit production in freshwaters and nitrogen (N) that in the sea. Before much human activity, however, co- limitation by N and P was probably normal, with systems developing ratios of N to P tending to the Redfield ratio. Single-factor limitation may be a symptom of human activity in many cases. It is widely believed that N fixation should compensate for N shortage because N fixers are ubiquitous and versatile, but this is not always the case and the issue has hitherto been considered largely with respect to plankton communities. Effects of N on macrophyte communi- ties provide justification for control of both nutrients, at least in shallow lakes and estuaries. Increased N loading reduces plant biodiversity, changes the struc- ture, and is associated with eventual loss, of macro- phyte communities. P control alone may suffice in many deep lakes where denitrification is low and stratified conditions favour cyanobacterial develop- ment. Therein may lie a resolution to current controversies. Keywords Limiting nutrient Á Biodiversity Á Redfield ratio Á Stoichiometry Á Phosphorus Á Restoration Á Estuaries Á Climate change Introduction When eutrophication was first noted as a problem, by Naumann (1931), and publicised in English by Hasler (1947), it was ascribed to both nitrogen (N) and phosphorus (P), and this ascription was held by subsequent early authors (Edmondson et al., 1956; Oglesby & Edmondson, 1966; Sawyer, 1966; Lund, 1967; Anonymous, 1969). The problem was associ- ated largely with urban wastewater effluents, which Guest editors: Zhengwen Liu, Bo-Ping Han & Ramesh D. Gulati / Conservation, management and restoration of shallow lake ecosystems facing multiple stressors B. Moss (&) School of Environmental Sciences, University of Liverpool, Liverpool, UK e-mail: brmoss@liverpool.ac.uk E. Jeppesen Á M. Søndergaard Á T. L. Lauridsen Department of Bioscience, Aarhus University, Vejlsøvej 25, 8600 Silkeborg, Denmark E. Jeppesen Á T. L. Lauridsen Á Z. Liu Sino-Danish Centre for Education and Research (SDC), Beijing, China E. Jeppesen Greenland Climate Research Centre (GCRC), Greenland Institute of Natural Resources, Kivioq 2, P.O. Box 570, 3900 Nuuk, Greenland Z. Liu Nanjing Institute of Geography & Limnology, Chinese Academy of Sciences, Nanjing 210008, China Z. Liu Institute of Hydrobiology, Jinan University, Guangzhou 510632, Guangdong, China 123 Hydrobiologia (2013) 710:3–21 DOI 10.1007/s10750-012-1033-0