Shifts in Lake N:P Stoichiometry and Nutrient Limitation Driven by Atmospheric Nitrogen Deposition
James J. Elser,1,*
Tom Andersen,2
Jill S. Baron,3
Ann-Kristin Bergström,4
Mats Jansson,4
Marcia Kyle,1
Koren R. Nydick,5
Laura Steger,1
Dag O. Hessen2
Human activities have more than doubled the amount of nitrogen
(N) circulating in the biosphere. One major pathway of this
anthropogenic N input into ecosystems has been increased regional
deposition from the atmosphere. Here we show that atmospheric
N deposition increased the stoichiometric ratio of N and phosphorus
(P) in lakes in Norway, Sweden, and Colorado, United States,
and, as a result, patterns of ecological nutrient limitation
were shifted. Under low N deposition, phytoplankton growth is
generally N-limited; however, in high–N deposition lakes,
phytoplankton growth is consistently P-limited. Continued anthropogenic
amplification of the global N cycle will further alter ecological
processes, such as biogeochemical cycling, trophic dynamics,
and biological diversity, in the world’s lakes, even in
lakes far from direct human disturbance.
2 Department of Biology, University of Oslo, Post Office Box 1027 Blindern, N-0316 Oslo, Norway.
3 United States Geological Survey and Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523, USA.
4 Department of Ecology and Environmental Science, Umeå University, 901 87 Umeå, Sweden.
5 Mountain Studies Institute, Post Office Box 426, 1315 Snowden Street, Silverton, CO 81433, USA.
* To whom correspondence should be addressed. E-mail: j.elser{at}asu.edu
