Abstract
Widespread long-term increases in dissolved organic carbon (DOC) concentrations (i.e., “browning”) have been observed in many lakes, but the ecological consequences are poorly understood. Some studies suggest a unimodal relationship between DOC and primary productivity, with peak productivity at intermediate DOC concentrations. This peak is hypothesized to result from the tradeoff between light absorbing properties of DOC, and increases in limiting nutrients with browning. Nevertheless, it is unclear whether nutrient stoichiometry is constant as lakes brown. Across both regional and national surveys, we found a positive linear relationship between DOC and both total and organic forms of nitrogen and phosphorus. However, long-term data from a suite of browning lakes indicates that total nutrients do not increase as DOC increases through time. Our results show that DOC and limiting nutrients are coupled spatially, but not temporally, and that this temporal mismatch challenges previous conceptualizations of the long-term effects of browning on productivity.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 182-191 |
| Number of pages | 10 |
| Journal | Limnology And Oceanography Letters |
| Volume | 6 |
| Issue number | 4 |
| DOIs | |
| State | Published - Aug 2021 |
Bibliographical note
Funding Information:We acknowledge support from the US National Science Foundation grants 1638704, 1754265, and 1761805 to KCR. We would like to thank Lacawac Sanctuary, The Darrin Freshwater Institute, Little Moose Field Station of Cornell University, University of Minnesota Itasca Biological Station, SUNY ESF Newcomb Campus, and Paul Smith's College for providing logistical support for our 2018 field survey, and the US EPA for providing publicly available national‐scale data. We also acknowledge Dan Josephson, Manuel Caballero, Natasha Karniski, Deb Mabey, Stephen Jane, Cody Sears, Katelyn Aupperle, and Lindsey Blake for providing field support and Dave Winkler for laboratory assistance. National Lakes Assessment Survey 2012 data were a result of the collective efforts of dedicated field crews, laboratory staff, data management and quality control staff, analysts and many others from EPA, states, tribes, federal agencies, universities, and other organizations. Please contact nars-hq@epa.gov with any questions.
Funding Information:
We acknowledge support from the US National Science Foundation grants 1638704, 1754265, and 1761805 to KCR. We would like to thank Lacawac Sanctuary, The Darrin Freshwater Institute, Little Moose Field Station of Cornell University, University of Minnesota Itasca Biological Station, SUNY ESF Newcomb Campus, and Paul Smith's College for providing logistical support for our 2018 field survey, and the US EPA for providing publicly available national-scale data. We also acknowledge Dan Josephson, Manuel Caballero, Natasha Karniski, Deb Mabey, Stephen Jane, Cody Sears, Katelyn Aupperle, and Lindsey Blake for providing field support and Dave Winkler for laboratory assistance. National Lakes Assessment Survey 2012 data were a result of the collective efforts of dedicated field crews, laboratory staff, data management and quality control staff, analysts and many others from EPA, states, tribes, federal agencies, universities, and other organizations. Please contact nars-hq@epa.gov with any questions.
Publisher Copyright:
© 2021 The Authors. Limnology and Oceanography Letters published by Wiley Periodicals LLC on behalf of Association for the Sciences of Limnology and Oceanography.