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Regional variability among nonlinear chlorophyll—phosphorus relationships in lakes
Author(s) -
Filstrup Christopher T.,
Wagner Tyler,
Soranno Patricia A.,
Stanley Emily H.,
Stow Craig A.,
Webster Katherine E.,
Downing John A.
Publication year - 2014
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2014.59.5.1691
Subject(s) - wetland , chlorophyll a , environmental science , chlorophyll , temperate climate , phosphorus , ecology , ecosystem , atmospheric sciences , biology , botany , chemistry , physics , organic chemistry
The relationship between chlorophyll a (Chl a ) and total phosphorus (TP) is a fundamental relationship in lakes that reflects multiple aspects of ecosystem function and is also used in the regulation and management of inland waters. The exact form of this relationship has substantial implications on its meaning and its use. We assembled a spatially extensive data set to examine whether nonlinear models are a better fit for Chl a —TP relationships than traditional log‐linear models, whether there were regional differences in the form of the relationships, and, if so, which regional factors were related to these differences. We analyzed a data set from 2105 temperate lakes across 35 ecoregions by fitting and comparing two different nonlinear models and one log‐linear model. The two nonlinear models fit the data better than the log‐linear model. In addition, the parameters for the best‐fitting model varied among regions: the maximum and lower Chl a asymptotes were positively and negatively related to percent regional pasture land use, respectively, and the rate at which chlorophyll increased with TP was negatively related to percent regional wetland cover. Lakes in regions with more pasture fields had higher maximum chlorophyll concentrations at high TP concentrations but lower minimum chlorophyll concentrations at low TP concentrations. Lakes in regions with less wetland cover showed a steeper Chl a —TP relationship than wetland‐rich regions. Interpretation of Chl a —TP relationships depends on regional differences, and theory and management based on a monolithic relationship may be inaccurate.