Experimental whole-lake increase of dissolved organic carbon concentration produces unexpected increase in crustacean zooplankton density

Global Change Biology
Notre Dame University, McGill University
By: , and 

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Abstract

The observed pattern of lake browning, or increased terrestrial dissolved organic carbon (DOC) concentration, across the northern hemisphere has amplified the importance of understanding how consumer productivity varies with DOC concentration. Results from comparative studies suggest these increased DOC concentrations may reduce crustacean zooplankton productivity due to reductions in resource quality and volume of suitable habitat. Although these spatial comparisons provide an expectation for the response of zooplankton productivity as DOC concentration increases, we still have an incomplete understanding of how zooplankton respond to temporal increases in DOC concentration within a single system. As such, we used a whole-lake manipulation, in which DOC concentration was increased from 8 to 11 mg L−1 in one basin of a manipulated lake, to test the hypothesis that crustacean zooplankton production should subsequently decrease. In contrast to the spatially derived expectation of sharp DOC-mediated decline, we observed a small increase in zooplankton densities in response to our experimental increase in DOC concentration of the treatment basin. This was due to significant increases in gross primary production and resource quality (lower seston carbon-to-phosphorus ratio; C:P). These results demonstrate that temporal changes in lake characteristics due to increased DOC may impact zooplankton in ways that differ from those observed in spatial surveys. We also identified significant interannual variability across our study region, which highlights potential difficulty in detecting temporal responses of organism abundances to gradual environmental change (e.g., browning).

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Experimental whole-lake increase of dissolved organic carbon concentration produces unexpected increase in crustacean zooplankton density
Series title Global Change Biology
DOI 10.1111/gcb.13260
Volume 22
Issue 8
Year Published 2016
Language English
Publisher Wiley
Contributing office(s) Great Lakes Science Center
Description 9 p.
First page 2766
Last page 2775
Country United States
State Michigan
Other Geospatial Long Lake
Online Only (Y/N) N
Additional Online Files (Y/N) N