TY  - JOUR
A1  - Brothers, Soren M.
A1  - Hilt, Sabine
A1  - Attermeyer, Katrin
A1  - Grossart, Hans-Peter
A1  - Kosten, Sarian
A1  - Lischke, Betty
A1  - Mehner, Thomas
A1  - Meyer, Nils
A1  - Scharnweber, Inga Kristin
A1  - Köhler, Jan
T1  - A regime shift from macrophyte to phytoplankton dominance enhances carbon burial in a shallow, eutrophic lake
JF  - Ecosphere : the magazine of the International Ecology University
N2  - Ecological regime shifts and carbon cycling in aquatic systems have both been subject to increasing attention in recent years, yet the direct connection between these topics has remained poorly understood. A four-fold increase in sedimentation rates was observed within the past 50 years in a shallow eutrophic lake with no surface in-or outflows. This change coincided with an ecological regime shift involving the complete loss of submerged macrophytes, leading to a more turbid, phytoplankton-dominated state. To determine whether the increase in carbon (C) burial resulted from a comprehensive transformation of C cycling pathways in parallel to this regime shift, we compared the annual C balances (mass balance and ecosystem budget) of this turbid lake to a similar nearby lake with submerged macrophytes, a higher transparency, and similar nutrient concentrations. C balances indicated that roughly 80% of the C input was permanently buried in the turbid lake sediments, compared to 40% in the clearer macrophyte-dominated lake. This was due to a higher measured C burial efficiency in the turbid lake, which could be explained by lower benthic C mineralization rates. These lower mineralization rates were associated with a decrease in benthic oxygen availability coinciding with the loss of submerged macrophytes. In contrast to previous assumptions that a regime shift to phytoplankton dominance decreases lake heterotrophy by boosting whole-lake primary production, our results suggest that an equivalent net metabolic shift may also result from lower C mineralization rates in a shallow, turbid lake. The widespread occurrence of such shifts may thus fundamentally alter the role of shallow lakes in the global C cycle, away from channeling terrestrial C to the atmosphere and towards burying an increasing amount of C.
KW  - calcite precipitation
KW  - CO2 emissions
KW  - global carbon cycle
KW  - metabolism
KW  - regime shift
KW  - sedimentation
KW  - submerged macrophytes
KW  - temperate zone
KW  - trophic status
Y1  - 2013
U6  - https://doi.org/10.1890/ES13-00247.1
SN  - 2150-8925
VL  - 4
IS  - 11
PB  - Wiley
CY  - Washington
ER  -