TY  - JOUR
A1  - Brothers, Soren M.
A1  - Hilt, Sabine
A1  - Meyer, Stephanie
A1  - Köhler, Jan
T1  - Plant community structure determines primary productivity in shallow, eutrophic lakes
T2  - Freshwater biology
N2  - Regime shifts are commonly associated with the loss of submerged macrophytes in shallow lakes; yet, the effects of this on whole-lake primary productivity remain poorly understood. This study compares the annual gross primary production (GPP) of two shallow, eutrophic lakes with different plant community structures but similar nutrient concentrations. Daily GPP rates were substantially higher in the lake containing submerged macrophytes (58623gCm(-2)year(-1)) than in the lake featuring only phytoplankton and periphyton (40823gCm(-2)year(-1); P<0.0001). Comparing lake-centre diel oxygen curves to compartmental estimates of GPP confirmed that single-site oxygen curves may provide unreliable estimates of whole-lake GPP. The discrepancy between approaches was greatest in the macrophyte-dominated lake during the summer, with a high proportion of GPP occurring in the littoral zone. Our empirical results were used to construct a simple conceptual model relating GPP to nutrient availability for these alternative ecological regimes. This model predicted that lakes featuring submerged macrophytes may commonly support higher rates of GPP than phytoplankton-dominated lakes, but only within a moderate range of nutrient availability (total phosphorus ranging from 30 to 100gL(-1)) and with mean lake depths shallower than 3 or 4m. We conclude that shallow lakes with a submerged macrophyte-epiphyton complex may frequently support a higher annual primary production than comparable lakes that contain only phytoplankton and periphyton. We thus suggest that a regime shift involving the loss of submerged macrophytes may decrease the primary productivity of many lakes, with potential consequences for the entire food webs of these ecosystems.
KW  - macrophytes
KW  - oxygen curves
KW  - periphyton
KW  - regime shift
KW  - trophic status
Y1  - 2013
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/34650
SN  - 0046-5070
VL  - 58
IS  - 11
SP  - 2264
EP  - 2276
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -