Delving deeper: Metabolic processes in the metalimnion of stratified lakes: Metalimnetic metabolism in lakes


Giling DP, Staehr PA, Grossart HP, Andersen MR, Boehrer B, Escot C, Evrendilek F, Gómez-Gener L, Honti M, Jones ID, Karakaya N, Laas A, Moreno-Ostos E, Rinke K & Scharfenberger U (2017) Delving deeper: Metabolic processes in the metalimnion of stratified lakes: Metalimnetic metabolism in lakes. Limnology and Oceanography, 62 (3), pp. 1288-1306.

Many lakes exhibit seasonal stratification, during which they develop strong thermal and chemical gradients. An expansion of depth‐integrated monitoring programs has provided insight into the importance of organic carbon processing that occurs below the upper mixed layer. However, the chemical and physical drivers of metabolism and metabolic coupling remain unresolved, especially in the metalimnion. In this depth zone, sharp gradients in key resources such as light and temperature co‐occur with dynamic physical conditions that influence metabolic processes directly and simultaneously hamper the accurate tracing of biological activity. We evaluated the drivers of metalimnetic metabolism and its associated uncertainty across 10 stratified lakes in Europe and North America. We hypothesized that the metalimnion would contribute highly to whole‐lake functioning in clear oligotrophic lakes, and that metabolic rates would be highly variable in unstable polymictic lakes. Depth‐integrated rates of gross primary production (GPP) and ecosystem respiration (ER) were modelled from diel dissolved oxygen curves using a Bayesian approach. Metabolic estimates were more uncertain below the epilimnion, but uncertainty was not consistently related to lake morphology or mixing regime. Metalimnetic rates exhibited high day‐to‐day variability in all trophic states, with the metalimnetic contribution to daily whole‐lake GPP and ER ranging from 0% to 87% and 

Limnology and Oceanography: Volume 62, Issue 3

FundersDanish Centre for Lake Restoration (CLEAR), Scientific and Technological Research Council of Turkey (TUBITAK), EMASESA and EMASESA
Publication date31/05/2017
Publication date online09/03/2017
Date accepted by journal02/12/2016