@article{89e5aa16557240edbf0d767c171a289d,
title = "Thermocline deepening boosts ecosystem metabolism: evidence from a large-scale lake enclosure experiment simulating a summer storm",
abstract = "Extreme weather events can pervasively influence ecosystems. Observations in lakes indicate that severe storms in particular can have pronounced ecosystem-scale consequences, but the underlying mechanisms have not been rigorously assessed in experiments. One major effect of storms on lakes is the redistribution of mineral resources and plankton communities as a result of abrupt thermocline deepening. We aimed at elucidating the importance of this effect by mimicking in replicated large enclosures (each 9 m in diameter, ca. 20 m deep, ca. 1300 m3in volume) a mixing event caused by a severe natural storm that was previously observed in a deep clear-water lake. Metabolic rates were derived from diel changes in vertical profiles of dissolved oxygen concentrations using a Bayesian modelling approach, based on high-frequency measurements. Experimental thermocline deepening stimulated daily gross primary production (GPP) in surface waters by an average of 63% for >4 weeks even though thermal stratification re-established within 5 days. Ecosystem respiration (ER) was tightly coupled to GPP, exceeding that in control enclosures by 53% over the same period. As GPP responded more strongly than ER, net ecosystem productivity (NEP) of the entire water column was also increased. These protracted increases in ecosystem metabolism and autotrophy were driven by a proliferation of inedible filamentous cyanobacteria released from light and nutrient limitation after they were entrained from below the thermocline into the surface water. Thus, thermocline deepening by a single severe storm can induce prolonged responses of lake ecosystem metabolism independent of other storm-induced effects, such as inputs of terrestrial materials by increased catchment run-off. This highlights that future shifts in frequency, severity or timing of storms are an important component of climate change, whose impacts on lake thermal structure will superimpose upon climate trends to influence algal dynamics and organic matter cycling in clear-water lakes.",
keywords = "climate variability, ecosystem productivity, extreme events, gross primary production, mesocosm, respiration, stratified lakes",
author = "Giling, {Darren P.} and Nejstgaard, {Jens C.} and Berger, {Stella A.} and Grossart, {Hans Peter} and Georgiy Kirillin and Armin Penske and Maren Lentz and Peter Casper and J{\"o}rg Sareyka and Gessner, {Mark O.}",
note = "Funding Information: We are grateful to P. Kasprzak and C. Engelhardt for advice and provision of data and to the entire TemBi and LakeLab teams for the preparation of the experiment and assistance with sampling. These teams include M. Arias, S. Beeske, M. Degebrodt, W. Eckert, A. Fuchs, L. Ganzert, S. Hamadouche, T. Hornick, T. Kettner, B. Laube, E. Mach, U. Mallok, K.C. Martinez-Cruz, M. Papke, R. Ro?berg, M. Sachtleben, M. Schnittger, G. Selmeczy and A. Sepulveda-Jauregui. We also thank P. Staehr, B. Obrador, J. Yen and R. Mac Nally for advice on metabolic estimation and statistical analysis, and C. McGilliard and B. Ferris for modified contour plotting code. J. Zwart and an anonymous reviewer provided constructive comments that improved this manuscript. This study was supported by a Leibniz Competition grant to PC and HPG (project ?Climate driven changes in biodiversity of microbiota? ? TemBi; SAW-2011-IGB-2), funding received by MOG from the German Federal Ministry of Education and Research (BMBF) for constructing the enclosure facility (no. 033L041B), and a Core Facility grant to MOG from the German Research Foundation (DFG) to operate the facility (no. GE 1775/2-1). Publisher Copyright: {\textcopyright} 2016 John Wiley & Sons Ltd Funding Information: We are grateful to P. Kasprzak and C. Engelhardt for advice and provision of data and to the entire TemBi and LakeLab teams for the preparation of the experiment and assistance with sampling. These teams include M. Arias, S. Beeske, M. Degebrodt, W. Eckert, A. Fuchs, L. Ganzert, S. Hamadouche, T. Hornick, T. Kettner, B. Laube, E. Mach, U. Mallok, K.C. Martinez-Cruz, M. Papke, R. Ro{\ss}berg, M. Sachtleben, M. Schnittger, G. Selmeczy and A. Sepulveda-Jauregui. We also thank P. Staehr, B. Obrador, J. Yen and R. Mac Nally for advice on metabolic estimation and statistical analysis, and C. McGilliard and B. Ferris for modified contour plotting code. J. Zwart and an anonymous reviewer provided constructive comments that improved this manuscript. This study was supported by a Leibniz Competition grant to PC and HPG (project {\textquoteleft}Climate driven changes in biodiversity of microbiota{\textquoteright} – TemBi; SAW-2011-IGB-2), funding received by MOG from the German Federal Ministry of Education and Research (BMBF) for constructing the enclosure facility (no. 033L041B), and a Core Facility grant to MOG from the German Research Foundation (DFG) to operate the facility (no. GE 1775/2-1). Funding Information: We are grateful to P. Kasprzak and C. Engelhardt for advice and provision of data and to the entire TemBi and LakeLab teams for the preparation of the experiment and assistance with sampling. These teams include M. Arias, S. Beeske, M. Degebrodt, W. Eckert, A. Fuchs, L. Ganzert, S. Hamadouche, T. Hornick, T. Kettner, B. Laube, E. Mach, U. Mallok, K.C. Martinez-Cruz, M. Papke, R. Ro?berg, M. Sachtleben, M. Schnittger, G. Selmeczy and A. Sepulveda-Jauregui. We also thank P. Staehr, B. Obrador, J. Yen and R. Mac Nally for advice on metabolic estimation and statistical analysis, and C. McGilliard and B. Ferris for modified contour plotting code. J. Zwart and an anonymous reviewer provided constructive comments that improved this manuscript. This study was supported by a Leibniz Competition grant to PC and HPG (project ?Climate driven changes in biodiversity of microbiota? ? TemBi; SAW-2011-IGB-2), funding received by MOG from the German Federal Ministry of Education and Research (BMBF) for constructing the enclosure facility (no. 033L041B), and a Core Facility grant to MOG from the German Research Foundation (DFG) to operate the facility (no. GE 1775/2-1). Publisher Copyright: {\textcopyright} 2016 John Wiley & Sons Ltd",
year = "2017",
month = apr,
day = "1",
doi = "10.1111/gcb.13512",
language = "English",
volume = "23",
pages = "1448--1462",
journal = "Global Change Biology",
issn = "1354-1013",
publisher = "Wiley-Blackwell",
number = "4",
}