Thermocline deepening boosts ecosystem metabolism

evidence from a large-scale lake enclosure experiment simulating a summer storm

Darren P. Giling, Jens C. Nejstgaard, Stella A. Berger, Hans Peter Grossart, Georgiy Kirillin, Armin Penske, Maren Lentz, Peter Casper, Jörg Sareyka, Mark O. Gessner

Research output: Contribution to journalArticle

16 Citations (Scopus)

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.
Original languageEnglish
Pages (from-to)1448-1462
Number of pages15
JournalGlobal Change Biology
Volume23
Issue number4
DOIs
Publication statusPublished - 1 Apr 2017
Externally publishedYes

Fingerprint

enclosure experiment
Enclosures
thermocline
Metabolism
Ecosystems
Lakes
Temperature distribution
metabolism
ecosystem
lake
summer
primary production
Experiments
lake water
Surface waters
respiration
Water
autotrophy
surface water
lake ecosystem

Cite this

Giling, Darren P. ; Nejstgaard, Jens C. ; Berger, Stella A. ; Grossart, Hans Peter ; Kirillin, Georgiy ; Penske, Armin ; Lentz, Maren ; Casper, Peter ; Sareyka, Jörg ; Gessner, Mark O. / Thermocline deepening boosts ecosystem metabolism : evidence from a large-scale lake enclosure experiment simulating a summer storm. In: Global Change Biology. 2017 ; Vol. 23, No. 4. pp. 1448-1462.
@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.}",
year = "2017",
month = "4",
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",

}

Giling, DP, Nejstgaard, JC, Berger, SA, Grossart, HP, Kirillin, G, Penske, A, Lentz, M, Casper, P, Sareyka, J & Gessner, MO 2017, 'Thermocline deepening boosts ecosystem metabolism: evidence from a large-scale lake enclosure experiment simulating a summer storm', Global Change Biology, vol. 23, no. 4, pp. 1448-1462. https://doi.org/10.1111/gcb.13512

Thermocline deepening boosts ecosystem metabolism : evidence from a large-scale lake enclosure experiment simulating a summer storm. / Giling, Darren P.; Nejstgaard, Jens C.; Berger, Stella A.; Grossart, Hans Peter; Kirillin, Georgiy; Penske, Armin; Lentz, Maren; Casper, Peter; Sareyka, Jörg; Gessner, Mark O.

In: Global Change Biology, Vol. 23, No. 4, 01.04.2017, p. 1448-1462.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Thermocline deepening boosts ecosystem metabolism

T2 - evidence from a large-scale lake enclosure experiment simulating a summer storm

AU - Giling, Darren P.

AU - Nejstgaard, Jens C.

AU - Berger, Stella A.

AU - Grossart, Hans Peter

AU - Kirillin, Georgiy

AU - Penske, Armin

AU - Lentz, Maren

AU - Casper, Peter

AU - Sareyka, Jörg

AU - Gessner, Mark O.

PY - 2017/4/1

Y1 - 2017/4/1

N2 - 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.

AB - 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.

KW - climate variability

KW - ecosystem productivity

KW - extreme events

KW - gross primary production

KW - mesocosm

KW - respiration

KW - stratified lakes

UR - http://www.mendeley.com/research/thermocline-deepening-boosts-ecosystem-metabolism-evidence-largescale-lake-enclosure-experiment-simu

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-84991795237&origin=resultslist&sort=plf-f&src=s&st1=10.1111%2fgcb.13512&st2=&sid=8b315be8e808e39aa1ec0c2824645258&sot=b&sdt=b&sl=22&s=DOI%2810.1111%2fgcb.13512%29&relpos=0&citeCnt=15&searchTerm=

U2 - 10.1111/gcb.13512

DO - 10.1111/gcb.13512

M3 - Article

VL - 23

SP - 1448

EP - 1462

JO - Global Change Biology

JF - Global Change Biology

SN - 1354-1013

IS - 4

ER -