marie elodie perga - gliding from limnology to paleolimnology to study the ecosystem-wide...
DESCRIPTION
This was a plenary talk given at the International Paleolimnology Symposium, Glasgow, August 2012.TRANSCRIPT
Gliding from limnology to paleolimnology to study the
ecosystem-wide consequences of human pressures on lake food webs
Marie-Elodie PergaAlpine Centre for Research on Lake Food Webs
French National Institute for Agronomical Research
Thonon Les Bains, France
Contributing authors:
B. Alric, F. Arnaud, V. Berthon, D. Debroas, I. Domaizon, V. Frossard, JP Jenny, A. Kirkham, M.
Manca, A. Marchetto, L. Millet, C. Pignol, JL Reyss, O. Savichtcheva, F. Sylvestre, V Verneaux.
From Neo to Paleo-limno: Is it just about switching tools and
timeframe?
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Neo-limnoEutrophication/re-oligotrophicationClimateBoth
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Paleo-limno
Problem-solving approaches predictions
Paleoclimatology
Data from WEB OF KNOWLEDGESM
François Hollande & David Cameron, le 18 mai 2012. REUTERS/Andrew Winning
Limnology & Oceanography 2009
Geoscience Canada 1994
Recent convergenceof Neo and Paleo-limno
issues:An example
Lakes/compartments are unevenly sensitive to climate
“Some lakes/proxies are more adequate than others to reconstruct past climate”
Lake response
Climate
Pale
o Neo
Lake sensitivity to climate change
Lake sensitivity to climate change shall depend on the intensity of local
forcings?
• Lake response to climate is highly context-dependent.• Interactions between local (nutrient, POPs…) and climate forcings
Comparable lakes submitted to similar climate, different intensities of local forcingsH: climate effects depends on the intensity of local human pressures
Similar eutrophication, different lakes and climates
The strength of interactive effects of climate and eutrophication are site-
specific
Members2009-2012
Benjamin ALRICVincent BERTHONIsabelle DOMAIZONValérie HAMELETAmy KIRKHAMMarie-Elodie PERGAOlga SAVICHTCHEVAClément VILLAR
Fabien ARNAUDJean-Philippe JENNYCécile PIGNOLPierre SABATIER
Jean-Louis REYSS
Victor FROSSARDLaurent MILLETValérie VERNEAUX
Jessica BLACKFlorence SYLVESTRE
Marina MANCAAldo MARCHETTO
Markus MOESTPiet SPAAK Nathalie COTTIN
Emmanuel NAFFRECHOUX
www.inra.fr/iper-retro
Lake Altitude (m asl)
Length (km)
Max Depth (m)
Surface area (km²)
Geneva 372 73 309 581.3
Bourget 240 18 145 44.5
Annecy 446 15 82 27.6
Lake Geneva
Lake AnnecyLake Bourget
20 km
Peri-alpine lakes : large, deep, moderately alkaline, monomictic
Our playgrounds
Glacial-tectonics origins15000-19000 years old
Climate (Winter temperature anomalies °C)
Year
Auer I et al. (2007) HISTALP - historical instrumental climatological surface time series of the Greater Alpine Region. Int. J. Climatol.
27:17-46
Climate forcings on the three lakes
Annecy
Bourget
Geneva
Annexation
Demography of the city of Annecy
Demography and human pressures over the last 150 years
Annexion
Demography of the city of Annecy
“France cleaning up the faces of her new sons to see them”
“Marmots are now fashionable”
Demography and human pressures over the last 150 years
L’Illustration, Journal Universel, June 30th 1860
Annexion
Demography of the city of Annecy
Demography and human pressures over the last 150 years
Franco-Prussian War
Crisis
Railway
Advertisement from the French railway company around 1920
Demography and human pressures over the last 150 years
Annexion
Demography of the city of Annecy
Franco-Prussian War
Crisis
Railway
Dvt of tourism
HydroelectricalPower, industry
International exposition of tourism and hydroelectrical power, 1925 Bar turning
industry in 1936
(Savoy)
Demography and human pressures over the last 150 years
Annexion
Demography of the city of Annecy
Franco-Prussian War
Crisis
Railway
Dvt of tourism
Hydroelectricalpower
High intern immigration
rate
Fisheries management/Whitefish Stocking
Local human forcings on the three lakes
Lake
TP c
once
ntr
ati
ons
(µgP L
-1)
Year
≈15 (µgP L-1)
≈120 (µgP L-1)
≈90 (µgP L-1)
Nutrient inputs
Annecy
Bourget
Geneva
1936-1997Early stages
1943-1965Early stages
1986-Late stages
1970-Early stages
Objectives
Reconstruct lake-scale biological and geochemical responses over the last 150 years.
Hierarchize the effects of human perturbations on lake processes (climate versus local perturbations-nutrient/fish).
Delineate the underlying processes
Coring
(Jenny et al, sub)> 200 cores ~8-10 000 sections to be dated
Lake Geneva Lake Bourget
(Jenny et al, sub)
Dating of reference cores
Laminated facies (from 1936 for lake Bourget, 1963 for Annecy and 1957 for Geneva) : ± 2 yearsNon-laminated facies : ± 5-10 years
Core correlations
Ecosystem-wide-responses?Panel of methodologies and scales targeted
Process
scaleObservatio
n levelTaxonomic level
SitesProxies/methodologies
Pelagos
Geneva
Bourget
Annecy
FUNCTION 1ary productionSi/Ti ; Si/Al, Ca/Mg
Photosynthetic pigments, δ13C SOM
COMM.
Diatoms Sub-fossil remains
Cyanobacteria qPCR based methods
Cladocerans Subfossil-remainsRotifers Resting eggs
GENUSgenetic
diversity
Synech.(cya)
Cloning-sequencing
SPECIES complex
Daphnia long. Reproductive
strategies
RFLP-microsat. on resting eggs
Benthos
FUNCTION
Sedimentation δ13C SOM, Rock-Eval…
Methanogenesis
δ13C biological remains
HypoxiaLamination presence,
Chironomids
COMM. Chironomids Subfossil head capsules
Y(response)= f(Climate)+f(Phosphorous inputs)+f(Fish predation or flood…)+ε
Generalized Additive Model (GAM)
PC
2
PC1Year
Infe
rred
TP
What are the environmental factors driving responses and when?
P = 5.21 x 10-4
Bourget
Univariate or dimension reduction
by ordination methods
Temporal contribution of covariates to GAM fitted
to Y
Simpson & Anderson (2009)
RECONTRUCTING LOCAL & CLIMATE FORCINGS
Reconstructing forcings1. Climate _ Air temperatures
-20
-10
0
10
20
30
40
1860
1880
1900
1920
1940
1960
1980
2000
Summer temp anomalies (1857-2008)
-50
-40
-30
-20
-10
0
10
20
30
40
1860
1880
1900
1920
1940
1960
1980
2000
Winter temp anomalies (1857-2008)
Histalp Locally monitored data (MeteoFrance)
Reconstructing forcings1. Climate _ Precipitations-floodsLogPre
cipit
ati
ons
(mm
)
Histalp
Locally monitored data (MeteoFrance)
60
70
80
90
100
110
120
130
140
150
160
1860
1880
1900
1920
1940
1960
1980
2000
Year
Long-term changes in annual precipitations
Flood frequency from detrital
proxies
Jenny et al. in prep
Reconstructing forcings1I. P concentrations
Weighted-averaging method from the Central European database(Berthon, Marchetto et al, in prep)
Year
Monitoring data
Reconstructed data
5
7
9
11
13
15
17
19
1880
1900
1920
1940
1960
1980
2000
TP
(µg
P.L
-1)
Lake ANNECY
Reconstructing forcings1I. P concentrations
Weighted-averaging method from the Central European database(Berthon, Marchetto et al, in prep)
Year
Monitoring data
Reconstructed data
0
10
20
30
40
50
60
70
80
90
6
7
8
9
10
11
12
13
14
1880
1900
1920
1940
1960
1980
2000
Da
ph
nia
ab
. (i
ng
.gs
ed
-1)
[TP
](µ
gP.
L-1
)
Lake ANNECY
Reconstructing local forcings1. P concentrations
Monitoring data
Reconstructed data
Reconstructing local forcings11. Fish predation pressure
•Size selective predation hypothesis (Brooks & Dodson, 1965)
• Jeppesen E et al.(2002) J. Paleolimnol.
110
115
120
125
130
135
140
145
0
5000
10000
15000
20000
25000
30000
35000
40000
1968 1978 1988 1998
Da
ph
nia
cla
w le
ng
th (
µm
)
Fis
h c
atc
he
s (
kg
)
Year
Annecy
=-0.426, P=0.008
110
120
130
140
150
160
0
100000
200000
300000
400000
500000
600000
700000
1892 1942 1992
Da
ph
nia
cla
w le
ng
th (
µm
)
Fis
h c
atc
he
s (
kg
)
Year
Geneva
=-0.340, P=0.009
=-0.511, P=1.58*10-6
Alric et al, revised
100
105
110
115
120
125
130
135
140
145
150
0
50000
100000
150000
200000
250000
1920 1970
Da
ph
nia
cla
w le
ng
th (
µm
)
Fis
h c
atc
he
s (
kg
)
Year
Bourget
HIERARCHIZING ENVIRONMENTAL FORCINGS
Relative impacts of climate and forcings (i) Diatoms
ANNECY
Nutr
ients
Fish
sto
cks
Tem
p
19371941194819531959196519711978198419932003
0
50
100
Year
% c
on
trib
uti
on
of
CC
OS
BOURGET
Nutr
ients
Fish
sto
cks
Tem
p1
86
0 18
80 1
90
0 20
001
92
0 19
40 1
96
0 19
80
Relative impacts of climate and forcings (i) Diatoms
187318891910192319401954196219711978198719952003
0
50
100AUIS AFOR SPAV
Year
% c
on
trib
uti
on
GENEVA
Fish
sto
cks
Nutr
ients
Tem
p1
88
0 19
00 2
00
019
20 1
94
0 19
60 1
98
0
Relative impacts of climate and forcings (i) Diatoms
Low velocity sinker & resistant to grazing
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
Sum
Win
ANNECY
BOURGET
GENEVA
CLIMATE
Compared relative impacts of forcings on pelagic components
(i) Diatoms
Nutrients Fish top-down Climate
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
DIA
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
DIA
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
DIA
Summer species
Early spring & late summer species
late summer species
Early spring species
Summer species
Date
Cladoceran
OM
Perga et al, in prep
δ13C(‰) δ13C(‰)
ANNECY BOURGET
δ13C(‰)
GENEVA
OM
Relative impacts of climate and forcings (ii) Pelagic C processes
Date
δ13C(‰) δ13C(‰)
ANNECY BOURGET
Cladoceran
OM
δ13C(‰)
GENEVA
Perga et al, in prep
Relative impacts of climate and forcings (ii) Pelagic C processes
TP(µgP.l-1)
Cla
doce
ran
δ1
3C
(‰)
[P] or light
depth
High δ13CDIC
Low δ13CDIC
thermocline
[Chl a]
Photi
c zo
ne
Low [P]
[P] or light
depth
High δ13CDIC
Low δ13CDIC
thermocline
[Chl a]
High [P]
Changes in pelagic δ13C related to [P]
1930’s
2000’s
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
Sum
Win
ANNECY
BOURGET
GENEVA
CLIMATE
Compared relative impacts of forcings on pelagic components(ii) Pelagic C processes
Nutrients Fish top-down Climate
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
DIA
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
DIA
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
DIA
Summer species
Early spring & late summer speciesDCM
late summer speciesDCM
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
Sum
Win
ANNECY
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
CLA
BOURGET
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
CLA
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
CLA
GENEVA
CLIMATE
Compared relative impacts of forcings on pelagic components
(iii) Cladocerans
Nutrients Fish top-down Climate
Pelagic vs littoral speciesBosmina species in interaction with fish predation
Bosmina versus Daphnia in interaction with fish
predation
Thermophilic species+ Pelagic vs littoral species
(Alric et al, revised)
ANNECY
BOURGET
GENEVA
Forcings contributions to changes in hypoxia volumes (Jenny et al.)
Volu
me o
f h
yp
oxic
wate
rs (
m3)
Date
T°+Ti
T°+Ti
T°
T°+Wind+Ti
TP
Compared relative impacts of forcings on oxic components (i) Hypoxia
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
Sum
Win
ANNECY
BOURGET
GENEVA
CLIMATE
Nutrients Fish top-down Climate
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
HYP
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
HYP
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
HYP
Compared relative impacts of forcings on oxic components (i) Hypoxia
LOCAL FORCINGS
CLIMATE
Top-down TP
Summer tempJuly temp
Winter tempDec temp Jan temp(Frossard et al, submitted)
Compared relative impacts of forcings on oxic components (ii) chironomid community
structure
Cores depth: 30m, 56m and 65 m
1940
SEN
SIT
IVIT
Y T
O C
LIM
ATE
SEN
SIT
IVIT
Y T
O L
OC
AL
FOR
CIN
GS
H. grimshawiParacladius
(Frossard et al, submitted)
S.coracinaM. contractaProcladius
ANNECYS.coracina
30 m
56 m
65 m
Top-down TP Summer temp
S.coracinaM. contractaProcladius Top-downJan temp July temp TP
TP Summer temp
1945
1945
1945
1985
1985
1940
(Frossard et al, in prep)
BOURGET
Hypoxic tolerantOxyphilous
1930
145 m1985
1930
1980
90 m
30 m 1980
SEN
SIT
IVIT
Y T
O C
LIM
ATE
SEN
SIT
IVIT
Y T
O L
OC
AL
FOR
CIN
GS
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
Sum
Win
ANNECY
BOURGET
CLIMATE
Nutrients Fish top-down Climate
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
LittC
DeepC
1880
1890
1900
1910
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
LittC
DeepC
Compared relative impacts of forcings on oxic components (ii) chironomid community
structure
δ13C(‰)-43 -38 -33 -28
1880
1900
1920
1940
1960
1980
2000
Frossard et al, in prep
δ13C OMδ13C Cladoceran remains
δ13C Littoral Chiros
Lake Annecy
Compared relative impacts of forcings on oxic components (iii) Benthic C processes
δ13C(‰)
δ13C OMδ13C Cladoceran remains
-43 -38 -33 -28
1880
1900
1920
1940
1960
1980
2000
δ13C Littoral Chiros
Frossard et al, in prep
-43 -38 -33 -28
1880
1900
1920
1940
1960
1980
2000
δ13C deep chiros
Deep methanogenesis/trophy
Lake Annecy
Compared relative impacts of forcings on oxic components (iii) Benthic C processes
δ13C(‰)
δ13C OMδ13C Cladoceran remains
δ13C Littoral Chiros
Frossard et al, in prep
δ13C deep chiros
Deep methanogenesis
Lake Bourget-40 -35 -30 -25
1820
1840
1860
1880
1900
1920
1940
1960
1980
2000
Compared relative impacts of forcings on oxic components (iii) Benthic C processes
DIFFERENTIAL LAKE/HABITATS SENSITIVITY TO CLIMATE CHANGE
P
Warmer summer
stratification
↑ water temperaturein summer
Longer oxic isolation of
hypolimnion
Fish stocking
Phytoplankton
Grazers
Increased oxic const.
[O2]interface
Cold winter
Increased size-selection
Decreased size of grazers
Decreased TTE
[O2]interfaceLitt. chiros
+
+
+
-
-
Fish predation++
Annecy 1950’s
↓Floods
Deep chirosIncreased oxic
const.
P
Warmer summer
stratification
Earlier stratifica
tion
Longer oxic isolation of
hypolimnion
Fish stocking
Phytoplankton
Grazers
Increased oxic const.
[O2]interface
Cold winter
Increased size-selection
Decreased size of grazers
Decreased TTE
[O2]interfaceLitt. chiros
+
+
-
- -
Fish predation++
Bourget 1950’s
↓Floods
HYPOXIADecrease
d O2 renewal
METHANOGENESIS
Deep chirosIncreased oxic
const.
P
Warmer summer
stratification
Longer growth season
Longer oxic isolation of
hypolimnion
Phytoplankton
Grazers
[O2]interface
Cold winter
Increased size-selection
Decreased size of grazers
+
+
+
Fish predation+
Geneva 1950’s
Annecy 1950’s Bourget 1950’s Léman 1950’s
Different lake vulnerability to the 1950’s warmer summers
Essentially related to hydrological and geomorphological differences
between lakes
• P triggered processes.
Pathways of 1950’s warmer summers effects
P
Warmer summer
stratification
Longer oxic isolation of
hypolimnion
Fish stocking
Phytoplankton
Grazers
Increased oxic const.
[O2]interface
warmer winter
Increased size-selection
Decreased size of grazers
Decreased TTE
[O2]interfaceLitt. chiros
+
- -
- -
Fish predation+++
Annecy since 1985
+
HYPOXIA
↑ water temperaturein summer
METHANOGENESIS
Deep chirosIncreased oxic
const.
0
2
4
6
8
10
12
j-74
j-76
d-77
d-79
d-81
d-83
d-85
d-87
d-89
d-91
d-93
d-95
d-97
d-99
d-01
d-03
d-05
Bot
tom
[O2]
mg.
l-1
Date
P
Warmer summer
stratificationLonger growth season
Longer oxic isolation of
hypolimnion
Phytoplankton
Grazers
[O2]interface
warmer winter
Decreased size-selection
Increased size of grazers
Increased
TTE
[O2]interfaceLitt. chiros
- - -
Fish predation+
Bourget since 1985
+
HYPOXIA
↓Floods
Decreased O2 renewal
+
spring bloom
DCM
METHANOGENESIS
Deep chirosIncreased oxic
const.
Fish stocking
P
Warmer summer
stratification
Longer growth season
Longer oxic isolation of
hypolimnion
Fish stocking
Phytoplankton
Grazers
[O2]interface
warmer winter
Increased size-selection
Decreased size of grazers
- -
Fish predation+++
Geneva since 1985
++
HYPOXIA
↓Floods
Decreased O2 renewal
DCM
METHANOGENESIS?
Conclusions-PerspectivesLakes vulnerability to climate changes• Hydrological-morphological characteristics count, even in similar lakes
• Benthic habitats more sensitive to climate than pelagic/littoral ones in deep lakes : Decoupling?
•Interactions local perturbations-climate stronger in littoral/pelagic habitats
• P matters, although its impact is stronger on pelagic/littoral than on benthic processes
•Fisheries management practices count !
