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The French Alpine Lakes Observatory (ALO): a tool for assessing the effects of the global change on lake ecology
Bernard Montuelle, Jean Marcel Dorioz, Jean Guillard
To cite this version:
Bernard Montuelle, Jean Marcel Dorioz, Jean Guillard. The French Alpine Lakes Observatory (ALO):
a tool for assessing the effects of the global change on lake ecology. SEFS7 - Ecological assessment of lakes, rivers and reservoirs : water quality management, Jun 2011, Girona, Spain. 0 p. �hal-02807077�
The French Alpine Lakes Observatory (ALO):
a tool for assessing the effects of global change on lake ecology.
Montuelle B., Dorioz J-M, Guillard J.
INRA, UMR Carrtel, Station d’Hydrobiologie Lacustre
75 avenue de Corzent - BP 511 - 74203 Thonon-les-Bains Cedex - France
SPECIAL SESSION « Assessing the impacts of global change and anthropogenic pressures on freshwater
ecosystems, a role for long term-ecological research.
Bourget Mesotrophe
(re-oligotrophisation) Léman
Mesotrophe (re-oligotrophisation
Annecy Oligotrophe
- French part of the Alps - 3 lakes
The Alpine Lakes Observatory
OBJECTIVES
« Scrutinizing, understanding and modelling the trajectories and the ecological mechanisms
controling the lake systems exposed to changes in anthropic and climatic pressures, at a 10
years time steps ».
ALO
Long-term Limnology
Short and mid term processes
Associated projects
- Long term surveys (state variables) - Biological and physicochemical processes controling water quality and productivity - Ecological trends
- Global change consequences - Functional ecology
- Fluxes assessment
- Trophic functionning and biodiversity
- small mountain lakes - BPC ecodynamic
> 10 years
1< < 10 years - Scientific knowledge - Tools for lake managers
Land Uses Pollutions
Regulations Standarts
Climate - 3 Sub systems and
specific functionnings
- Fluxes and internal exchanges
- External drivers
Lake
Water uses
(fishing, recreational…) flux./proc.
Flux./proc.
Watershed- rivers
soils
Flux./proc Atmosphere
T, light, deposits,
The ALO
1800 1970
Modelisations
Scénarios for ecological trajectories
Time 1/ Long term observations
Paleolimnology (retro observation)
Direct observations
2010
Ecological trajectory of lakes
(structures, biodiversity, fluxes)
Changes in anthropic pressures and climat change
0 20 40 60 80 100 120
ANNECY
LEMAN BOURGET
Ptot µg/L
1950 1980 2010
Anneville 2010, pers com
1/ Long term observations: the global physico-chemical changes
Oxygen
(bottom- Léman) NO3
Ntot
0-10m Léman
100 m.
200 m.
bottom
4,4 4,9 5,4 5,9 6,4 6,9
1950 1960 1970 1980 1990 2000 2010
Years Temperature (C°)
Léman
1/ Long term observations: trophic network dynamics (Leman)
Anneville 2010, pers com
Long-term changes in the functionning of the pelagic communities
Increasing predation
Decreasing ZoopK biomass
increasing PhytopK biomass
Whitefish
Zooplankton
Phytoplankton
0 50 100 150 200 250 300 350
0 50 100 150 200 250 300
2.5 2.7 2.9 3.1 3.3 3.5 3.7
74 80 86 92 98 04
Ca tc he s (t ons )
Log (Bio v+ 1) (µ g. l
-1) Bio vol ume (ml .m
-2)
years
0 1000 2000 3000 4000 5000 6000 7000
1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Biomasse (µg/L)
Zygophycées Chlorophycées Diatomées Xanthophycées Chrysophycées Euglenophycées Cryptophycées Dinophycées Cyanobactéries
1/ Long term observations: algae diversity
Anneville 2010, pers com
Long-term changes in the diversity of planctonic communities
- Variability
- 2 periods
1860 - 1886
1886 - 1910
1910 - 1940
1940- fin 1960s Fin 1960s –Auj.
phytoplankton
nutrients
No whitefish
whitefish
Sediment OM
Sediment OM
Sediment OM
Sediment OM
Sediment OM phytoplankton phytoplankton phytoplankton phytoplankton
nutrients nutrients nutrients nutrients
1/ Long term observations: Paleolimnology
Perga M-E, 2010, Limnol Oceanogr.150 years of bottom-up and top-down response of trophic network (Lake Annecy)
Conceptual model on changes of trophic network Study of sediment cores:
- Macro remains of organisms
- Preserved macro- molecules (pigments) - Isotopic characteristics of remains and OM (13C and 15N)
Oligotrophic nutrient
Whitefish nutrient TD
TD
+
BU BU
2/ Short term observations: microbial loop changes (Le Bourget)
Main C transfer pathway High Predation pressure
BU BU BU
+ TD
Domaizon & Comte , 2006
