Changes in freshwater ecosystems

due to climate change -

Which adaptation?Daniel Gerdeaux, INRA Thonon, Dpt EFPA

http://www.clermont.inra.fr/urep/accae

2000 : Water Framework Directive with the following key aims:

•expanding the scope of water protection to all waters, surface waters and groundwater

•achieving "good status" for all waters by a set deadline

•water management based on river basins

•"combined approach" of emission limit values and quality standards

•getting the prices right

•getting the citizen involved more closely

•streamlining legislation

Restoration, protection …. and adaptation?

Ecological status of French waterbodies

highVery bad

bad

moderate

good

indeterminate

(deviation from Reference. conditions)

Reference conditionsInsignificantly disturbed biology,

hydro-morphology and physico-chemistry (Wallin et al, 2003)

RESTORATION

2015-2027

WFD

Climate Change : - warming

- hydrology

- solar radiation

Lake Geneva 5m below the surface

10

11

12

13

1970 1975 1980 1985 1990 1995 2000 2005

An

nu

al

meam

Wate

r te

mp

era

ture

(°C

)

3500

4000

4500

5000

5500

1980 1985 1990 1995 2000 2005 2010

annual solar radiation on Lake Geneva (MJ.m-2)

An example : Lake Geneva

P ot (µgP/l)

1960 1965 1970 1975 1980 1985 1990 1995 2000

0

20

40

60

80

100

Several parameters are changing

Start of thermal stratification

1 may

15 may

29 may

12 june

26 june

1970 1980 1990 2000

0

2

4

6

8

10

12

Oxyg

en

(mg/l)

1986 1990 1994 1998

Lack of overturns , then anoxy atthe bottom in Lake Geneva

Consequences on physico-chemical parameters

Some variations or changes due to : reoligotrophication, climate change, ….

1986-1991

> 1991

1974-1985

J F M A M J Jt A S O N D0

500

1000

1500

Biomasse (µg.l-1)

J F M A M J Jt A S O N D0

500

1000

1500

2000

2500

0500

1000

1500

2000

J F M A M J Jt A S O N D

spring summerfall

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1974

1976

1978

1980

1982

1984

1986

1988

1990

1992

1994

1996

1998

2000

2002

2004

2006

2008

A B C D EF G H1 J KLm Lo M N PR S1 T U W1W2 X1 Y Z Non classé

Biomasse m

oyenne annuelle

(µg/L)

Phytoplankton in Lake Geneva:

changes in seasonality, the

phytoplankton assemblages and the

functional associations of species

(Reynolds et al 2002)

What is due to -reoligotrophication

-climate change

-fishery….. ?

An example : Lake Geneva

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009

Orthophosphate - PO4 (µgP/l) - Lake Geneva

Today the upper layers (0-30m) in Lake Geneva are almost oligotrophic while before

1986 the P depletion in the upper layers was brief and not deep

Jan. Feb. Mar April Jun Jul. Augt Sep. Oct. Nov.Déc. May

Algae

Zooplankton

eggs

Alguae

Zooplankton

eggs

70’s

2000’s

Changes in Lake Geneva (reoligotriphication, warming, stocking)

favourable to whitefish (Coregonus lavaretus) unfavorable to arctic

char (Salvelinus arcticus) two cold water species

(Arctic char reproduction is not possible above 7°C during ovogenesis)

A better match between

egg hatching and

zooplankton dynamics

Two “cold species” two different responses

An example : Lake Geneva

1970 1974 1978 1982 1986 1990 1994 1998

50

100

150

200

250

300

Witefish catches in Lake GENEVA350

strength of cohort

1993.1994

1995

1996.

1997.

1998

1999.

2000.

2001.

2002.

0

10

20

30

40

50

60

70

80

90

100

5..7 5..8 5. .9 6.. 0 6.. 1 6..2 6..3 6..4 6. .5 6.. 6

mean annual temperature at 100 m

R²= 0.543

• Changes due to numerous causes

•Habitats deterioration

•Eutrophication and reoligotrophcation

•Management of resources, overexploitation

•Pollution

•Invasive species

•Climate

•Climate changes influence directly the biodiversity (stenothermy) and indirectly by

their influence on other causes of deterioration

•Difficult to understand the role of climate change separately from the effects of other

environmental, social and economic changes that affect waterbodies

•KEY POINTS :

•Biological indicators of warming are useful tools. Eco-physiological studies on new

indicators are necessary : Direct effects

•But the responses of ecosystems to a stressor are often not linear

•The impacts of climate change will be different at different scales across different

regions.

•necessity to maintain and extend high quality, long-term monitoring to better

understand the key processes that control system responses to climate change and to

take into account the inter-annual variations in ecosystems AND THE UNCERTAINTY

•Biological indicators of warming are useful tools. Eco-physiological studies on new

indicators are necessary :

lists of biological indicators : http://www.climate-and-freshwater.info/

Indicators potentially suited to detect the effects of Climate Change on

European aquatic ecosystems

Aquatic species which are affected by (or benefiting from) Climate Change

Need for more (better?) biological indicatorsExploration of the influence of global warming on the chironomid community in a manipulated shallow

groundwater system.

Guillaume Tixier, Kevin P. Wilson,D. Dudley Williams. 2008

examined the response of the groundwater chironomid community : warming decreased the total

abundance of chironomids

whereas no significant change in taxonomic richness was apparent.

taxon composition changed markedly during both the manipulation and the recovery period. Whereas

Heterotrissocladius disappeared during the manipulation in the treatment block, other coldstenothermal

taxa such as Micropsectra, Parametriocnemus and Heleniella remained unaffected.

Conversely, Corynoneura, Polypedilum and Thienemannia gracilis disappeared but were not reported as

coldstenothermal. The chironomid community composition in the system changed from a

Heterotrissocladius, Brillia, and Tanytarsini-dominated community during the pre-manipulation towards one

dominated by Parametriocnemus, Polypedilum, Orthocladius/Cricotopus and Corynoneura during the

recovery. Although increased temperature had a strong effect, chironomid occurrence was also influenced by

a number of other abiotic variables, such as dissolved oxygen, depth, ammonia concentration and TDS (Total

dissolved solids).

Trophic index (TI) as a function of total phosphorus (TP; upper

panel) and chlorophyll a (Chl a, lower panel). Left: Black dots represent

samples from reference lakes, grey dots others. Horizontal dashed line

gives the upper 95th percentile of the TI from reference lakes (= 2.11).

Right: Same data, with quantile regression, showing the median (bold

line) as well as the 5th and 95th percentiles (dashed lines).

Analysis of the trophic index shows that

phytoplankton communities exhibit highly

non-linear responses to eutrophication in

Norwegian lakes. Reference lakes

are characterized by very similar TIs despite

having considerable variation in total

phosphorus and chlorophyll a

concentrations. TI exhibits a non-linear

distribution along the eutrophication

gradient which separates unimpacted from

impacted sites in the study area. We further

show that TI exhibits smaller seasonal

variations than chlorophyll a, making it a

more reliable indicator for lake monitoring.

Few similar data on the

responses to warming

Performance of a new phytoplankton composition metric along a eutrophication

gradient in Nordic lakes. Ptacnik , Solimini,Brettum, Hydrobiologia (2009) 633:75–82

•The responses of ecosystems to a

stressor are often not linear :

Catastrophic shifts in ecosystems

Marten Scheffer, Steve Carpenter, Jonathan A. Foley, Carl Folke & Brian Walkerk, Nature

2001

A graphical model of alternative stable states in shallow lakes on the basis

of three assumptions: (1) turbidity of the water increases with the nutrient level; (2)

submerged vegetation reduces turbidity; and (3) vegetation disappears when a critical

turbidity is exceeded. In view of the first two assumptions, equilibrium turbidity can be

drawn as two different functions of the nutrient level: one for a vegetation-dominated

situation, and one for an unvegetated situation. Above a critical turbidity, vegetation

will be absent, in which case the upper equilibrium line is the relevant one; below this

turbidity the lower equilibrium curve applies. As a result, at lower nutrient levels, only

the vegetation-dominated equilibrium exists, whereas at the highest nutrient levels,

there is only an unvegetated equilibrium. Over a range of intermediate nutrient levels,

two alternative equilibria exist: one with vegetation, and a more turbid one without

vegetation, separated by a (dashed) unstable equilibrium.

External conditions affect the resilience of multi-stable ecosystems to

perturbation. The bottom plane shows the equilibrium curve .The

stability landscapes depict the equilibria and their basins of attraction

at five different conditions. Stable equilibria correspond to valleys; the

unstable middle section of the folded equilibrium curve corresponds

to a hill. If the size of the attraction basin is small, resilience is small

and even a moderate perturbation may bring the system into the

alternative basin of attraction.

•What is the influence of climate change

on shifts in ecosystems? Extreme events

and “catastrophic shifts”

•The impacts of climate change will be different

at different scales across different regions.

1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

4.4

4.6

4.8

5.0

5.2

5.4

5.6

5.8

6.0

4.2

4.0

Années

Tem

péra

ture

°C

The consequences of warming will be different in Lake Geneva (309m red line)

and in Lake Annecy (65m, blue line)

The consequences of warming will be different in Lake Ammersee

and in Lake Annecy

•The impacts of climate change will be different

at different scales across different regions.

Lake Ammersee Lake Annecy

Danis, P.A., von Grafenstein, U., Masson-Delmotte, V., Planton, S., Gerdeaux, D. Moisselin, J.M. (2004): Vulnerability of

two European lakes in response to future climatic changes. Geophysical Research Letters 31.

Surface maximum water temperature

Mean annual air temperatureBottom water temperature

Winters without overturn and oxygenation of the bottom

48

1216

2024

T °C

•The impacts of climate change will be different at

different scales across different regions

•but similar interannual variability In Muggelsee, the phytoplankton biovolume during late

winter/early spring was related to the NAO index. In Lake

Constance, where phytoplankton growth was inhibited by

intense downward mixing during all years studied, this was not

the case. However, in both lakes, interannual variability in

water temperature, in Daphnia spring population dynamics and

in the timing of the clear-water phase, were all related to the

interannual variability of the NAO index. The Daphnia spring

population dynamics and the timing of the clear-water phase

appear to be synchronized by the NAO despite large

differences between the lakes in morphometry, trophic status

and hushing and mixis regimes, and despite the great distance

between the lakes (similar to 700 km). This suggests that a

great variety of lakes in central Europe may possibly have

exhibited similar interannual variability during the last 20 years.Straile & Adrian GLOBAL CHANGE BIOLOGY 2000

Example : Lake Dynamics Monitoring Stations in UK

•The impacts of climate change will be different at

different scales across different regions

•but similar interannual variability

http://www.eurolimpacs.ucl.ac.uk/

It is necessary to maintain and extend high quality, long-term monitoring

to better understand the key processes that control system responses to

climate change and to take into account the inter-annual variations in

ecosystems (for example influence of NAO on European lakes) : a

database to archive key temporal data-sets will be very useful.

Conclusion :

•Biological indicators of warming are essential tools :

•need more studies for a quantitative understanding of

climate change effects on structure and functioning of

freshwater ecosystems

•The impacts of climate change will be different at different scales

across different regions. (ecoregions)

•The responses of ecosystems to a stressor are often not linear

•Extreme events will be more frequent

•necessity to maintain and extend high quality, long-term

monitoring to better understand the key processes that

control system responses to climate change and to take into

account the inter-annual variations in ecosystems and the

uncertainty : adaptation of the baseline of reference

conditions

Conclusion :

Implications of climate change for restoration and protection measures

Measures should be fully climate resilient

No regret measures

Avoid measures that will fail under future climatic conditions

Developing solutions to build resilience

Thanks for your attention