Impact of climate on shifts in stable states
in shallow lakes
South American Lake Gradient Analysis
Sarian Kosten
Wageningen University
The Netherlands
Project outline
Research questions
Preliminary results
Outline
Temperate shallow lakes tend to be in
either of two alternative stable states.
Preliminary work suggests that shallow
lakes may be very sensitive to climatic
change.
Low nutrient
High nutrient
83 lakes
Latitude 5 – 55 degrees south
Sample sites
83 lakes
Latitude 5 – 55 south
Low altitude / coastal
Shallow lakes (average 1.8 m [4.5 – 0.5])
Area between 9 and 250 ha.
November 2004 – March 2006
Mid-summer samples
All sampled by the same team
Questions
How do algae react to higher temperatures?
• N versus P-limitation?
• reach higher concentrations?
How do macrophytes react to higher temperatures?
• resist higher turbidities?
• disappear at higher nutrient levels?
Does the interaction between algae and macrophytes
change at higher temperatures?
Questions
How do algae react to higher temperatures?
• N versus P-limitation?
• reach higher concentrations?
How do macrophytes react to higher temperatures?
• resist higher turbidities?
• disappear at higher nutrient levels?
Does the interaction between algae and macrophytes
change at higher temperatures?
Gyllstrom et al., 2005
N. American & European lakes
(Mazumder 1994)
192 (sub)tropical lakes
(Huszar et al. 2006)
Huszar et al., 2006
Algae reach a higher biomass – at a given
total-P concentration - in colder climates
Why do algae reach lower concentrations at
a certain nutrient leven when the
temperature increases?
• Both production and respiration will
increase but respiration increases relatively
more than production
(Lopez-Urrutia et al., 2006)
Preliminary results from our study:
Trophic state
Köppen Climate Classification
Tropical
with distinct dry season
Tropical – Subtropical
with and without dry
season
Subtropical
Polar
tundra
All lakes
Polar
Subtropic
Tropic
Total phosphorus (μg L-1)
Log Chl-a
Log Tot-P
R2
1.5
1.4
1.9
1.6
0.59
0.94
0.56
0.38
Next 2 slides is I did not show because of lack of time, but isn’t it
interesting to see that we have a dominance of N limitation along
almost the entire gradient. It will be nice to compare that with other
shallow lakes around the globe.
Limiting nutrient
Nitrogen limited
Phosphorus limited
Redfield ratio
N:P = 16:1
SLOPE EXACTLY THE SAME FOR ALL REGIONS!!
Polar
Subtropics
Tropics
Chl-a (μg/l)
All lakes
Total nitrogen (μg/l)
Log Chl-a
Log Tot-N
R2
1.1
1.1
1.1
1.1
0.78
0.72
0.81
0.69
Overall the algae seem to reach a slightly
higher biomass at a given total-P level at
higher temperatures
In a comparative study between temperate and artic
lakes Flanagan et al. (2003) found higher biomasses
at higher temperatures as well.
Why would warmer be better for algae?
•Low enzyme activity when cold (Markager et al. 1999)
•Presence of cyanobacteria
•Absence of large zooplankton
Questions
How do algae react to higher temperatures?
• N versus P-limitation?
• reach higher concentrations?
How do macrophytes react to higher
temperatures?
• resist higher turbidities?
• disappear at higher nutrient levels?
Does the interaction between algae and macrophytes
change at higher temperatures?
Coverage percentage
of submerged plants
Average Kd in lakes with a small (<30%) and a
large (>30%) coverage of submerged plants
Kd [m-1]
8
6
4
2
0
RN <30
RN >70 (Sub)tropical
RJ <30 RJ >70
Tropical
UY<30
UY >70
Subtropical
TF<30Polar
TF>70
climate zone
Lakes with a coverage percentage of submerged plants <30%
Lakes with a coverage percentage of submerged plants >30%
light intensity (average)
at plant canopy
light intensity
[E m-2 min-1]
200
150
100
50
0
Tropical
RN
(Sub)tropical
RJ
Subtropical
UY
climate zone
Polar
TF
Maximum nutrient concentration at which
submerged macrophytes occur
tot N or P
(mg/l)
6
4
max tot-P
max tot-N
2
0
RN
RJ
UY
climate zone
TF
How do macrophytes react to
higher temperatures?
Do they occur at higher turbidities? >>> NO
Do they occur at higher nutrient levels? >>> NO
Why?
Not only temperature changes but total daily
irradiance as well.
Unbalance of data set
Questions
How do algae react to higher temperatures?
• N versus P-limitation?
• reach higher concentrations?
How do macrophytes react to higher temperatures?
• resist higher turbidities?
• disappear at higher nutrient levels?
Does the interaction between algae and
macrophytes change at higher temperatures?
Water clearing effect of
submerged
macropytes
Tropical
climate
"water-clearing-effect" of
submerged plants (%)
Tropical climate
100
50
chl-a
0
turbidity
-50
-100
0.0
0.1
0.6
Total-N (mgN/l)
Tropical - Subtropical climate
"water-clearing-effect" of
submerged plants (%)
50
100
50
chl-a
0
turbidity
-50
-100
chl-a
0.2
turbidity
0
0.2
0.2
0.3
0.3
0.8
0.9
0.9
Total-N (mgN/l)
Subtropical climate
-50
-100
0.0
0.1
0.6
"water-clearing-effect" of
submerged plants (%)
100
50
chl-a
0
turbidity
-50
-100
Total-N (mgN/l)
0.0 0.1 0.2
0.2 0.3 0.4 1.0
1.1 1.3 2.4
Total-N (mgN/l)
Polar climate
"water-clearing-effect" of
submerged plants (%)
"water-clearing-effect" of
submerged plants (%)
100
100
50
chl-a
0
turbidity
-50
-100
0.1
0.1
0.4
0.4
0.9
Total-N (mgN/l)
1.0
1.4
5.3
Preliminary results
We found a small effect on the
TP chl-a relationship
We did not find submerged
macrophytes in more turbid
conditions in warmer climates
We found a water clearing
effect of submerged
macropytes along the whole
climate gradient
NWO/WOTRO
The National Geographic Society
The Schure-BeijerinckPopping fund
Kosten Watersport bv.
Gissell Lacerot
Andy Lotter
Bart Koelmans
Carla Kruk
Christina Branco
David da Motta Marques
Erik Jeppesen
Egbert van Nes
Fabio Roland
Jeroen de Klein
John Beijer
Jose Luiz Attayde
Jose Paggi
Katleen van der Gucht
Luc de Meester
Marten Scheffer
Miquel Lurling
Nestor Mazzeo
Susana de Paggi
Vera Huszar
www.salga.wur.nl