1 Case studies on CHAB control – successful or otherwise Petra Visser Aquatic Microbiology University of Amsterdam The Netherlands
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1
Case studies on CHAB control – successful or otherwise
Petra Visser Aquatic Microbiology
University of Amsterdam The Netherlands
?
How to prevent excessive growth of
cyanobacteria?
4
First, a water system analysis is needed: - Water and nutrient balance
- Quantification of external and internal loading - Identification of dominant cyanobacterial species
How to prevent excessive growth of
cyanobacteria?
5
Methods limiting nutrient loading • reduction of external nutrient loading • dredging bottom sediment / hypolimnetic aeration • flock & lock
Methods affecting the aquatic foodweb • biomanipulation Methods affecting the hydrodynamics • flushing • artificial deep mixing
Cyanocides • Persistent chemicals • Hydrogen peroxide
How to prevent excessive growth of
cyanobacteria?
6
Methods limiting nutrient loading • reduction of external nutrient loading • dredging bottom sediment / hypolimnetic aeration • flock & lock
Methods affecting the aquatic foodweb • biomanipulation Methods affecting the hydrodynamics • flushing • artificial deep mixing
Cyanocides • Persistent chemicals • Hydrogen peroxide
How to prevent excessive growth of
cyanobacteria?
7
Methods limiting nutrient loading • reduction of external nutrient loading • dredging bottom sediment / hypolimnetic aeration • flock & lock
Methods affecting the aquatic foodweb • biomanipulation Methods affecting the hydrodynamics • flushing • artificial deep mixing
Cyanocides • Persistent chemicals • Hydrogen peroxide
Flock & Lock application
Case studies: - Lake Rauwbraken - Lake De Kuil
Courtesy Miquel Lürling
Flock & Lock Untreated
Cyanobacteria dominance
Post-treatment Flocculent + solid P-fixative
Flocculation
Clear water
Precipitation Low biomass eukaryote algae
Sediment capping P P P
Flock & Lock = Tackling bloom + internal loading
Courtesy Miquel Lürling
Mean summer TP concentration (g L-1)
1 10 100 1000
Mea
n su
mm
er c
hlor
ophy
ll-a
conc
entra
tion
(g
L-1)
0.1
1
10
100
2000200120022003200420062007200920102011201220132014
Mesotrophic
Eutrophic
Hypertrophic
Oligotrophic
Mean summer TP concentration (g L-1)
1 10 100 1000
Mea
n su
mm
er c
hlor
ophy
ll-a
conc
entra
tion
(g
L-1)
0.1
1
10
100
200620072008200920102011201220132014Oligotrophic
Mesotrophic
Eutrophic
Hypertrophic
Before Before
After After
Lake Rauwbraken 2.5 ha
Treated April 2008 2 ton PAC + 18 ton Phoslock Full application costs: € 50.000,-
Lake De Kuil 6.7 ha
Treated May 2009 4 ton Fe(III)Cl3 + 42 ton Phoslock Full application costs: € 140.000,-
Flock & Lock application
Lürling et al. 2013; 2014
Flock & Lock application
Succesful case studies: Yes Features lake: isolated, no or low external loading Advantages: short term solution Disadvantages: costly, metals stay in system
How to prevent excessive growth of
cyanobacteria?
12
Methods limiting nutrient loading • reduction of external nutrient loading • dredging bottom sediment / hypolimnetic aeration • flock & lock
Methods affecting the aquatic foodweb • biomanipulation Methods affecting the hydrodynamics • flushing • artificial deep mixing
Cyanocides • Persistent chemicals • Hydrogen peroxide
Flushing
Macrophyte abundance Macrophyte
abundance Macrophyte abundance
Restoration Borderlakes
14
total P Chl-a transparency
non-algal light attenuation % filamentous cyano’s macrophyte coverage
Ibelings et al. 2007
Flushing as strategy against cyanobacteria? A modeling approach in Lake Volkerak
15
- Monitoring the population dynamics of Microcystis - Modeling different scenarios
Verspagen et al. 2006
f1(I)
light intensity [µmol photons m-2 s-1]0 500 1000 1500 2000
grow
th ra
te [d
-1]
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
f2(T)
temperature T [oC]0 4 8 12 16 20 24
grow
th a
nd m
orta
lity
[d-1
]
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
growth rate µmortality rate (m x10)
f3(h)
salinity h [g/L]0 5 10 15 20 25 30
relative growth rate
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
)()()( 321 hfTfIfαµ =
Growth rate depends on light intensity (I), temperature (T), and salinity (h)
Growth rate dependence of environmental factors
Visser et al. 1997; Verspagen et al. 2006
• Scenario 0: current situation • Scenario A: continuous flushing rate (75 m3/s) • Scenario B: low flushing in summer (65 m3/s) high flushing in winter (125 m3/s)
Flushing with fresh water
Verspagen et al. 2006
Flushing
Succesful case studies: Yes Features lake: preferably with the possibility to use nutrient-poor inlet water Advantages: sustainable
How to prevent excessive growth of
cyanobacteria?
19
Methods limiting nutrient loading • reduction of external nutrient loading • dredging bottom sediment / hypolimnetic aeration • flock & lock
Methods affecting the aquatic foodweb • biomanipulation Methods affecting the hydrodynamics • flushing • artificial deep mixing
Cyanocides • Persistent chemicals • Hydrogen peroxide
Case study: Lake ‘Nieuwe Meer’ Amsterdam
Artificial Mixing
High turbulence: sinking species win
Modelling the effect of mixing on phytoplankton
Low turbulence: buoyant species win
Sinking diatoms
Buoyant cyanobacteria
Huisman et al. 2004
Modelling the effect of mixing on phytoplankton
Sinking diatoms
Buoyant cyanobacteria
Lake Nieuwe Meer A = mixing off B = mixing on
Huisman et al. 2004
Artificial mixing shifted the cyanobacterial dominance to algae
Visser et al. 1996; Huisman et al. 2004
Succesful Unsuccesful Lake Brooker, USA (Cowell et al. 1987)
Sheldon Lake, USA (Oberholster et al. 2006)
Fischkaltersee, Germany (intermittent , Steinberg & Zimmermann, 1988)
Fischkaltersee, Germany (continuous, Steinberg 1983)
Solomon Dam, Australia (Hawkins & Griffith (1993)
East Sidney Lake, USA (Barbiero et al. 1996)
Nieuwe Meer, The Netherlands (Visser et al. 1996b; Jöhnk et al. 2008)
North Pine Dam, Australia (Antenucci et al. 2005; Burford & O’Donohue. 2006)
Lake Dalbang, South Korea (Heo & Kim, 2004)
Lake Yogo, Japan (Tsukada et al. 2006)
Bleiloch reservoir, Germany (Becker et al. 2006)
Ford Lake, USA (Lehman et al. 2013; Lehman 2014)
Visser et al. in press
Lakes with artificial mixing to prevent cyanobacterial growth
Pre-conditions for successful applications of artificial mixing
1) the mixing rate should be sufficiently high to entrain the cyanobacteria in the turbulent flow,
2) the mixing should be deep enough to sufficiently limit light availability,
3) the aerators or mechanical mixers should be distributed such that a sufficiently large part of the lake is well-mixed
Artificial mixing
Succesful case studies: Yes and No Features lake: deep, preferably bath-tub-shaped Advantages: short term solution Disadvantages: costly, should be in operation every season
How to prevent excessive growth of
cyanobacteria?
27
Methods limiting nutrient loading • reduction of external nutrient loading • dredging bottom sediment / hypolimnetic aeration • flock & lock
Methods affecting the aquatic foodweb • biomanipulation Methods affecting the hydrodynamics • flushing • artificial deep mixing
Cyanocides • Persistent chemicals • Hydrogen peroxide
Conventional cyanocides/algicides
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metal-ions (mainly copper sulphate or aluminum salts) chemically synthesized herbicides (diuron, endothall)
Disadvantages:
persistence in water and/or sediments
non-selectivity i.e. it can harm also other biota in aquatic ecosystems
toxins are released after cell lysis and remain in the water
Jancula and Marsalek 2011; Jancula et al. in press
Advantages of using hydrogen peroxide
HP breaks down in 1-2 days (2H2O2 2H20 + O2)
Selective killing of cyanobacteria, other phytoplankton are hardly affected
Microcystins break down in 1-2 days Effective in very low concentration: a 3% solution
is diluted 15.000x
30
Cyanobacteria are a lot more sensitive to HP !
Lab experiments
Background: why use hydrogen peroxide?
Drabkova et al. 2007
Selective suppression of cyanobacteria with hydrogen peroxide
Case study: Lake Koetshuis, Veendam
• Surface area 12 ha • Phosphate concentration
0.1 mg P/L
• Since 2007: Planktothrix agardhii dominated
• Lake was often closed for recreation
Cya
noba
cter
ia (1
03 ce
lls m
L-1 )
0
200
400
600
800
1000
1200
Mic
rocy
stin
con
cent
ratio
n (µ
g L-
1 )
0
5
10
15
20
25
0
500
1000
1500
2000
2500
0
5
10
15
20
25
Treated lake
Control lake
Apr May Jun Jul Aug Sep
The results: 1) Strong decrease of
cyanobacteria
2) Microcystins rapidly degraded
3) Remedy lasted for several weeks
Microcystin (µg/L)
Cya
noba
cter
ia 1
0e6
cells
/L
Matthijs et al. 2012
Cyanobacterial number and microcystin concentration in the lake
H2O2
2D Graph 1
X Data
06-Jul 20-Jul 03-Aug 17-Aug 31-Aug 14-Sep
Zoop
lank
ton
(num
ber L
-1)
0
40
80
120
160
200
Phyt
opla
nkto
n (1
03 c
ells
mL-
1 )
0
10
20
30
40
Cya
noba
cter
ia (1
03 c
ells
mL-
1 )
0
100
200
300
400
500
600
700green algaediatomschrysophytescryptophytescyanobacteria
Effects of HP on phytoplankton and zooplankton H2O2
Matthijs et al. 2012
Time after H2O2 application (days)0 1 2 3
H2O
2 co
ncen
tratio
n (m
g L-
1 )
0.0
0.5
1.0
1.5
2.0
2.5
Hydrogen peroxide
Breakdown of HP in the lake
Matthijs et al. 2012
35 35
Other HP Applications in The Netherlands:
Veendam 2009; 2010; 2011 (Planktothrix, Woronichina)
Born 2009 (Microcystis)
Haarlem 2009 (Planktothrix)
Hardenberg 2011 (Aphanizomenon, Anabaena)
Cyano’s always collapsed
And learning moments..
Rotterdam, in study (Gloeothrichia)
Hydrogen peroxide
Succesful case studies: Yes Features lake: preferably cyano-dominated phytoplankton Advantages: leaves no traces behind, does not harm other biota, kills cyanobacteria selectively and breaks down microcystins Disadvantages: should be repeated every year
Hydrogen peroxide (HP) applications
Please take the following considerations into account for a HP application: - Our recommendation is to test a lake sample with different concentrations of
HP in advance to evaluate the effectiveness of an application and monitor the HP concentration and the photosynthetic yield (using a PAM fluorometer)
- HP should not increase the final concentration of 5 mg/L to make sure that algae, zooplankton and bacteria (probably responsible for microcystin degradation) are not harmed
- Presence of many eukaryotic algae and mucilage in colonies (Microcystis) may degrade the HP degradation too fast
- The HP concentration should be > 2 mg/l during at least 5 hours and the decline in photosynthetic vitality should be strong enough (> 80% of the starting value as a proxy) to avoid sudden recovery
- Please contact Petra Visser or Hans Matthijs for advice: [email protected] or [email protected]
Special Issue in Aquatic Ecology 2015:
Cyanobacterial blooms. Ecology,
prevention, mitigation and control.
Eds: Petra Visser, Bas Ibelings,
Jutta Fastner & Myriam Bormans
Future research
- Knowledge on the ecophysiology of cyanobacteria is needed to discover new techniques
- Fine-tuning of the different existing methods
- Lake treatment studies should also be published in scientific literature
- Decision support tool for lake managers
Acknowledgements
Hans Matthijs Jef Huisman Jolanda Verspagen Miquel Lürling Renee Talens
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