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 1

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4 How to prevent excessive growth of cyanobacteria? First, a water system analysis is needed: - Water and nutrient balance - Quantification of external and internal loading - Identification of dominant cyanobacterial species 4

5 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

6 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

7 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

8 Courtesy Miquel Lürling Flock & Lock application Case studies: - Lake Rauwbraken - Lake De Kuil

9 Untreated Flock & Lock Flocculent + solid P-fixative Post-treatment Cyanobacteria dominance Flocculation Precipitation Low biomass eukaryote algae Clear water P P P Sediment capping Flock & Lock = Tackling bloom + internal loading Courtesy Miquel Lürling

10 Flock & Lock application Mean summer chlorophyll-a concentration ( g L -1 ) Hypertrophic Eutrophic Mesotrophic Oligotrophic Lake Rauwbraken 2.5 ha After Before Mean summer TP concentration ( g L -1 ) Hypertrophic Lake De Kuil 6.7 ha Before Eutrophic Mesotrophic After Oligotrophic Mean summer TP concentration ( g L -1 ) 100 Mean summer chlorophyll-a concentration ( g L -1 ) Treated April ton PAC + 18 ton Phoslock Full application costs: ,- Treated May ton Fe(III)Cl ton Phoslock Full application costs: ,- Lürling et al. 2013; 2014

11 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

12 How to prevent excessive growth of cyanobacteria? 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 12

13 Flushing Macrophyte abundance Macrophyte abundance Macrophyte abundance

14 Restoration Borderlakes total P Chl-a transparency non-algal light attenuation % filamentous cyano s macrophyte coverage 14 Ibelings et al. 2007

15 Flushing as strategy against cyanobacteria? A modeling approach in Lake Volkerak - Monitoring the population dynamics of Microcystis - Modeling different scenarios 15 Verspagen et al. 2006

16 Growth rate dependence of environmental factors µ = α f ( I) f2( T ) f3( 1 h Growth rate depends on light intensity (I), ) growth rate [d -1 ] f 1 (I) temperature (T), and salinity (h) growth and mortality [d -1 ] light intensity [µmol photons m -2 s -1 ] 1.5 f 2 (T) growth rate µ mortality rate (m x10) f 3 (h) relative growth rate temperature T [ o C] salinity h [g/l] Visser et al. 1997; Verspagen et al. 2006

17 Flushing with fresh water Scenario 0: current situation Scenario A: continuous flushing rate (75 m 3 /s) Scenario B: low flushing in summer (65 m 3 /s) high flushing in winter (125 m 3 /s) Verspagen et al. 2006

18 Flushing Succesful case studies: Yes Features lake: preferably with the possibility to use nutrient-poor inlet water Advantages: sustainable

19 How to prevent excessive growth of cyanobacteria? 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 19

20 Artificial Mixing Case study: Lake Nieuwe Meer Amsterdam

21 Modelling the effect of mixing on phytoplankton High turbulence: sinking species win Sinking diatoms Buoyant cyanobacteria Low turbulence: buoyant species win Huisman et al. 2004

22 Modelling the effect of mixing on phytoplankton Lake Nieuwe Meer A = mixing off B = mixing on Sinking diatoms Buoyant cyanobacteria Huisman et al. 2004

23 Artificial mixing shifted the cyanobacterial dominance to algae Visser et al. 1996; Huisman et al. 2004

24 Lakes with artificial mixing to prevent cyanobacterial growth Succesful Lake Brooker, USA (Cowell et al. 1987) Unsuccesful 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

25 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

26 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

27 How to prevent excessive growth of cyanobacteria? 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 27 Hydrogen peroxide

28 Jancula and Marsalek 2011; Jancula et al. in press Conventional cyanocides/algicides 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 28

29 Advantages of using hydrogen peroxide HP breaks down in 1-2 days (2H 2 O 2 2H O 2 ) 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 x

30 Background: why use hydrogen peroxide? Lab experiments Cyanobacteria are a lot more sensitive to HP! Drabkova et al

31 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

32 Cyanobacterial number and microcystin concentration in the lake Treated lake H 2 O The results: Cyanobacteria Cyanobacteria (10 3 cells 10 e 6 ml cells -1 ) /L Control lake Microcystin concentration (µg L -1 ) Microcystin (µg/l) 1) Strong decrease of cyanobacteria 2) Microcystins rapidly degraded 3) Remedy lasted for several weeks Apr May Jun Jul Aug Sep 0 Matthijs et al. 2012

33 Effects of HP on phytoplankton and zooplankton Phytoplankton (10 3 cells ml -1 ) H 2 O 2 green algae diatoms chrysophytes cryptophytes cyanobacteria 2D Graph Cyanobacteria (10 3 cells ml -1 ) Zooplankton (number L -1 ) Jul 20-Jul 03-Aug 17-Aug 31-Aug 14-Sep Matthijs et al X Data

34 H2O2 concentration (mg L -1 ) Breakdown of HP in the lake Hydrogen peroxide Time after H2O2 application (days) Matthijs et al. 2012

35 Other HP Applications in The Netherlands: Veendam 2009; 2010; 2011 (Planktothrix, Woronichina) Cyano s always collapsed Haarlem 2009 (Planktothrix) Hardenberg 2011 (Aphanizomenon, Anabaena) And learning moments.. Rotterdam, in study (Gloeothrichia) Born 2009 (Microcystis)

36 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

37 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: p.m.visser@uva.nl or h.c.p.matthijs@uva.nl

38 Special Issue in Aquatic Ecology 2015: Cyanobacterial blooms. Ecology, prevention, mitigation and control. Eds: Petra Visser, Bas Ibelings, Jutta Fastner & Myriam Bormans

39 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

40 Acknowledgements Hans Matthijs Jef Huisman Jolanda Verspagen Miquel Lürling Renee Talens

41 Thank you 41