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Ecological Engineering 70 (2014) 263–267

Contents lists available at ScienceDirect

Ecological Engineering

jou rn al hom ep age: www.elsev ier .com/ locate /eco leng

hort communication

olidago canadensis L. extracts to control algal (Microcystis) bloomsn ponds

ingying Huanga, Yu Baia, Yan Wangb,∗, Hainan Konga,∗∗

School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai, ChinaSchool of Public Health, Shanghai Jiao Tong University, Shanghai, China

r t i c l e i n f o

rticle history:eceived 16 December 2013eceived in revised form 21 April 2014ccepted 22 May 2014

a b s t r a c t

Landscape ponds often suffer from the overgrowth of nuisance algae (including cyanobacteria). The use ofSolidago canadensis L. as an algicide in a natural water column was evaluated in this study. The results showthat when S. canadensis L. extracts were added to the outdoor enclosures, Microcystis biomass decreasedby more than 70% after 5 d and more than 80% after 25 d. The initial negative effects of the extracts on

eywords:lgal controlater quality

cotoxicologyandscape pond

the water quality were not long-lasting. In addition, the extracts had lower toxicity to Daphnia magnaand zebrafish than to Microcystis aeruginosa. In conclusion, S. canadensis extracts effectively controlledMicrocystis growth in a natural water column, and it is reasonable to expect that the extracts have feweradverse effects on the aquatic ecosystem. This study suggests that using this plant as an algicide to controlMicrocystis blooms in landscape ponds is feasible.

© 2014 Elsevier B.V. All rights reserved.

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. Introduction

Nutrient levels gradually increase over time in landscape lakesnd ponds due to continuous accumulation of pollutants, primar-ly from surface run-off and excessive fish feeding (Chen et al.,013). As a result, eutrophication is a common phenomenon in

andscape lakes and ponds that always leads to algal blooms. Thevergrowth of nuisance algae (including cyanobacteria) increasesurbidity and anoxia, produces toxins and decreases biodiversity,dversely affecting the value and aesthetic appeal of the water bodyAnsari et al., 2010; Codd, 2000). Thus, direct reduction of algaen eutrophic water bodies is an urgent issue, although it does notolve the eutrophication problem. Chemical secretions or extracts

f many plants, e.g., Myriophyllum spicatum, Phragmites australisnd Typha orientalis (Chen et al., 2012; Li and Hu, 2005; Rojo et al.,013), have been reported to inhibit the growth of algae. Among

∗ Corresponding author at: School of Public Health, Shanghai Jiao Tong University,o.227, South Chong Qing Road, Shanghai 200025, China.el./Fax: 86-021-63842157.∗∗ Corresponding author at: School of Environmental Science and Engineering,hanghai Jiao Tong University, No.800, Dong Chuan Road, Shanghai 200240, China.el./Fax: 86-021-34203735.

E-mail addresses: wangyan66@sjtu.edu.cn (Y. Wang), hnkong@sjtu.edu.cnH. Kong).

(erbtstoltTo

ttp://dx.doi.org/10.1016/j.ecoleng.2014.05.025925-8574/© 2014 Elsevier B.V. All rights reserved.

hese is barley straw, which has been used successfully in field tri-ls in the States and Britain (Barrett et al., 1999; Ferrier et al., 2005;pencer and Lembp, 2007).

Landscape lakes or ponds are usually located in central areaf urban communities, and an alien invasion species Solidagoanadensis is often found near these areas. S. canadensis, in theamily Compositae, is a perennial plant native to North America.. canadensis was initially introduced to China as an ornamental inhe 1930s and then escaped into the wild and spread rapidly (Lut al., 2007). Today, this alien weed appears in various habitats, e.g.,armlands, roadsides and green belts. Our previous study reportedhat S. canadensis L. extracts could be obtained using a simple pro-ess and the extracts exerted algistatic activity in the laboratoryHuang et al., 2013). To date, studies have focused almost on thefficacy of plant products on controlling the algal growth. Althoughesearchers consider these substances derived from plants to beiodegradable and more eco-friendly than synthetic algicides dueo their natural origin (Jancula and MarSálek, 2011), there are fewtudies evaluating their impacts on water quality and environmen-al risks. To further assess the effects of S. canadensis L. extractsn Microcystis blooms under natural conditions, a trial was estab-

ished in outdoor enclosures in a landscape pond. The effects ofhe extracts on algal biomass and water quality were discussed.o evaluate the feasibility of application, their effects on aquaticrganisms were also considered.

2 Engineering 70 (2014) 263–267

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64 Y. Huang et al. / Ecological

. Materials and methods

.1. Preparation of S. canadensis L. extracts

S. canadensis L. was collected in Shanghai Jiao Tong University,ried for 48 h at 80 ◦C, crushed and then soaked in 95% ethanol fiveimes in the dark, for 24 h each time. All of the ethanol extracts werehen concentrated and then dissolved in warm double-distilledater. Petroleum ether was used repeatedly to remove the lipid-

oluble components. The remaining water-soluble componentsere the target extracts and dissolved in double-distilled water.oncentrations of the extracts are expressed as the water-solubleomponent mass per volume of solvent (g L−1).

.2. Enclosure experiments

Enclosure experiments lasted from September 3rd to December4th and were performed in three enclosures established in a land-cape pond in Shanghai Jiao Tong University (31◦01′N, 121◦25′E).ach enclosure was approximately 1 m2 in area and 1.2 m in depth.icrocystis blooms were induced in the enclosures by addingicrocystis aeruginosa and nutrients (NaNO3 and KH2PO4). Whenicrocystis blooms were observed in the three enclosures, two con-

entrations of S. canadensis L. extracts (10 and 50 mg L−1) weredded to the two treatment enclosures; the third enclosure wassed as the control. Water samples in each enclosure were takenrom 0.1, 0.6 and 1.1 m depths and then mixed to assess the changen water quality. Chlorophyll a (Chl a), pH, TN, TP and CODcr werenalyzed according to Standard Methods (APHA, 1995, 1999).

.3. Safety of the extracts to aquatic organisms

The extracts were filtered through 0.45 �m glass fiber filteraper and stored at 4 ◦C.

The inhibition test of M. aeruginosa was performed in an artifi-ial climate chamber at 25 ± 1 ◦C, with a 14:10 L/D cycle and anllumination of 3500 lx. The extracts were added to Erlenmeyerasks containing BG11 medium, and the medium was inoculatedith M. aeruginosa culture. The initial cell density was approxi-ately 2 × 105 cells mL−1. The extracts from 0 to 0.3 g L−1 were

mployed, using three replicate flasks for each dose. The effectsf the extracts were expressed using the inhibition ratio (IR). IR isefined as follows: IR (%) = (C − T/C) × 100, where T and C are cellensity of treatment and control, respectively.

Daphnia magna was maintained in aerated tap water with.222 g L−1 CaCl2, 0.060 g L−1 MgSO4, 0.065 g L−1 NaHCO3 and.006 g L−1 KCl at 20 ± 1 ◦C with a 16:8 L/D cycle. Neonates, nolder than 24 h at the beginning of the test, were exposed to dif-erent concentrations of the extracts in 50 mL of the medium inach vessel. The acute immobilization test was performed accord-ng to the OECD guideline 202 (OECD, 2004). Fifty neonates, dividednto five groups of 10 neonates each, were used for each test con-entration and for the control. The neonates were not fed duringhe test. After 24, 48 and 72 h, the immobilization of Daphnia wasecorded. The extracts from 0 to 2 g L−1 were employed. Repro-uction tests were performed according to OECD guideline 211OECD, 1998). Ten neonates were maintained individually for eachest concentration and for the control. The test duration was 21 d.he medium was renewed every 2 d, and the animals were fedith Scenedesmus obliquus. The offspring produced by each par-

nt animal were counted and removed daily. The extracts from 0

o 0.5 g L−1 were employed in the reproduction tests.

Zebrafish were domesticated a month before the test. The fishaintained in aerated tap water at 23 ± 1 ◦C with a 16:8 L/D cycle.

he average weight of the experimental fish was 0.1345 ± 0.0065 g.

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Fig. 1. Effects of S. canadensis L. extracts on Microcystis blooms in the enclosures.

he acute test was performed according to the OECD guideline 203OECD, 1992). Zebrafish were exposed to different concentrationsf the extracts in 1 L of aerated tap water in each vessel. Thirty fish,ivided into three groups of 10 fish each, were used for each testoncentration and for the control. The fish were not fed from 24 hefore the test to the end of the test. After 24, 48 and 72 h, theumber of dead fish was recorded. Dead fish were removed whenbserved. The extracts from 0 to 0.5 g L−1 were employed for theest.

Significant differences between the data were detected by anNOVA, and results were considered significant at a p-level <0.05.he EC50 and LC50 values were calculated by SPSS Statistics 20.0sing probit analysis.

. Results and discussion

.1. Effects of the extracts on the algal growth in enclosures

Algal biomass decreased in the enclosures following addition ofhe extracts (Fig. 1). The Chl a concentration in the control enclo-ure remained between 100 and 180 �g L−1 over the course ofpproximately one month. Conversely, in the 10 and 50 mg L−1

xtracts-treated enclosures, the Chl a concentration decreasedignificantly from 120 to 30 �g L−1 and from 136 to 36 �g L−1,espectively, and the removal ratios of the algae were 75.42% and3.30% after 5 d, respectively. After 25 d, the removal ratios were1.47% and 78.55%, respectively. Although the Chl a concentra-ion in the treated enclosures remained at a low level (20 �g L−1)fter 60 d, the value was also low (30 �g L−1) in the control enclo-ure. A possible reason was that the low temperature (November)nhibited algal growth.

The significant decrease in the algal biomass following additionf the extracts suggested that the extracts have algistatic activityn a natural water column. Although dry plant material would beirectly applied in water bodies suffering from algal blooms, thisrocess is not likely to produce rapid, visible results because ofhe low naturally decomposition rate. Decomposition of dry plant

aterial is necessary to release sufficient chemicals to effectivelyontrol algae, and the decomposition process is subject to temper-ture and oxygen levels. For example, barley straw requires at leastne to two weeks of decomposition above 68 ◦F with a high oxygen

evel, and it commonly takes several months to effectively controln algal bloom (Lembi, 2002). However, most algal blooms lead toxygen reduction in water bodies, which makes plant decomposi-ion more difficult. In our study, the Chl a concentration decreased

Y. Huang et al. / Ecological Engineering 70 (2014) 263–267 265

Table 1EC50 of Microcystis aeruginosa and LC50 of Daphnia magna and zebrafish followingexposure to the extracts. Data represent means with associated error bars (SD).

Time 24 h 48 h 72 h

M. aeruginosa – 0.30 ± 0.02 0.26 ± 0.02

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D. magna 2.02 ± 0.08 1.42 ± 0.07 1.19 ± 0.04Zebrafish 0.42 ± 0.03 0.33 ± 0.04 0.32 ± 0.03

ignificantly in a very short time after addition of the extracts. Thus,irect applying plant extracts could accelerate the production of

nhibitory effects, which would be an emergency measure to con-rol erupted algal blooms. Moreover, the application of the extractsas less influence on the aesthetic appeal of the water body.

.2. Effects of the extracts on the water quality in enclosures

After addition of the extracts, water quality changed obviouslyn a short time (Fig. 2). During the first 3 d, the pH decreased.8, 1.3 and 3.7 unit in the control enclosure and the 10 and0 mg L−1 extracts-treated enclosures, respectively. Only in 1 d,bvious increases in the TP (0.36 to 0.50 mg L−1) and CODcr (35.41o 54.67 mg L−1) were observed in the 50 mg L−1 extracts-treatednclosure, whereas there were no remarkable changes in TP andODcr in the 10 mg L−1 extracts-treated enclosure. However, the

ncrease of the TN was unobserved in the treated enclosures.Over time, the pH values in the three enclosures tended to be

onsistent at approximately 8.5. The TN in the three enclosuresaried widely over the course of the experiment. During the latertage of the experiment, the TN remained a high level in the con-rol enclosure and decreased slightly in the treated enclosures.fter 25 d, the TP decreased by 46.96%, 52.71% and 19.11%, and

he CODcr decreased by 32.01%, 55.27% and 44.38% in the con-rol enclosure and 10 and 50 mg L−1 extracts-treated enclosures,espectively. During the later stage of the experiment, the TP andODcr in the treated enclosures were lower than in the controlnclosure, except the TP in 50 mg L−1 extracts-treated enclosure.

It was possible that addition of the extracts had a negative influ-nce on water quality because it decreased the pH and increase theP and COD in the initial stage. However, the ephemeral increase inutrients did not stimulate the algal growth, and the water quality

n the treated enclosures improved notably over time. Similarly, nodverse effect on water quality was observed during the process ofsing barley straw to control algae (Everall and Lees, 1996). Beforearley straw was added to Valley Lake in Minnesota, the trans-arency, chlorophyll and TP were 3 m, 36 �g L−1 and 71 �g L−1,espectively; whereas after the addition of barley straw in 2000nd 2001, the transparency increased to 6 m, and the chlorophyllnd TP decreased to 7 and 37 �g L−1, respectively (Lembi, 2002).hese results suggested that addition of plants or plant extractsad fewer adverse effects on water quality.

.3. Safety of the extracts for aquatic organisms

The EC50 and LC50 values decreased with time and were lowern M. aeruginosa than in D. magna and zebrafish (Table 1). Exposureo the extracts for 72 h resulted in an EC50 value of 0.26 g L−1 in M.eruginosa and a LC50 value of 1.19 g L−1 in D. magna and 0.32 g L−1

n zebrafish; besides, cell density of M. aeruginosa and survivalumber of D. magna and zebrafish were significantly decreasedp < 0.05) when the extracts concentration increased to 0.15, 0.2

nd 1.0 g L−1, respectively.

The effects of the extracts on D. magna reproduction are shownn Table 2. The extracts significantly decreased the survival numbernd average survival time of the parent animals at concentrations

Fig. 2. Effects of S. canadensis L. extracts on the water quality in the enclosures: pH(a), TN (b), TP (c) and CODCr (d).

266 Y. Huang et al. / Ecological Engineering 70 (2014) 263–267

Table 2Reproduction response of Daphnia magna after 21 d of exposure to the extracts. Data represent means with associated error bars (SD).

Control 0.05 g L−1 0.1 g L−1 0.2 g L−1 0.3 g L−1 0.5 g L−1

The survival of the parent animals 10 10 10 10 4 0Average survival time of the parent animals (d) 21 21 21 21 12.90 ± 7.20* 8.00 ± 3.58*

Time to production first brood (d) 8.80 ± 0.98 10.00 ± 1.63 8.88 ± 1.62 10.33 ± 2.00 8.17 ± 0.37 –Total number of living offspring per animal alive 41.00 ± 5.14 44.78 ± 14.54 50.89 ± 32.79 19.44 ± 15.2* 22.75 ± 13.83 –

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Total number of living offspring per animal per day 3.11 ± 0.36 3.7

* Significantly different (p < 0.05) from control.

f 0.3 g L−1 and higher (p < 0.05). The time to production of the firstrood was affected little by the extracts (p > 0.05). At concentrationsf 0.2 g L−1 and higher, the extracts decreased the total number offfspring per animal alive and the total number of offspring pernimal per day, but among the two parameters, only at concen-ration of 0.2 g L−1, the total number of living offspring per animallive was significantly different from the control (p < 0.05). Whenxposed to 0.5 g L−1 extracts, the parent animals survived from 5o 17 d, but did not have any offspring throughout their lives.

When algicides are introduced into water bodies, the environ-ental risks they pose are of concern. Synthetic algicides, includingetals, herbicides and polyacrylamide, are always low-cost options

ut are also toxic to non-target species, accumulate in the envi-onment and deplete water quality (Jancula and MarSálek, 2011).or example, aluminum cause a rapid decrease in the pH of waterodies and has negative effects on zooplankton due to adhesion ofarticles to their filtering apparatuses or through entrapment of theooplankton in floccules (Jancula et al., 2011). Diuron is moderatelyoxic to fish (48 h-LC50 from 4.3 to 42 mg L−1) and slightly toxic toquatic invertebrates (48 h-LC50 from 1 to 2.5 mg L−1) (Giacomazzind Cochet, 2004). Our results showed the acute toxicity of thextracts to D. magna and zebrafish was lower than to M. aeruginosa.n the reproduction test, the living offspring of D. magna decreasedn the medium with 0.2 g L−1 extracts that was renewed every 2 d.onsidering that the extracts are biodegradable due to their naturalrigin and do not remain a high level in water bodies, it is rea-onable to expect that the extracts have fewer adverse effects onhe aquatic ecosystem. However, our research on their safety wasreliminary and the ecological effects of the extracts need furthertudy.

It should be noticed that the effective dose of S. canadensis L.xtracts required for algal inhibition in the laboratory was largerhan that in a natural water column, and there were some simi-ar reports on barley straw. In a series of studies of Gibson et al.1990) and Welch et al. (1990), experiments in laboratory studyad approximately 10 times more barley straw dosage than in thehesterfield Canal study. In the laboratory M. aeruginosa was be

nhibited with from 70 to 230 g m3 of barley straw (Martin andidge, 1999); while, Barrett et al. (1999) reported an effectiveontrol of reservoir phytoplankton at a dosage as low as 6 g m3. Con-eivable reasons for this difference was that culture condition forlgae is more suitable in laboratory, and organic chemicals woulde more toxic under the dynamic conditions that occur in the fieldnd a static test would underestimate toxicity (Geyer et al., 1985;ouany et al., 1983; Martin and Ridge, 1999). Whether this is trueequires further investigation.

. Conclusion

Our study demonstrated S. canadensis L. extracts efficiently con-rol Microcystis blooms in a natural water column, and they hadewer adverse effects on the water quality and ecological system.t provides an environment-friendly way to use this weed as an

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mergency measure to control erupted algal blooms in landscapeonds or small lakes.

cknowledgment

This research was supported by the National Natural Scienceoundation of China under grant no. 21077074.

ppendix A. Supplementary data

Supplementary material related to this article can be found,n the online version, at http://dx.doi.org/10.1016/j.ecoleng.014.05.025.

eferences

nsari, A.A., Gill, S.S., Khan, F.A., 2010. Eutrophication: threat to aquatic ecosystems.In: Ansari, A.A., Lanza, G.R. (Eds.), Eutrophication: Causes, Consequences andControl. Springer, Germany, pp. 143–170.

PHA, 1995. Standard Methods for the Examination of Water and Wastewater, 19ed. American Public Health Association, Washington, DC.

PHA, 1999. Standard Methods for the Examination of Water and Wastewater, 20ed. American Public Health Association, Washington, DC.

arrett, P.R.F., Littlejohn, J.W., Curnow, J., 1999. Long-term algal control in a reservoirusing barley straw. Hydrobiologia 415, 309–313.

hen, J., Zhang, H., Han, Z., Ye, J., Liu, Z., 2012. The influence of aquatic macrophyteson Microcystis aeruginosa growth. Ecol. Eng. 42, 130–133.

hen, X., Huang, X., He, S., Yu, X., Sun, M., Wang, X., Kong, H., 2013. Pilot-scalestudy on preserving eutrophic landscape pond water with a combined recyclingpurification system. Ecol. Eng. 61, 383–389.

odd, G.A., 2000. Cyanobacterial toxins, the perception of water quality, and theprioritisation of eutrophication control. Ecol. Eng. 16, 51–60.

verall, N.C., Lees, D.R., 1996. The use of barley-straw to control general andblue–green algal growth in a Derbyshire reservoir. Water. Res. 30, 269–276.

errier, M.D., Butler Sr., B.R., Terlizzi, D.E., Lacouture, R.V., 2005. The effects of barleystraw on the growth of freshwater algae. Bioresour. Technol. 96, 1788–1795.

eyer, H., Scheunert, I., Korte, F., 1985. The effects of organic environmental chem-icals on the growth of the alga Scenedesmus subspicatus: a contribution toenvironmental biology. Chemosphere 14, 1355–1369.

iacomazzi, S., Cochet, N., 2004. Environmental impact of diuron transformation: areview. Chemosphere 56, 1021–1032.

ibson, M.T., Welch, I.M., Barrett, P.R.F., Ridge, I., 1990. Barley straw as an inhibitorof algal growth. II: Laboratory studies. J. Appl. Phycol. 2, 241–248.

uang, Y., Bai, Y., Wang, Y., Kong, H., 2013. Allelopathic effects of the extracts froman invasive species Solidago canadensis L. on Microcystis aeruginosa. Lett. Appl.Microbiol. 57, 451–458.

ancula, D., MarSálek, B., 2011. Critical review of actually available chemicalcompounds for prevention and management of cyanobacterial blooms. Chemo-sphere 85, 1415–1422.

ancula, D., Mikula, P., Marsálek, B., 2011. Effects of polyaluminium chloride on thefreshwater invertebrate Daphnia magna. Chem. Ecol. 27, 351–357.

ouany, J.M., Ferard, J.F., Vasseur, P., Gea, J., Truhaut, R., Rast, C., 1983. Interest ofdynamic tests in acute ecotoxicity assessment in algae. Ecotoxicol. Environ. Saf.7, 216–228.

embi, C.A., 2002. Barley straw for algae control. In: Aquatic Plant Manage-ment Publication APM-1-W. Purdue University, South Bend, IN, Available fromhttp://www.btny.purdue.edu/pubs/APM/APM-1-W.pdf.

i, F.M., Hu, H.Y., 2005. Isolation and characterization of a novel antialgal allelo-chemical from Phragmites communis. Appl. Environ. Microb. 71, 6545–6553.

u, J.Z., Weng, E.S., Wu, X.W., Weber, E., 2007. Potential distribution of Solidago

canadensis in China. Acta Phytotaxon. Sin. 45, 670–674.

artin, D., Ridge, I., 1999. The relative sensitivity of algae to decomposing barleystraw. J. Appl. Phycol. 11, 285–291.

ECD, 2004. OECD Guidelines for Testing of Chemicals. Guideline 202: Daphnia sp.,Acute immobilisation Test. OECD Publishing.

Engin

O

O

R

Scontrol method in Northern California Rice Fields. J. Aquat. Plant Manage. 45,

Y. Huang et al. / Ecological

ECD, 1992. OECD Guidelines for Testing of Chemicals. Guideline 203: Fish, AcuteToxicity Test. OECD Publishing.

ECD, 1998. OECD Guidelines for Testing of Chemicals Guideline 211: Daphniamagna Reproduction Test. OECD Publishing.

ojo, C., Segura, M., Rodrigo, M.A., 2013. The allelopathic capacity of submergedmacrophytes shapes the microalgal assemblages from a recently restoredcoastal wetland. Ecol. Eng. 58, 149–155.

W

eering 70 (2014) 263–267 267

pencer, D., Lembp, C., 2007. Evaluation of barley straw as an alternative algal

84–90.elch, I.M., Barrett, P.R.F., Gibson, M.T., Ridge, I., 1990. Barley straw as an inhibitor

of algal growth. I: Studies in the Chesterfield Canal. J. Appl. Phycol. 2, 231–239.