東湖富營養(yǎng)化的成因和治理對策

東湖富營養(yǎng)化的成因分析和治理對策EutrophicationofLakeDonghu:CauseAnalysisandRemedyStrategy劉建康JiankangLIU中科院水生生物研究所InstituteofHydrobiology,theChineseAcademyofSciencesSeriouseutrophicationinLakeDonghu東湖富營養(yǎng)化十分嚴(yán)重1．二十年前東湖富營養(yǎng)化的綜合評價和氮磷收支 ComprehensiveevaluationofDonghu’seutrophicationinthe1980sanditsN,PbudgetsEutrophicationofthelakebeganinthemid-1950sandproceededratherfast.

東湖的富營養(yǎng)化開始于五十年代中期，進(jìn)程頗為快速。Early1980s: NO3-N,NO2-N,NH4-N,TN,PO4-P,TP,SiO2Phytoplankton

Averagedailyprimarygrossproduction Biomass Chlorophylla

Acomprehensiveevaluationofstatusofeutrophication:onthewayoftransitionfromeutrophictohyper-eutrophic(Cai,1993)八十年代初期NO3-N,NO2-N,NH4-N,TN,PO4-P,TP,SiO2浮游植物: 日平均初級生產(chǎn)量生物量葉綠素a東湖當(dāng)時已處于富營養(yǎng)化向超富營養(yǎng)化過渡的階段（蔡慶華，1993）

氮的總輸入量: 536t/a總負(fù)荷量: 19.22g/m2磷的總輸入量: 87.8t/a總負(fù)荷量: 3.15g/m2輸入-輸出差: 總氮 323.2t/a（占總輸入量60.3%） 總磷 67.7t/a（占總輸入量77.1%）

（張水元等，1984）

Ninput: 536t/aTotalloading: 19.22g/m2Pinput: 87.8t/aTotalloading: 3.15g/m2Differenceininputandoutput: N 323.2t/a（60.3%oftotalinput） P 67.7t/a（77.1%oftotalinput）

（Zhangetal，1984）

AbundanceandspeciescompositionofphytoplanktoninLakeDonghuduring1956－1975,andthedynamicsofprimaryproductivity2．1956-1975年東湖浮游藻類數(shù)量和種類組成情況，和初級生產(chǎn)力的演變Theaverageannualtotalnumberofphytoplanktonwassteadilyontheincrease1950s: 27-949 ind/ml1960s: 156-4662 ind/ml1970s： 1000-35000 ind/ml

浮游藻類年平均總數(shù)不斷增加50年代：27-949個/ml60年代：156-4662個/ml70年代：1000-35000個/ml（饒欽止、章宗涉，1980）（JaoandZhang，1980）Pronouncedchangeoccurredinthespeciescompositionofphytoplankton1956-1957: PyrrophytaBacillariophyta1960s: CyanophytaChlorophyta

MicrocystisAphanizomenonAnabaenaetc.

種類組成明顯改變1956－1957: 甲藻硅藻60年代： 藍(lán)藻 綠藻（饒欽止、章宗涉，1980）微囊藻（Microcystis）束絲藻（Aphanizomenon）魚腥藻（Anabaena）等（JaoandZhang，1980）Primaryproductivityofphytoplanktonincreasedrapidly

浮游藻類初級生產(chǎn)量急劇增加

1963－1990年:最高生產(chǎn)層日產(chǎn)量平均每年增長0.256mgO2/天 水柱最高日產(chǎn)量平均每年增長0.243gO2/m2﹒天1973－1985年:水柱日產(chǎn)量平均每年增長0.554g/m2﹒天

（戎克文等，1995）1963-1990:Averagedailyproductionatthelayerofmaximumproductionincreasedby0.256mgO2perday, Maximumdailyproductionofwatercolumnincreasedby0.243gO2/m2perday.1973-1985:Dailyproductionofwatercolumnincreasedby0.554gO2/m2perday.（Rongetal.，1995）Aggravationofexogenicpollutionthroughthedischargeofurbanhouseholdsewageaswellasindustrialwastewaterinanimmenseamount;Thedisappearanceofaquaticmacrophytesreducedthecompetitionfornutrients,causingtheluxuriantproliferationofphytoplankton;DikeconstructionwithinthelakediminishedtheexchangeofwatermassbetweenGuozhenghuareaandotherlakeareaswithlowerloadingofNandP.(Rongetal.,1995)1）城市生活活污水和工業(yè)業(yè)廢水大量排排入，外源污污染加?。?）水草的消消失減輕了對對養(yǎng)料的競爭爭，促使浮游游藻類大量繁繁殖；3）湖內(nèi)人工工堤的修筑，，減少了郭鄭鄭湖區(qū)與其他他氮磷含量較較低的湖區(qū)之之間的水團(tuán)交交流（戎克文等，1995）Thedistinctionbetween“fish-stocking”and“intensefish-farming””3．魚類“放放養(yǎng)”與“精精養(yǎng)”的區(qū)別別不同養(yǎng)殖類型型的劃分Differenttypesoffishculture放養(yǎng)密度Density天然餌料Naturalfood精養(yǎng)Intensive半精養(yǎng)Semi-intensive粗養(yǎng)Extensive管理水平投入和回收抗病能力人工飼料Artificialfeed4．放養(yǎng)不同同種類的魚給給湖泊生態(tài)系系統(tǒng)帶來的不不同影響ImpactsonlakeecosystemsaredifferentwhendifferentfishspeciesarestockedGrasscarpstockingresultedinthedisappearanceofmacrophytes草魚（Ctenopharyngodonidellus）的放養(yǎng)導(dǎo)致水水生植物的消消失沉水植物的消消失給水生態(tài)態(tài)系統(tǒng)帶來了了一系列的影影響1）水生大型型植物能起到到凈化水質(zhì)的的作用，它的的消失直接削削弱了水體自自凈的能力2）水生大型型植物是與浮浮游植物競爭爭養(yǎng)料的，前前者的消失使使后者能獨(dú)享享養(yǎng)料資源，，導(dǎo)致浮游藻藻類的大量孳孳生，反過來來通過在養(yǎng)料料和光照方面面的競爭優(yōu)勢勢，進(jìn)一步壓壓制水草的恢恢復(fù)1)Aquaticmacrophytesplaytheroleofpurifyingthewaterquality,theirdisappearanceattenuatesdirectlytheselfpurificationcapabilityofthewaterbody.2)Aquaticmacrophytescompetefornutrientsandlightwithphytoplankton3)Macrophyteisthesubstratumonwhichtheadhesiveeggsofmanyfish,snail,andaquaticinsectspeciesaredeposited;lackingofmacrophyteswoulddeprivetheseeggsofsuchsubstratumanddepressthehatchingratessubstantially;4）Macrophytesalsoserveasasortofrefugeforthefryoffishandlarvaeofaquaticinvertebrates.Themortalityoftheseanimalswouldbemarkedlyincreasedintheabsenceofsuchrefuge,thuswouldfurtheraffectthebiodiversityoftheecosystem沉水植物的消消失給水生態(tài)態(tài)系統(tǒng)帶來了了一系列的影影響3）水草是好好幾種產(chǎn)粘性性卵的魚類、、螺類以及水水生昆蟲卵粒粒附著的基質(zhì)質(zhì)，產(chǎn)出的魚魚卵、蟲卵、、和螺的卵囊囊沒有水草可可資附著，卵卵的孵化率大大大降低4）水草也是是許多幼魚和和水生無脊椎椎動物躲避敵敵害的隱蔽場場所，少了這這樣的避難所所，這類動物物死亡的機(jī)率率大增，進(jìn)而而影像響到該該生態(tài)系統(tǒng)的的生物多樣性性。Donghu:團(tuán)頭魴（MegalobramaamblvcephaiaYih）是草食性魚類類Bluntsnoutbream(Megalobramaamblicephala),alsoknownas“WuchangFish””,islikewiseagrasseater,thoughlessvoracious;itsstockinginlakeisnotrecommended.鯉魚（Cyprinuscarpio）是生活在水水體底層的魚魚類。它以螺螺蚌等底棲動動物為食，習(xí)習(xí)慣在底泥中中覓食，動輒輒把水?dāng)嚋?。。鯉魚在泥底底中的掘進(jìn)習(xí)習(xí)性使它易于于從圍圈邊緣緣逃逸；鯉魚魚的捕撈也比比較困難。湖泊放養(yǎng)對象象中不包括鯉鯉魚Thecommoncarp(Cyprinuscarpio)isafishlivingonthebottomofwaterbody,feedingonbenthicanimalslikesnails,clams,andinsectlarvae.Searchingforfoodinthesediment,thefishisverylikelytostirupthebottomdepositandmakesthewaterturbid.Itisalsodifficulttocapture.Itisnotatargetfishforlakestocking.鯽魚（Carassiusauratus）的食性較廣廣，肉味也較較好，但野生生的品種生長長緩慢，一般般不是放養(yǎng)對對象，但鯽魚魚有些品種生生長明顯較快快，有些品種種主食浮游生生物，將來有可能發(fā)發(fā)展成為放養(yǎng)養(yǎng)對象。Thecruciancarp,i.e.,thewildvarietyofgoldfish(Carassiusauratus),hasawiderfoodspectrum,andtastesbetter,butthewildbreedgrowsupslowly,hencenotachoiceforstocking.鱖魚（Sinipercachuatsi）是吃魚的魚魚類，肉味好好，又少細(xì)刺刺，經(jīng)濟(jì)價值值較高?，F(xiàn)在已有科研研部門在小雜雜魚類豐多的湖泊中中放養(yǎng)鱖魚，，效果看來較好好。Themandarinfish(Sinipercachautsi)isapiscivorousfish,feedingonotherfishspecies.Itistasty,devoidoffineskeletalspines,andfetcheshighprice.Certainresearchinstituteshavetriedtostockthisfishintolakeswithplentyoftrashfishes,andtheresultseemspromising.Donghu:河蟹、蝦等是是有潛力的放放養(yǎng)對象Crabandprawnaresomeotherpotentialstockingspecies重要的是，不不論哪種對象象，都要衡量量其放養(yǎng)后的的生態(tài)影響就水體中氮、、磷的負(fù)荷而而論，只要輸輸出水體的漁漁獲物中氮、、磷的含量大大大超過輸入入水體的全部部“魚種”的的氮、磷含量量加上這些““魚種”生長長代謝過程中中所排泄的氮氮磷總量，那那么這種放養(yǎng)養(yǎng)對延緩富營營養(yǎng)化的進(jìn)度度還有積極意意義Theimportantpointis:whatevertheanimalmaybe,weshouldgiveheedtoitsecologicalimpactfollowingthestocking.TakingtheloadingofNandPintoconsideration,solongasthecontentofNandPinthefishcrop(i.e.,theoutput)plustheNandPexcretedbythestockedfishduringtheirstayinthelakeexceedsenormouslythosecontainedinthestockedfingerling(i.e.,theinput),thensuchstockingwillbeofpositivesignificanceforretardingtheprocessofeutrophication.5．放養(yǎng)鰱、、鳙的生態(tài)影影響Ecologicaleffectsofthestockingofsilvercarpandbig-headcarpBothsilvercarp(Hypophthalmichysmolitrix)andbig-headcarp(Aristichthysnobilis)areplanktonfeeders鰱魚（Hypophthalmichthysmolitrix）和鳙魚（Aristichthysnobilis）都是吃浮游游生物的魚類類，前者食譜譜以浮游植物物為主，雜有有少量浮游動動物；后者主主要也吃浮游游植物，但其其腸道中浮游游動物的數(shù)量量多于鰱魚腸腸道中的數(shù)量量。這兩種魚魚都是我國““四大家魚””的成員，其其人工繁殖的的技術(shù)也已經(jīng)經(jīng)普及，所以以在我國的湖湖泊、水庫里里廣泛放養(yǎng)，，產(chǎn)量較大，，缺點(diǎn)是產(chǎn)值值不高。西方國家（不不產(chǎn)鰱、鳙））的水生生物物學(xué)家受傳統(tǒng)統(tǒng)“食物鏈””的影響，長長期以來把控控制藻類過盛盛的希望寄托托在浮游動物物身上，所以以認(rèn)為，為了了遏制藻類水水華，應(yīng)該保保護(hù)浮動物，，這樣就需要要清除吃浮游游動物的鳙和和鰱。實(shí)際上上，鰱、鳙控控制大型浮游游藻類（如微微囊藻）所形形成的水華的的本領(lǐng)，比起起浮游動物來來要高強(qiáng)得多多鰱鳙濾濾食大大型浮浮游藻藻類小型藻藻類發(fā)發(fā)展旺旺盛小型藻藻類水水華Carpsarecapableoffilteringmedium-sizedandlarge-sizedphytoplanktonSmall-sizedalgaeincreasesWaterbloomofsmall-sizedalgaeappears6．在在東湖湖里進(jìn)進(jìn)行的的圍隔隔實(shí)驗(yàn)驗(yàn)Enclosureexperimentsinsidethelake什么導(dǎo)導(dǎo)致了了東湖湖藍(lán)藻藻“水水華””的消消失？？營養(yǎng)鹽鹽的變變化？？牧食浮浮游動動物的的變化化？濾食性性魚類類的變變化？？自1985年夏夏季，，藍(lán)藻藻水華華消失失ThediappearanceofMicrocystisbloomfromLakeDonghuin1985Whatisthecauseofthedisappearanceofwaterbloom?Nutrients？Predator？？Filteringfishes？？Enclosureexperimentinthesummerof1989EightcubiformenclosureswereinstalledwithinthelakeTheenclosureswithbottomandsidesweremadeofimpermeablepolyethylenecloth,eachmeasuring2.5msquareatthefourverticalsidesandatthebottom.Theenclosuresarefilledwithlake-watertothedepthof2m;thuseachenclosureheld12.5m3oflake-water.Thelake-waterwasfilteredthroughaplanktonnetbeforebeingintroducedintotheenclosuresinordertopreventtheunintendedintroductionoffishfry.1989年年夏季季的實(shí)實(shí)驗(yàn)圍隔用用不透透水的的聚乙乙烯材材料制制成2.5m見方方上面敞敞開、、下面面有底底的水水箱，，湖水2.0m深（（湖水水容積積12.5m3）湖水用用浮游游生物物網(wǎng)濾濾過，，以避避免把把小魚魚苗帶帶進(jìn)圍圍隔。。Purpose:Howdoesthestockingofsilvercarpandbig-headcarpinfluencethecommunitystructureofphytoplanktonintheenclosure?Canthedensestockingoffisheliminatewaterbloom?目的：：1）鰱鰱和鳙鳙的放放養(yǎng)如如何影影響圍圍隔內(nèi)內(nèi)浮游游植物物的群群落結(jié)結(jié)構(gòu)？？2）魚魚的密密集放放養(yǎng)能能否消消滅水水華？？Fig.藻類體體積(Algalvolume(mm3L-1)1989年年5-10月各各圍隔隔中和和周圍圍湖水水中浮浮游植植物總總量、、藍(lán)藻藻生物物量和和鞭毛毛藻生生物量量變動動情況況Changesinthebiomassoftotalphytoplankton,cyanobacteriaandflagellatesintheenclosuresandthesurroundinglakewaterintheDonghuLakeduringMay-Oct.1989(afterSheiandLiu,1991)E3E5E7Lakewater1989年年5-10月各各圍隔隔中和和周圍圍湖水水中浮浮游植植物總總量、、藍(lán)藻藻生物物量和和鞭毛毛藻生生物量量變動動情況況Changesinthebiomassoftotalphytoplankton,cyanobacteriaandflagellatesintheenclosuresandthesurroundinglakewaterintheDonghuLakeduringMay-Oct.1989(afterSheiandLiu,1991)Thefluctuationofchlorophyll-acontentandthebiovolumeofthetotalphytoplanktoninthethreeenclosureswassimilarinpattern,butinthefish-free#7,thevaluesweremuchhigherthanintheenclosuresstockedwithfishandintheambientlake-water.Theintroductionoffishbroughtaboutmarkedchangesnotonlyinthebiovolumeoftotalphytoplankton,butalsointhecompositionofthedominantgroup.Intheenclosuresstockedwithfish,theproportionofCyanophyceaewasmeager.Intheenclosureswithoutfish,largecolony-formingMicrocystiswaspredominant(SheiandLiu,1991).三個個圍圍隔隔中中葉葉綠綠素素a的的含含量量和和浮浮游游植植物物總總體體積積的的波波動動情情況況相相似似，，但但在在無無魚魚的的#7中中，，數(shù)數(shù)值值要要比比有有魚魚的的圍圍隔隔和和周周圍圍湖湖水水中中高高的的多多，，魚魚的的引引入入，，不不僅僅給給浮浮游游植植物物的的總總體體積積而而且且對對優(yōu)優(yōu)勢勢類類群群的的組組成成帶帶來來了了明明顯顯的的改改變變。。養(yǎng)養(yǎng)了了魚魚的的圍圍隔隔中中，，藍(lán)藍(lán)藻藻的的比比例例很很小小，，沒沒有有魚魚的的圍圍隔隔，，微微囊囊藻藻屬屬（（Microcystis）的的大大型型群群體體獨(dú)獨(dú)占占優(yōu)優(yōu)勢勢（SheiandLiu,1991））Experimentinthesummerof1990Thepurposeofthisexperimentwas:1)torestorewater-bloominmoreoftheenclosures;2)tointroducesilvercarpandbig-headcarpintothoseenclosurescoveredalreadywithwater-bloom,toseeifthebloomcanbeconsumedbythefish;3)tomonitorthechangeinthesizestructureofphytoplanktoncommunityinenclosuresaftertheintroductionoffish.1990年年夏夏季季的的實(shí)實(shí)驗(yàn)驗(yàn)?zāi)康牡模海?））使使更更多多的的圍圍隔隔里里重重現(xiàn)現(xiàn)水水華華；；2））在在水水華華已已覆覆蓋蓋水水面面的的圍圍隔隔里里引引進(jìn)進(jìn)鰱鰱和和鳙鳙，，看看水水華華能能否否被被魚魚吃吃掉掉；；3））監(jiān)監(jiān)測測圍圍隔隔中中引引入入魚魚以以后后浮浮游游植植物物群群落落在在大大小小結(jié)結(jié)構(gòu)構(gòu)方方面面的的變變化化。。#1Silvercarp,6(averagebodyweight148g),totalstockingdensity71g/m3#2Big-headcarp,6(averageweight176g),totalstockingdensity64.5g/m3#3Silvercarp,4(average21g),big-headcarp,2(averageweight32g),totalstockingdensity12g/m3#4Silvercarp,4(average23g),big-headcarp2(averageweight32g).totalstockingdensity13g/m3#5Silvercarp,3(average152g),big-headcarp,3(averageweight172g),totalstockingdensity78g/m3#6Nofish用了6個圍隔隔，圍隔的位位置和大小與與1989年年相同，各圍圍隔放養(yǎng)魚類類的情況如下下：#1鰱魚6尾尾（平均體重重148g）#2鳙魚6尾尾（平均176g）#3鰱魚4尾尾（平均21g）#4鰱魚4尾尾（平均23g）#5鰱魚3尾尾（平均不152g））#6不放魚LuxuriantMicrocystisbloomoccurredinenclosures#l,#2,#5and#6.Inenclosures#1,#2and#5,thebiomassofphytoplanktonwassubstantiallyreduced.Intheenclosureswithoutfish(#6),thebloom,onceformed,persistedtotheendoftheexperiment.Inenclosures#3and#4,totalchlorophyll-aamountremainedlowthroughouttheexperiment,andontheaverage,morethan80%ofthetotalphytoplanktonwascomposedofthosesmallerthan30μ(SheiandLiu,1992).微囊藻水華大大量出現(xiàn)在#1、#2、#5和#6圍隔里。養(yǎng)了魚的第1、2、5號號圍隔里，浮浮游植物的生生物量大為減減少在沒有養(yǎng)魚第第６號圍隔里里，水華一經(jīng)經(jīng)出現(xiàn)，就持持續(xù)到實(shí)驗(yàn)終終了（SheiandLiu,1992）Fig.lChangesinchlorophyll-aamountinbothtotalphytoplanktonandthosesmallerthan30μmintheenclosureandsurroundinglakewaterinDonghuLakeduringApril-August,1990.Arrowindicatestheintroductionoffish(afterXie1996)Enclosureexperimentinthesummerof1992Thisexperimentwasaimed:1)toascertaintheroleofsilvercarpandbig-headcarpintheeliminationofMicrocystisbloom,2)tofindoutwhetherthestockingofgrasscarphadthesameeffect.1992年夏夏季的實(shí)驗(yàn)?zāi)康模海保┳C實(shí)鰱、、鳙在消除微微囊藻水華中中所起的作用用；２）找出放養(yǎng)養(yǎng)草魚是否有有同樣效應(yīng)。。#1and#2Blanktest,nofishwasstockedin.#3Grasscarp,3(averagebodyweight187g),totalstockingdensity45g/m3#4Grasscarp,3(average229g),totalstockingdensity55g/m3#5Silvercarp,3(average137g),totalstockingdensity33g/m3#6Silvercarp,2(average133g),totalstockingdensity21g/m3#7Big-headcarp,4(average233g),totalstockingdensity75g/m3#8Big-headcarp,4(average216g),totalstockingdensity69g/m3實(shí)驗(yàn)用了８個個圍隔，在七七月份至九月月份進(jìn)行，８８月21日，，各圍隔養(yǎng)入入魚類如下：：#１和#２ 空白試試驗(yàn)，不放入入魚類#3 草魚魚 ３尾（（平均體重187g）#4 草魚３３尾（平平均229g）#5 鰱魚魚 ３尾（（平均137g）#6 鰱魚魚 ２尾（（平均133g）#7 鳙魚４４尾（平平均233g）#8 鳙魚４４尾（平平均216g）EnclosuresTherewasnowater-bloominalltheseenclosureswhentheexperimentstartedonJuly6th.Twoweeksafterwards,athinlayerofbloomoccurredinmostoftheenclosures;thedominantphytoplanktonlaterturnedtobeMicrocystisinallcases.BytheendofJuly,therewasthicklayerofwater-bloominmostoftheenclosures.Inmid-Augustallenclosureswerecoveredwithathickbloomlayer.７月６日開始始時所有圍隔隔都沒有水華華兩星期后，大大多數(shù)圍隔出出現(xiàn)一層薄薄薄的水華后來來，優(yōu)勢浮游游植物成為微微囊藻７月底，大多多數(shù)圍隔里有有厚層水華８月中旬全部部圍隔都有稠稠密水華層Intheenclosuresstockedwithbig-headcarp(#7and#8,withstockingrateof63-75gfishpercubicmeterofwater),thetotalbiomassofphytoplanktondiminishedrapidly.Waterbloominthesetwoenclosuresdisappearedtwoweeksaftertheintroductionoffish.Grasscarpstockedintoenclosures#3and#4didnotreducethebiomassofphytoplanktonatall,andthewater-bloom,onceformed,lastedtotheendoftheexperiment(Sheiletal.,1993).放入鳙魚的7號和8號圍圍隔（放養(yǎng)密密度為每立方方米水含魚65－75克克）克，導(dǎo)致致浮游植物總總生物量迅速速減少。這兩兩個圍隔在魚魚放入兩星期期后水華全部部消失。第3號和第4號號圍隔里放養(yǎng)養(yǎng)的草魚，完完全沒有減少少浮游植物的的生物量，水水華一經(jīng)形成成，就持續(xù)到到實(shí)驗(yàn)終了（（Sheietal.,1993）。Withbig-headcarp,water-bloomwascompletelyeliminatedatthestockingdensity(biomass)of69－75g/m3;withsilvercarp,theamountofwater-bloomintheenclosureswasmateriallydiminishedatthestockingdensityof21－33g/m3,buttherewasremnantbloompersistingtotheendofexperiment.Accordingly,theeffectivebiomassofsilvercarpandbig-headcarpforthecontrolofwater-bloomshouldbe33－69g/m3.Effectivestockingdensity(biomass)forsilvercarpandbig-headcarpshouldbe46－50g/m3(LiuandXie,1999)當(dāng)鳙魚的放放養(yǎng)密度（（用生物量量表示）為為65－76g/m3時，水華全全部被消滅滅；當(dāng)鰱魚魚的放養(yǎng)密密度為21－33g/m3時，圍隔中中水華的量量大為減少少，但直到到實(shí)驗(yàn)終了了仍有少量量群體殘留留。因此，，鰱、鳙控控制水華的的有效生物物量應(yīng)在33－65g/m3的范圍內(nèi)。。有效放養(yǎng)密密度（生物物量）應(yīng)該該是46－－50g/m3(劉、謝1999)。7．為什么么微囊藻水水華17年年來沒有在在東湖重現(xiàn)現(xiàn)？WhyMicrocystisbloomdidnotrecurinLakeDonghuinthepast17years?武漢東湖漁漁產(chǎn)量FishyieldinLakeDonghu鰱鳙生物量量的穩(wěn)步增增長導(dǎo)致微微囊藻水華華的消失IncreaseintheyieldofbigheadcarpandsilvercarpresultedinthedisappearanceofMicrocystisbloomThestrategyadoptedbytheupholdersofconventional“biomanipulation”is:tostockpiscivorousfishspeciesintothewaterbodytosuppresstheplanktivorousfish,soastoreinforcethezooplanktonpopulation,whichistoberelieduponforwater-bloomcontrol(Starling,1993)常軌的生物物操縱（Biomanipulation）論論者用來控控制水體富富營養(yǎng)化的的對策是：：在水體中放放養(yǎng)食魚性性魚類（piscivorousfish））以抑制食食浮游生物物的魚類（（planktivorousfish），，借此壯大大浮游動物物種群，然然后依靠浮浮游動物來來控制藻類類（Starling,1993）Astothecontroloffilamentousalgaeandlarge,colonialalgaelikeMicrocystis,thenzooplanktonincludingDaphniaareutterlyhelpless.Filter-feedingfisheslikesilvercarpandbig-headcarp,underappropriatestockingdensity,arecapableofsuppressingMicrocystisbloomeffectively(LiuandXie,1999).浮游動物只只能攝食細(xì)細(xì)菌、較小小的浮游動動物、和小小型藻類，，因而有助助于增進(jìn)水水的透明度度?？刂平z狀藻藻類和像微微囊藻之類類的大型群群體，那么么包括Daphnia在內(nèi)的的浮游動物物是完全無無能為力的的。濾食浮游浮浮生物的魚魚類像鰱和和鳙，在適適當(dāng)?shù)姆硼B(yǎng)養(yǎng)密度下，，是能有效效地遏止微微囊藻水華華的（劉、謝，，1999）8.東湖富富營養(yǎng)化的的治理對策策CountermeasuresforthecontrolofeutrophicationinLakeDonghuStartfromthecentraltreatmentofhouseholdsewageOnthebasisoftheeffectivenessofsewagetreatment,todecidewhetheraselectivedredgingofthebottomdepositisnecessary.Priortothefulfillmentofcentralsewagetreatment,preventionagainsttheresurrectionofcyanobacteriabloomatpresentcanonlyresorttothestockingofsilvercarpandbig-headcarp.根據(jù)東湖湖富營養(yǎng)養(yǎng)化當(dāng)前前情況，，治理首首先應(yīng)該該從生活活污水的的集中處處理著手手，然后后視處理理的效果果而決定定是否需需要對湖湖底淤泥泥進(jìn)行重重點(diǎn)清除除。在污污水處理理尚未到到位之前前，防止止藍(lán)藻水水華的暴暴發(fā)目前前還只能能依賴鰱鰱、鳙的的放養(yǎng)措措施.Fromalong-termpointofview,therepairoftheecosystem,includingtherecoveryofmacrophytesinthelake,therehabilitationofbenthicinvertebratecommunity,aswellastheconstructionofverticalwetlandsewagetreatmentinstallation(tobeintegratedwithtourismconstruction)inresidentialareabeyondthereachofsewagepipelinesystem,andtheselectiverectificationofthelake’’swatershed,soastoreducethesourceofpollution,tolessenthePandNloadingofthelake-water,etc.從長遠(yuǎn)來來說，生生態(tài)系統(tǒng)統(tǒng)的整治治，包括括修復(fù)湖湖內(nèi)水生生植被，，重建底底棲無脊脊椎動物物群落，，結(jié)合旅旅游景點(diǎn)點(diǎn)建設(shè)，，在截污污管道系系統(tǒng)以外外的零星星居民點(diǎn)點(diǎn)建立人人工垂直直濕地污污水處理理設(shè)施，，在東湖湖流域（（匯水區(qū)區(qū)）進(jìn)行行重點(diǎn)整整治，減減少污染染源，以以降低東東湖湖水水中的磷磷、氮負(fù)負(fù)荷，是是治理富富營養(yǎng)化化的必由由之路。。?WhatdoesIETC““PlanningandManagementofL