洪湖养殖区水生植物种子库现状及水生植被恢复策略研究

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1、⑨硕士学位论文MASTER’STHESISAbstractLakeHonghuisthelargestlakeinHubeiProvinceandoncehadthesamewaterlevelcyclewiththeYangtzeRiver．ButnOWithasbeenchangedintotheshallowlakebecauseoftheartificialcontrolofwaterlevel．Ithasgreatchangesbetweentheinter-annualsandwithinoneye

2、ar．LakeHonghuhasthegoodnameoflandoffishandrice，whichhasallimportantroleineconomy．However,LakeHonghuhasbeguntohavelarge—scaleaquaculturesince1990．Ithascausedseriousdamagetowaterecology．Thewaterqualityhasatrendofseriouseutrophicationandfishstocksaredepleted．In

3、ordertoprotecttheecologyofLakeHonghuandstudyofaquaticvegetationrestorationstrategies，wehavechosenatypicalfarmingregiontohavetheconventionalsurveyofaquaticvegetation，waterqualitysurvey,zooplanktonsurvey,seedbanksurvey,naturalrecoverytest．Theresultsastbllows：(

4、1)Thereareseldomwater-submergedplantsinexperimentalregionofaquaculture，onlyhaveallextremelysmallnumberofwaterplantslikereeds，wildricegrassandsomefloating—leavedlotus，hardlytofindotherlargetypeplants．(2)WaterqualityistheIIIdegreeonexperimentalsite，trophicatio

5、nlevelismild，andtrophicationleveloftransparencyreachestomoderate．Waterqualityhasasignificantdifferenceofexperimentalsiteonebetween2007and2008．(3)ThenumberofzooplanktonisthepeakoftheyearfromMaytoOctober,thequantityis93ind／L～2607ind

6、L，andtheamountofzooplankton

7、hasasignificantdifferenceduringtwoperiods．(4)Sedimentseedbankshave14kindsofaquaticplantswithanaveragedensityof4674-345ind／mz．(5)Naturalrecoverytestshave5and14kindsofaquaticplantsrestoration，thecoveragereachesto100％and30％respectively．Studyshowsthat：(1)density

8、ofherbivorousfishisSOlargethataquaticvegetation，especiallysubmergedvegetationbeginssuccessiontodisappearance；densityoffilter-feedingfishisSOlargethatitdirectlycausesthedeclineofthetotalnumberofzooplanktons，smallerindividuals，thereductionoftypes；densityofamou

9、ntoffishisSOlargethatitdirectlycausesthedeclinetransparencyofshallowwater,deteriorationofwaterquality．(2)Over-breedingisthemainfactorforthedegradationofaquaticvegetationandmainlimitingfactorforr