DOI: /j.aquabot Published: 01/11/2016. Peer reviewed version. Cyswllt i'r cyhoeddiad / Link to publication

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1 PRIFYSGOL BANGOR / BANGOR UNIVERSITY Herbivory on freshwater and marine macrophytes Bakker, Elisabeth S.; Wood, Kevin A.; Pages Fauria, Jordi; (Ciska) Veen, G.F. ; Christianen, Marjolin J.A.; Santamaria, Luis; Nolet, Bart A.; Hilt, Sabine Aquatic Botany DOI: /j.aquabot Published: 01/11/2016 Peer reviewed version Cyswllt i'r cyhoeddiad / Link to publication Dyfyniad o'r fersiwn a gyhoeddwyd / Citation for published version (APA): Bakker, E. S., Wood, K. A., Pages Fauria, J., (Ciska) Veen, G. F., Christianen, M. J. A., Santamaria, L.,... Hilt, S. (2016). Herbivory on freshwater and marine macrophytes: A review and perspective. Aquatic Botany, 135, DOI: /j.aquabot Hawliau Cyffredinol / General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal? Take down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. 09. Mar. 2019

2 1 Herbivory)on)freshwater)and)marine)macrophytes:)a)review)and)perspective) ElisabethS.Bakker a,kevina.wood b,jordif.pagès c,g.f.(ciska)veen d,marjolijnj.a.christianen e, LuisSantamaría f,barta.nolet g,andsabinehilt h a DepartmentofAquaticEcology,NetherlandsInstituteofEcology(NIOOYKNAW), Droevendaalsesteeg10,6708PBWageningen,TheNetherlands,l.bakker@nioo.knaw.nl b Wildfowl&WetlandsTrust,Slimbridge,Gloucestershire,GL27BT,UnitedKingdom, kevin.wood@wwt.org.uk c SchoolofOceanSciences,BangorUniversity,MenaiBridge,Anglesey,LL595AB,UnitedKingdom, j.pages@bangor.ac.uk d DepartmentofTerrestrialEcology,NetherlandsInstituteofEcology(NIOOYKNAW), Droevendaalsesteeg10,6708PBWageningen,TheNetherlands,c.veen@nioo.knaw.nl e GroningenInstituteforEvolutionaryLifeSciences,UniversityofGroningen,P.O.Box11103,9700CC Groningen,TheNetherlands,Marjolijn.Christianen@gmail.com f SpatialEcologyGroup,DepartmentofWetlandEcology,DoñanaBiologicalStation(EBDYCSIC),C/ Américovespucios/n,IsladelaCartuja,E41092Sevilla,Spain,luis.santamaria@ebd.csic.es 1

3 g DepartmentofAnimalEcology,NetherlandsInstituteofEcology(NIOOYKNAW),Droevendaalsesteeg 10,6708PBWageningen,TheNetherlands,b.nolet@nioo.knaw.nl h LeibnizYInstituteofFreshwaterEcologyandInlandFisheries,Müggelseedamm301,12587Berlin, Germany,hilt@igbYberlin.de Correspondingauthor:ElisabethS.Bakker,DepartmentofAquaticEcology,NetherlandsInstituteof Ecology(NIOOYKNAW),Droevendaalsesteeg10,6708PBWageningen,TheNetherlands, l.bakker@nioo.knaw.nl Authorcontributions:ESB,KAW,SHandBAN:developingideaandstructureofthepaper;ESB,KAW, GFVandJFP:dataanalysisandgraphics;ESB,KAW,JFP,GFV,MJAC,LS,BANandSHcontributedto writingofthemanuscript 41 2

4 3 Abstract Untilthe1990s,herbivoryonaquaticvascularplantswasconsideredtobeofminorimportance,and 44 thepredominantviewwasthatfreshwaterandmarinemacrophytesdidnottakepartinthefood 45 web:theirprimaryfatewasthedetritivorouspathway.inthelast25years,asubstantialbodyof 46 evidencehasdevelopedthatshowsthatherbivoryisanimportantfactorintheecologyofvascular 47 macrophytesacrossfreshwaterandmarinehabitats.herbivoresremoveonaverage40y48%ofplant 48 biomassinfreshwaterandmarineecosystems,whichistypically5y10timesgreaterthanreportedfor 49 terrestrialecosystems.thismaybeexplainedbythelowerc:nstoichiometryfoundinsubmerged 50 plants.herbivoresaffectplantabundanceandspeciescompositionbygrazingandbioturbationand 51 therewithalterthefunctioningofaquaticecosystems,includingbiogeochemicalcycling,carbon 52 stocksandprimaryproduction,transportofnutrientsandpropagulesacrossecosystemboundaries, 53 habitatforotherorganismsandthelevelofshorelineprotectionbymacrophytebeds. 54 Withongoingglobalenvironmentalchange,herbivoreimpactsarepredictedtoincrease.Thereare 55 pressingneedstoimproveourmanagementofundesirableherbivoreimpactsonmacrophytes(e.g. 56 leadingtoanecosystemcollapse),andtheconflictsbetweenpeopleassociatedwiththeimpactsof 57 charismaticmegayherbivores.whilesimultaneously,thelongytermfutureofmaintainingbothviable 58 herbivorepopulationsandplantbedsshouldbeaddressed,asbothbelongincompleteecosystems 59 andhavecoyevolvedintheselongbeforetheincreasinginfluenceofman.betterintegrationofthe 60 freshwater,marine,andterrestrialherbivoryliteratureswouldgreatlybenefitfutureresearch 61 efforts Keywords:*climate*change,*conservation,*ecosystem*functions,*grazing,*seagrass,*stoichiometry* 65

5 66 1.! Introduction:)25)years)of)research)on)herbivory)on)macrophytes Setting*the*scene* In the 1990s two seminal papers appeared in Aquatic Botany that urged for a complete changeintheparadigmthathadbeendominatingmacrophyteecology.despitesomeearlyworkon theimpactofwaterbirdsonfreshwaterandmarineangiosperms(juppandspence,1977;jacobset al.,1981),untilthen,herbivoryonaquaticvascularplantswasconsideredtobeofminorimportance, and the predominant view was that freshwater and marine macrophytes did not take part in the foodweb(e.g.shelford(1918)andtheirprimaryfatewasthedetritivorouspathway(polunin,1984; DuarteandCebrian,1996).Butin1991,Lodgearguedthat,contrarytoconventionalwisdom,live freshwatermacrophytesareengagedinaquaticfoodwebs.in1998,cebrianandduartehighlighted that,whileseagrassessufferedmodestherbivoryratesonaverage,suchrateswerehighlyvariable, andtheimportanceofseagrassyherbivoreinteractionsshouldnotbediscounted.followingonfrom these two papers, Lodge (1998) provided further evidence for the important role of herbivores in freshwater habitats, as compared to other biomes; and Valentine and Heck (1999) demonstrated thatgrazingonseagrassesiswidespreadintheworld'soceans. Together,theselandmarkpapersputmacrophyteherbivoryonthemap.Sincethen,there has been a strong increase in the amount of studies that investigated herbivory on freshwater macrophytes and seagrasses. In this study, we review what we have learned in the 25 years that followedtheappearanceoflodge(1991).furthermore,weidentifynewtopicsthathaveemerged overthistime.thesenewtopicsincludethefastchangesthatmayoccurinmacrophyteyherbivore relationships with the ongoing global environmental change, as well as the potential conflicts betweenherbivoreconservationandherbivoreimpactsonaquaticecosystems.finally,wediscuss how we can improve our understanding of herbivore impacts and what tools may help us in 4

6 achieving this. Following the approach of the seminal papers listed above, we focus primarily on aquaticangiosperms(submerged,floatingandemergent)andaddressbothfreshwaterandmarine ecosystems Why*thinking*about*herbivory*on*macrophytes*has*changed*over*the*last*25*years The paradigm shift in our perception of macrophyte herbivory, from being considered negligibletobeingacknowledgedasakeyfactorshapingbenthicecosystems,isnotonlycausedby anincreaseinscientificinterestfosteredbytheselandmarkpapers:theeffectofherbivorybecame alsomoreconspicuousoverthelast25years.thereasonsforthisaremethodological,anthropogenic andecological. Methodologicalimprovementsforestimatingherbivoryincludedobservationmethods,such as bite mark counts (Cebrian and Duarte, 1998), experimental approaches, such as herbivore exclusions(seepooreetal.(2012)andwoodetal.(2016)forsynthesesofmarineandfreshwater habitats, including macroyalgae) and direct methods, including video bite counts or isotopic signatures(seetable4fordetails). Anthropogeniceffectsincludedincreasesinthedensitiesofaquaticandmarineherbivoresas a result of increased protection, predator removal, food subsidies from agriculture, and the introductionofexoticherbivores(estesetal.,2011).forexample,steepincreasesinherbivoryrates have been reported for sea turtles in the Arabian Sea and Indonesia (Kelkar et al., 2013b, a), (Christianenetal.,2014),forherbivorousfishintheMediterranean(Pagesetal.,2012)andforgeese in Northwestern Europe and North America (Jefferies et al., 2003; Van Eerden et al., 2005). However,itshouldbenotedthatdespiterecentlocalincreasesinherbivory,whichhaveattracted attention to the role of herbivores in benthic ecosystems, over longer time frames in particularly speciesoflargeherbivoreshaveexperiencedstrongglobaldeclines(jackson,1997;mccauleyetal., 2015;Bakkeretal.2016b). 5

7 Furthermore, the recent spread of exotic herbivores had major consequences for macrophyteestablishmentandsurvivalin many areas worldwide.for example,tropical lessepsian rabbitfishes (Siganus* spp.) cause overgrazing of macroalgae and seagrasses at the Eastern Mediterranean (Verges et al., 2014b), chubs and rabbit fishes (Kyphosus* spp. and Siganus* spp., Siganidae)overgrazeAustralianandJapanesekelpforests(Vergesetal.,2014a),NorthYAmericanredY swamp crayfish (Procambarus* clarkii) have depleted submerged plant meadows in shallow lakes acrosseurope(rodriguezetal.,2003;gherardiandacquistapace,2007;vanderwaletal.,2013), andintentionalintroductionsofgrasscarp(ctenopharyngodon*idella)havebeenconsideredathreat tonativemacrophytes(wittmannetal.,2014). EcologicaleffectsarerelatedtotheoligotrophicationofmanyEuropeanfreshwatersystems, whichresultedintheirreycolonizationwithsubmergedmacrophytes(jeppesenetal.,2005).inmany systems,however,theimpactofaquaticherbivoressufficedtohaltorreversesuchrecolonization (KörnerandDugdale,2003;Hilt,2006;Bakkeretal.,2013;Hiltetal.,2013;Eigemannetal.,2016). 2.! Quantitative)impacts)of)herbivores)in)aquatic)systems !Quantitative*impact*of*herbivores*on*plant*biomass*across*ecosystems* AgrowingbodyofprimaryresearchhasdemonstratedherbivoreYinducedchangesinoneor moremeasuresofmacrophyteabundance,includingbiomass,twoydimensionalcover,volume,and individualdensity(kirschetal.,2002;marklundetal.,2002;tomasetal.,2005;pradoetal.,2007; Christianenetal.,2012;Pagesetal.,2012;Woodetal.,2012a;Kelkaretal.,2013b,a;Christianenet al.,2014;bakkeretal.,2016b).thesestudies,synthesizedinseveralreviews(cyrandpace,1993; ValentineandDuffy,2006;Gruneretal.,2008;Pooreetal.,2012),confirmedherbivoresaskey driversofbenthicecosystemsaroundtheworld.theoverwhelmingmajorityofstudiesreporteda reductioninmacrophyteabundanceasaresultofherbivory.indeed,arecentmetayanalysisof326 6

8 7 experimentsinwhichfreshwaterherbivoreswereexcludedfoundthatherbivoryreduced 141 macrophytebiomassby47.2±3.4%(average±ci)(woodetal.,2016).ofthese,300experiments 142 reportedareductioninmacrophytebiomass,while26experimentsreportedpositiveeffectsorno 143 changes.similarly,ametayanalysisongrazingimpactsonmarinemacrophytesfoundthatherbivores 144 reducemacrophyteabundance(bothsubmergedangiospermsandmacroyalgae)by68%onaverage 145 (Pooreetal.,2012). 146 Despitetheirhistoricaldisregard,theremovalofvascularplantbiomassbyherbivoresis,onaverage, 147 muchlargerinaquaticthaninterrestrialecosystems.themostrecentmetayanalysesavailablefor 148 terrestrial,freshwaterandmarinehabitats(turcotteetal.,2014;woodetal.,2016)showthat 149 medianbiomassremovalbyherbivoresis4y8%interrestrialecosystems,whileitis44y48%in 150 freshwaterand40y44%inmarineecosystems(fig1ayc).thus,herbivoresremoveonaverage5y timesmorevascularplantbiomassinaquaticecosystemsthaninterrestrialones. 152 Yet,theimpactofherbivoresonvascularplantbiomassremovalismuchmorevariableinaquatic 153 thaninterrestrialecosystems,anditrangesasbroadlyasbetween0and100%ofbiomassremoval 154 (Fig1aYc).Underlyingexplanationsforthelargerangeofherbivoreeffectsinaquaticecosystemsare 155 stillunknown.potentialmechanismsinvolvebottomyupeffects,suchasvariationinplant 156 productivity,nutritionalquality,stoichiometry,resistanceandtolerancetograzing(cebrianetal., );andtopYdowneffects,suchasvariationinherbivoreabundance,feedingefficiency,size, 158 taxonomy,mobility,metabolismandpredatoreffects(boreretal.,2005) !BottomEup*effects:*the*plant s*perspective* ! Primary*productivity*and*herbivory*rates) 162 Studiesinaquaticsystemstraditionallyfocussedonprimaryproductionofphytoplanktoninpelagic 163 habitats,andonlyrecentlylittoralareasreceivedmoreattention(vadeboncoeuretal.,2002; 164

9 Brothersetal.,2013).TheoreticalpredictionsbasedonLotkaYVolterramodelssuggestthatgrazing shouldincreasewithprimaryproductivity(gruneretal.,2008),becauseasplantsproducemore tissuesordosoatfasterrates,herbivorescanincreasetheirratesofconsumption.thisprediction reliesintheassumptionthatherbivoryratesarebottomyupregulatedbytheavailabilityofplant tissues.empiricalevidenceishoweverconflicting.ametayanalysisbycyrandpace(1993)concluded thatherbivoryincreaseswithprimaryproductioninbothterrestrialandaquaticsystems.however,a morerecentmetayanalysisfoundnosignificanteffectofproductivityonherbivory(orinteraction strength)inaquaticsystems(e.g.(boreretal.,2005)).infact,itiswidelyrecognizedthatfoodquality anddefencesalsohavemajoreffectsonherbivoreperformancethatmightmaskanyherbivoryy productivityrelationship.usingaplantgrowthmodel,hiddingetal.(2016)suggestedthatherbivore grazingeffectsonmacrophytesbecomeimportantabovecertainthresholdsinperiphytonshading andthusreducedproductionofplants. 177 ) ! Plant*stoichiometry* Differencesinherbivoryratesacrossplanttaxahavealsobeenattributedtodifferencesin plant quality, as perceived by herbivores (Lodge, 1991; Cronin et al., 2002). Generally, there is a positive relationship between the nitrogen content in the plant s tissue and its consumption by herbivores(cebrianandlartigue,2004).thispatternholdsbothwithinandacrossecosystems(elser et al., 2000; Cebrian and Lartigue, 2004; Cebrian et al., 2009). Hence, it has been suggested that higherherbivoreconsumptionratesinaquaticplantsmightbeexplainedbytheirhigherqualityas food arisingfromthelackofcarbonyrichstructuralcompoundsthatstrengthencellwalls,increase resistance to herbivores, and reduce digestibility in terrestrial plants (Gruner et al., 2008). Unfortunately, most comparisons between aquatic and terrestrial systems undertaken to date restrictedtheirestimatesofaquaticherbivorytophytoplanktonconsumption,thusgivinglimitedor noinformationontheconsumptionofaquaticmacrophytes(elseretal.,2000).comparingherbivory 8

10 rateson,andfoodquality(e.g.,nitrogencontent)of,aquaticandterrestrialvascularplantswouldbe more informative, because they have a close phylogenetic affinity and most differences could be attributedtotheecosystemstheyinhabit(hay,1991;grossandbakker,2012;burkepile,2013) AcompilationofdataonC:Nratiosofvascularplantsinterrestrial,freshwaterandmarine ecosystems reveals that they differ strongly between these systems (Fig 1dYf). Median C:N ratio decreased strongly from terrestrial vascular plants (25Y30) and marine macrophytes (24Y28) to freshwater macrophytes (12Y16) (Fig 1dYf). The high N content (thus low C:N ratio) of freshwater macrophytesmayindicateahigherqualitytoherbivores,potentiallyexplainingthehighherbivory ratesfoundinfreshwatersystems.takingintoaccountthevariationingrowthformsthatoccursin aquaticecosystemsmakesthispatternstronger(fig2ayd).herbivoryratesareloweronemergent macrophytes (median freshwater = 36Y48%; median marine = 24Y36%) than on submerged macrophytes(medianfreshwaterandmarine=48y60%)inbothfreshwaterandmarineecosystems (Fig2a,b).ThesedifferencesfitcloselytheC:Nratioofthedifferentplantgrowthforms,asemergent macrophytes have higher C:N ratios (median freshwater = 28Y32; median marine = 24Y28) than submerged macrophytes (median freshwater = 8Y12; median marine = 20Y24), particularly in freshwaterecosystems(fig2c,d) Our data compilation indicates that differences in plant quality between terrestrial plants and macrophytes show close links to variation in herbivory rates. Submerged plants need less structural components, resulting in higher N content and higher rates of herbivory. In contrast, herbivory rates and N content of emergent macrophytes are similar to those found in terrestrial plants(fig1a,1d,2ayd).althoughncontentisacknowledgedasanimportantdeterminantofplant qualitytoherbivores,othernutrientsandsecondarycompoundsmayalsoinfluenceit.forexample, freshwater macrophytes and seagrassess have antiyherbivore defenses (Verges et al., 2008; Gross andbakker,2012),whichmaycauselow palatabilityy eveninhighlynutritiousspecies.phenolics, terpenoidsandnitrogenatedcompoundscanbeefficientdeterrentsofaquaticherbivores,although 9

11 deterrence of generalist herbivores often comes at the cost of higher preference by specialised consumers(vergesetal.,2007).interestingly,infreshwatersystems,theconcentrationsofphenolic compounds decrease from emergent to floating to submerged plants (Smolders et al., 2000), suggestingnotonlyhighernutritionalquality,butalsolessdefendedtissues,resultingingenerally higherpalatabilityofsubmergedplants.however,thisissuestilldeservesmoreresearch,sincemost work has focused on macroyalgae (e.g. (Hay, 1996)). Besides the differences between ecosystems discussedabove,spatialandtemporalvariationinherbivoryatpopulationandindividualyplantlevel has also been linked to plant quality (C:N, % N) and to the presence of antiyherbivore defences (HackerandBertness,1995;Preen,1995;Vergesetal.,2007;Pradoetal.,2010) !TopEdown*effects:*the*herbivore s*perspective* ! Herbivore*density* Withinindividualherbivorespecies,herbivoreimpactonaquaticplantabundanceispositively relatedtoherbivoredensity(stottandrobson,1970;valentineandheck,1991;woodetal.,2012a; Kelkaretal.,2013b).However,analysesofherbivoreimpactsacrossmultipleherbivorespecieshave foundnorelationshipbetweenherbivoredensityandmacrophyteabundance,probablyduetothe confoundingeffectsofinterspecificdifferencesinherbivoreecology(marklundetal.,2002;woodet al.,2012a).forexample,amongplantyeatingwaterfowl,substantialdifferencesexistinmeanadult bodymass(fromthe24gofocellatedcrake,micropygia*schomburgkii,tothe12,000goftrumpeter swan,cygnus*buccinator),whichisknowntoinfluencethespecies dietandtheabsolutequantityof vegetationconsumed(woodetal.,2012a).consequently,whenherbivoredensitieswereestimated asbiomassdensities(thusaccountingforinterspecificdifferencesinindividualbodymass),a significantnegativerelationshipbetweenherbivorebiomassdensityandmacrophyteabundancewas detected(woodetal.,2012a;woodetal.,2016).onlyatrelativelylowherbivoredensitieswere 10

12 11 positivechangesinplantabundancereported,suggestingthatinaquaticsystemsgreaterherbivore 239 densitiesoverwhelmplantcompensatorygrowthresponses(woodetal.,2016). 240 * ! Size,*mobility*and*taxonomy*of*herbivores* 242 Byvirtueoftheirsize,largeterrestrialherbivoresarecriticalagentsofchangeandmaintenanceof 243 theecosystemstheyinhabit(owenysmith,1988;bakkeretal.,2016a).inaquaticenvironments,large 244 herbivoreshavealsobeenidentifiedaskeyspecies(mccauleyetal.,2015),oftenconsidered 245 ecosystemengineers(e.g.(bakkeretal.,2016b)).itisnotsurprising,thus,thatarecentmetayanalysis 246 foundsignificantlystrongerimpactsofmacrograzers(fishes,urchinsandlargemolluscs)than 247 mesograzers(amphipods,isopodsandsmallmolluscs)onmarinemacrophytes(algae,seagrassesand 248 saltmarshes)(pooreetal.,2012). 249 AnotherrecentmetaYanalysisbyWoodetal(2016)foundsubstantialbetweenYtaxadifferencesin 250 effectsofherbivoresontheabundanceoffreshwaterandmarinemacrophytes.echinoderms, 251 molluscs,andfishhadrelativelylargeimpactsonplants,whileinsectsandbirdshadrelativelylow 252 impacts.thereasonforthesedifferencesmaybethemobilityandhabitatpreferencesofeachof 253 thesegroups.fullyaquaticspeciesthatliveunderwaterpermanently,havebeenshowntoproduce 254 thegreatestimpactsonaquaticplants(bakkeretal.,2016b),whilefacultativeaquaticgrazers,such 255 asinsectsandbirds,spreadtheiractivitymorebetweendifferentecosystems(thankstotheirhigh 256 mobility),thusspreadingalsotheirimpactbetweensuchecosystems.woodetal.(2016)also 257 pointedoutthefactthatsomeherbivores(suchasechinoderms,crayfishandmolluscs)have 258 restrictedmobilityandproduceintenseimpactsduetotheirbulkgrazingstrategies,sincethey 259 consumemultipletissuestypesandspecies,thusaffectingagreaterproportionofaplantcommunity 260 (Lodgeetal.,1998)

13 ! Herbivory*and*omnivory* 263 Mostanimalsthatconsumeaquaticplantsareomnivores,veryfewarestrictherbivores. 264 Thereisapositiverelationshipbetweenbodysizeanddegreeofherbivoryinaquaticomnivores:the 265 largertheconsumer,themoreimportantplantconsumption(granivoryandfolivory,particularlythe 266 latter)isintheirdiet(clementsetal.,2009;woodetal.,2012a).hence,percapita,largeherbivores 267 havethelargestimpactonplantabundancethroughgrazing.thehighlevelofgeneralisticfeeding 268 andomnivoryofaquaticplantconsumersmayberelatedtothehigherimpactofherbivoryon 269 aquaticplants,becauseitmayrelaxtheeffectofdirectdensitydependenceonconsumers:whenever 270 consumersovergrazeplants,theycanswitchtoalternativefoodsources(algae,detritusoranimal 271 prey)withinornearbythewaterbody(greyandjackson,2012).furthermore,inaquaticsystems, 272 largeherbivoresandomnivoresoftenfeedonbothabovegroundandbelowgroundplantmaterial, 273 whichmaymultiplytheirimpactonplants,duetothedepletionofundergroundplantresourcesfor 274 regrowth. 275 HerbivoreimpactmayalsobeenhancedbynonYconsumptiveeffects,whicharedocumented 276 tobesevereinfreshwaterandmarinemacrophytes,e.g.bioturbation(lodge,1991).byinitiating 277 barepatches,herbivorescancreatefocalpointsforfurthererosionofmacrophytemeadowsby 278 wavesinshallowareas(christianenetal.,2013).trampling,fecaldepositionandincreasingnutrient 279 concentrationsmayalsoplayarole.whilstpreviousauthorshavecautionedagainsttheassumption 280 thatherbivoreeffectsonplantsrepresentexclusivelygrazinglossesduetoconsumption(mitchell 281 andwass,1996b),manystudiescontinuetoignoretherolesofnonyconsumptiveeffects !Latitude* 284 Potentialvarianceinherbivoreimpactsonplantabundanceacrossdifferentlatitudeshasbeena 285 topicofgrowinginterestamongecologists.however,theevidenceforaroleoflatitudinaleffectsis 286

14 13 limited.forexample,inmacrophytefeedingassayscarriedoutbymorrisonandhay(2012),onlyone 287 outofthreecrayfishspeciesshowedapreferenceassociatedwithlatitude(apreferenceforhigher 288 latitudeplants).schemskeetal.(2009)arguedthat,acrossallecosystems,herbivoreimpactsare 289 greateratlowerlatitudes.incontrast,ametayanalysisbygruneretal.(2008)reportedanincreasein 290 herbivoreeffectsathigherlatitudesinfreshwaterecosystems,butnotinmarineecosystems.three 291 morerecentmetayanalyseswithlargersamplesizesfoundnoevidenceoflatitudinalgradientsin 292 herbivoreimpactsonaquaticmacrophyteabundances,someincludingbothvascularplantsand 293 macroyalgae(molesetal.,2011;pooreetal.,2012;woodetal.,2016) ! Ecosystem)consequences)of)herbivory 296 Withtheestablishmentofherbivoryasaanimportantfactorregulatingplantabundance,Lodge 297 (1991)endedhisreviewwiththeconclusionthat thefunctionalimportanceofgrazingremains 298 largelyuntested.indeed,thishasbeenanemergingfieldofresearchoverthelast25years,with 299 particularprogressoverthelast5years.bytheirpresence,herbivoresmayinducedirectchangesin 300 plantdynamicsandindirecteffectsonecosystemfunctioning(fig.3).theeffectsofmarine 301 herbivoresmayincludestimulatedproductionofseagrass(valentineetal.,1997;moranand 302 Bjorndal,2005;Vonketal.,2008b;Christianenetal.,2012),changesinseagrassmeadowstructure 303 (Laletal.,2010),andthereductionofthefluxoforganicmatterandnutrientstosedimentsand 304 plants(byshortcircuitingthedetritalcycle;(thayeretal.,1982;vonketal.,2008a)ortheirexportto 305 nearbyhabitats(christianenetal.,2012).insaltmarshesandaquaticecosystems,anadditional 306 effectofherbivoresisthereturnofnutrientsthroughfaecesandurine(bazelyandjefferies,1985; 307 Hiketal.,1991;Franketal.,2000),thoughinseagrassgrazedbyturtlesthiseffectisreducedby 308 nutrienttransporttoturtlerestingareas(christianenetal.,2012)

15 14 3.1Plant*abundance*and*species*composition*and*diversity 311 Whilethelargelynegativeimpactsofherbivoresonmacrophyteabundancehavebeenwell 312 documentedthroughshortytermexclosurestudies,thepersistenceofsucheffectsitisoftenless 313 clear.inparticular,highlyymobileherbivoressuchaswaterfowlcancauselargereductionsinplant 314 abundancebeforeswitchingtoungrazedsites(woodetal.,2012b).ecosystemresponsesto 315 fluctuatinggrazingpressurehavereceivedlittleattentiontodate.however,thereissomeevidence 316 thatrepeatedepisodesofgrazingovertime,suchasbybreedingcoloniesofsnowgeese(chen* 317 caerulescens)inwetlands,cancausesustainedlongytermshiftsinspeciescompositionanddeclines 318 inplantabundance(kerbesetal.,1990).wherenonyselective,generalistherbivoresfeedonmixed 319 assemblagesofmacrophyte,herbivorescanincreasespeciesevennessbyreducingtheabundanceof 320 dominantcompetitorsrelativetosubydominantmacrophytespecies(hiddingetal.,2010b;woodet 321 al.,2012b).however,whentheyfavorcertainsubordinateplantspeciesoverthedominant,theycan 322 reduceeveness(hiddingetal.2010a). 323 Herbivoryintropicalseagrasses(e.g.byseaurchinsandgreenturtles)caninfluencespecies 324 composition(vonketal.,2008b;kelkaretal.,2013b;hernandezandvantussenbroek,2014),but 325 oftenincontrastingways.intropicalmultispeciesmeadows,slowgrowingclimaxseagrassspecies 326 (Thalassia*hemprichii)werepromotedbysmallherbivores(urchins),whileinmoreintensivelygrazed 327 meadowsspeciesdifferenceinherbivore sgrazingpreferencesresultedinthedominanceoffast 328 growingpioneerspecies(kelkaretal.,2013b).largergrazersthatconsumebelowgroundplantparts 329 andcreatebaresedimentpatches,suchasgreenturtlesanddugongs,alsointroducespecies 330 heterogeneitybysettingbackspeciessuccessioningrazedplots(aragonesetal.,2006;christianenet 331 al.,2013) Ecosystem*functions*and*services*of*aquatic*herbivores 334

16 *Seed*and*propagule*dispersal 335 Besidestheirdirecteffectsontheirfoodplants,aquaticherbivoresprovideakeyserviceforaquatic 336 ecosystems:thepassivedispersalofabroadvarietyofaquaticorganisms,includingthe 337 aforementionedfoodplants,aswellasmanyothertaxaattachedorassociatedtothem(figuerola 338 andgreen,2002a;brochetetal.,2010a;vanleeuwenetal.,2012).dispersalbymostinlandywater 339 herbivorescontributestotheredistributionofindividualswithinsinglewetlandsandamongnearby 340 ones;whilewaterbirds(mostnotably,migratoryspecies)arethemainvectoroflongydistance 341 dispersalamongwetlandssituatedatseparatedwatersheds,fromregionaltocontinentalscales 342 (Vianaetal.,2013b;Vianaetal.,inpress).Amongwaterbirds,thefrequencyandscaleoflongY 343 distancedispersaleventsisknowntovarywiththevector smorphology,todependonthemigratory 344 strategyandtoscalenegativewithbodymass(greenandfiguerola,2005;vianaetal.,2013b;viana 345 etal.,2013a).inthemarineenvironment,bioticdispersalbyherbivores(seaturtles,ducksandfish) 346 hasbeenreportedforseagrasses(sumoskiandorth,2012)andpassivetransportofotherorganisms 347 isalsoknowntooccur(e.g.sessileinvertebratestransportedbyseaturtlesandcrabs(winston, ).Theoppositeprocessmayalsotakeplace e.g.anecdotalevidencesuggeststhatgreenturtle 349 hatchlingsusekelpraftsforpassivedispersal(carrandmeylan,1980). 350 Interrestrialsystems,animalYmediateddispersalisoftenfacilitatedbyrewardsencasingthe 351 propagulesorattachedtotheseeds(suchasfruits,elaiosomesandsomepods).incontrast,aquatic 352 plantseedstypicallylackrewards;hence,theirdispersalismediatedbytheingestionofplant 353 vegetativepartsbyherbivores( foliageinthefruit,sensujanzen(1984)),theoccasionalsurvivalof 354 seedsingestedbygranivores(e.g.teals(brochetetal.,2010b))ortheaccidentalingestionofseeds 355 bycarnivores/omnivores(notablyfilteryfeeders,suchasflamingoesandshovelers(verhoeven,1980; 356 Figuerolaetal.,2003).Thisdifferenceresultsinmajordifferencesinselectionpressures,whichcan 357 betracedtodifferencesinpredominantseedtraits(table1).aquaticplantseedsaretypicallysmall, 358 whichfacilitatestheiringestionmixedwiththefoliage,theirsurvivaltogutpassage,andaprolonged 359

17 16 gutypassagetimesresultinginlongerdispersaldistances(muellerandvandervalk,2002; 360 CharalambidouandSantamaria,2005;Soonsetal.,2008;Figuerolaetal.,2010).Largerseedsoften 361 havethickandimpermeablecoats,necessarytowithstandtheirseverescarificationinwaterbirdguts 362 (whichtendtoretainselectivelysuchlargerseeds(kleyheeg,2015)andtheseverephysicoychemical 363 treatmentexertedbytheirguts(figuerolaetal.,2002;santamariaetal.,2002).suchcoattypes 364 oftenresultinstrongphysicaldormancies,whichmaypostponeseedgerminationuntilingestionbya 365 potentialdispersalvectorhastakenplace(e.g.inseedscollectedfromthesedimentbankby 366 granivoresandfilterfeeders(figuerolaetal.,2003).invertebratepropagulesdispersedbywaterfowl 367 typicallyshowsimilartraits:smallsize,onetoseveralprotectivecoats,anddelayedorstochastic 368 hatching(charalambidouandsantamaria,2002).insomecases,theencasementofrestingeggsin 369 themother sbodymayprovidebothprotectionagainsttheirdigestionandarewardtopotential 370 dispersers havingthusafunctionanalogoustothatofplantfruits,whosefunctionalandadaptive 371 valueofsuchatraitremainstobestudied. 372 Externaldispersalmaytakeplaceattachedtotheanimal sfurorplumage,oradheredtomudy 373 stainedsurfacesinthebodyorfeet(figuerolaandgreen,2002b;frischetal.,2007).available 374 evidencesuggests,however,thatitislessfrequentthaninternaldispersal(brochetetal.,2010b). 375 Onceagain,smallpropagulesaremuchmorelikelytobecomeattachedoradhered,andremainin 376 suchsituationlongenoughforlongydistancedispersaltooccur.othertraitsthathavebeengenerally 377 assumedtofacilitateexternaldispersal,suchasflatshapesandsuitablesurfacestructures(hooks, 378 thorns,hairs),areknowntooccurinplantandinvertebratepropagules(e.g.vivianysmithandstiles 379 (1994)).Asabove,theirfunctionalandadaptivevalueremainstobestudied. 380 Propaguledispersal,particularlyoverlongdistances,influencesthepopulation,geneticand 381 communitystructureofaquaticorganisms(vianaetal.,2014).hence,itisbroadlyregardedasakey 382 ecosystemserviceprovidedbyaquaticherbivores.itseffectis,however,moreevidentwhensuch 383 immigrantsencounteremptyniches(e.g.colonizationofdisturbed,neworrestoredwetlands)than 384

18 17 whentheyfaceresidentgenotypesorspecies,establishedbeforetheirarrival(louetteandde 385 Meester,2005).Insuchcases,theimmigrant sestablishmentmaybeprecludedbybioticresistance 386 arisingfromintrayandinteryspecificcompetition,mortalitycausedbynaturalenemiesand 387 environmentalfiltering(e.g.habitatchangescausedbyotherspecies).eventhen,theprocessof 388 propaguledispersalrepresentsakeyelementofecosystemresilience particularlyininlandwaters, 389 whicharefragmentedandisolatedbynature.suchresiliencemayprovevital,inthenearfuture,for 390 ecosystemadaptationtoglobalchange byfacilitatingrapidrangeshiftsandthereadjustmentof 391 geneticstructure(e.g.locallyyadaptedgenotypes)causedbytheacceleratingchangesin 392 environmentalconditionsassociatedtoglobalwarming,landusechangesandtheperturbationof 393 globalnutrientcycles(amezagaetal.,2002;röckstrometal.,2009;robledoyarnuncioetal.,2014). 394 Propaguledispersalbyaquaticherbivoresmayalsoentailnegativeeffectsfornativespeciesand 395 ecosystemswhenitmediatesthearrivalandspreadofalienspecies(reynoldsetal.,2015).examples 396 includebothplantandinvertebratespecies(charalambidouetal.,2003;brochetetal.,2009;munoz 397 etal.,2013),althoughtheeffectofdispersalonhumanymediateddispersalisoftenpredominantor 398 difficulttodisentangle(weiszandyan,2010;vanleeuwenetal.,2013).itisalsoworthnotingthat, 399 despitetheirpotentialroleasseeddispersers,aquaticherbivoresmayalsoreducethefrequencyof 400 propaguledispersalbyreducingpropaguleproduction duetotheconsumptionofplantvegetative 401 parts(e.g.(woodetal.,2012a;darnellanddunton,2015))andtheinvertebratesattachedor 402 associatedtothem *Biogeochemical*cycling* 405 Grazingandbioturbationbyaquaticherbivorescanhavedirectandindirecteffectson 406 biogeochemicalcycling.inoligotrophicsystems,grazingbysmallerherbivorescanhavepositive 407 effectsbyconservingnutrientswithinthemeadowandclosingthecyclingofnutrientsfromleaf 408 material.leafmaterialcanbeshredded(seaurchins,(vonketal.,2008b)),burrowed(alpheid 409

19 18 shrimp,(vonketal.,2008a))orexcretedaftergrazing(fish,(kirschetal.,2002)),thusstimulating 410 nutrientretention.largerherbivoressuchasgreenturtlesanddugongsmaytravelbetweendifferent 411 habitatsandstimulateexportofnutrientsbetweenforaging(seagrass)andresting(coralreefs)areas 412 (Christianenetal.,2012). 413 Byforagingandrestinginterrestrialandaquaticenvironments,herbivoresprovideaquaticYterrestrial 414 linkages,transportingcarbon,nutrientsandcontaminantsfromlandtowater(forinstance 415 hippopotamushippopotamus*amphibius*(subaluskyetal.,2015),waterbirds(hahnetal.,2008; 416 Chaichanaetal.,2010)orlargesavannaherbivores(Moss,2015)orvice*versa(forinstancebymoose 417 Alces*sp.(Bumpetal.,2009)).Ithasrecentlybeensuggestedthatthedeclineinlargeherbivore 418 densitiesandtheextinctionoflatepleistocenemegafaunacausedastrongreductioninthecapacity 419 oftransportofphosphorusfromnutrienthotspots,suchasstreamsorfloodplains,towardsless 420 fertileinlandareas(doughtyetal.,2016).longdistancetravelofmigratoryherbivoresalso 421 contributestotransportofnutrientsacrosssitesofvaryingfertility(bauerandhoye,2014). 422 Inseagrassmeadows,grazingbymesoherbivorescanincreaseproductivityandpossiblycarbon 423 sequestration.howeverbelowygroundgrazing(e.g.bydensepopulationsofgreenturtles)orother 424 factorsofdisturbanceintheseagrassrootmatcancausereleaseofancientcarbon,whichmay 425 contributetoincreasedglobalwarming(macreadieetal.,2015).similarly,earlyseasonbelowy 426 groundforagingbypinkyfootedgeese(anser*brachyrhynchus)issufficienttostronglyreducecsink 427 strengthandsoilcstocksofarctictundra(vanderwaletal.,2007).recentstudiesaretherefore 428 stressingthatitiscriticaltomaintainintactpredatorpopulationsthatcontrollargeherbivore 429 densitiestopreventgrazeraggregation,protectcarbonstocksandavoidseagrassmeadowcollapse 430 (Atwoodetal.,2015).Inasubtropicalseagrassecosystem,largepredators(e.g.tigersharks)induce 431 plantspeciesshiftsbychangingtheforagingtacticsoflargegrazers,suchasturtleanddugongs 432 (Heithausetal.,2007).Underlowpredationrisk,dugongsandseaturtlesforagedbyexcavating 433

20 nutrientyrichrhizomesofseagrasses.underhighpredationrisks,theychangedtheirforagingtactics, whichstimulatedslowygrowingpioneerspeciesandenhancedcarbonstocks Aquaticherbivorescanalsoenhancemethaneemissionthroughthedamageofemergentplant stems(greylaggeese(anser*anser)(dingemansetal.,2011);grasshoppers(petruzzellaetal.,2015)). ThestemsofemergentmacrophyteshavewellYdevelopedlacunarsystemsforgastransport;hence, brokenstemsmayactlike chimneys,providinganopenconnectionbetweenthesedimentandthe atmospherethatbypassesthewaterlayer.ontheotherhand,herbivorescanreducemethane emissionthroughbioturbationandremovalofsubmergedplantbeds(bodelieretal.,2006) *Coastal*protection Seagrasses,mangrovesandsaltmarshesofferimportantcoastalprotectionandsediment stabilizationservices.forseagrassesthisfunctionisgenerallyattributedtoseagrasscanopy properties(hendriksetal.,2010)andcouldbealteredbyherbivory.althoughintensivelygrazed seagrassmeadowshavebeenshowntomaintaintheircapacityforeffectivesedimentstabilization, thisfunctiondegradeswhenherbivoresswitchtobelowgroundgrazing,whichcausesdecreasedbed elevation,erosionandreducedcoastalprotection(christianenetal.,2013).similarly,livestock grazingcanlowersaltmarshes accretionrates(nolteetal.,2015),weakeningtheresilienceand coastalprotectionfunctionofthesesystems *Habitat*for*other*organisms* Macrophytesplayanimportantroleinstructuringaquaticcommunitiesbecausetheyprovide physicalstructure,increasehabitatcomplexityandheterogeneity,affectoxygenandnutrient concentrationsandproviderefugefrompredation(carpenterandlodge,1986;jeppesenetal., 19

21 ).Macrophytesalsoreleasedissolvedorganiccarbon(DOC)whichcanbeusedbymicrobesin 457 theperiphytonorplankton(findlayetal.,1986).therefore,byconsumingmacrophytes,herbivores 458 maydeterioratethehabitatforotherorganisms.fishproductivitywasfoundtobelowerinseagrass 459 meadowsgrazedbygreenturtles(arthuretal.,2013)andaftermeadowcollapsecausedby 460 overgrazing(reportedforturtlesin(christianenetal.,2013).similarly,herbivorousfishes,dugongs, 461 geeseandotherwaterbirdshavebeenfoundtodrasticallyreduceinvertebratebiomassinseagrass 462 meadowsandsaltmarshes(marklundetal.,2002;sherfyandkirkpatrick,2003;skilleteretal.,2007; 463 Pagesetal.,2012).Impactsoninvertebratesmayoccurevenwheretheproportionalreductionof 464 vegetationislow(bortolusetal.,1998) Primary*production* 467 Submergedandemergentmacrophytescansignificantlycontributetotheprimaryproductionof 468 aquaticecosystems(blindowetal.,2006;brothersetal.,2013).thisholdsespeciallyforsmalllakes 469 whichrepresentapproximately99%ofalllakes(downingetal.,2006;verpoorteretal.,2014).direct 470 studiesontheeffectofherbivoryonaquaticplantgrowthandproductionarescarcebecause 471 quantificationoftheimpactofgrazingratesonplantproductionrequirescoupledmeasurementsof 472 ageydependentgrazinglossandturnoverrateofplanttissue(sandyjensenetal.,1994).ingeneral, 473 fastturnoveroftheplanttissue(i.e.highspecificgrowthrate)cancompensateforintenseherbivory 474 undernonylimitingresourceconditions(sandyjensenandjacobsen,2002).cherry&gough(2009) 475 foundthatnymphaea*odoratamaytoleratemoderatelevelsofherbivorybyreallocatingbiomass 476 andresourcesaboveground.onthecontrary,standsofmyriophyllum*spicatumretracttheir 477 resourcestobelowgroundpartsafterdefoliationbyaquaticcaterpillars(milerandstraile,2010). 478 Waterhyacinths(Eichhornia*crassipes)werealsofoundtofullycompensateforlowlevelsof 479 continuousdefoliation,regardlessofnutrientavailability(sotiandvolin,2010).inseagrass 480 ecosystems,reportedeffectsoflargeherbivoreswerepositiveforintermediatedensitiesofgreen 481

22 21 turtles(e.g.anincreasedtolerancetoeutrophication),andnegativeforhighdensitiesofgreen 482 turtles(e.g.switchtobelowgroundgrazingcausingmeadowcollapse)(christianenetal.,2012; 483 Christianenetal.,2013).Similarly,moderatelevelsofsimulatedfishherbivorystimulatedseagrassin 484 primaryproduction(i.e.compensatorygrowth),whileveryhighlevelsofherbivorydecreasedit 485 (Vergesetal.,2008). 486 AtwholeYecosystemlevel,herbivoryonsubmergedmacrophytesmayhavedifferenteffectsongross 487 primaryproduction(gpp).ifherbivoryresultsinashiftfromclearywatertoturbidconditions(see 488 below),gppcanbeexpectedtodecline,atleastunderintermediateconcentrationsoftotal 489 phosphorus(brothersetal.,2013).ontheotherhand,largegrazersthatremoveoldseagrassleaves 490 coveredinephiphytesandhavebeenreportedtoincreaseprimaryproduction(valentineetal., ;MoranandBjorndal,2005;Christianenetal.,2012) Regime*shifts 494 Shalloweutrophiclakesandlowlandriversmayexistintwoalternativestablesteadystates,aclearY 495 waterstatedominatedbysubmergedmacrophytesandaturbid,phytoplanktonydominatedstate 496 (Schefferetal.,1993;Hiltetal.,2011;Hilt,2015).Indeeperlakes,submergedmacrophytesmayalso 497 contributetothestabilisationofclearywaterconditions(hiltetal.,2010;sachseetal.,2014).shifts 498 betweenclearywaterandturbidstateshavebeenattributedtochangesinnutrientloading,inthe 499 abundanceofzooplanktivorousfish(e.g.bybiomanipulation)and/orinmacrophytecover(scheffer 500 etal.,1993;sondergaardetal.,2007;bakkeretal.,2010).herbivoryonmacrophytesmayalsoplaya 501 significantroleforshiftingmacrophyteydominatedsystemsintotheturbidstate,orpreventingthe 502 shiftfromturbidyintoclearywaterconditions.mitchell&wass(1996a)concludedthatthe 503 cumulativeeffectofwaterfowlgrazingconsumptionwassmallbutmightbecomecriticalwhenother 504 conditionsformacrophytegrowthbecomelimiting(duee.g.tolightlimitationcausedbyhighwater 505 turbidity).arecentmodelingstudyindeedshowedthatherbivoryonmacrophytesoftenbecomes 506

23 22 importantincombinationwithadditionalstressbyperiphytonshading(hiddingetal.,2016). 507 Herbivorybybirdsandfishmaythustriggerthelossofsubmergedvegetationunderhighnutrient 508 loading(vandonkandotte,1996;paiceetal.,inpress),possiblyincombinationwithotherstress 509 factors.similarly,afterreductionsinnutrientloading,herbivorousbirds)mayinhibittheexpected 510 recoveryofmacrophytes(lauridsenetal.,1993;søndergaardetal.,1996;hilt,2006) ! Perspectives:)historical)and)future)changes)in)herbivore)grazing)pressure) 514 Herbivoremanagementandglobalenvironmentalchange,includingwaterlevelfluctuations, 515 eutrophication,temperatureriseandinvasivespecies,feedbackonherbivorenumbers,herbivore 516 distributionandgrazingpressure *Changes*in*herbivore*assemblages*over*time* 519 Thereisagrowingbodyofevidencethatherbivoreassemblageshavevariedovertimeconsiderably 520 intheirdiversityandabundance,andarelikelytocontinuetovaryinthefuture.throughouthuman 521 history,peoplehaveexploitedmanyaquaticherbivorespecies,includingwaterfowl,sirenians, 522 beavers,andmuskrats,forfood,recreation,andanimalproductssuchasskins,furs,feathers,and 523 oils(domning,1982;kitchenerandconroy,1997).humanoverexploitationhashadcatastrophic 524 effectsonmanyherbivorepopulations,withawiderangeofspeciesexperiencingreduced 525 populationsizesandgeographicranges,andevenextinction(jessen,1970;turveyandrisley,2006). 526 Profoundhistoricalchangesinherbivoreassemblageswereparticularlyevidentinshallowseasand 527 coastalhabitats,wherethediversityanddistributionsofmammalianmegayherbivores(sirenians 528 suchasmanateesanddugongs)werereducedheavilyduetohuntingbyhumans(whitehead,1978; 529 Jackson,1997;TurveyandRisley,2006;McCauleyetal.,2015).Freshwatersystemshavealsoseen 530

24 23 thelossofmanylargeybodiedherbivorespecies,inparticularmammals(moss,2015;bakkeretal., b).Additionally,duringthetwentiethcenturyarangeofsemiYaquaticherbivorespecies 532 switchedfromaquatictoterrestrialfeeding,particularlyduringwinter(laubek,1995),further 533 reducingherbivoreabundanceanddiversitywithinaquaticsystems.suchhabitatshiftshavebeen 534 mostwidelydocumentedforavianherbivoressuchasspeciesofswans,geese,ducksandrails 535 (Jefferiesetal.,2003;VanEerdenetal.,2005).Thesubstantialeffectsofhumansonaquatic 536 herbivoresmeantthatthetwentiethcenturyrepresentedalowpointforherbivoreabundanceand 537 diversityacrossaquaticsystems.indeed,wefinditinterestingtonotethatearlierauthorsdrewtheir 538 conclusionsontheapparentunimportanceofplantyherbivoreinteractionsinaquaticecosystems 539 basedonresearchconductedduringaperiodinwhichaquaticherbivoreswererelativelyscarce.for 540 Carribeancoastalecosystemsithasevenbeendocumentedthatthesewereseverelydegradedlong 541 beforeecologistsbegantostudythem,throughthedecimationoflargevertebratesincludinggreen 542 turtlesandmanateesbyabouttheyear1800(jackson1997). 543 Stricterhuntingregulationsandconservationeffortsinthesecondhalfofthetwentiethcenturyhave 544 facilitatedrecoveriesintherangeandpopulationsizesofmanykeyaquaticherbivorespecies(nolet 545 androsell,1998).anexampleistheeurasianbeaver(castor*fiber),reducedbyoverhuntingatthe 546 beginningofthetwentiethcenturytoc.1200individualsineightisolatedpopulationsacrosseurope 547 (NoletandRosell,1998;HalleyandRosell,2002).Followinggreaterlegalprotectionsfromhunting, 548 theeurasianbeaverunderwentsustainedpopulationrecoveryandhasreyestablishedpopulationsin 549 allareaswithinitsformernaturalrange(withtheexceptionofportugal,italy,andthesouthern 550 Balkans),withatotalpopulationofatleast1.04millionindividuals(Halleyetal.,2012).Manyspecies 551 ofherbivorouswaterfowlintemperateregionshavemadesimilarrecoveries(bellrose,1976;ankney, ).Ofthe21goosespecies(Anserspp.andBrantaspp.)forwhoselongYtermpopulationtrendsin 553 Europeareknown,16speciesarecurrentlyincreasing(Foxetal.,2010).Recentchangesin 554 agriculturalpracticeshaveresultedingreaterterrestrialfoodavailabilityforoverwintering 555 waterfowl,withlargerspeciesbenefitingmoreintermsofpopulationgrowth(jefferiesetal.,2003; 556

25 24 VanEerdenetal.,2005).Althoughmanyreptilianherbivoresremainendangered,certainspecies 557 suchasthegreenturtle(chelonia*mydas)haverecentlyshownsignsofpopulationrecoveryin 558 responsetothreedecadesofconservationefforts(chaloupkaetal.,2008). 559 Therecoveryofspeciesofaquaticherbivoreshasbeenaidedbytherecentinterestinrewilding 560 ecosystems(donlanetal.,2006).thekeyrolesthatextinctorextirpatedlargeherbivoresplayedin 561 thestructureandfunctioningofterrestrialecosystemshasreceivedgrowingrecognitionfrom 562 researchers(donlanetal.,2006;sandometal.,2014;bakkeretal.,2016a;doughtyetal.,2016). 563 Recently,ithasbeenproposedthatlargeherbivoresmayhaveplayedequallyYimportantrolesin 564 regulatingthestructureandfunctioningofaquaticecosystems(moss,2015;bakkeretal.,2016b). 565 Speciesofaquaticherbivorewhichcanactasecosystemengineers,suchasthebeaver,aretypically 566 primecandidatesforrewildingprojectsduetothewiderecosystembenefitsthatresultfromsuch 567 engineering(collenandgibson,2001).therecentfindingthatbeaver screationofpondsincreased 568 thediversityofherbivorouswaterfowlwithinthelandscapeindicatesthatnaturalrecolonizationand 569 rewildingmayresultinwiderchangestoherbivoreassemblagesthanthetargetspeciesalone, 570 throughthefacilitationofdifferentherbivoretaxa(nummiandholopainen,2014). 571 Therecoveryofpredatorpopulations,vianaturalrecoveryandconservationefforts,canalsoaffect 572 plantyherbivoreinteractions(estesetal.,2011).evidencefromterrestrialandmarinesystemsshows 573 thatherbivoreimpactsonplantscanbereducedaspredatornumbersrecover,becausepredators 574 notonlylowerherbivoreabundancethroughdirectconsumption,butalsoalterherbivore 575 distributionsandreducegrazingintensitythroughindirecteffectsofpredatoravoidancebehavior 576 ( landscapeoffear sensu(madinetal.,2011;kuijperetal.,2013).similarresultscouldbefoundfor 577 interactionsbetweenpredators,herbivores,andmacrophytesinaquaticsystems,butlittleresearch 578 hasbeencarriedouttodate.forexample,arecentstudyfoundthatgreenturtle(chelonia*mydas) 579 habitatusereflectedtradeyoffsbetweenfoodresources,bodycondition,andriskofpredationby 580 tigersharks(galeocerdo*cuvier)inseagrassbeds(heithausetal.,2007).adeclineintigershark 581

26 25 numbersmaythusresultinastrongincreaseofgreenturtlegrazingonseagrassbeds,potentially 582 resultinginaseagrassbedcollapse(heithausetal.,2014) *Exotic*herbivore*species* 585 ThespreadofnonYnativespecieshasbeenakeydriveroftemporalchangesinaquaticherbivore 586 assemblagesinrecentdecades.awiderangeofherbivoretaxahaveestablishedinvasivepopulations 587 knowntoimpactonnativemacrophytes.wellydocumentedexamplesincludebirdssuchasthemute 588 swaninnorthamerica(tatuetal.,2007),mammalssuchasthemuskratineurope(danell,1979; 589 Sarneeletal.,2014),fishessuchasthelessepsianrabbitfishesintheMediterranean(Vergesetal., a),molluscssuchasthegoldenapplesnailinAsia(Carlssonetal.,2004),andcrustaceanssuch 591 asredswampcrayfishineurope(gherardiandacquistapace,2007;vanderwaletal.,2013).despite 592 attemptstopreventspeciestransferandestablishmentthroughimprovedbiosecurity,ratesof 593 invasionremainatahistorichigh(cohenandcarlton,1998;jacksonandgrey,2013) *Climate*change*and*temperature*rise* 596 Futureenvironmentalchangeisalsopredictedtoalterherbivoreassemblages.Inparticular,climateY 597 drivenfactorssuchasseaylevelriseandchangesinvegetationphenologyandabundancehavethe 598 potentialtoalterwhere,whenandhowmuchherbivoresfeed,andthushavethepotentialtoalter 599 plantyherbivoreinteractionsacrossaquaticsystems(stillmanetal.,2015).forexample,northward 600 shiftsinwinteringrangeinresponsetowarminghavebeenrecordedforseveralwaterfowlspecies, 601 includingsemiyaquaticherbivoreslikegreylaggeese(ramoetal.,2015).furthermore,food 602 requirementschangewithtemperature.withincreasingtemperatures,theenergyrequirementsof 603 temperateectothermanimalsincreaseandtheyconsumemorefood.furthermore,theymaychange 604 theirdietinresponsetotemperature,whichhasconsequencesforthedegreeofplantconsumption. 605

27 26 Omnivorousfishincreasetheirrelativeconsumptionofplantmaterialwithincreasingtemperatures 606 (Prejs,1984;BehrensandLafferty,2007,2012),apatternthatisrecentlyalsofoundincopepods 607 feedingonseston(boersmaetal.,2016).forendothermsthispatternmaybetheopposite,astheir 608 energyrequirementsdecreasewithincreasingtemperatures,butthishypothesisawaitsempirical 609 testing.warmertemperaturesmayalsoinducehigherperiphytonshadingofmacrophytes(mahdyet 610 al.,2015),makingthemmorepronetoherbivory(hiddingetal.,2016) *Herbivore*impacts*under*human*control 613 Whereherbivoreimpactsonmacrophytesaffecthumanactivities,suchasconservation,recreation, 614 andaquaculture,theymaybeviewedasundesirable.inmostcasesitshouldbenotedthatproblems 615 causedbyherbivoresareoftenthedirectorindirectconsequenceofearlierhumanactions.for 616 instance,ongoingeutrophicationoflakesreducestheresilienceofsubmergedplantbedstograzing 617 duetoincreasedshadingbyperiphytonwhichprofitsfromthenutrientloading(hiddingetal.,2016), 618 andreyestablishmentofsubmergedvegetationcanbeinhibitedbygrazersaswell(hauxwelletal., ).Thecombinedhuntingoflargepredatorsandthecreationofmarineprotectedreserves,as 620 theplacewherelargeherbivoresaresafe,haslocallyresultedinverystronggrazingpressureon 621 seagrassbedsbygreenseaturtles(christianenetal.2014). 622 Suchherbivoreimpactscanleadtoconflictsbetweenpeopleinterestedinherbivorewelfareand 623 conservation,andthoseinterestedintheactivitybeingaffectedbytheherbivore(redpathetal., ).Todate,conflictshavearisenduetoovergrazingbyreptilian,mammalian,andavian 625 herbivores(table2).incontrast,wecouldfindnoevidenceofconflictsassociatedwithinvertebrate 626 herbivory,whichmayreflectdifferencesinhumanvaluesratherthanecologicalimpact.indeed, 627 evidencefromarecentmetayanalysisshowedthatvertebrateherbivoresdonothaveconsistently 628 greaterimpactsonmacrophytesthaninvertebrateherbivores(woodetal.,2016).vertebrate 629 herbivoressuchaswaterfowl,turtles,andsireniansareoftenconsideredcharismatic,andattempts 630

28 27 tomanagetheirnumbers,behaviourordistributionsarelikelytoattractmoreoppositionfrom 631 conservationandwelfaregroupsthanthemanagementofinvertebrateherbivores(bremnerand 632 Park,2007;Small,2012).Consequently,itcanbedifficulttoimplementmanagementtoalleviatethe 633 effectsofovergrazing(coluccyetal.,2001). 634 Despitetheseconflicts,notallherbivoreimpactsonmacrophytesareviewedasnegativebypeople. 635 Herbivoreshaveproventobeeffectivebiocontrolagentstohelpreduceanderadicateundesirable 636 macrophytes,suchasoverabundantorinvasivespecies(newman,2004;cudaetal.,2008).awide 637 rangeofherbivorebiocontrolagentshavebeenusedglobally(table3).biocontrolofmacrophytes 638 throughherbivoryhasreceivedgrowinginterestfromresearchersandmanagers,particularlyas 639 somebiotypesofinvasivemacrophytes(e.g.hydrilla*verticillata)havedevelopedresistanceto 640 commonlyyusedherbicides(cudaetal.,2008).moretargetedbiocontrolcanbeachievedby 641 invertebrateherbivores,whichtypicallyshowgreaterspecificityformacrophytespeciesrelativeto 642 vertebrateherbivores(lodge,1991;newman,1991).sincewilson(1964)arguedthat noinsects 643 haveyetbeenusedforthebiologicalcontrolofaquaticweeds,awiderangeofspeciesof 644 coleopteran,lepidopteran,anddipteranbiocontrolagentshavebeenusedsuccessfully(newman, ;Cudaetal.,2008).Boththeconflictsrelatedtoovergrazing,andtheuseofherbivoresas 646 biocontrolagents,showtheimportanceofimprovingourunderstandingplantyherbivore 647 interactions.forexample,understandingthedensityydependenceofherbivoreimpactson 648 macrophyteabundancecaninformthedensitiesofbiocontrolagentsrequiredtoreduce 649 overabundantmacrophytes(cudaetal.,2008),orallowlakemanagerstopredicttheresponseof 650 macrophytestochangesinwildherbivoredensity(woodetal.,2012a) ! How)to)improve)understanding)of)herbivore)impacts *BottomEup*versus*topEdown*control*across*environmental*gradients* 654

29 28 Lodge(1991)endedhisreviewwiththeconclusionthat Tounderstandtheinfluenceofherbivory 655 (relativetootherbioticandabioticfactors)onmacrophytepopulationsandassemblages,extensive 656 comparisonsofgrazingdamageacrossenvironmentalgradientsandacrossmacrophyteandgrazer 657 speciesmustbemade. WhereasmetaYanalyseshaveprovidedvaluableinsightintheimpactof 658 differentherbivoresbothonangiospermsandmacroyalgae(pooreetal.,2012;woodetal.,2016), 659 andtherelationshipbetweenmacrophytepalatabilityandherbivoreimpactreceivedincreasing 660 attentionduringthelastdecade,thevariationintheintensityandimpactsofherbivoryalong 661 environmentalgradientshasbeenscantlyexplored.bakkerandnolet(2014)suggestedthat 662 herbivoreimpactmayincreaseatnutrientyrichconditions,duetoacombinationofhigherplant 663 palatabilityandlowertolerancetograzingdamagecausedbyadditionalstressfactors(suchas 664 reducedlightavailabilityduetoperiphytonshading(hiddingetal.,2016).inanexperimentalpond 665 system,herbivorybymallardsprovedtohavestrongerimpactonsubmergedmacrophytesunder 666 eutrophicthanunderoligotrophicconditions.wearenotaware,however,ofanyfieldtestsforthis 667 theory.alternatively,herbivoresmayfacilitatesubmergedmacrophyteswithincreasing 668 eutrophication,forexamplewhenmoderatedensitiesofsmallgrazerssuchasfreshwatersnailsclean 669 submergedplantsfromepiphytes,whichbecomesmoreimportantundereutrophicconditions 670 (Bakkeretal.,2013).Also,whenintensegrazingstimulatestheformationofnewshoots,whichare 671 notyetcolonizedbyepiphytes,largegrazerssuchasgreenseaturtles,cancompensatethenegative 672 effectofeutrophicationforseagrassgrowthtoacertainextent(christianenetal.,2012) *Integrating*marine*and*freshwater*studies* 675 Traditionally,freshwatermacrophytesandseagrasseshavelargelybeenstudiedseparately.Todate, 676 theliteratureonfreshwaterandmarineherbivoreimpactshavenotbeenintegrated,andhave 677 largelydevelopedseparatelydespitetheobviousareasofoverlap.ifcrossysystemcomparisonswere 678 beingmade,thesewereoftenmarineyterrestrialorfreshwateryterrestrialcomparisonsandcan 679

30 29 includebothvascularplantsandalgae(hay,1991;elseretal.,2000;burkepile,2013).thisis 680 unfortunatebecause,leavingafewobviousdifferencesapart(suchasthehighersalinityand 681 connectivityofmarinesystems),theecologyofmarineandinlandywatervascularmacrophytes 682 showsveryfewdifferences.yet,integrativeworkonfreshwaterandmarinevascularmacrophytes 683 stillawaitsitsmoment *Herbivore*assemblages:*towards*functional*groups* Forabetterunderstandingofherbivoreimpact,researchersshouldconsiderthewholecommunity 688 ofherbivores,whichcompeteandfacilitateeachother.thishasalreadybeendoneforterrestrial 689 systemslongago(mcnaughton,1985),butexamplesforaquaticsystemsarerare.onesuchexample 690 istheherbivorecommunityinashallowfreshwaterlakethatforagesonpondweedbeds,consisting 691 mainlyofpotamogeton*pectinatus.thesproutingplantsarebeinggrazedbyresidentwaterfowl 692 specieslikemuteswans(cygnus*olor),mallards(anas*platyrhynchos),gadwall(anas*strepera)and 693 coots(fulica*atra).theintensityandtimingofgrazingdeterminehowmuchaboveygroundplant 694 materialisremainingandgrowing(hootsmans,1999).attheendofthesummer,belowyground 695 tubersarebeingformeddependingontheamountofaboveygroundplantmaterial(vanwijk,1988). 696 Thus,moreand,notably,earlierwaterfowlgrazinginsummerresultsinlesstuberbiomassinautumn 697 (Klaassenetal.,2006;Gyimesietal.,2011).Inautumn,tubersarebeingdepletedbymigratoryswans 698 (Bewick sswanscygnus*columbianus)anddivingducks(mainlytuftedducksaythya*fuligulaand 699 pochardsaythya*ferina)untilagrazingthreshold(noletetal.,2001).thedivingducksbenefitfrom 700 thetramplingactivityoftheswans,withoutnegativelyaffectingtheswans intakerate;thistherefore 701 classifiesascommensalism(gyimesietal.,2012).inaccordancewithasequentialpopulationmodel 702 (Jonzénetal.,2002),highesttuberbiomassandinparticulartuberproductionwasgenerallyfoundat 703 sitesforageddowntointermediatethresholdsinthepreviousautumn.inthissystemapositive 704

31 30 feedbackbetweentubergrazingandtuberproductionresultedfromareductioninselfyshadingora 705 decreaseinneighbourcompetition(nolet,2004) Together,theinteractionswithinherbivorecommunitieswilldeterminetheeffectofherbivore 708 diversity,atopicrarelytoucheduponinaquaticvascularplantbeds(butseemarinemacroyalgaeand 709 seagrasssystems,e.g(duffyetal.,2003;burkepile,2013).whereasallinteractionsatthespecies 710 levelareinteresting,awayforwardcanbetogeneralizebeyondspeciesbygroupingherbivoresin 711 guildsorfunctionalgroupsandworkingoutwhichtraitsbestexplaintheirrelativeeffects.suchtraits 712 couldincludebodysize,diet(herbivoryyomnivory),habitat(terrestrialyaquaticlinkages),migratory 713 strategy(sedentaryversusmigratory)andmovementecology(foragingranges).recently,grouping 714 oflargesavannaherbivoresprovedtobeusefultounderstandtheirecosystemimpacts(hempsonet 715 al.,2015).similarly,theecosystemfunctionsofaquaticlargeherbivoresmaybeunderstoodfrom 716 theirhabitatuse,inparticularhowdependentontheaquaticsystemstheyareincombinationwith 717 theirmovementecology(bakkeretal.,2016b) Tools*to*study*herbivore*impacts 720 Practically,thehighvarianceinestimatesofmacrophyteabundance,evenwithinasinglestudy 721 system,canmakeherbivoreeffectsdifficulttodetectinaquaticsystemswithoutlargesamplesizes 722 (Woodetal.,2012b).However,numerousmethodshavebeendevelopedandemployedtodetect 723 and/orquantifyherbivoryonmacrophytesandseagrasses(table4).themostdirectapproachfor 724 detectionandquantificationofeffectsisatechniqueknownastethering(kirschetal.,2002;tomas 725 etal.,2005;pradoetal.,2007;pagesetal.,2014).withthistechniqueitispossibletoestimatethe 726 biomass(orcmofleaf)eatendaily,i.e.directherbivoryrates(seetable4).anotherdirectapproach 727 todetectandquantifyherbivoreeffectsareinsituexclosurecageswithsubsequentbiomass 728 measurementsinyandoutside. 729

32 31 Otherlessdirectherbivorydetectionandquantificationmethodsfocusingonmacrophytesinclude 730 visualestimationsofleafdamageandmeasurementsofmacrophyteperformanceacrossnaturallyy 731 occuringspatialortemporalgradientsinherbivoreassemblageproperties(e.g.density)(table4). 732 Aerialphotographstakenfromdrones(Brandtetal.,2015),echoYsounding(Jägeretal.,2004)and 733 remotesensing(silvaetal.,2008)mayincreasinglybeingusedinthefutureforlargerscale 734 quantificationsofmacrophyteconsumptionbyherbivores.attheherbivoreside,underwatervideos, 735 aquariumfeedingexperiments,molecularmarkers,stableisotopesignatures,gutandfaeces 736 analyses,andwholeylakefishtelemetryhavebeenapplied(table4). 737 Finally,mechanisticmodelsallowassessmentsofherbivoryoverlargerspatialandtemporalscales 738 thanfieldybasedmethods,e.g.longytermpredictionsoffutureherbivory.theyinitiallyneedtobe 739 testedagainstfielddatatodemonstrateaccuracyandhavebeendevelopedforboth,theherbivores 740 andtheplants(table4).recently,aplantgrowthmodelsforaspecificmacrophytespecieshasbeen 741 usedtodetectasynergybetweenherbivoryandshadingbyperiphytonasadditionalstressor 742 (Hiddingetal.,2016).Simulationmodelsofherbivoreforagingcanbeusefultoolstopredictforaging 743 impacts,andteststrategiesforgrazingmanagement(woodetal.,2014a;noletetal.,2016) ! Conclusions) 746 Overthelast25years,asubstantialbodyofevidencehasdevelopedthatshowsthatherbivoryisan 747 importantfactorintheecologyofmacrophytesacrossfreshwaterandmarinehabitats.compilingthe 748 mostrecentdata,weconcludethatherbivoreimpactsinfreshwaterandmarineecosystemsare 749 typically5y10timesgreaterthanthosereportedforterrestrialecosystems.thiscorrespondswith 750 lowerc:nstoichiometryofsubmergedaquaticplants.furthermore,aquatichabitatsare 751 characterizedbylargevariationingrazingpressure.considerablechangeshaveoccurred,andare 752 predictedtooccur,inherbivorediversityandabundance,withwideimplicationsforthecomposition 753 anddynamicsofmacrophytecommunities,aswellasforthestructureandfunctioningofaquatic 754

33 ecosystems.therearepressingneedstoimproveourmanagementofundesirableherbivoreimpacts onmacrophytes(e.g.leadingtoanecosystemcollapse),andtheconflictsbetweenpeopleassociated withtheimpactsofcharismaticmegayherbivores.whilesimultaneously,thelongytermfutureof maintainingbothviableherbivorepopulationsandplantbedsshouldbeaddressed,asbothbelongin completeecosystemsandhavecoyevolvedintheselongbeforetheincreasinginfluenceofman MostresearchtodatehasfocusedontheshortYtermimpactsofherbivoresonmacrophyte abundanceandcommunitycomposition.tounderstandtherolesofherbivoresmorefullyweneed toconsidertheirlongerytermimpactsandtheroleofherbivoryinthe(coy)evolutionofboth macrophyteandherbivorespecies.furthermore,abetterintegrationofthefreshwater,marine,and terrestrialherbivoryliteratureswouldgreatlybenefitfutureresearchefforts Acknowledgements) JFPacknowledgesfinancialsupportfromtheWelshGovernmentandHigherEducationFunding CouncilforWalesthroughtheSêrCymruNationalResearchNetworkforLowCarbon,Energyand Environment

34 33 Literature) Allsopp,W.H.L.,1960.Themanatee:ecologyanduseforweedcontrol.Nature188, Amezaga,J.M.,Santamaria,L.,Green,A.J.,2002.BioticwetlandconnectivityYsupportinganew 779 approachforwetlandpolicy.actaoecol.23,213y Ankney,C.D.,1996.Anembarrassmentofriches:Toomanygeese.J.WildlifeManage.60,217Y Aragones,L.V.,Lawler,I.R.,Foley,W.J.,Marsh,H.,2006.Dugonggrazingandturtlecropping:grazing 782 optimizationintropicalseagrasssystems?oecologia149,635y Arthur,R.,Kelkar,N.,Alcoverro,T.,Madhusudan,M.D.,2013.Complexecologicalpathwaysunderlie 784 perceptionsofconflictbetweengreenturtlesandfishersinthelakshadweepislands.biol. 785 Conserv.167,25Y Atkinson,M.J.,Smith,S.V.,1983.CYNYPratiosofbenthicmarineplants.Limnol.Oceanogr.28,568Y Atwood,T.B.,Connolly,R.M.,Ritchie,E.G.,Lovelock,C.E.,Heithaus,M.R.,Hays,G.C.,Fourqurean, 789 J.W.,Macreadie,P.I.,2015.Predatorshelpprotectcarbonstocksinbluecarbonecosystems. 790 NatureClimateChange5,1038Y Bakker,E.S,Dobrescu,I.,Straile,D.,Holmgren,M.,2013.Testingthestressgradienthypothesisin 792 herbivorecommunities:facilitationpeaksatintermediatenutrientlevels.ecology94,1776y Bakker,E.S.,Gill,J.L.,Johnson,C.N.,Vera,F.W.M.,Sandom,C.J.,Asner,G.P.,Svenning,J.C.,2016a. 795 CombiningpaleoYdataandmodernexclosureexperimentstoassesstheimpactofmegafauna 796 extinctionsonwoodyvegetation.p.natl.acad.sci.usa113,847y Bakker,E.S.,Nolet,B.A.,2014.ExperimentalevidenceforenhancedtopYdowncontroloffreshwater 798 macrophyteswithnutrientenrichment.oecologia176,825y

35 34 Bakker,E.S.,Pagès,J.F.,Arthur,R.,Alcoverro,T.,2016b.Assessingtheroleoflargeherbivoresinthe 800 structuringandfunctioningoffreshwaterandmarineangiospermecosystems.ecography39, Y Bakker,E.S.,Sarneel,J.M.,Gulati,R.D.,Liu,Z.W.,vanDonk,E.,2013.Restoringmacrophytediversity 803 inshallowtemperatelakes:bioticversusabioticconstraints.hydrobiologia710,23y Bakker,E.S.,VanDonk,E.,Declerck,S.A.J.,Helmsing,N.R.,Hidding,B.,Nolet,B.A.,2010.Effectof 805 macrophytecommunitycompositionandnutrientenrichmentonplantbiomassandalgal 806 blooms.basicappl.ecol.11,432y Barends,F.,2002.TheMuskrat(Ondatra*zibethicus):expansionandcontrolintheNetherlands.Lutra ,97Y Bauer,S.,Hoye,B.J.,2014.Migratoryanimalscouplebiodiversityandecosystemfunctioning 810 Worldwide.Science344,54Y Bazely,D.R.,Jefferies,R.L.,1985.GoosefecesYasourceofnitrogenforplantYgrowthinagrazedsaltY 812 marsh.j.appl.ecol.22,693y Behrens,M.D.,Lafferty,K.D.,2007.Temperatureanddieteffectsonomnivorousfishperformance: 814 implicationsforthelatitudinaldiversitygradientinherbivorousfishes.can.j.fish.aquat.sci ,867Y Behrens,M.D.,Lafferty,K.D.,2012.GeographicVariationinthedietofOpaleye(Girella*nigricans) 817 withrespecttotemperatureandhabitat.plosone7,e Bellrose,F.C.,1976.Thecomebackofthewoodduck.WildlifeSoc.B.4,107Y Bennett,S.,Bellwood,D.R.,2011.Latitudinalvariationinmacroalgalconsumptionbyfishesonthe 820 GreatBarrierReef.Mar.Ecol.YProg.Ser.426,241YU Blindow,I.,Hargeby,A.,Meyercordt,J.,Schubert,H.,2006.Primaryproductionintwoshallowlakes 822 withcontrastingplantformdominance:aparadoxofenrichment?limnol.oceanogr.51, Y

36 35 Bodelier,P.L.E.,Stomp,M.,Santamaria,L.,Klaassen,M.,Laanbroek,H.J.,2006.AnimalYplantYmicrobe 825 interactions:directandindirecteffectsofswanforagingbehaviourmodulatemethane 826 cyclingintemperateshallowwetlands.oecologia149,233y Boersma,M.,Mathew,K.A.,Niehoff,B.,Schoo,K.L.,FrancoYSantos,R.M.,Meunier,C.L., Temperaturedrivenchangesinthedietpreferenceofomnivorouscopepods:nomoremeat 829 whenit'shot?ecol.lett.19,45y Borer,E.T.,Seabloom,E.W.,Shurin,J.B.,Anderson,K.E.,Blanchette,C.A.,Broitman,B.,Cooper,S.D., 831 Halpern,B.S.,2005.Whatdeterminesthestrengthofatrophiccascade?Ecology86,528Y Bortolus,A.,Iribarne,O.O.,Martinez,M.M.,1998.Relationshipbetweenwaterfowlandtheseagrass 833 Ruppia*maritimainasouthwesternAtlanticcoastallagoon.Estuaries21,710Y Bownes,A.,2014.SuitabilityofaleafYminingfly,Hydrelliasp.,forbiologicalcontroloftheinvasive 835 aquaticweed,hydrilla*verticillatainsouthafrica.biocontrol59,771y Bownes,A.,Hill,M.P.,Byrne,M.J.,2010.Evaluatingtheimpactofherbivorybyagrasshopper, 837 Cornops*aquaticum(Orthoptera:Acrididae),onthecompetitiveperformanceandbiomass 838 accumulationofwaterhyacinth,eichhornia*crassipes(pontederiaceae).biol.control53,297y Brandt,E.C.,Petersen,J.E.,Grossman,J.J.,Allen,G.A.,Benzing,D.H.,2015.Relationshipsbetween 841 spatialmetricsandplantdiversityinconstructedfreshwaterwetlands.plosone10, 842 e Bremner,A.,Park,K.,2007.PublicattitudestothemanagementofinvasivenonYnativespeciesin 844 Scotland.Biol.Conserv.139,306Y Brochet,A.L.,GauthierYClerc,M.,Guillemain,M.,Fritz,H.,Waterkeyn,A.,Baltanas,A.,Green,A.J., a.Fieldevidenceofdispersalofbranchiopods,ostracodsandbryozoansbyteal(Anas* 847 crecca)inthecamargue(southernfrance).hydrobiologia637,255y

37 36 Brochet,A.L.,Guillemain,M.,Fritz,H.,GauthierYClerc,M.,Green,A.J.,2009.Theroleofmigratory 849 ducksinthelongydistancedispersalofnativeplantsandthespreadofexoticplantsin 850 Europe.Ecography32,919Y Brochet,A.L.,Guillemain,M.,Fritz,H.,GauthierYClerc,M.,Green,A.J.,2010b.Plantdispersalbyteal 852 (Anas*crecca)intheCamargue:duckgutsaremoreimportantthantheirfeet.Freshw.Biol ,1262Y Brothers,S.M.,Hilt,S.,Meyer,S.,Kohler,J.,2013.Plantcommunitystructuredeterminesprimary 855 productivityinshallow,eutrophiclakes.freshw.biol.58,2264y Bump,J.K.,Tischler,K.B.,Schrank,A.J.,Peterson,R.O.,Vucetich,J.A.,2009.Largeherbivoresand 857 aquaticyterrestriallinksinsouthernborealforests.j.anim.ecol.78,338y Burkepile,D.E.,2013.Comparingaquaticandterrestrialgrazingecosystems:isthegrassreally 859 greener?oikos122,306y Carlsson,N.O.L.,Brönmark,C.,Hansson,L.A.,2004.Invadingherbivory:Thegoldenapplesnailalters 861 ecosystemfunctioninginasianwetlands.ecology85,1575y Carpenter,S.R.,Lodge,D.M.,1986.Effectsofsubmersedmacrophytesonecosystemprocesses. 863 Aquat.Bot.26,341Y Carr,A.,Meylan,A.B.,1980.EvidenceofpassivemigrationofgreenturtlehatchlingsinSargassium. 865 Copeia,366Y Cebrian,J.,Duarte,C.M.,1998.Patternsinleafherbivoryonseagrasses.Aquat.Bot.60,67Y Cebrian,J.,Lartigue,J.,2004.Patternsofherbivoryanddecompositioninaquaticandterrestrial 868 ecosystems.ecol.monogr.74,237y Cebrian,J.,Shurin,J.B.,Borer,E.T.,Cardinale,B.J.,Ngai,J.T.,Smith,M.D.,Fagan,W.F., Producernutritionalqualitycontrolsecosystemtrophicstructure.PLoSOne4,e Chaichana,R.,Leah,R.,Moss,B.,2010.Birdsaseutrophicatingagents:anutrientbudgetforasmall 872 lakeinaprotectedarea.hydrobiologia646,111y

38 37 Chaloupka,M.,Bjorndal,K.A.,Balazs,G.H.,Bolten,A.B.,Ehrhart,L.M.,Limpus,C.J.,Suganuma,H., 874 Troeeng,S.,Yamaguchi,M.,2008.Encouragingoutlookforrecoveryofaonceseverely 875 exploitedmarinemegaherbivore.globalecol.biogeogr.17,297y Charalambidou,I.,Ketelaars,H.A.M.,Santamaria,L.,2003.Endozoochorybyducks:influenceof 877 developmentalstageofbythotrephesdiapauseeggsondispersalprobability.divers.distrib ,367Y Charalambidou,I.,Santamaria,L.,2002.Waterbirdsasendozoochorousdispersersofaquatic 880 organisms:areviewofexperimentalevidence.actaoecol.23,165y Charalambidou,I.,Santamaria,L.,2005.Fieldevidenceforthepotentialofwaterbirdsasdispersers 882 ofaquaticorganisms.wetlands25,252y Cherry,J.A.,Gough,L.,2009.TradeYoffsinplantresponsestoherbivoryinfluencetrophicroutesof 884 productioninafreshwaterwetland.oecologia161,549y Christianen,M.J.A.,Govers,L.L.,Bouma,T.J.,Kiswara,W.,Roelofs,J.G.M.,Lamers,L.P.M.,van 886 Katwijk,M.M.,2012.Marinemegaherbivoregrazingmayincreaseseagrasstolerancetohigh 887 nutrientloads.j.ecol.100,546y Christianen,M.J.A.,Herman,P.M.J.,Bouma,T.J.,Lamers,L.P.M.,vanKatwijk,M.M.,vanderHeide, 889 T.,Mumby,P.J.,Silliman,B.R.,Engelhard,S.L.,deKerk,M.V.,Kiswara,W.,vandeKoppel,J., Habitatcollapseduetoovergrazingthreatensturtleconservationinmarineprotected 891 areas.p.r.soc.bybiol.sci.281, Christianen,M.J.A.,vanBelzen,J.,Herman,P.M.J.,vanKatwijk,M.M.,Lamers,L.P.M.,vanLeent, 893 P.J.M.,Bouma,T.J.,2013.LowYcanopyseagrassbedsstillprovideimportantcoastal 894 protectionservices.plosone8,e Clayton,J.S.,1996.AquaticweedsandtheircontrolinNewZealandlakes.LakeReserv.Manage.12, Y Clements,K.D.,Raubenheimer,D.,Choat,J.H.,2009.Nutritionalecologyofmarineherbivorous 898 fishes:tenyearson.funct.ecol.23,79y

39 38 Cloern,J.E.,Canuel,E.A.,Harris,D.,2002.Stablecarbonandnitrogenisotopecompositionofaquatic 900 andterrestrialplantsofthesanfranciscobayestuarinesystem.limnol.oceanogr.47,713y Coetzee,J.A.,Byrne,M.J.,Hill,M.P.,2007.ImpactofnutrientsandherbivorybyEccritotarsus* 903 catarinensisonthebiologicalcontrolofwaterhyacinth,eichhornia*crassipes.aquat.bot.86, Y Cohen,A.N.,Carlton,J.T.,1998.Acceleratinginvasionrateinahighlyinvadedestuary.Science279, Y Collen,P.,Gibson,R.J.,2001.Thegeneralecologyofbeavers(Castorspp.),asrelatedtotheir 908 influenceonstreamecosystemsandriparianhabitats,andthesubsequenteffectsonfishya 909 review.rev.fishbiol.fisher.10,439y Coluccy,J.M.,Drobney,R.D.,Graber,D.A.,Sheriff,S.L.,Witter,D.J.,2001.Attitudesofcentral 911 MissouriresidentstowardlocalgiantCanadageeseandmanagementalternatives.Wildlife 912 Soc.Bull.29,116Y Creed,R.P.,Sheldon,S.P.,1993.TheeffectoffeedingbyaNorthAmericanweevil,Euhrychiopsis* 914 lecontei,oneurasianwatermilfoil(myriophyllum*spicatum).aquat.bot.45,245y Cronin,G.,Lodge,D.M.,Hay,M.E.,Miller,M.,Hill,A.M.,Horvath,T.,Bolser,R.C.,Lindquist,N.,Wahl, 916 M.,2002.Crayfishfeedingpreferencesforfreshwatermacrophytes:Theinfluenceofplant 917 structureandchemistry.j.crust.biol.22,708y Cuda,J.P.,Charudattan,R.,Grodowitz,M.J.,Newman,R.M.,Shearer,J.F.,Tamayo,M.L.,Villegas,B., Recentadvancesinbiologicalcontrolofsubmersedaquaticweeds.J.Aquat.Plant 920 Manage.46,15Y Cyr,H.,Pace,M.L.,1993.Magnitudeandpatternsofherbivoryinaquaticandterrestrialecosystems. 922 Nature361,148Y Danell,K.,1979.ReductionofaquaticvegetationfollowingthecolonizationofaNorthernSwedish 924 Lakebythemuskrat,Ondatra*zibethica.Oecologia38,101Y

40 39 Darnell,K.M.,Dunton,K.H.,2015.Consumptionofturtlegrassseedsandseedlingsbycrabsinthe 926 westerngulfofmexico.mar.ecol.yprog.ser.520,153y DeKluijver,A.,Ning,J.,Liu,Z.,Jeppesen,E.,Gulati,R.D.,Middelburg,J.J.,2015.Macrophytesand 928 periphytoncarbonsubsidiestobacterioplanktonandzooplanktoninashalloweutrophiclake 929 intropicalchina.limnol.oceanogr.60,375y Dingemans,B.J.J.,Bakker,E.S.,Bodelier,P.L.E.,2011.Aquaticherbivoresfacilitatetheemissionof 931 methanefromwetlands.ecology92,1166y Domning,D.P.,1982.CommercialexploitationofmanateesTrichechusinBrazilcirca Biol. 933 Conserv.22,101Y Donlan,C.J.,Berger,J.,Bock,C.E.,Bock,J.H.,Burney,D.A.,Estes,J.A.,Foreman,D.,Martin,P.S., 935 Roemer,G.W.,Smith,F.A.,Soule,M.E.,Greene,H.W.,2006.Pleistocenerewilding:An 936 optimisticagendafortwentyyfirstcenturyconservation.am.nat.168,660y Dorenbosch,M.,Bakker,E.S.,2012.Effectsofcontrastingomnivorousfishonsubmerged 938 macrophytebiomassintemperatelakes:amesocosmexperiment.freshw.biol.57,1360y DosSantos,V.M.,Matheson,F.E.,Pilditch,C.A.,Elger,A.,2012.Isblackswangrazingathreatto 941 seagrass?indicationsfromanobservationalstudyinnewzealand.aquat.bot.100,41y Doughty,C.E.,Roman,J.,Faurby,S.,Wolf,A.,Haque,A.,Bakker,E.S.,Malhi,Y.,DunningJr.,J.B., 943 Svenning,J.C.,2016.Globalnutrienttransportinaworldofgiants.P.Natl.Acad.SciUSA113, Y Downing,J.A.,Prairie,Y.T.,Cole,J.J.,Duarte,C.M.,Tranvik,L.J.,Striegl,R.G.,McDowell,W.H., 946 Kortelainen,P.,Caraco,N.F.,Melack,J.M.,Middelburg,J.J.,2006.Theglobalabundanceand 947 sizedistributionoflakes,ponds,andimpoundments.limnol.oceanogr.51,2388y Duarte,C.M.,1990.Seagrassnutrientcontent.Mar.Ecol.YProg.Ser.67,201Y Duarte,C.M.,Cebrian,J.,1996.Thefateofmarineautotrophicproduction.Limnol.Oceanogr.41, Y

41 40 Duffy,J.E.,Richardson,J.P.,Canuel,E.A.,2003.Grazerdiversityeffectsonecosystemfunctioningin 952 seagrassbeds.ecol.lett.6,637y Eigemann,F.,Mischke,U.,Hupfer,M.,Hilt,S.,2016.Biologicalindicatorstrackdifferentialresponse 954 ofpelagicandlittoralareastonutrinetloadreductioningermanlakes.ecol.indic.61,905y Elser,J.J.,Fagan,W.F.,Denno,R.F.,Dobberfuhl,D.R.,Folarin,A.,Huberty,A.,Interlandi,S.,Kilham, 957 S.S.,McCauley,E.,Schulz,K.L.,Siemann,E.H.,Sterner,R.W.,2000.Nutritionalconstraintsin 958 terrestrialandfreshwaterfoodwebs.nature408,578y Estes,J.A.,Terborgh,J.,Brashares,J.S.,Power,M.E.,Berger,J.,Bond,W.J.,Carpenter,S.R.,Essington, 960 T.E.,Holt,R.D.,Jackson,J.B.C.,Marquis,R.J.,Oksanen,L.,Oksanen,T.,Paine,R.T.,Pikitch, 961 E.K.,Ripple,W.J.,Sandin,S.A.,Scheffer,M.,Schoener,T.W.,Shurin,J.B.,Sinclair,A.R.E., 962 Soule,M.E.,Virtanen,R.,Wardle,D.A.,2011.Trophicdowngradingofplanetearth.Science ,301Y Figuerola,J.,Charalambidou,I.,Santamaria,L.,Green,A.J.,2010.Internaldispersalofseedsby 965 waterfowl:effectofseedsizeongutpassagetimeandgerminationpatterns. 966 Naturwissenschaften97,555Y Figuerola,J.,Green,A.J.,2002a.Dispersalofaquaticorganismsbywaterbirds:areviewofpast 968 researchandprioritiesforfuturestudies.freshw.biol.47,483y Figuerola,J.,Green,A.J.,2002b.Howfrequentisexternaltransportofseedsandinvertebrateeggsby 970 waterbirds?astudyindonana,swspain.arch.hydrobiol.155,557y Figuerola,J.,Green,A.J.,2005.Effectsofpremigratoryfastingonthepotentialforlongdistance 972 dispersalofseedsbywaterfowl:anexperimentwithmarbledteal.revuedecologieylaterre 973 EtLaVie60,283Y Figuerola,J.,Green,A.J.,Santamaria,L.,2002.Comparativedispersaleffectivenessofwigeongrass 975 seedsbywaterfowlwinteringinsouthywestspain:quantitativeandqualitativeaspects.j. 976 Ecol.90,989Y

42 41 Figuerola,J.,Green,A.J.,Santamaria,L.,2003.Passiveinternaltransportofaquaticorganismsby 978 waterfowlindonana,southywestspain.glob.ecol.biogeogr.12,427y Findlay,S.,Carlough,L.,Crocker,M.T.,Gill,H.K.,Meyer,J.L.,Smith,P.J.,1986.Bacterialgrowthon 980 macrophyteleachateandfateofbacterialproduction.limnol.oceanogr.31,1335y Fourqurean,J.W.,Jones,R.D.,Zieman,J.C.,1993.Processesinfluencingwatercolumnnutrient 982 characteristicsandphosphoruslimitationofphytoplanktonbiomassinfloridabayfl,usay 983 inferencesformspatialdistributions.estuar.coast.shelfs.36,295y Fourqurean,J.W.,Manuel,S.,Coates,K.A.,Kenworthy,W.J.,Smith,S.R.,2010.Effectsofexcluding 985 seaturtleherbivoresfromaseagrassbed:overgrazingmayhaveledtolossofseagrass 986 meadowsinbermuda.mar.ecol.yprog.ser.419,223y Fox,A.D.,Ebbinge,B.S.,Mitchell,C.,Heinicke,T.,Aarvark,T.,Colhoun,K.,Clausen,P.,Dereliev,S., 988 Farago,S.,Koffijberg,K.,Kruckenberg,H.,Loonen,M.J.J.E.,Madsen,J.,Mooij,J.,Musil,P., 989 Nilsson,L.,Pihl,S.,vanderJeugd,H.,2010.Currentestimatesofgoosepopulationsizesin 990 westerneurope,agapanalysisandanassessmentoftrends.ornissvecica20,115y France,R.L.,1996.Stableisotopicsurveyoftheroleofmacrophytesinthecarbonflowofaquatic 992 foodwebs.vegetatio124,67y Franceschini,M.C.,deNeiff,A.P.,Galassi,M.E.,2010.Isthebiomassofwaterhyacinthlostthrough 994 herbivoryinnativeareasimportant?aquat.bot.92,250y Frank,D.A.,Groffman,P.M.,Evans,R.D.,Tracy,B.F.,2000.Ungulatestimulationofnitrogencycling 996 andretentioninyellowstoneparkgrasslands.oecologia123,116y Frisch,D.,Green,A.J.,Figuerola,J.,2007.Highdispersalcapacityofabroadspectrumofaquatic 998 invertebratesviawaterbirds.aquat.sci.69,568y Gherardi,F.,Acquistapace,P.,2007.InvasivecrayfishinEurope:theimpactofProcambarusclarkiion 1000 thelittoralcommunityofamediterraneanlake.freshw.biol.52,1249y Gosling,L.M.,Baker,S.J.,1989.TheeradicationofmuskratsandcoypusfromBritain.Biol.J.Linn.Soc ,39Y

43 42 Green,A.J.,Figuerola,J.,2005.RecentadvancesinthestudyoflongYdistancedispersalofaquatic 1004 invertebratesviabirds.divers.distrib.11,149y Grey,J.,Jackson,M.C.,2012.'Leavesandeatsshoots':directterrestrialfeedingcansupplement 1006 invasiveredswampcrayfishintimesofneed.plosone7,e Gross,E.M.,Bakker,E.S.,2012.TheroleofplantsecondarymetabolitesinfreshwatermacrophyteY 1008 herbivoreinteractions:limitedorunexploredchemicaldefences?.in:iason,g.r.,dicke,m., 1009 Hartley,S.E.(Eds.),TheEcologyofPlantSecondaryMetabolites:FromGenestoGlobal 1010 Processes.CambridgeUniversityPress,BritishEcologicalSociety,pp.154Y Gross,E.M.,Johnson,R.L.,Hairston,N.G.,2001.Experimentalevidenceforchangesinsubmersed 1012 macrophytespeciescompositioncausedbytheherbivoreacentria*ephemerella* 1013 (Lepidoptera).Oecologia127,105Y Gruner,D.S.,Smith,J.E.,Seabloom,E.W.,Sandin,S.A.,Ngai,J.T.,Hillebrand,H.,Harpole,W.S.,Elser, 1015 J.J.,Cleland,E.E.,Bracken,M.E.S.,Borer,E.T.,Bolker,B.M.,2008.AcrossYsystemsynthesisof 1016 consumerandnutrientresourcecontrolonproducerbiomass.ecol.lett.11,740y Gyimesi,A.,deVries,P.P.,deBoer,T.,Nolet,B.A.,2011.Reducedtuberbanksoffennelpondweed 1018 duetosummergrazingbywaterfowl.aquat.bot.94,24y Gyimesi,A.,vanLith,B.,Nolet,B.A.,2012.CommensalforagingwithBewick sswanscygnus*bewickii 1020 doublesinstantaneousintakerateofcommonpochardsaythya*ferina.ardea100,55y Hacker,S.D.,Bertness,M.D.,1995.AherbivoreparadoxYwhysaltYmarshaphidsliveonpoorYquality 1022 plants.am.nat.145,192y Hahn,S.,Bauer,S.,Klaassen,M.,2008.Quantificationofallochthonousnutrientinputinto 1024 freshwaterbodiesbyherbivorouswaterbirds.freshw.biol.53,181y Halley,D.,Rosell,F.,Saveljev,A.,2012.PopulationanddistributionofEurasianBeaver(Castor*fiber) Balt.For.18,168Y Halley,D.J.,Rosell,F.,2002.Thebeaver'sreconquestofEurasia:status,populationdevelopmentand 1028 managementofaconservationsuccess.mammalrev.32,153y

44 43 Hangelbroek,H.H.,Ouborg,N.J.,Santamaria,L.,Schwenk,K.,2002.Clonaldiversityandstructure 1030 withinapopulationofthepondweedpotamogetonpectinatusforagedbybewick'sswans Mol.Ecol.11,2137Y Hanlon,S.G.,Hoyer,M.V.,Cichra,C.E.,Canfield,D.E.,2000.Evaluationofmacrophytecontrolin Floridalakesusingtriploidgrasscarp.J.Aquat.PlantManage.38,48Y Hanson,K.C.,Cooke,S.J.,Suski,C.D.,Niezgoda,G.,Phelan,F.J.S.,Tinline,R.,Philipp,D.P., Assessmentoflargemouthbass(Micropterus*salmoides)behaviourandactivityatmultiple 1036 spatialandtemporalscalesutilizingawholeylaketelemetryarray.hydrobiologia582,243y Hauxwell,J.,Osenberg,C.W.,Frazer,T.K.,2004.Conflictingmanagementgoals:Manateesand 1039 invasivecompetitorsinhibitrestorationofanativemacrophyte.ecol.appl.14,571y Havel,J.E.,Bruckerhoff,L.A.,Funkhouser,M.A.,Gemberling,A.R.,2014.Resistancetodesiccationin 1041 aquaticinvasivesnailsandimplicationsfortheiroverlanddispersal.hydrobiologia741,89y Hay,M.E.,1991.MarineterrestrialcontrastsintheecologyofplantYchemicaldefensesagainst 1044 herbivores.trendsecol.evol.6,362y Hay,M.E.,1996.Marinechemicalecology:What'sknownandwhat'snext?J.Exp.Mar.Biol.Ecol ,103Y Heithaus,M.R.,Alcoverro,T.,Arthur,R.,Burkholder,D.A.,Coates,K.A.,Christianen,M.J.,Kelkar,N., 1048 Manuel,S.A.,Wirsing,A.J.,Kenworthy,W.J.,FourqureanJ.W.,2014.Seagrassesintheageof 1049 seaturtleconservationandsharkoverfishing.frontiersinmarinescience1, Heithaus,M.R.,Frid,A.,Wirsing,A.J.,Dill,L.M.,Fourqurean,J.W.,Burkholder,D.,Thomson,J., 1051 Bejder,L.,2007.StateYdependentriskYtakingbygreenseaturtlesmediatestopYdowneffects 1052 oftigersharkintimidationinamarineecosystem.j.anim.ecol.76,837y Hempson,G.P.,Archibald,S.,Bond,W.J.,2015.AcontinentYwideassessmentoftheformand 1054 intensityoflargemammalherbivoryinafrica.science350,1056y

45 44 Hendriks,I.E.,Bouma,T.J.,Morris,E.P.,Duarte,C.M.,2010.Effectsofseagrassesandalgaeofthe 1056 CaulerpafamilyonhydrodynamicsandparticleYtrappingrates.Mar.Biol.157,473Y Hernandez,A.L.M.,vanTussenbroek,B.I.,2014.Patchdynamicsandspeciesshiftsinseagrass 1058 communitiesundermoderateandhighgrazingpressurebygreenseaturtles.mar.ecol.y 1059 Prog.Ser.517,143Y Hernandez,M.C.,Sacco,J.,Walsh,G.C.,2011.BiologyandhostpreferenceoftheplanthopperTaosa* 1061 longula(hemiptera:dictyopharidae),acandidateforbiocontrolofwaterhyacinth.biocontrol 1062 Sci.Techn.21,1079Y Hidding,B.,Bakker,E.S.,Hootsmans,M.J.M.,Hilt,S.,2016.Synergybetweenshadingandherbivory 1064 triggersmacrophytelossandregimeshiftsinaquaticsystems.oikos,doi: /oik Hidding,B.,Bakker,E.S.,Keuper,F.,deBoer,T.,deVries,P.P.,Nolet,B.A.,2010.Differencesin 1067 toleranceofpondweedsandcharophytestovertebrateherbivoresinashallowbaltic 1068 estuary.aquat.bot.93:123y Hidding,B.,Meirmans,P.G.,Klaassen,M.,deBoer,T.,Ouborg,N.J.,Wagemaker,C.A.M.,Nolet,B.A., Theeffectofherbivoresongenotypicdiversityinaclonalaquaticplant.Oikos123, Y Hidding,B.,Nolet,B.A.,deBoer,T.,deVries,P.P.,Klaassen,M.,2010.AboveYandbelowYground 1073 vertebrateherbivorymayeachfavouradifferentsubordinatespeciesinanaquaticplant 1074 community.oecologia162,199y Hik,D.S.,Sadul,H.A.,Jefferies,R.L.,1991.Effectsofthetimingofmultiplegrazingsbygeeseonnet 1076 abovegroundprimaryproductionofswardsofpuccinellia*phryganodes.j.ecol.79,715y Hilt,S.,2006.RecoveryofPotamogeton*pectinatusL.standsinashalloweutrophiclakeunder 1078 extremegrazingpressure.hydrobiologia570,95y Hilt,S.,2015.RegimeshiftsbetweenmacrophytesandphytoplanktonYconceptsbeyondshallow 1080 lakes,unravellingstabilizingmechanismsandpracticalconsequences.limnetica34,467y

46 45 Hilt,S.,Henschke,I.,Rucker,J.,Nixdorf,B.,2010.Cansubmergedmacrophytesinfluenceturbidity 1082 andtrophicstateindeeplakes?suggestionsfromacasestudy.j.environ.qual.39,725y Hilt,S.,Kohler,J.,Adrian,R.,Monaghan,M.T.,Sayer,C.D.,2013.Clear,crashing,turbidandbackY 1084 longytermchangesinmacrophyteassemblagesinashallowlake.freshw.biol.58,2027y Hilt,S.,Kohler,J.,Kozerski,H.P.,vanNes,E.H.,Scheffer,M.,2011.Abruptregimeshiftsinspaceand 1086 timealongriversandconnectedlakesystems.oikos120,766y Hootsmans,M.J.M.,1999.ModellingPotamogeton*pectinatus:forbetterorforworse.Hydrobiologia ,7Y Jackson,J.B.C.,1997.ReefssinceColumbus.CoralReefs16,S23YS Jackson,M.C.,Grey,J.,2013.AcceleratingratesoffreshwaterinvasionsinthecatchmentoftheRiver 1091 Thames.Biol.Invas.15,945Y Jacobs,R.P.W.M.,DenHartog,C.,Braster,B.F.,Carriere,F.C.1981.GrazingoftheseagrassZostera* 1093 noltiibybirdsatterschelling(dutchwaddensea).aquat.bot.10,241y Jäger,P.,Pall,K.,Dumfahrt,E.,2004.Amethodofmappingmacrophytesinlargelakeswithregardto 1095 therequirementsofthewaterframeworkdirective.limnologica34,140y Janzen,D.H.,1984.Dispersalofsmallseedsbybigherbivores:foliageisthefruit.Am.Nat.123,338Y Jefferies,R.L.,Rockwell,R.F.,Abraham,K.F.,2003.Theembarrassmentofriches:agriculturalfood 1099 subsidies,highgoosenumbers,andlossofarcticwetlandsyacontinuingsaga.environ.rev ,193Y Jeppesen,E.,Søndergaard,M.,Jensen,J.P.,Havens,K.E.,Anneville,O.,Carvalho,L.,Coveney,M.F., 1102 Deneke,R.,Dokulil,M.T.,Foy,B.,Gerdeaux,D.,Hampton,S.E.,Hilt,S.,Kangur,K.,Kohler,J., 1103 Lammens,E.,Lauridsen,T.L.,Manca,M.,Miracle,M.R.,Moss,B.,Noges,P.,Persson,G., 1104 Phillips,G.,Portielje,R.,Schelske,C.L.,Straile,D.,Tatrai,I.,Willen,E.,Winder,M.,2005.Lake 1105 responsestoreducednutrientloadingyananalysisofcontemporarylongytermdatafrom casestudies.freshw.biol.50,1747y

47 46 Jeppesen,E.,Søndergaard,M.,Søndergaard,M.,Christoffersen,K.,1998,Thestructuringroleof 1108 submergedmacrophytesinlakes.springer Jessen,R.L.,1970.MallardpopulationtrendsandhuntinglossesinMinnesota.J.WildlifeManage.34, Y Jonzén,N.,Nolet,B.A.,Santamaría,L.,Svensson,M.G.E.,2002.Seasonalherbivoryandmortality 1112 compensationinaswanypondweedsystem.ecol.model.147,209y Jupp,B.J.,Spence,D.H.N.,1977.Limitationsofmacrophytesinaeutrophiclake,LochLeven:II.Wave 1114 action,sedimentsandwaterfowlgrazing.j.ecol.65,431y Kelkar,N.,Arthur,R.,Marba,N.,Alcoverro,T.,2013a.Greenturtleherbivorydominatesthefateof 1116 seagrassprimaryproductioninthelakshadweepislands(indianocean).mar.ecol.yprog.ser ,235Y Kelkar,N.,Arthur,R.,Marba,N.,Alcoverro,T.,2013b.Greenerpastures?HighYdensityfeeding 1119 aggregationsofgreenturtlesprecipitatespeciesshiftsinseagrassmeadows.j.ecol.101, Y Kerbes,R.H.,Kotanen,P.M.,Jefferies,R.L.,1990.DestructionofwetlandhabitatsbyLesserSnow 1122 GeeseYAkeystonespeciesonthewestYcoastofHudsonYBay.J.Appl.Ecol.27,242Y King,R.A.,Gornall,R.J.,Preston,C.D.,Croft,J.M.,2002.PopulationdifferentiationofPotamogeton* 1124 pectinatusinthebalticseawithreferencetowaterfowldispersal.mol.ecol.11,1947y Kirsch,K.D.,Valentine,J.F.,Heck,K.L.,2002.ParrotfishgrazingonturtlegrassThalassia*testudinum: 1126 evidencefortheimportanceofseagrassconsumptioninfoodwebdynamicsoftheflorida 1127 KeysNationalMarineSanctuary.Mar.Ecol.YProg.Ser.227,71Y Kitchener,A.C.,Conroy,J.W.H.,1997.ThehistoryoftheEurasianbeaverCastor*fiberinScotland Mamm.Rev.27,95Y Klaassen,R.H.G.,Nolet,B.A.,Bankert,D.,2006.MovementofforagingTundraSwansexplainedby 1131 spatialpatternincrypticfooddensities.ecology87,2244y

48 47 Kleyheeg,E.,2015,Seeddispersalbyageneralistduck:ingestion,digestionandtransportationby 1133 mallards(anas*platyrhynchos).universityofutrecht Körner,S.,Dugdale,T.,2003.IsroachherbivorypreventingreYcolonizationofsubmerged 1135 macrophytesinashallowlake?hydrobiologia506,497y Körner,S.,Schreiber,E.S.G.,Walz,N.,2002.HerbivoryonsubmergedmacrophytesYwho'stoblame? 1137 Verh.Internat.Ver.Limnol.28,967Y Kuijper,D.P.J.,deKleine,C.,Churski,M.,vanHooft,P.,Bubnicki,J.,Jedrzejewska,B.,2013.Landscape 1139 offearineurope:wolvesaffectspatialpatternsofungulatebrowsinginbialowiezaprimeval 1140 Forest,Poland.Ecography36,1263Y Lal,A.,Arthur,R.,Marba,N.,Lill,A.W.T.,Alcoverro,T.,2010.Implicationsofconservinganecosystem 1142 modifier:increasinggreenturtle(chelonia*mydas)densitiessubstantiallyaltersseagrass 1143 meadows.biol.conserv.143,2730y Laubek,B.,1995.HabitatusebyWhooperSwansCygnus*cygnusandBewick'sSwansCygnus* 1145 columbianus*bewickiiwinteringindenmark:increasingagriculturalconflicts.wildfowl46,8y Lauridsen,T.L.,Jeppesen,E.,Andersen,F.O.,1993.Colonizationofsubmergedmacrophytesin 1148 shallowfishmanipulatedlakevæng:impactofsedimentcompositionandwaterfowlgrazing Aquat.Bot.46,1Y Letson,M.A.,Makarewicz,J.C.,1994.Anexperimentaltestofthecrayfish(Orconectesimmunis)asa 1151 controlmechanismforsubmersedaquaticmacrophytes.lakereserv.manage.10,127y Lodge,D.M.,1991.HerbivoryonfreshYwatermacrophytes.Aquat.Bot.41,195Y Lodge,D.M.,Cronin,G.,VanDonk,E.,Froelich,A.J.,1998,Impactofherbivoryonplantstandingcrop: 1154 comparisonsamongbiomes,betweenvascularandnonyvascularplants,andamong 1155 freshwaterherbivoretaxa.in:jeppesen,e.,søndergaard,m.,christoffersen,k.(eds.),the 1156 structuringroleofsubmergedmacrophytesinlakes.springeryverlag,newyork,pp.149y

49 48 Louette,G.,DeMeester,L.,2005.Highdispersalcapacityofcladoceranzooplanktoninnewly 1158 foundedcommunities.ecology86,353y Macreadie,P.I.,TrevathanYTackett,S.M.,Skilbeck,C.G.,Sanderman,J.,Curlevski,N.,Jacobsen,G., 1160 Seymour,J.R.,2015.Lossesandrecoveryoforganiccarbonfromaseagrassecosystem 1161 followingdisturbance.p.r.soc.bybiol.sci.282, Mader,E.,vanVierssen,W.,Schwenk,K.,1998.Clonaldiversityinthesubmergedmacrophyte 1163 PotamogetonpectinatusL.inferredfromnuclearandcytoplasmicvariation.Aquat.Bot.62, Y Madin,E.M.P.,Madin,J.S.,Booth,D.J.,2011.Landscapeoffearvisiblefromspace.ScientificReports , Mahdy,A.,Hilt,S.,Filiz,N.,Beklioglu,M.,Hejzlar,J.,Ozkundakci,D.,Papastergiadou,E., 1168 Scharfenberger,U.,Sorf,M.,Stefanidis,K.,Tuvikene,L.,Zingel,P.,Søndergaard,M., 1169 Jeppesen,E.,Adrian,R.,2015.Effectsofwatertemperatureonsummerperiphytonbiomass 1170 inshallowlakes:apanyeuropeanmesocosmexperiment.aquat.sci.77,499y Mao,Z.G.,Gu,X.H.,Zeng,Q.F.,Gu,X.K.,Li,X.G.,Wang,Y.P.,2014.Productionsourcesandfoodweb 1172 ofamacrophyteydominatedregioninlaketaihu,basedongutcontentsandstableisotope 1173 analyses.j.greatlakesres.40,656y Marklund,O.,Sandsten,H.,Hansson,L.A.,Blindow,I.,2002.Effectsofwaterfowlandfishon 1175 submergedvegetationandmacroinvertebrates.freshw.biol.47,2049y McCauley,D.J.,Pinsky,M.L.,Palumbi,S.R.,Estes,J.A.,Joyce,F.H.,Warner,R.R.,2015.Marine 1177 defaunation:animallossintheglobalocean.science347,247y McNaughton,1985.EcologyofaGrazingEcosystem:TheSerengeti.Ecol.Monogr.55,260Y Mendonca,R.,Kosten,S.,Lacerot,G.,Mazzeo,N.,Roland,F.,Ometto,J.P.,Paz,E.A.,Bove,C.P., 1180 Bueno,N.C.,Gomes,J.H.C.,Scheffer,M.,2013.Bimodalityinstableisotopecomposition 1181 facilitatesthetracingofcarbontransferfrommacrophytestohighertrophiclevels Hydrobiologia710,205Y

50 49 Miler,O.,Straile,D.,2010.Howtocopewithasuperiorenemy?Plantdefencestrategiesinresponse 1184 toannualherbivoreoutbreaks.j.ecol.98,900y Mitchell,S.F.,Wass,R.T.,1996a.Grazingbyblackswans(Cygnus*atratusLatham),physicalfactors, 1186 andthegrowthandlossofaquaticvegetationinashallowlake.aquat.bot.55,205y Mitchell,S.F.,Wass,R.T.,1996b.Quantifyingherbivory:Grazingconsumptionandinteraction 1188 strength.oikos76,573y Moles,A.T.,Bonser,S.P.,Poore,A.G.B.,Wallis,I.R.,Foley,W.J.,2011.Assessingtheevidencefor 1190 latitudinalgradientsinplantdefenceandherbivory.funct.ecol.25,380y Moran,K.L.,Bjorndal,K.A.,2005.Simulatedgreenturtlegrazingaffectsstructureandproductivityof 1192 seagrasspastures.mar.ecol.prog.ser.305,235y Morrison,W.E.,Hay,M.E.,2012.ArelowerYlatitudeplantsbetterdefended?Palatabilityof 1194 freshwatermacrophytes.ecology93,65y Moss,B.,2015.Mammals,freshwaterreferencestates,andthemitigationofclimatechange Freshw.Biol.60,1964Y Mueller,M.H.,vanderValk,A.G.,2002.Thepotentialroleofducksinwetlandseeddispersal Wetlands22,170Y Munoz,J.,Amat,F.,Green,A.J.,Figuerola,J.,Gomez,A.,2013.Birdmigratoryflywaysinfluencethe 1200 phylogeographyoftheinvasivebrineshrimpartemia*franciscanainitsnativeamerican 1201 range.peerj1,unspe Newman,R.M.,1991.HerbivoryanddetrivoryonfreshwatermacrophytesbyinvertebratesYa 1203 review.j.n.am.benth.soc.10,89y Newman,R.M.,2004.BiologicalcontrolofEurasianwatermilfoilbyaquaticinsects:basicinsights 1205 fromanappliedproblem.arch.hydrobiol.159,145y Nichols,T.C.,2014.TenyearsofresidentCanadaGoosedamagemanagementinaNewJerseytidal 1207 freshwaterwetland.wildlifesoc.bull.38,221y

51 50 Nolet,B.A.,2004.OvercompensationandgrazingoptimisationinaswanYpondweedsystem?Freshw Biol.49,1391Y Nolet,B.A.,Gyimesi,A.,Klaassen,R.H.G.,2006.PredictionofbirdYdaycarryingcapacityonastaging 1211 site:atestofdepletionmodels.j.anim.ecol.75,1285y Nolet,B.A.,Gyimesi,A.,vanKrimpen,R.R.D.,deBoer,W.F.,Stillman,R.A.,2016.Predictingeffectsof 1213 waterregimechangesonwaterbirds:insightsfromstagingswans.plosone11,e Nolet,B.A.,Langevoord,O.,Bevan,R.M.,Engelaar,K.R.,Klaassen,M.,Mulder,R.J.W.,VanDijk,S., Spatialvariationintuberdepletionbyswansexplainedbydifferencesinnetintake 1216 rates.ecology82,1655y Nolet,B.A.,Rosell,F.,1998.ComebackofthebeaverCastor*fiber:Anoverviewofoldandnew 1218 conservationproblems.biol.conserv.83,165y Nolte,S.,Esselink,P.,Bakker,J.P.,Smit,C.,2015.Effectsoflivestockspeciesandstockingdensityon 1220 accretionratesingrazedsaltmarshes.estuar.coast.shelfs.152,109y Nummi,P.,Holopainen,S.,2014.WholeYcommunityfacilitationbybeaver:ecosystemengineer 1222 increaseswaterbirddiversity.aquat.conserv.24,623y Olsen,Y.S.,Valiela,I.,2010.EffectofsedimentnutrientenrichmentandgrazingonTurtleGrass 1224 Thalassia*testudinuminJobosBay,PuertoRico.EstuariesCoasts33,769Y OwenYSmith,R.N.,1988,Megaherbivores:theinfluenceofverylargebodysizeonecology CambridgeUniversityPress,Cambridge Pages,J.F.,Farina,S.,Gera,A.,Arthur,R.,Romero,J.,Alcoverro,T.,2012.Indirectinteractionsin 1228 seagrasses:fishherbivoresincreasepredationrisktoseaurchinsbymodifyingplanttraits Funct.Ecol.26,1015Y Pages,J.F.,Gera,A.,Romero,J.,Alcoverro,T.,2014.Matrixcompositionandpatchedgesinfluence 1231 plantyherbivoreinteractionsinmarinelandscapes.funct.ecol.28,1440y Paice,R.L.,Chambers,J.M.,Robson,B.J.,2016.Outcomesofsubmergedmacrophyterestorationina 1233 shallowimpounded,eutrophicriver.hydrobiologiadoi /s10750y015y2441y

52 51 Panov,V.E.,Caceres,C.,2007.Roleofdiapauseindispersalofaquaticinvertebrates.Diapausein 1235 AquaticInvertebratesTheoryandHumanUse.Springer,Netherlands Perry,D.,Perry,G.,2008.Improvinginteractionsbetweenanimalrightsgroupsandconservation 1237 biologists.conserv.biol.22,27y Petruzzella,A.,Guariento,R.D.,Gripp,A.d.R.,Marinho,C.C.,FigueiredoYBarros,M.P.,Esteves,F.d.A., Herbivoredamageincreasesmethaneemissionfromemergentaquaticmacrophytes Aquat.Bot.127,6Y Polunin,N.V.C.,1984.Thedecompositionofemergentmacrophytesinfreshwater.AdvancesinEcol Res.14,115Y Poore,A.G.B.,Campbell,A.H.,Coleman,R.A.,Edgar,G.J.,Jormalainen,V.,Reynolds,P.L.,Sotka,E.E., 1244 Stachowicz,J.J.,Taylor,R.B.,Vanderklift,M.A.,Duffy,J.E.,2012.Globalpatternsintheimpact 1245 ofmarineherbivoresonbenthicprimaryproducers.ecol.lett.15,912y Prado,P.,Romero,J.,Alcoverro,T.,2010.Nutrientstatus,plantavailabilityandseasonalforcing 1247 mediatefishherbivoryintemperateseagrassbeds.mar.ecol.yprog.ser.409,229y Prado,P.,Tomas,F.,Alcoverro,T.,Romero,J.,2007.ExtensivedirectmeasurementsofPosidonia* 1249 oceanicadefoliationconfirmtheimportanceofherbivoryintemperateseagrassmeadows Mar.Ecol.YProg.Ser.340,63Y Preen,A.,1995.ImpactsofDugongforagingonseagrasshabitatsYobservationalandexperimental 1252 evidenceforcultivationgrazing.mar.ecol.yprog.ser.124,201y Prejs,A.,1984.Herbivorybytemperatefreshwaterfishesanditsconsequences.Environ.Biol.Fish ,281Y Ramo,C.,Amat,J.A.,Nilsson,L.,Schricke,V.,RodriguezYAlonso,M.,GomezYCrespo,E.,Jubete,F., 1256 Navedo,J.G.,Masero,J.A.,Palacios,J.,Boos,M.,Green,A.J.,2015.LatitudinalYrelated 1257 variationinwinteringpopulationtrendsofgreylaggeese(anser*anser)alongtheatlantic 1258 flyway:aresponsetoclimatechange?plosone10,e

53 52 Redpath,S.M.,Gutierrez,R.J.,Wood,K.A.,Young,J.C.,2015.Conflictsinconservation:navigating 1260 towardssolutions.cambridgeuniversitypress,cambridge,uk Reynolds,C.,Miranda,N.A.F.,Cumming,G.S.,2015.Theroleofwaterbirdsinthedispersalofaquatic 1262 alienandinvasivespecies.divers.distrib.21,744y RobledoYArnuncio,J.J.,Klein,E.K.,MullerYLandau,H.C.,Santamaría,L.,2014.Space,timeand 1264 complexityinplantdispersalecology.movementecol.2, Röckstrom,J.,Steffen,W.,Noone,K.,Persson,A.,Chapin,F.S.,Lambin,E.F.,Lenton,T.M.,Scheffer, 1266 M.,Folke,C.,Schellnhuber,H.J.,Nykvist,B.,deWit,C.A.,Hughes,T.,vanderLeeuw,S., 1267 Rodhe,H.,Sorlin,S.,Snyder,P.K.,Costanza,R.,Svedin,U.,Falkenmark,M.,Karlberg,L., 1268 Corell,R.W.,Fabry,V.J.,Hansen,J.,Walker,B.,Liverman,D.,Richardson,K.,Crutzen,P., 1269 Foley,J.A.,2009.Asafeoperatingspaceforhumanity.Nature461,472Y Rodriguez,C.F.,Becares,E.,FernandezYAlaez,M.,2003.ShiftfromcleartoturbidphaseinLake 1271 Chozas(NWSpain)duetotheintroductionofAmericanredswampcrayfish(Procambarus* 1272 clarkii).hydrobiologia506,421y Ross,E.,1971.BiologicalcontrolofpondweedswithChineseGeese.HawaiiFarmSci.20,11Y Rushing,W.N.,1973.WaterhyacinthresearchinPuertoRico.HyacinthContr.J.13,48Y Sachse,R.,Petzoldt,T.,Blumstock,M.,Moreira,S.,Patzig,M.,Rueker,J.,Janse,J.H.,Mooij,W.M., 1276 Hilt,S.,2014.ExtendingoneYdimensionalmodelsfordeeplakestosimulatetheimpactof 1277 submergedmacrophytesonwaterquality.environ.modell.softw.61,410y SandYJensen,K.,Jacobsen,D.,2002.Herbivoryandgrowthinterrestrialandaquaticpopulationsof 1279 amphibiousstreamplants.freshw.biol.47,1475y SandYJensen,K.,Jacobsen,D.,Duarte,C.M.,1994.Herbivoryandresultingplantdamage.Oikos69, Y Sandom,C.J.,Ejrnaes,R.,Hansen,M.D.D.,Svenning,J.C.,2014.Highherbivoredensityassociated 1283 withvegetationdiversityininterglacialecosystems.p.natl.acad.sci.usa111,4162y

54 53 Santamaria,L.,Charalambidou,I.,Figuerola,J.,Green,A.J.,2002.Effectofpassagethroughduckgut 1285 ongerminationoffennelpondweedseeds.arch.hydrobiol.156,11y Sarneel,J.M.,Huig,N.,Veen,G.F.,Rip,W.,Bakker,E.S.,2014.Herbivoresenforcesharpboundaries 1287 betweenterrestrialandaquaticecosystems.ecosystems17,1426y Scharnweber,K.,Syvaranta,J.,Hilt,S.,Brauns,M.,Vanni,M.J.,Brothers,S.,Kohler,J.,KnezevicYJaric, 1289 J.,Mehner,T.,2014.WholeYlakeexperimentsrevealthefateofterrestrialparticulateorganic 1290 carboninbenthicfoodwebsofshallowlakes.ecology95,1496y Scheffer,M.,Hosper,S.H.,Meijer,M.YL.,Moss,B.,Jeppesen,E.,1993.Alternativeequilibriain 1292 shallowlakes.trendsecol.evol.8,275y Schemske,D.W.,Mittelbach,G.G.,Cornell,H.V.,Sobel,J.M.,Roy,K.,2009.Istherealatitudinal 1294 gradientintheimportanceofbioticinteractions?annu.rev.ecol.evol.s.40,245y Schwartz,D.P.,Maughan,O.E.,Gebhart,G.E.,1986.EffectivenessofBlueTilapiaasaweedYcontrol 1296 agentinponds.progressivefishyculturist48,259y Shelford,V.E.,1918,Conditionsofexistence.In:Ward,H.B.,Whipple,G.C.(Eds.),FeshwaterBiology JohnWiley,NewYork,pp.21Y Sherfy,M.H.,Kirkpatrick,R.L.,2003.InvertebrateresponsetosnowgooseherbivoryonmoistYsoil 1300 vegetation.wetlands23,236y Silva,T.S.F.,Costa,M.P.F.,Melack,J.M.,Novo,E.M.L.M.,2008.Remotesensingofaquaticvegetation: 1302 theoryandapplications.environ.monit.assess.140,131y Skilleter,G.A.,Wegscheidl,C.,Lanyon,J.M.,2007.EffectsofgrazingbyamarinemegaYherbivoreon 1304 benthicassemblagesinasubtropicalseagrassbed.mar.ecol.prog.ser.351,287y Small,E.,2012.ThenewNoah'sArk:beautifulandusefulspeciesonly.Part2.Thechosenspecies Biodiversity13,37Y Smolders,A.J.P.,Vergeer,L.H.T.,vanderVelde,G.,Roelofs,J.G.M.,2000.Phenoliccontentsof 1308 submerged,emergentandfloatingleavesofaquaticandsemiyaquaticmacrophytespecies: 1309 whydotheydiffer?oikos91,307y

55 54 Solomon,C.T.,Carpenter,S.R.,Clayton,M.K.,Cole,J.J.,Coloso,J.J.,Pace,M.L.,VanderZanden,M.J., 1311 Weidel,B.C.,2011.Terrestrial,benthic,andpelagicresourceuseinlakes:resultsfroma 1312 threeyisotopebayesianmixingmodel.ecology92,1115y Søndergaard,M.,Bruun,L.,Lauridsen,T.,Jeppesen,E.,Madsen,T.V.,1996.Theimpactofgrazing 1314 waterfowlonsubmergedmacrophytes:insituexperimentsinashalloweutrophiclake Aquat.Bot.53,73Y Søndergaard,M.,Jeppesen,E.,Lauridsen,T.L.,Skov,C.,VanNes,E.H.,Roijackers,R.,Lammens,E., 1317 Portielje,R.,2007.Lakerestoration:successes,failuresandlongYtermeffects.J.Appl.Ecol ,1095Y Soons,M.B.,vanderVlugt,C.,vanLith,B.,Heil,G.W.,Klaassen,M.,2008.Smallseedsizeincreases 1320 thepotentialfordispersalofwetlandplantsbyducks.j.ecol.96,619y Soti,P.G.,Volin,J.C.,2010.Doeswaterhyacinth(Eichhornia*crassipes)compensateforsimulated 1322 defoliation?implicationsforeffectivebiocontrol.biol.control54,35y Stillman,R.A.,Wood,K.A.,Gilkerson,W.,Elkinton,E.,Black,J.M.,Ward,D.H.,Petrie,M., Predictingeffectsofenvironmentalchangeonamigratoryherbivore.Ecosphere6,art Stott,B.,Robson,T.O.,1970.Efficiencyofgrasscarp(Ctenopharyngodon*idella*Val)incontrolling 1326 submergedwaterweeds.nature226,870y& Subalusky,A.L.,Dutton,C.L.,RosiYMarshall,E.J.,Post,D.M.,2015.Thehippopotamusconveyorbelt: 1328 vectorsofcarbonandnutrientsfromterrestrialgrasslandstoaquaticsystemsinsubysaharan 1329 Africa.Freshw.Biol.60,512Y Sumoski,S.E.,Orth,R.J.,2012.BioticdispersalineelgrassZostera*marina.Mar.Ecol.YProg.Ser.471, Y Tatu,K.S.,Anderson,J.T.,Hindman,L.J.,Seidel,G.,2007.Muteswans'impactonsubmergedaquatic 1333 vegetationinchesapeakebay.j.wildlifemanage.71,1431y Thayer,G.W.,Engel,D.W.,Bjorndal,K.A.,1982.EvidenceforshortYcircuitingofthedetrituscycleof 1335 seagrassbedsbythegreenturtle,chelonia*mydas.j.exp.mar.biol.ecol.62,173y

56 55 Tomas,F.,Turon,X.,Romero,J.,2005.SeasonalandsmallYscalespatialvariabilityofherbivory 1337 pressureonthetemperateseagrassposidonia*oceanica.mar.ecol.yprog.ser.301,95y Turcotte,M.M.,Davies,T.J.,Thomsen,C.J.M.,Johnson,M.T.J.,2014.Macroecologicaland 1339 macroevolutionarypatternsofleafherbivoryacrossvascularplants.p.r.soc.bybiol.sci.y 1340 BiologicalSciences281, Turvey,S.T.,Risley,C.L.,2006.ModellingtheextinctionofSteller'sseacow.Biol.Lett.2,94Y Vadeboncoeur,Y.,VanderZanden,M.J.,Lodge,D.M.,2002.Puttingthelakebacktogether: 1343 Reintegratingbenthicpathwaysintolakefoodwebmodels.Bioscience52,44Y Valentine,J.F.,Duffy,J.E.,2006,Thecentralroleofgrazinginseagrassecology.In:Larkum,A.W.D., 1345 Orth,R.J.,Duarte,C.M.(Eds.),Seagrasses:Biology,EcologyandConservation.Springer,pp Y Valentine,J.F.,Heck,K.L.,1991.TheroleofseaYurchingrazinginregulatingsubtropicalseagrass 1348 meadowsyevindencefromfieldmanipulationsinthenortherngulfofmexico.j.exp.mar Biol.Ecol.154,215Y Valentine,J.F.,Heck,K.L.,1999.Seagrassherbivory:evidenceforthecontinuedgrazingofmarine 1351 grasses.mar.ecol.yprog.ser.176,291y Valentine,J.F.,Heck,K.L.,Busby,J.,Webb,D.,1997.Experimentalevidencethatherbivoryincreases 1353 shootdensityandproductivityinasubtropicalturtlegrass(thalassia*testudinum)meadow Oecologia112,193Y VanderPijl,L.,1982,Principlesofdispersal.SpringerYVerlag,Berlin VanderWal,J.E.M.,Dorenbosch,M.,Immers,A.K.,Forteza,C.V.,Geurts,J.J.M.,Peeters,E.,Koese,B., 1357 Bakker,E.S.,2013.Invasivecrayfishthreatenthedevelopmentofsubmergedmacrophytesin 1358 lakerestoration.plosone8,e VanderWal,R.,Sjogersten,S.,Woodin,S.J.,Cooper,E.J.,Jonsdottir,I.S.,Kuijper,D.,Fox,T.A.D., 1360 Huiskes,A.D.,2007.SpringfeedingbypinkYfootedgeesereducescarbonstocksandsink 1361 strengthintundraecosystems.globalchangebiology13,539y

57 56 VanDonk,E.,Otte,A.,1996.Effectsofgrazingbyfishandwaterfowlonthebiomassandspecies 1363 compositionofsubmergedmacrophytes.hydrobiologia340,285y VanEerden,M.R.,Drent,R.H.,Stahl,J.,Bakker,J.P.,2005.Connectingseas:westernPalaearctic 1365 continentalflywayforwaterbirdsintheperspectiveofchanginglanduseandclimate.glob ChangeBiol.11,894Y VanLeeuwen,C.H.A.,Huig,N.,VanderVelde,G.,VanAlen,T.A.,Wagemaker,C.A.M.,Sherman, 1368 C.D.H.,Klaassen,M.,Figuerola,J.,2013.Howdidthissnailgethere?Severaldispersalvectors 1369 inferredforanaquaticinvasivespecies.freshw.biol.58,88y VanLeeuwen,C.H.A.,VanderVelde,G.,vanLith,B.,Klaassen,M.,2012.Experimentalquantification 1371 oflongdistancedispersalpotentialofaquaticsnailsinthegutofmigratorybirds.plosone7, 1372 e VanNes,E.H.,Scheffer,M.,vandenBerg,M.S.,Coops,H.,2003.Charisma:aspatialexplicit 1374 simulationmodelofsubmergedmacrophytes.ecol.modell.159,103y VanWijk,R.J.,1988.EcologicalstudiesonPotamogeton*pectinatusL.I.Generalcharacteristics, 1376 biomassproductionandlifecyclesunderfieldconditions.aquat.bot.31,211y VanderZanden,H.B.,Bjorndal,K.A.,Bolten,A.B.,2013.Temporalconsistencyandindividual 1378 specializationinresourceusebygreenturtlesinsuccessivelifestages.oecologia173,767y Veen,G.F.,Sarneel,J.M.,Ravensbergen,L.,Huig,N.,vanPaassen,J.,Rip,W.,Bakker,E.S., Aquaticgrazersreducetheestablishmentandgrowthofriparianplantsalongan 1382 environmentalgradient.freshw.biol.58,1794y Verges,A.,Becerro,M.A.,Alcoverro,T.,Romero,J.,2007.Variationinmultipletraitsofvegetative 1384 andreproductiveseagrasstissuesinfluencesplantyherbivoreinteractions.oecologia151, Y Verges,A.,Perez,M.,Alcoverro,T.,Romero,J.,2008.Compensationandresistancetoherbivoryin 1387 seagrasses:inducedresponsestosimulatedconsumptionbyfish.oecologia155,751y

58 57 Verges,A.,Steinberg,P.D.,Hay,M.E.,Poore,A.G.B.,Campbell,A.H.,Ballesteros,E.,Heck,K.L.,Booth, 1389 D.J.,Coleman,M.A.,Feary,D.A.,Figueira,W.,Langlois,T.,Marzinelli,E.M.,Mizerek,T., 1390 Mumby,P.J.,Nakamura,Y.,Roughan,M.,vanSebille,E.,SenGupta,A.,Smale,D.A.,Tomas, 1391 F.,Wernberg,T.,Wilson,S.K.,2014a.Thetropicalizationoftemperatemarineecosystems: 1392 climateymediatedchangesinherbivoryandcommunityphaseshifts.p.r.soc.bybiol.sci , Verges,A.,Tomas,F.,Cebrian,E.,Ballesteros,E.,Kizilkaya,Z.,Dendrinos,P.,Karamanlidis,A.A., 1395 Spiegel,D.,Sala,E.,2014b.Tropicalrabbitfishandthedeforestationofawarmingtemperate 1396 sea.j.ecol.102,1518y Verhoeven,J.T.A.,1980.TheecologyofRuppiaYdominatedcommunitiesinwesternYEurope Aspectsofproduction,consumptionanddecomposition.Aquat.Bot.8,209Y Verpoorter,C.,Kutser,T.,Seekell,D.A.,Tranvik,L.J.,2014.AglobalinventoryoflakesbasedonhighY 1400 resolutionsatelliteimagery.geophys.res.lett.41,6396y Viana,D.S.,Figuerola,J.,Schwenk,K.,Manca,M.,Hobæk,A.,Mjelde,M.,Preston,C.D.,Gornall,R.J., 1402 Croft,J.M.,King,R.A.,Green,A.J.,Santamaría,L.,2016.Assemblymechanismsdetermining 1403 highspeciesturnoverinaquaticcommunitiesoverregionalandcontinentalscales.ecography ,281Y Viana,D.S.,Santamaria,L.,Michot,T.C.,Figuerola,J.,2013a.AllometricscalingoflongYdistanceseed 1406 dispersalbymigratorybirds.am.nat.181,649y Viana,D.S.,Santamaria,L.,Michot,T.C.,Figuerola,J.,2013b.Migratorystrategiesofwaterbirds 1408 shapethecontinentalyscaledispersalofaquaticorganisms.ecography36,430y Viana,D.S.,Santamaria,L.,Schwenk,K.,Manca,M.,Hobaek,A.,Mjelde,M.,Preston,C.D.,Gornall, 1410 R.J.,Croft,J.M.,King,R.A.,Green,A.J.,Figuerola,J.,2014.Environmentandbiogeography 1411 driveaquaticplantandcladoceranspeciesrichnessacrosseurope.freshw.biol.59,2096y

59 58 VivianYSmith,G.,Stiles,E.W.,1994.DispersalofsaltYmarshseedsonthefeetandfeathersof 1414 waterfowl.wetlands14,316y Vonk,J.A.,Kneer,D.,Stapel,J.,Asmus,H.,2008a.Shrimpburrowintropicalseagrassmeadows:An 1416 importantsinkforlitter.estuar.coast.shelfs.79,79y Vonk,J.A.,Pijnappels,M.H.J.,Stapel,J.,2008b.InsituquantificationofTripneustes*gratillagrazing 1418 anditseffectsonthreecoyoccurringtropicalseagrassspecies.mar.ecol.prog.ser.360,107y Weisz,E.J.,Yan,N.D.,2010.Relativevalueoflimnological,geographic,andhumanusevariablesas 1421 predictorsofthepresenceofbythotrepheslongimanusincanadianshieldlakes.can.j.fish Aquat.Sci.67,462Y Wheeler,G.S.,Center,T.D.,2001.ImpactofthebiologicalcontrolagentHydrellia*pakistanae(Diptera 1424 :Ephydridae)onthesubmersedaquaticweedHydrilla*verticillata(Hydrocharitaceae).Biol Control21,168Y Wheeler,G.S.,Van,T.K.,Center,T.D.,1998.HerbivoreadaptationstoalowYnutrientfood:Weed 1427 biologicalcontrolspecialistspodoptera*pectinicornis(lepidoptera:noctuidae)fedthe 1428 floatingaquaticplantpistia*stratiotes.environ.entomol.27,993y Whitehead,P.J.P.,1978.AncientrecordsofthepresenceoftheCaribbeanmanateeTrichechus* 1430 manatusinbrazil.actaamazonica8,497y Wilson,F.,1964.Biologicalcontrolofweeds.Annu.Rev.Entomol.9,225Y& Wilson,H.R.,Harms,R.H.,Damron,B.L.,1977.Potentialofgeeseincontrolandutilizationofwater 1433 hyacinths.poultrysci.56,1360y Winston,J.E.,2012.Dispersalinmarineorganismswithoutapelagiclarvalphase.Integr.Comp.Biol ,447Y Wittmann,M.E.,Jerde,C.L.,Howeth,J.G.,Maher,S.P.,Deines,A.M.,Jenkins,J.A.,Whitledge,G.W., 1437 Burbank,S.R.,Chadderton,W.L.,Mahon,A.R.,Tyson,J.T.,Gantz,C.A.,Keller,R.P.,Drake, 1438 J.M.,Lodge,D.M.,2014.GrasscarpintheGreatLakesregion:establishmentpotential,expert 1439

60 perceptions,andreyevaluationofexperimentalevidenceofecologicalimpact.can.j.fish. Aquat.Sci.71,992Y999. Wood,K.A.,O'Hare,M.T.,McDonald,C.,Searle,K.R.,Daunt,F.,Stillman,R.T.,2016.Herbivore regulationofplantabundanceinaquaticecosystems.biologicalreviewsdoi: /brv Wood,K.A.,Stillman,R.A.,Clarke,R.T.,Daunt,F.,O'Hare,M.T.,2012a.Theimpactofwaterfowl herbivoryonplantstandingcrop:ametayanalysis.hydrobiologia686,157y167. Wood,K.A.,Stillman,R.A.,Clarke,R.T.,Daunt,F.,O'Hare,M.T.,2012b.Understandingplant communityresponsestocombinationsofbioticandabioticfactorsindifferentphasesofthe plantgrowthcycle.plosone7,e Wood,K.A.,Stillman,R.A.,Daunt,F.,O'Hare,M.T.,2014a.Cansacrificialfeedingareasprotect aquaticplantsfromherbivoregrazing?usingbehaviouralecologytoinformwildlife management.plosone9,e Wood,K.A.,Stillman,R.A.,Daunt,F.,O'Hare,M.T.,2014b.Chalkstreamsandgrazingmuteswans. BritishWildlife25,171Y176. Wood,K.A.,Stillman,R.A.,Daunt,F.,O'Hare,M.T.,2015.Theswangrazingconflictinchalkrivers.In: Redpath,S.M.,Gutierrez,R.J.,Wood,K.A.,Young,J.C.(Eds.),Conflictsinconservation: navigatingtowardssolutions.cambridgeuniversitypress,cambridge,uk,pp.134y

61 60 Captions)to)figures) Figure1.Frequencydiagramofpercentageofherbivory(%herbivory)onvascularplants(a:mean 1462 percentdamage;b,c:netprimaryproductionremoval)andbiomassc:nratio(g/g)across(a,d) 1463 terrestrial,(b,e)freshwaterand(c,f)marineecosystems.freshwaterandmarinedataincludeboth 1464 submergedandemergentplants.themedianvaluesineachpanelareindicatedwithanarrow 1465 accompaniedby M Datasources:terrestrial(a)herbivory:percentageofleafareadamaged(Turcotteetal.2014),(d) 1467 biomassc:nratio:infoliage(elseretal.2000);freshwater(b)herbivory:percentageofemergentand 1468 submergedvascularplantbiomassremovedbyherbivoresinherbivoreexclosure/enclosureor 1469 addition/removalexperiments(woodetal.2016),(e)biomassc:nratio:insubmergedandemergent 1470 vascularplants(cloernetal.2002;bakkerunpublisheddata);marine,(c)herbivory:percentageof 1471 emergentandsubmergedvascularplantbiomassremovedbyherbivoresinherbivore 1472 exclosure/enclosureoraddition/removalexperiments(woodetal.2016),percentageofleafarea 1473 damagedinseagrasses(cebrianandduarte1998)(f)biomassc:nratio:inseagrassleaves(atkinson 1474 &Smith1983,Duarte1990,Fourqureanetal.1993,CebrianandDuarte1998,Fourqureanetal ,OlsenenValiela2010),insaltmarshplants(Cloernetal.2002).Thedurationoftheherbivroy 1476 studiesvariedfrominstantaneousmeasurementsofpercentageleafdamageinterrestrialplantsand 1477 seagrassestoexclosuresstudiesinfreshwaterandmarineecosystemsrangingfromaboutaweekto 1478 multiplestudyyears(studydurationsreportedinwoodetal.2016whofoundnoeffectofstudy 1479 durationonpercentageherbivoreplantbiomassremoval) Figure2.Frequencydiagramofnetprimaryproductionremoval(%herbivory)andbiomassC:N(g/g) 1482 forvascularfreshwaterandmarinemacrophytesofdifferentgrowthforms(emergentand 1483

62 submerged).emergentplantsincludefloatingplantsandwetlandorsaltmarshplants.themedian valuesineachpanelareindicatedwithanarrowaccompaniedby M.DatasourcesasinFig Figure3.Synthesizingschemeindicatingtheeffectsofherbivoresonmacrophytebedsandthe functioningofshallowfreshwater(a)andmarine(b)aquaticecosystems.herbivoresaffectplant abundanceandspeciescompositionbygrazingandbioturbation.theirpresencealters biogeochemicalcyclingandprimaryproduction,theytransportnutrientsandpropagulesacross ecosystemboundaries,modifyhabitatforotherorganismsandaffectthelevelofshoreline protectionbymacrophytebeds.symbolsinthefigurearecourtesyoftheintegrationandapplication Network,Univ.ofMarylandCenterforEnvironmentalScience(ian.umces.edu/symbols/). 61

63 1494# 1495# Table#1.#Plant#and#herbivore#traits#promoting#propagule#dispersal#by#aquatic#herbivores.# # Trait# Effect# References# Herbivores) # # Ability#to#chew#or#grind#food# The#presence#of#a#gizzard#or#grinding#teeth#reduces#propagule#survival.#Among#waterfowl,#heavier# gizzards#reduce#seed#survival#but#higher#grit#content#may#enhance#germination#of#undigested#seeds.# Figuerola#et#al.#(2002)# Furry#or#sticky#appearance#of# Animals#with#a#surface#on#which#propagules#can#attach#disperse#more#propagules# # animal#body# Diet#selection# Targeted#feeding#on#seeds#may#result#in#more#transport,#but#also#in#more#seed#predation# #thus# reducing#the#transport#through#untargeted#feeding#which,#particularly#when#mixed#with#large#bulks#of# food#(plant#parts,#animal#food,#debris),#may#result#in#high#propagule#survival.## Figuerola#et#al.#(2003)# Travelling#distance# Larger#travelling#distances#results#in#further#potential#dispersal,#particularly#for#migratory#species#that# cover#long#distances#in#single#leaps# Viana#et#al.#(2013b)# Habitat#use# Animals#with#specialized#use#of#aquatic#habitats#are#more#likely#to#deposit#the#propagules#in#suitable# habitat.#in#particular,#targeted#arrival#to#aquatic#habitats#at#stopovers#may#increased#the#deposition#of# Figuerola#and#Green#(2005)# # 62#

64 propagules##ingested#at#departure#sites,#especially#after#the#first#drinking#and#feeding#bout.# Plants) # # Propagule#dimensions# Small,#round#seeds#survive#digestive#tract#better#than#large,#elongated#seeds.#Small#size,#in#particular,# may#enhance#ingestion#mixed#with#vegetative#plant#material,#increasing#propagule#ingestion#( foliage#is# the#fruit,#sensu#janzen#(1984))#and#survival#to#gut#passage.# Mueller#and#van#der#Valk# (2002);#Soons#et#al.#(2008);# Figuerola#et#al.#(2010)# Hardness#and#permeability#of# seed#coat# Adaptations#for# epizoochorous#dispersal# Thicker,#harder#and#less#permeable#seed#coats#increase#survival#to#disperser s#gut#passage,#but#may# reduce#germination#in#the#absence#of#uningested#seeds.# Hooks,#rough#or#sticky#surface#have#been#proposed#to#enhance#dispersal#potential# Mueller#and#van#der#Valk# (2002);#Santamaria#et#al.# (2002);#Figuerola#et#al.# (2010)# Van#der#Pijl#(1982)# # Resistance#to#dessication# Organism s#and/or#propagule s#resistance#to#dessication#may#enhance#epizoochorous#dispersal#of# aquatic#organisms# Panov#and#Caceres#(2007);# Havel#et#al.#(2014)# 1496# 1497# # # 1498# # # # 63#

65 64# # Table#2.#An#overview#of#reported#conservation#conflicts#that#have#arisen#from#the#impacts#of#overgrazing#by#herbivores#on#macrophytes.# 1499# # 1500# Herbivore# Issue# Parties#in#conflict# Location(s)# Duration# Current#status# References# Green#turtle# (Chelonia)mydas)# Overgrazing#of#seagrasses#can# undermine#conservation#efforts# in#protected#areas#and#reduce# fish#catches#for#local#people# Turtle#and#seagrass# conservationists,# fishermen# IndoaPacific# oceans# 1980s#a# present# Ongoing# Arthur#et#al.#(2013);# Christianen#et#al.# (2014)# West#Indian# manatee# (Trichechus) manatus)# Overgrazing#has#hindered# efforts#to#restore#submerged# macrophyte#beds# Manatee#and# macrophyte# conservationists# Freshwater#and# brackish# ecosystems#in# southaeast#usa# 1990s#a# present# Ongoing# Hauxwell#et#al.#(2004)# Beaver#(Castor) spp.)# Impacts#on#aquatic#habitats,#via# effects#on#vegetation#and#wider# ecosystem#(e.g.#fish)# Conservationists,# animal#welfare# groups,#fishermen,# and#statutory#wildlife# management# Freshwater# habitats#across# North#America,# Russia# Unknown#a# present# Ongoing# Nolet#and#Rosell# (1998);#Collen#and# Gibson#(2001);#Halley# and#rosell#(2002)#

66 65# # agencies# Coypu#(Myocastor) coypus)#and# muskrat#(ondatra) zibethicus)# Overgrazing#on#emergent# macrophytes#degrades#aquatic# habitats# Conservationists,# animal#welfare#groups,# and#statutory#wildlife# management#agencies# Freshwater# lakes#and# wetlands#in# Europe# 1930s# # present# Resolved#by# 1970s#via# extirpation#of# coypu#in#britain;# ongoing# elsewhere#in# Europe# Gosling#and#Baker# (1989);#Barends# (2002)# Mute#swan# (Cygnus)olor)# Overgrazing#of#macrophytes# degrades#aquatic#habitats# Conservationists,# animal#welfare# groups,#and#statutory# wildlife#management# agencies# Freshwater# habitats#in# Europe#and#USA# 1950s#a# present# Ongoing# Perry#and#Perry# (2008);#Wood#et#al.# (2014b,#2015)# Geese#(Anser)spp.,# Branta#spp.,#and# Chen#spp.)# Overgrazing#of#emergent# macrophytes#degrades#wetland# habitats# Conservationists,# animal#welfare# groups,#and#statutory# wildlife#management# Canadian#Arctic# and#subaarctic# wetlands,# freshwater#lakes# 1970s#a# present# Ongoing# Kerbes#et#al.#(1990);# Nichols#(2014)#

67 agencies# and#wetlands#in# Europe#and# North#America# 1501# # 1502# # 1503# # 66#

68 1504# 1505# Table#3.#A#summary#of#key#herbivore#taxa#used#as#biocontrol#agents#in#the#management#of#macrophytes.# # Herbivore#biocontrol#agent# Target#macrophyte(s)# Herbivore#generalist#or# References# specific?# West#Indian#manatee# Wide#range#of##macrophyte#species,#including#Cabomba)aquatica,# Generalist# Allsopp#(1960)## (Trichechus)manatus)# Anacharis#spp.,#Leersia#spp.,#Utricularia#spp.# Geese#(Anser)spp)# Wide#range#of#macrophyte#species# Generalist# Ross#(1971);#Wilson#et# al.#(1977)## Grass#carp# Wide#range#of#macrophyte#species,#including#invasive#species#such#as# Generalist# Clayton#(1996);#Hanlon# (Ctenopharyngodon)idella)# Hydrilla)verticillata# et#al.#(2000)## Cichlid#fishes,#e.g.#blue#tilapia# Wide#range#of#macrophyte#species# Generalist# Schwartz#et#al.#(1986)## (Oreochromis)aureus)# Crayfish,#e.g.#papershell# crayfish#(orconectes)immunis)# Wide#range#of#submerged#macrophyte#species# Generalist# Letson#and# Makarewicz#(1994)## Weevils,#e.g.#milfoil#weevil# Speciesaspecific#biocontrol#agents#identified#for#many#macrophyte# Specialist# Creed#and#Sheldon# # 67#

69 (Euhrychiopsis)lecontei),# Hydrilla#tuber#weevil#(Bagous) affinis)# species,#e.g.#hydrilla#(hydrilla)verticillata),#eurasian#water#milfoil# (Myriophyllum)spicatum)# (1993);#Newman# (2004)# Apple#snails#(Pomacea#spp.)# Wide#range#of#macrophyte#species# Generalist# Rushing#(1973)## Dipteran#larvae,#e.g.#Asian# Speciesaspecific#biocontrol#agents#identified#for#many#macrophyte# Specialist# Wheeler#and#Center# hydrilla#leafamining#fly# species,#e.g.#hydrilla)verticillata# (2001);#Bownes#(2014)# (Hydrellia)pakistanae)# Lepidopteran#larvae,#e.g.# Speciesaspecific#biocontrol#agents#identified#for#many#macrophyte# Both#generalist#and# Wheeler#et#al.#(1998);# waterlettuce#moth# species# specialist#species#reported# Gross#et#al.#(2001);# (Spodoptera)pectinicornis)# Newman#(2004)# Hemiptera,#e.g.#Eccritotarsus) Speciesaspecific#biocontrol#agents#identified#for#many#macrophyte# Specialist# Coetzee#et#al.#(2007);# catarinensis# species,#e.g.#water#hyacinth#(eichhornia)crassipes)# Hernandez#et#al.#(2011)## Orthoptera,#e.g.#water# Speciesaspecific#biocontrol#agents#identified#for#many#macrophyte# Specialist# Bownes#et#al.#(2010)# hyacinth#grasshopper# species,#e.g.#water#hyacinth#(eichhornia)crassipes)# (Cornops)aquaticum)# 1506# 1507# # # 68#

70 1508# 1509# Table#4.#Different#methodologies#used#to#detect#and#quantify#herbivory#on#macrophytes.# # Methodology# Explanation# References# Exclosures# # Installation#of#cages#(fully#closed#or#open#at#the#bottom)#to#protect#macrophytes#from# different#herbivores#(fish,#muskrats,#waterfowl,#crayfish,#turtles)## Søndergaard#et#al.#(1996);# Körner#et#al.#(2002);#Hilt#(2006);# Christianen#et#al.#(2012);#Poore# et#al.#(2012);#veen#et#al.#(2013);# Van#der#Wal#et#al.#(2013);# Sarneel#et#al.#(2014)# Tethering# Shoot#herbivory#rates#(cm#shoota1#daya1)#are#estimated#for#marked#shoots#by# measuring#leaf#elongation#over#time.# Kirsch#et#al.#(2002);#Tomas#et#al.# (2005);#Prado#et#al.#(2007);# Pages#et#al.#(2014)## Underwater#videos# Video#recording#and#quantification#of#fish#activities#including#plucking#of#leaves## Körner#&#Dugdale#(2003);# Bennett#&#Bellwood#(2011);# Verges#et#al.#(2014b)# Visual#estimation#of#leaf#damage# # Francescini#et#al.#(2010)# # 69#

71 Natural#gradients# Measure#macrophyte#performance#(e.g.#growth#rate,#biomass,#etc)#across#naturallya occuring#gradients#in#herbivore#assemblage#properties#(e.g.#density)## Wood#et#al.#(2012b)# Drones# Identificaton#of#muskrat#damage#in#constructed#wetlands#by#digitizing#lowaaltitude# aerial#photographs## Brandt#et#al.#(2015)# Molecular#markers# # Assessments#of#genetic#variation#in#plants#across#environmental#or#geographical# (latitudinal)#gradients#using#different#molecular#markers# Mader#et#al.#(1998);# Hangelbroek#et#al.#(2002)#;#King# et#al.#(2002);#hidding#et#al.# (2014)# Stable#isotope#analyses# # Measurement#of#carbon,#nitrogen#and#hydrogen#stable#isotopes#in#resources#and# consumers#and#application#of#mixing#models# France#et#al.#(1996);#Solomon#et# al.#(2011);#dorenbosch#and# Bakker#(2012);#Mendonca#et#al.# (2013);#Vander#Zanden#et#al.# (2013);#Scharnweber#et#al.# (2014);#De#Kluijver#et#al.#(2015)# Gut#analyses#and#stable#isotope# analyses# Gut#analyses#in#fish#combined#with#stable#isotope#analyses#of#basal#food#resources#and# fish# Mao#et#al.#(2014)# # 70#

72 Telemetry# Wholealake#fish#telemetry# Hanson#et#al.#(2007)# Bird#counting#and#determination# # Dos#Santos#et#al.#(2012)# of#lignin#content#in#faeces# Laboratory#feeding#rate# determination#in#fish## Determination#of#fish#feeding#rates#in#aquaria## Körner#&#Dugdale#(2003)# Mechanistic#models# Simulations#of#foraging#herbivores#or#effects#on#plant#growth#can#predict#the#location,# timing,#and#magnitude#of#herbivore#effects#on#macrophytes# Hootsmans#(1999);#Van#Nes#et# al.#(2003);#nolet#et#al.#(2006);# Wood#et#al.#(2014a);#Nolet#et#al.# (2016);#Hidding#et#al.#(2016)# 1510# # 1511# # # 71#

73 1512# # 1513# # 72#

74 1514# # 1515# # 73#