Numeric Nutrient Endpoint Development for San Francisco Bay Estuary: Literature Review and Data Gaps Analysis

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1 Technical Report 0644 Numeric Nutrient Endpoint Development for San Francisco Bay Estuary: Literature Review and Data Gaps Analysis Lester McKee a, Martha Sutula b, Alicia Gilbreath a, Julie Beagle a, David Gluchowski a, and Jenifer Hunt a a San Francisco Estuary Institute (SFEI), San Francisco, CA b Southern California Coastal Water Research Project (SCCWRP), Costa Mesa, CA EXECUTIVE SUMMARY TheCaliforniaStateWaterResourcesControlBoard(SWRCB)isdevelopingnutrientwaterquality objectivesforthestate ssurfacewaters,usinganapproachknownasthenutrientnumericendpoint (NNE)framework.TheNNEestablishesasuiteofnumericendpointsbasedontheecologicalresponseof anaquaticwaterbodytonutrientover enrichment(eutrophication,e.g.algalbiomass,dissolved oxygen).inadditiontonumericendpointsforresponseindicators,thenneframeworkmustinclude modelsthatlinktheresponseindicatorstonutrientloadsandothermanagementcontrols.thenne frameworkisintendedtoserveasnumericguidancetotranslatenarrativewaterqualityobjectives.the NNEframeworkiscurrentlyunderdevelopmentforestuaries.BecauseSanFranciscoBayrepresents California slargestestuary(70%byareaofestuarinehabitatstatewide),itmeritsdevelopmentofan estuary specificnneframework.thepurposeofthisdocumentistoreviewliteratureanddatarelevant totheassessmentofeutrophicationinsanfranciscobay,withthegoalofprovidinginformationto formulateaworkplantodevelopnnesforthisestuary.thereviewhadthreeobjectives:1)evaluate indicatorstoassesseutrophicationandotheradverseeffectsofanthropogenicnutrientloadinginsan FranciscoBay,2)SummarizeexistingliteratureinSFBayusingindicatorsandidentifydatagaps,and3) InvestigatewhatdataandtoolsexisttoevaluatethetrendsinnutrientloadingtotheBay. RecommendedNNEIndicatorsforSFBay TheNNEassessmentframeworkisthestructuredsetofdecisionrulesthathelpstoclassifythe waterbodyincategoriesfromminimallytoverydisturbed,inordertodetermineifawaterbodyis meetingbeneficialuses,ortoestablishtmdlnumerictargets.developmentofanassessment frameworkbeginsbychoosingresponseindicators,whichwerereviewedusingfourcriteria:1)strong linkagetobeneficialuses,2)well vettedmeansofmeasurement,3)canmodeltherelationship betweentheindicator,nutrientloadsandothermanagementcontrols,and4)hasanacceptablesignal: noiseratiotoassesseutrophication.indicatorsvariedamongfourhabitattypes:1)unvegetated subtidal,2)seagrassandbrackishsav,3)intertidalflats,and4)tidallymutedhabitats(e.g.estuarine dikedbaylands).twotypesofindicatorsweredesignated.primaryindicatorsarethosewhichmetall evaluationcriteriaandwouldthereforebeexpectedtobeaprimarylineofevidenceofthenne assessmentframeworkforsfbay.supportingindicatorsfellshortofmeetingevaluationcriteria,but maybeusedassupportinglinesofevidence.thisterminologyisusedinordertoprovideasenseof levelofconfidenceinhowtheindicatorsshouldbeemployedinamultiplelinesofevidencecontext. i

2 Thereviewfoundfourtypesofindicatorsmetallevaluationcriteriaandaredesignatedasprimary: dissolvedoxygen,phytoplanktonbiomass,productivity,andassemblage,andcyanobacterialabundance andtoxinconcentration(allsubtidalhabitats),macroalgalbiomassandcover(intertidalhabitat,tidally mutedhabitats,andseagrasshabitats).otherindicatorsevaluatedmetthreeorfewerofthereview criteriaanddesignatedassupportingindicators:habcellcountsandtoxinconcentration,ureaand ammonium(allsubtidal),lightattenuationandepiphyteload(seagrass/brackishsav).ultimately,the realdistinctionbetween primary and supporting andhowtheseclassesofindicatorswouldbeused asmultiplelinesofevidenceinannneassessmentisentirelydependentonindicatorgroupand particularapplicationstospecifichabitattypes.someprimaryindicators(e.g.dissolvedoxygen)could bestand alone,whileforotherssuchasphytoplanktonbiomass,productivityandassemblage,thesf BayTechnicalAdvisoryTeamstronglyrecommendsusingthemasmultiplelinesofevidence,asuseof anyonealoneislikelytobeinsufficientlyrobust. Theuseofammoniumasanindicatorreceivedreview,duetoitshypothesizedroleinlimiting phytoplanktonprimaryproductionvianitrateuptakeinhibitioninsuisunbayandthelowersacramento River.TheSFBayTechnicalAdvisoryTeamchosetoincludeitasasupportingindicatorbecausethe importanceofammoniuminhibitionofdiatombloomsrelativetootherfactorscontrollingprimary productivitybaywideisnotwellunderstood.additionalreviewandsynthesisarerecommended, pendingcurrentlyfundedstudies,toidentifypotentialammoniumthresholds. ToWhatExtentisSFBayDemonstratingSymptomsofEutrophication,UtilizingNNEIndicators? Ofthefourhabitattypes,onlyunvegetatedsubtidalhabitathadadequatedatatomakeanassessment ofeutrophication.dissolvedoxygeninsfbaysubtidalhabitatismuchhigherandphytoplankton biomassandproductivityislowerthanwouldbeexpectedinanestuarywithsuchhighnutrient enrichment,implyingthateutrophicationiscontrolledbyprocessesotherthanasimplenutrientlimitationofprimaryproduction.however,allregionsofthesfbayhaveexperiencedsignificant increasesinphytoplanktonbiomasssincethelate1990's.recentanalysisofwaterqualitydatacollected byusgsfrom1978to2009showasignificantincreaseinwatercolumnchlorophylla(30 50%per decadefromsuisuntosouthbayrespectively)andasignificantdeclineindoconcentrations(1.6to 2.5%perdecadeinSouthBayandSuisunBayrespectively).Thusevidenceisbuildingthatthehistoric resilienceofsfbaytotheharmfuleffectsofnutrientenrichmentisweakening.thecausesforthebay widetrendsincludechangesinwaterclarityduetolesssuspendedsediment,lowermetalinhibitiondue toimprovementsinwastewatertreatment,increasedseedingfromoceanpopulations,declinesin consumptionbybivalvesduetoincreasesinpredationbyjuvenileenglishsoleandspeckledsanddabs, anddeclinesinphytoplanktonconsumptionbyconsumersduetorecentnewinvasivespecies introductions.datasuggestthatprimaryproductivityinsuisunbayislimitedbystronggrazingpressure byinvasiveclams,lightlimitationbyhighturbidity,andammoniuminhibitionofdiatomuptakeof nitrate.fewharmfulalgalblooms(habs)havebeenreportedrecentlyinsfbay.however,therehave beenhistoricaloccurrences,andrecentlycyanobacteriaanddinoflagellatebloomshavebeen increasinglydocumented. ii

3 iii WhatAretheNutrientLoadstoSFBayFromVariousSources? NutrientsloadstoSFBayfromexternalsourcesarepoorlyunderstood,thoughdataexistwithwhichto improvepublishedloadestimatesfromsomesources.forthemostpart,publishedloadestimatesare outdatedbyoneoreventwodecadesorbasedondatathatwerenotcollectedforloadsestimation. DataGapsandRecommendedNextSteps TheSFBayNNEframeworkconsistsoftwoprinciplecomponents:1)primaryandsupportingindicators usedinanassessmentframeworktoassesseutrophicationofsfbayhabitatsand2)modelsthatlink theseindicatorsbacktonutrientloadsandothermanagementcontrolsoneutrophication.thereare fivemajorrecommendations:1)developannneassessmentframeworkforsfbay,2)quantifyexternal nutrientsloads,3)developasuiteofmodelsthatlinknneresponseindicatorstonutrientloadsand otherco factors,4)implementamonitoringprogramtosupporttheuseofthenneinsfbaytomanage nutrients,and5)coordinatedevelopmentofthesfbaynneworkplanwithnutrientmanagement activitiesinsacramentoandsanjoaquindelta.thesfbaytechnicaladvisoryteamassumedthesan FranciscoBayWaterBoardwillprioritizethesenextsteps,withreview/feedbackfromitsadvisory groups. DevelopanNNEassessmentframeworkforSFBay DevelopmentofanNNEassessmentframeworkforSFBayinvolvesspecifyinghowprimaryand supportingindicatorswouldbeusedasmultiplelinesofevidencetodiagnoseadverseeffectsof eutrophication.thetablebelowsummarizesdatagapsandrecommendednextstepsfordevelopment ofansfbaynneassessmentframeworkbyhabitattype.datagapsandrecommendationsgenerallyfall intofourcategories:1)monitoringtoassessbaselinelevelsofindicatorsofinterestwheredataare currentlylacking,2)analysisofexistingdata,3)fieldstudiesorexperimentstocollectdatarequiredfor endpointdevelopment,and4)formationofexpertworkgroupstorecommendapproachtoassessment frameworkdevelopmentandsynthesizeinformationtobeusedinsettingnumericendpoints. Type Indicator Designation DataGaps RecommendedNextSteps SubtidalHabitat Dissolved oxygen Primary Wealthofdataexists. TechnicalAdvisoryTeam doesnothaveexpertise toreviewadequacyofdo objectives.reviewdid notaddressdissolved oxygendatainthetidally mutedhabitatsofsfbay. ConsiderupdateofsciencesupportingBasin Plandissolvedoxygenobjectives,ifwarranted byadditionalreviewbyfisheriesexperts. ReviewcouldbeforentireBayorlimitedto thetidallymutedareasofthebay. biomass, productivity, andassemblage Primary Needareviewofscience supportingselectionof endpoints.improved predictionoffactors controllingassemblage Recommenddevelopmentofawhitepaper andaseriesofexpertworkshopstodevelop NNEassessmentframeworkfor phytoplanktonbiomass,productivity, taxonomiccomposition/assemblages,

4 iv Type Indicator Designation DataGaps RecommendedNextSteps HABspecies abundanceand toxinconc. Cyanobacteria= primary; OtherHAB =supporting LittledataonHABtoxin concentrationsinsurface watersandfaunaltissues. abundanceand/orharmfulalgalbloomtoxin concentrations.recommendaugmentation ofcurrentmonitoringtoinclude measurementofhabtoxinconcentrationsin waterandfaunaltissues. SubtidalHabitat(Continued) Ammoniumand urea Supporting Lackofunderstandingof importanceofammonia limitationofnitrate uptakeindiatomsonbay productivityvis à vis otherfactors.lackof dataonureainsfbay Recommendformulationofaworkinggroup ofsfbayscientiststosynthesizeavailable dataonfactorsknowntocontrolprimary productivityindifferentregionsinthebay, andevaluatepotentialammoniumendpoints. Recommendcollectingadditionaldataon ureaconcentrationsinsfbayviausgs s waterqualitysamplingoveratwoyear period. Macrobenthos taxonomy, abundanceand biomass Co factor Lackofinformationon howtousecombination oftaxonomy,abundance, andbiomasstoassess eutrophication RecommendutilizationofIE EMPdatasetto exploreuseofmacrobenthostobeused reliablytodiagnoseeutrophicationdistinctly fromotherstressorsinoligohalinehabitats. Thismayinvolveincludingbiomassinthe protocoltoimproveabilitytodiagnose eutrophication. SeagrassHabitat biomass, epiphyteload andlight attenuation biomass= primary, epiphyteload andlight attenuation= secondary Poordataavailabilityof dataonstressorstosf Bayseagrassbeds. Studiesneededto establishlight requirementsforseagrass andtoassesseffectsof lightattenuation Recommend1)Continuedmonitoringof aerialextentofseagrassevery3 5years (currentlynofurthersystemscalemonitoring isplannedbeyond2010),2)studiesto establishlightrequirementsforsfbay seagrassspecies,3)developmentofa statewideworkgrouptodevelopan assessmentframeworkforseagrassbasedon phytoplanktonbiomass,macroalgae,and epiphyteloadand4)collectionofbaseline datatocharacterizeprevalenceofmacroalgal bloomsonseagrassbeds. Studiescharacterizingthresholdsofadverse effectsofmacroalgaeonseagrasscurrently underwayinothercaliforniaestuariesshould beevaluatedfortheirapplicabilitytosfbay. Macroalgae biomassand cover Primary Datagapsincludestudies toestablishthresholdsof macroalgalbiomass, coveranddurationthat adverselyaffectseagrass habitat IntertidalFlatHabitat Macroalgal biomassand cover Primary Lackofbaselinedataon frequency,magnitude (biomassandcover)and durationofmacroalgal bloomsintheseintertidal flats Recommendcollectionofbaselinedataon macroalgae,microphytobenthosand sedimentbulkcharacteristics. RecommendinclusionofSFBayscientistsand stakeholdersonstatewideworkgroupto developanassessmentframeworkfor macroalgaeonintertidalflats. Sediment nutrients Supporting MPBtaxonomy andbiomass Supporting

5 v Type Indicator Designation DataGaps RecommendedNextSteps MutedSubtidalHabitat Macroalgae Primary Lackofbaselinedata onbiomassandcover inmutedhabitattypes Recommendcollectionofbaselinedata onmacroalgae,dissolvedoxygen, phytoplanktonbiomass,taxonomic compositionandhabspecies/toxin concentrationinthesehabitattypes. Recommendationtodevelopan assessmentframeworkbasedon macroalgae,phytoplanktonand dissolvedoxygeninthesehabitattypes. Onecomponentofthisdiscussion shouldbeadecisiononbeneficialuses thatwouldbetargetedforprotection andtowhatextentthelevelof protectionorexpectationforthis habitattypedifferfromadjacent subtidalhabitat. biomass, assemblage, HABtoxin conc. biomass, cyanobacteria= primary; assemblageand otherhabs= supporting Lackofbaselinedata onbiomassand community composition,habtoxin concentrations Dissolved oxygen Primary Somedataondissolved oxygenexist.unclear whatlevelsofdo requiredtoprotect mutedhabitat beneficialuses QuantifyNutrientLoads Thetablebelowprovidesasummaryofdatagapsandrecommendednextsteps.Recommendations generallyfallintotwocategories:1)revisingandupdatingestimatesofnutrientsfromthedifferent sources,basedonexistingdataand2)identificationofdataneededtodevelopadynamicloading model. Source DataGapsIdentified RecommendedNextSteps Atmospheric Deposition Norecentlypublished dataonwet&dry atmosphericdeposition Loadslikelyrelativelysmall.Literaturereviewtodeterminerangeof NandPdepositionratesforWestCoastcoastalurbanareas. Recommendbaselineatmosphericdepositionmonitoringofwet anddrynandpdepositionover1 2yearperiodtobetterconstrain estimates. Terrestrial Loadsfrom Delta Dryweather concentrationsavailable throughrmp.nodata availableonwetweather concentrations Loadslikelylarge.RecommendanalysisofexistingRMPdatato estimatedryweathernutrientloads.initiatewetweatherdata collectionofnutrientsatthemallardislanddwrsamplinglocation (headofsuisunbay)tosupportimproveddailyloadsestimatesfor 1995 present.

6 vi Municipal Effluent Dataavailablethrough15 ofapprox.40publicly OwnedTreatmentWorks Loadslikelylarge.Synthesizenutrientdischargeandconcentration datatoestimateloadsoverperiodoflast10 20years.Encourageall treatmentplantsthatdischargetothebaytobeginanalyzing effluentfortotalanddissolvedinorganicnutrientsandtosubmit thesedatatothesfrwqcbonaregularbasis.recommendthatthe POTWsconductalaboratoryinter comparisononnutrientmethods toassurecomparabilityofestimates. Industrial Effluent Somedataavailablefrom the1990s Loadslikelysmallrelativetomunicipalwastewater.Synthesize availabledatatoprovideinformationforprioritizationofanyfuture steps. Stormwater Lackofwetweatherdata sufficienttodevelopa dynamicloadingmodel Loadslikelylarge.Synthesizedatatoprovideanupdatedestimate ofstormwatercontributionstoassistprioritizationofnextsteps. Scopethedataneedsassociatedwiththedevelopmentofa dynamicloadingmodel. Groundwater Dataavailablefrom79 USGSmonitoringstations. Flowdatanotwell understood Loadslikelysmall.Refinecurrentloadsestimatesafterreviewby localusgsgroundwaterexpertsinordertosupportprioritizationof nextstepsifany. Exchangewith CoastalOcean Somedataavailablefor fluxesofwaterand sedimentsduringselected tidesandseasons Initiateaworkgroupoflocalexpertstodesignasamplingprogram fornutrientfluxatthegoldengateboundary.theintentwiththis programwouldbetodevelopmodelsthatsimulatefluxatthe ocean bayinterface. DevelopLoad ResponseModels AnimportantcomponentofimplementingtheNNEframeworkinSFBayisthedevelopmentofloadresponsemodelsthatcansimulatetheecologicalresponseoftheEstuarytonutrientsandother importantco factors.severaltypesofmodelsneedtobedeveloped,fittingintotwogeneralcategories: 1)Air,oceanicandwatershedloadingmodel(s),whichestimatetheamountofnutrientsandsediment reachingthesfbayestuaryandwheretheyoriginate,and2)anestuarywaterqualitymodel,which simulatestheecosystemresponsetonutrientloadsandothermanagementcontrols.sufficientdataand knowledgeofsfbaymustexisttosupportthedevelopmentofsystemwidedynamicsimulationmodels topredictphytoplanktonbiomass/communityresponseandrelationshipstomodelsofsecondary productivity.thisisnotlikelyintheshortterm,soitisimportanttoconsiderthatthedevelopmentofa morecomplexmodelshouldfollowthetestingoutofkeyconceptsandassumptionsinsmaller,simpler models. ScopingthedevelopmentoftheseNNEloadresponsemodelsshouldbeginthroughuseofempirical dataandstudiestodevelopcoarsenutrientbudgetsforsfbay.existingdatathatdescribethetiming andmagnitudeofexternalsources,internalsources,sinks,andpathwaysoftransformationsuchas benthicnutrientflux,nitrification,denitrification,etc.wouldbecompiledinordertosynthesizecurrent understandingofsourcesandfateofnutrientsaswellasidentifycriticaldatagapsinadvanceofthe modelingstrategydevelopment.

7 Second,areviewofexistingmodelsandtheirapplicationsshouldbeundertaken,withtheintentof understandingwhatexistingtoolsmaybeusedtoleverageefforts. Duringthisstrategyworkshop,participantswoulddescribethemodelingobjectives,determinewhether existingtoolscanbeusedinthiseffort,identifykeydatagapsandstudies,andidentifyadditionalwork elementsneededtobeginthismajorworkelement.theproductofthiseffortwouldbethe identificationoftheappropriatemodels,aphasedworkplan,timelineandbudgettodevelopthese models,andidentificationofandcoordinationamongkeyinstitutions,programsandstakeholders.this informationcouldbesynthesizedintoaworkplantodeveloptheloadingandestuarywaterquality modelsandapreliminarytimelineandbudgetforphaseioftheeffort. ConductaMonitoringProgramtoDevelopandImplementtheNNEFrameworkinSFBay ThedevelopmentanduseofanNNEframeworkforSanFranciscoBayiscompletelycontingentonthe continuedavailabilityofmonitoringdatatoformulate,testandperiodicallyassessthestatusofthebay withrespecttoeutrophication.overthepastfortyyears,theusgshasconductedaresearchprogramin thesubtidalhabitatofsfbay,withpartialsupportbythesfbayregionalmonitoringprogram(rmp) since1993.thisusgsresearchprogramcannotbeconsideredreplacementforaregularlyfunded monitoringprogram.thesfbaytechnicaladvisoryteamstronglyrecommendsthata nutrients/eutrophicationmonitoringstrategybedevelopedandfundedforsuccessfuldevelopmentand implementationofthenneinsfbay. CoordinateDevelopmentoftheSFBayNNEFrameworkwithNutrientManagementintheDelta DevelopmentandimplementationofaNNEframeworkforSFBaywillrequireimprovecoordination withnutrientmanagementactivitiesinthesanjoaquinandsacramentoriverdelta.preliminary discussionsonthistopichavejustbegunwiththecentralvalleywaterboardstaff.otherentities,for example,theinteragencyecologicalprogramshouldbeengaged.coordinationshouldbeimproved,at minimum,withrespecttoanyfuturemonitoringand/ormodelingofnutrientloading,transportand sourceidentification,assfbayandthedeltaexchangenutrientsacrosstheiraquaticandterrestrial boundaries.coordinationwouldbefurtherenhancedbyasimilarreviewofnnecandidateindicators, summaryofexistingscience,andidentificationofdatagapsandrecommendednextstepsspecifically forthedelta. Full Text ftp://ftp.sccwrp.org/pub/download/documents/technicalreports/644_sfbaynne_litreview.pdf vii