OCEAN ACIDIFICATION AND NARRAGANSETT BAY FISHERIES With guest speaker Nathan Rebuck, NOAA researcher Warwick (Tri-City) Elks Lodge December 14, 2016 Part1.Causesofoceanandcoastalacidification OceanacidificationhasbeencalledtheotherCO2problem.Ithinkeveryonehasheardof globalwarmingorclimatechangebutcarbondioxideisalsomakingmarinewatermore acidic.Theoceanisn’tactuallyacidic,becauseit’saboveapHof7,butit’sbecomingmore acidiceventhoughit’sstillbasic.Thereareacoupletowaystomeasureacidification(see below).YoucanlookatpH.DICisdissolvedinorganiccarbon.pCO2isthepressureof carbondioxidethat’sinthewater.Andomega(Ω)isthesaturationstate–it’showthermodynamicallystablesomethinglikeaclamshellisinwater.IfyouthrowinaclamshellandΩ isbelowone,itwilldissolve,ifΩ isaboveone,itwilljustsittherebecauseit’sperfectly happybeingwhereitis. 1 There’sbeenakindofbiasedfocusinthemediaontheincreasingatmosphericcarbon dioxide–that’sfromburningfossilfuels,itsitsintheairandgetsabsorbedintothewater. That’saglobalproblemaffectingeverywhereequally.Butit’snottheonlysourceof acidification.Incoastalareas,it’sactuallyprobablyaprettyminorone.Theprimaryonein coastalareasisupstreameutrophication.SoifwehaveanalgaebloomupnearProvidence, andallthatstuffcomesdownhere,that’sgoingtoturnintoacidicwateraswegetfurther downthebay.I’llshowyouhowthatworksinacoupleslides. Andthenthere’salsootherchemicalsthatcanbeputoutbyfactories.Ifyourememberthe acidrainscare,orcrisis,backinthelate‘80sandearly‘90s,thatwaskillingallthelakesin theAdirondacksandallthetroutweredisappearing–thatwascausedbyfactorsinthe MidwestpumpingwhatarecalledNOxandSox–nitrates,sulfates,sulfides,thingslikethat– intotheatmosphere.Itreactswiththerainwater,fallsdown,wasdroppingthepHofsome ofthoselakesdownto4,whichisextremelylow.Sotherewerethesebeautifulpristine lakesupinthemiddleofthewoodsthatdidn’thaveanylifeinthembecauseofthis airbornepollutant. Butcarbondioxideisabigbogeyman.Tenbilliontonsofcarbongetreleasedintothe atmosphereperyearbymankindaroundtheglobe(Figure1).About50%ofitjustsits there,hangsoutintheatmosphereandcirculatesaround.Aboutaquarterofitgetsstored onlandinsomeformorfashion–asatreetrunkorleaflitterthat’slyingthereorget absorbedintothesoil.Andthenanotherquarterofthattenbilliontonsgetsabsorbedinto theoceanwater,andtheneithergetsabsorbedintothebiotaorjustsitstherechemicallyin thewateritself. 2 Fig.1 ThisiscalledtheKeelingcurve(Figure2).It’safamouspicturethatshowsthecarbon dioxidegoingfromabout320ppmin1960toabout410ppmrightnow.Soglobalcarbon dioxideisincreasingintheatmosphere. Fig.2 3 Ifyoudrillanicecoreinaglacier,youcanfindairbubblesthatareahundredyearsold, twohundredyearsold,athousandyearsold.Sotheyprovidearecordofcarbondioxide (Figure3).ThisshowsYear0upto2005.Youcanseesincethelastglaciation,whichwas about10,000yearsago,thingshavebeenprettystable,rightupuntilaround1980,when mankindstartedburningallthesefuelsinthemid-19thcentury,andthecurvejuststarts goingthroughtheroof.Andofcourse,we’reatthetopofit. Fig.3 Sowhydoestheatmospheremattertopeoplewhoworkwater?Imentionedthatitmakes itmoreacidic.Thesearetheonlytwochemicalfactsthatyouneedtoremember: 1.Carbondioxideinthewatermakesthewatermoreacidic(Figure4). 2.Plantstakeincarbondioxideandreleaseoxygen.Andthingsthateatplants breatheinoxygenandreleasecarbondioxide(Figure5). Soifwecombinethosetwothings(Figure6),thenwe’vegotthingsthattakeinsugarand oxygenandpumpourcarbondioxide.Thatcarbondioxidethenkicksbackintothisfirst equation.Prettymuchanytimeyouhaveanaccumulationofrottingstuff,youhavean increaseinacidification.It’sthesameprocessascarbondioxideintheatmosphere,it’sjust adifferentvehicletogetitthere…. 4 Fig.4 Fig.5 5 Fig.6 It’salotofstuff:erosion,factoryoutputs,stormwaterrunoff,fertilizerfromfarmfields,the leavesthatcomeoffthetrees.Butthentheotherpartofitisiseutrophication(Figure7): whenyougetexcessnutrientsinthewateranditcreatesphytoplanktonbloomsthatsink anddie,andthebacteriaconsumealltheoxygen,andreleasecarbondioxide.Those phytoplanktonbloomscanreallyconcentratecarbondioxideanddisruptthedistribution ofwhereoxygenandcarbondioxideshouldbe. Fig.7 6 Part2.Howarecoastalandestuarinesystemsdifferentfromtheopenocean? Fig.8 This(Figure8)issomedatafromdowninLongIslandSound.Thisisaclassictextbook exampleofhowacidificationcancomefromthelandtothewater.SothisisstartinginNew Yorkandcomingallthewayouthere(lefttoright).AlltheeffluentcomingoutofNewYork Cityishere(left-handsideofthegraphs).Thisisoxygen(topgraph)–there’saverylow oxygenzoneintheWesternSound.ThenextoneispH(secondfromtop),whichisalso verylowintheWest.Andthenthere’scarbondioxideitself(thirdfromtop)andaragonite (bottom).Asyoucansee,thegradientgoesWesttoEast.AsyougetfurtheroutLongIsland Sound,thewatergetscleaner,orlessacid. This(Figure9)isatransectrunningfromCapeCod,downtheshelf,andoutpastthe canyons.Andthisisshowingtheamountofcarbonstoredinwater.Youcanseethedeep waterisreallyhighinacidity,reallyhighincarbondioxide.SoasopposedtoLongIsland Sound,whereyouhavealotofcarbondioxidepollutioncomingfromtheland,there’s actuallyalotofaciditystoreddownhereduetothephytoplanktonaggregatingsink.That’s waterthathasn’tseenthesurfaceinacouplehundredyearsthat’sjustbeenaccumulating phytoplanktonnutrientsandlosingoxygenandgainingcarbondioxide. 7 Fig.9 Themagnitudeofacidificationwillbedeterminedbythreethings:atmosphere, decomposinglocalorganiccomponents(whichareveryimportantinbaysandestuaries), andtheupwellingofacidifiedwaterfromdeepwaters.Andthisalloccursalongwith temperatureandsalinitycycles,whichhaveaninfluenceonacidity.Likeanincreasein watertemperaturemakeswatermoreacidic.Andregional-scalehydrography:GulfStream, etc.Andthenthere’sinter-annualvariability.It’safairlycomplexsystem.It’sreally importanttohavealotofdata. 8 Part3.Biologicalandecologicalimpacts Solet’stalkaboutwhatthisacidificationisgoingtodo.Therehavebeenafewstudiesin therealworldandmanyinthelab.Mostofwhatweknowaboutstuffaroundherehas beeninthelab.Therearealotofdocumentednegativeeffectsoncorals,certaintypesof phytoplankton,bivalvesandcrustaceans.Somestudieshaveshownthatcrustaceansaren’t thataffected.ChangesinpHcausestressinfishthataretryingtobreathe.Theacidicwater actuallydissolvesthecalciumshellsifit’sacidicenough.ThehighpCO2increasesthe uptakeforseaweedsandphytoplankton–theyactuallygrowbetterwithhighcarbon dioxide. ThisisastudythatwasdoneatStonybrook,outonLongIsland(Figure10).Theytookhard clamsandbayscallopsandtheyputtheminfourdifferentcarbondioxidelevels:preindustrialatmosphericlevels,present-dayatmosphericlevels,theyear2050,andtheyear 2100.It’sprettyclearasday:youcanseethatscallopsgotsmallerandkindofdisfigured. Abnormalitieswentup.Sointhelab,ifyouputaclaminacidwater,itgrowsmoreslowly. Betweenpresent-dayand2100levels,therewasabouta10%decreaseingrowth. Inthisgraph(Figure11)fromthesamestudy,youcanseethatinthepreindustriallevels, theyhad70%survivaloftheirlarvae,andupinthepresentday,it’scloserto40%,and onceyougetuptoprojected1500ppm,survivalisdownto10%or20%. 9 Fig.10 Fig.11 10 Thenextgraph(Figure12)showsabuoyneartheIsleofShoalsneartheNew Hampshire/Maineborder.Thelighterbluecoloristheaircarbondioxide,andthedarker blueisthewatercarbondioxide.Youcanseethatonaverage,they’reaboutthesame.But asyougothroughaseason,whathappensisthatthewatergetscoldandabsorbscarbon dioxide,andthepCO2goesup.Andthenoncethatspringbloomhitsandphytoplankton startdrawinginthecarbondioxide,itgoesdown.Andthenassoonasthespringbloomis over,itstartsbeingrespired,startsrotting,thatcarbondioxidestatesgoingbackup.Sothe carbondioxidethat’sinthewaterisbouncingaroundthelevelthat’sintheatmosphere. Andthatdependsontemperatureandhowmuchupstreamstuffyou’rekickingin. Fig.12 TheseweresomeguysoveratEPAandStonybrook(Figure13).Theywentfrom ProvidencetolowerBay.Whenyoureadthegraphs,NorthtoSouthislefttoright.They tooksamplesofcarbondioxide.Asyou’dexpect,theupperBayhasreallyhighcarbon dioxide.Andthislevel–around2,000or2,500ppm–that’smorethanthe100-year atmosphericprojections.Sowhenwe’relookingatopenoceanstuff,they’regoingtosee someeffectsin50yearsor100yearswhencarbondioxideconcentrationsgetthishigh. Wellthat’salreadyhappeningintheupperBay.Thiswater’salreadygotalotofcarbon dioxide,isalreadyveryacidiccomparedtowhatitprobablywas100or200yearsago. 11 Fig.13 Ikeeptalkingaboutoxygen.ThesamepeopleatStonybrookwiththehardclams(Figure 14),thisisclamstheyhadinregularwater(firstcolumn),andtheydidrelativelyalright. Thentheydidlow-oxygen(secondcolumn)andtheydidalright.ThentheydidlowpH (thirdcolumn)andtheydidOK.Butthentheythrewthemtogether(fourthcolumn).It’s thecombinationoflowoxygenandlowpH.It’sthemultiplestressorsthing. Fig.14 12 Andthis(Figure15)isjustshowingacorrelationbetweendissolvedoxygenandpH.You canseethered,that’swherethingsstarthurting.Youcanseewheretheproblemsare.So basedonthatpreviousstudy,youcanassumethatwherethelowoxygenandlowpH overlapiswhereyou’regoingtoseeproblems.Butyoucanseetherearesomedifferences. Andthat’sbecausethepH,whileitrespondstothelowoxygenandtherotting,italso respondstochangesintemperature.Andtheactofgettingridofthatcarbondioxideisa littlebitslowerthantheactofgettingoxygenin…. Fig.15 Ifyou’vegotcleanwater,ittendstostayclean.Thisisanidealizedpicture(Figure16).If you’vegotthingscyclingphytoplankton,highfiltration,ifyou’vegotalotofclams,itlooks prettygood.Onceyoustartlosingthatfiltrationcapacity,yougethighphytoplankton crowdingouttheseagrass,yougetlowoxygen,anditstartsgettingugly. 13 Fig.16 AquickrundownofsomeoftheotherspeciesthatareimportantinRI.Therehaveonly beenafewstudiesdoneonlobsters.Someofthemhaveactuallyshownthatlobstersgrow betterunderhighcarbondioxideconditions.Oneshowedaslightdecreaseinlength.Soit’s kindofupintheair.Seascallops–they’retoughtocultureinthelab,sonobodyknows.But ifyoulookatsomeoftheotherscallopsaroundtheworld,somedoOKandsomeare impacted.Soit’stoughtosaywhat’sgoingtohappenwiththem.Butbasically,anything withahardshellisnegativelyimpacted–whetherit’sclams,oysters,bayscallops,anything likethat.Andfishiskindofamixedbag.Certainfishdon’tseemtomind.Generallyif something’susedtocomingintofreshwater,thenit’sprobablyalittlebetteradapted. Striperscomeupandspawninfreshwater,sotheydon’tparticularlycarewhatthepHof saltwaterisbecauseit’sgreaterthanwhatthey’reusedtoanyway.Whereastherehave beensomeeffectsonfluke.Winterflounderdidn’thavetoomanyeffects.Alotofpeopleare lookingatcod.Nothingreallyturningupthere.Nottoomuchknownaboutfish.It’salotof thetropicalfishesthatareshowingsensitivity.Becausetheenvironmentonacoralreed hasaverysteadypH.Itonlyfluctuatesatinybit.Theydon’thaveseasons.SoIthinkthose fisharesousedtoaconstantpHthatevensmallchangesinthepHcanmakeabig difference.Whereasaroundhere,we’vegothugeswingsdayandnight…Certaincrabshave beenshowntogrowmoreslowly,certaincrabsdon’tseemtocare.Alotofthosecrabsthat liveindeepwaterwhereit’salreadyacidicdon’tseemtobeaffected…Silversideshave shownaslightnegativeeffect.Squidhaveaslightlynegativeeffect.Acidificationhas changedthingsandit’sgoingtochangethingsinthefuture.Therearegoingtobewinners andlosers. 14 Insum,therearemanyinteractingstressorsandmanyunknowns(Figure17). Fig.17 15 Part4.What’sinstoreinthenext5years?50years?100years? Sotoputatimeframeonthesethings,whatcanweexpect?This(Figure17)isamodel outputthatgivesyouasense.Rightnowwe’reat410ppmcarbondioxideinthe atmosphere.Thismodelcameoutafewyearsago.Ifyoufollowthebusiness-as-usual emissionstrack,in100yearswe’llbeuparound1,000ppmintheatmosphereandthe oceanpHdrops.2-.4.Whichishuge. Fig.18 Butletsgobacktothis(Figure19).We’vealreadygotareasinshorethatareacidifiedtothe degreethattheseglobalmodelsaresayingtheoceanwillgetin100years.Sothingsare happeninginshore. ThisisafairlycomplicatedmodelthatsomeresearchersatWHOIdevelopedtolookatthe seascallopfishery(Figure20).TheredisthepHoftheoceanifyoudon’tchange atmosphericcarbondioxide.AndtheblueisthepHifyouallowcarbondioxidetocontinue toriseonabusinessasusualscenario.Theycoupledthechemicalmodel(top)toa biologicalmodel(middle),whichshowedachangeinscallopbiomass–abouta20%drop overthenext30years.Andthentheyfitthatintoasocioeconomicmodel(bottom),which saidthattherevenuedropsabout15%.ButlikeI’vebeensaying,alotofthebayisalready atthat50-yearhorizonduetoeutrophication. 16 Fig.19 Fig.20 17 Ialsowanttoputalittlebitofcontexthere(Figure21).Thisisthedataonhistorical scalloplandings.Backinthe‘50sitwaskindofmiddling.Inthe‘70sitdroppedwaydown. Thingskindofbouncedbackup.We’vebeendoingreallywellinthelasttenyears. Fig.21 Andthenthisistheirmodelontopofthat(Figure22).Thisisthechangebasedon acidificationrelativetowhatwe’veseenhistorically.So20%iskindofabignumber.But relativetosomeoftheotherchanges,it’sstillprettysmall.Andtheotherthingisthatthisis amodel,it’sprettysmooth–that’snevergoingtoactuallyhappeninreality.The managementthingsaregoingtohappen,stocksaregoingtochange,it’sgoingtobeawarm yearoracoldyear.Thingsaregoingtobouncearound.Soevenontopofthismodel,inthe next50years,thingsaregoingtobebouncingaroundtosomedegree.It’sjustthatthe negativeeffectoftheacidificationiskindofhummingalonginthebackground.And dependingonhowstrongitis,youmightnotevennoticeit.Liketheacidificationthat’s probablyoccurredinthebayinthelast30years.Becausetherearesomanyvariationsand regulations,peoplefishing,temperature,youmightnotevennoticethatthere’sthis negativepressurepushingdownonthevariousstocksandpopulationsthatareintheBay. AndIjustextrapolatedoutto2100here(Figure23).Thequestioniswhendoyoustart worryingabouta20%change?Whendoyoustartworryingaboutan80%change?...The atmosphericimpactsinthenextfiveyearsarenotgoingtobeaproblem–sleepwell,no bigdeal.Thenext50years?Maybe.Incoastalwaters,we’realreadyatthis50-yearhorizon, duetotheeutrophicationandthecarbonthatgetskickedin.Sowhat’stherighttimeto worryaboutacidification?Isittherighttimenow?Dowewaituntilthingsgetbetter?Do wewaittofixthenitrogenandbringbackeelgrass? 18 Fig.22 Fig.23 19 Andit’snotjustacidification–you’vealsogotwarmingtemperatures,hypoxia,suboptimal food,insteadofthesenicefatjuicydiatomsyoustartgettingtheseuglybrownalgaeand cyanobacteriathattheshellfishdon’tlikeasmuch,theydon’tgrowaswell(Figure24).The pointis,acidificationisn’tgoingtohappeninavacuum.It’snotlikewe’regoingtoseealine trendingdownwardsandsay‘that’sacidification.It’sgoingtoberunninginthe background.We’renotgoingtonotice.Everyone’sgoingtobetalkingaboutmanagement actionsandotherthings,becausethey’remoreimmediatelyimportant.Butoveradecadal timeframe,thisisgoingtohaveanoticeableimpact. Fig.24 Thisistheinsomniacsurvey(Figure25).Youmighthaveseenthissurvey.Thisshowslow oxygenzones.Thelowoxygenzonesaregoingtobehighacidity95%ofthetime.It’sjust thatpeoplehaven’treallybeentalkingaboutthisacidification,andhopefullythey’llstart.… 20 Fig.25 Part5.Take-homemessages Acidificationishappeningallovertheglobeanditwillcontinuetoincreaseinseverityeven ifwecompletelystopcarbonemissionstoday–there’sstillenoughcarbondioxideinthe airthattheoceansaregoingtocontinuetogetmoreacidic.Peoplehaven’tthoughtabout carbonintermsofacidity.Nowthey’reopeningtheireyesandrealizingthatit’snotjust carbonandoxygen,it’salsopHandacidity. Eutrophicationinmanyestuariesalreadyhasusuptowhattheglobalmodelssaythe oceanisgoingtobeuptoin50years.Andthefisheriesaredifferentbecauseofthis.You guysknow:thingshavechanged.Howmuchofitisduetothis,howmuchistemperature, howmuchislandusechanges?That’stheopenquestion.Butthisisdefinitelyafactorthat hasinfluencedthingstothispoint. IntheNortheastShelf,ifyou’refishingoffshoreyouprobablywon’tnoticeanythingfor20 years,30years.Butitwillprobablybeunrecognizablein100years. They’restartingtogetintomultigenerationalstudies.Someofthoselowlarvalsurvivaland lowgrowthrateshaveactuallybeentemperedifyouletthemothersgrowupinacidified waterandthenspawninacidifiedwater,andthenspawnagain,andsoon.Itmustbegene expressionorsomething,it’snotactuallyevolution–butmultigenerationaleffectsseemto belessthanifyoutakeaneggandthrowitinacidifiedwater.Butallofthesearechanging baselinesinhighlyvariablesystems.Itgetsdifficulttodoinalab. 21 Changeisinevitableinsomeform,andpeoplearegoingtoneedtoadapt.Gottobeflexible tosustainfisheriesandfishermen.That’swhatwe’regoingtoneedtodomovingforward. Moreinformation: 22 Groupdiscussion Understandingoceanacidification • I’vereadthatNarragansettBayisoneofthe15or20estuariesmostlikelytobe affectedbyoceanacidification.Whatisthat?Nathan:becauseofthenitrogeninputs. Anywhereyouhaveproblemswithanoxia,you’realsogoingtohaveproblemswith acidification.It’sthatrespirationequation–therottingalgaecauseslowoxygen, andthatoxygenislowbecauseit’sbeenconvertedtocarbondioxide,whichisthe samestuffasatmosphericcarbondioxide,anditleadstoacidification.Acidification andanoxiaaretwosidestothesamecoin. • AretheymonitoringpHinthebay?Nathan:Notreally.Alittlebit.TheycollectpH dataattheNarragansettBayNationalEstuarineResearchReserveonPrudence Island.TheproblemisthatpHisareallynoisymeasurement.Withinasingleday, you’llgetswingsthatareaslargeasatmosphericchangeswouldhavebeenoverthe last20years.Soit’seasiertopickuponlow-oxygenevents,butgenerallyhardto measurepH. • Sotheyhaven’tseenanychangeinpHinthebay?Nathan:NotthatI’mawareof.But theyseelowoxygen,andifyouseelowoxygen,thephysicsdictatethatyouhave lowpH. • Willwarmerwatertemperaturesincreasetheacidity?Nathan:Yes. • WhatwasthebaselinepHlevelforthebay?Nathan:Itdependsonsalinity.The freshwaterthatdumpsintothebayisaround6.5.Saltwater,onceyougetawayfrom thefreshwater,isaround8.1Sotheaverageisprobablyaround7.7. Nitrogenreductionandecosystemchange: • InRhodeIsland,wecan’tcontrolcarbonemissionsandwhatthepowerplantsinthe Midwestaredoing.Butwe’recontrollingnitrogeninputsbycontrollingthesewer plants.Willthenitrogenreductionsthataretakingplaceatthesewerplantstake careorthecarbonbuildupandlowpHproblem?Nathan:Yes.Thesimpleansweris yes.Themorecomplicatedanswerisyes,buttherearesomeotherlinkagesthatare morecomplicated.Ifyoudecreasenitrogen,yougetlessphytoplanktongrowth,and ideallyyoucouldgetmoreeelgrass.Eelgrassmakesabigdifferenceinengineering somepositivefeedbackloopsintheestuarinesystem. • Manyfishermenareconcernedaboutthenitrogenremovals.We’relearningthat theyreducedthenitrogeninputstothebaybig-time.Nowwe’reworriedthat there’snotenough,especiallyduringadrought.Andthenforthefirsttimeever,we hadaharmfulalgaebloom,andwe’retryingtoconnectthedotsonthat.Thewater isreallyclear–youcanseedown30feet.Andthey’redoingthisnitrogenremoval withoutevenknowingwhattheeffectsmightbe.Nathan–I’veheardaboutthose concerns.Thereisn’tdataonwhetherornottheyaretrue.Itmakessensethatifyou pumpnitrogenintothebay,it’sgoingtoturnintoproductivity.It’sgoingtobeeaten byclams,andyou’llhavemoreclams.Thatmakeslogicalsense.Butatthesame time,Icouldcomeupwithanargumentthatwedidn’thaveallthisnitrogen discharge200yearsago,andthebaywaschockfullofclams. 23 • • • • • • Wellwhatwe’veheardisthatit’sa“grandexperiment”.Quahogsmightgetbumped, butsomethingelsemightcomeback.Wewon’twanttobethepetridish.Everytime youpullastring,anotherstringcomes. Thereareanumberoflong-timefishermenwhosawabigchangeeversincethat tunnelwasbuilt.Whateverthey’redumpinginthewaterismakingthebaypeopleclean,butit’swipingouttheareasandingredientsthatfisheriesandnurseriesneed. We’veseenadrasticdeclineincertainfishandintheamountsoffish.We’re concernedthatSavetheBayispushingforittobetooclean,justbecausetheywant toopentheProvidenceRivertoswimming.Nathan:I’veonlybeeninRIforafew years,butIhavealwaysbeentoldthatoncethesummersetsinandthewater warmsup,there’snotenoughoxygenandtheydon’tlikeit.Myunderstandingwas thatitwasthenutrientsthatflowinfromProvidencethatcausetheproblem.The fishwouldratherenjoytheoxygenlevelsdownthebayinsteadofswimmingup here. Maybethere’saparallelbetweenwhathappenswhenaconventionalfarmgoes organic–thesystemgoesthroughaperiodofshockbeforeit’sabletostabilizeand startsustainingitsownecosystemservicesagain.Maybeallthisweirdstuff’s happeninginthebaybecausetherateofremovalofnitrogenfromwastewaterhas beentoofasttogivethebayachangetoadapt.Ashocktothesystem.Nathan:It’s definitelyabigperturbation.Changingsomethingasfundamentalasnutrientlevels hastohavesomesortofrippleeffectandittakesawhiletoreachstasis.Itwill eventuallyreachequilibrium.Idon’tknowifanyoneisstudyingthatinthebay. Soundslikethereisatrade-offbetweennitrogenandoxygen.Ifwesay‘let’sputthe breaksonnitrogenremoval’thenweneedtorecognizethetrade-offbetweenthe potentialfertilizationvalueofnitrogenandthepotentialofnitrogentocause acidification.It’slikeGoldilocks. We’retryingtomakesenseoutoftherecentharmfulphytoplanktonbloom.It’s somethingthathasalwayshappenedinMaineandontheCape.Butitnever happenedherebefore,andthereasonisthatitcomesupwiththecoldwaterwhen there’sanortheastrunofweather–thatkicksupallthestufffromdowndeep,an upwellingeffect.Nathan:that’swhathappensontheWestCoast.Theirshelfisvery narrow,only10milesout.Sothey’vegotreallydeepwaternearthecoast.Whena southwindcomesandpushesthesurfacewateroffshore,itpullsupthered-hot acidifiedwaterfromthedepths.IthasareallylowpHandkillstheoysterlarvaein theaquaculturetanks. Theyareseeingsomebenefitsfromthenitrogenreduction.LikearoundConimicut Point,thereusedtobeaccumulationsofseaweedandtheneighborswould complain.Thathasn’thappenedinthreeorfouryears,duetothenitrogen reduction. Estuarinerestoration: • Let’sapproachmarinerestorationlikepermaculture–insteadofecosystem engineering,justsetuptheconditionsfortheecosystemtothriveonitsown,heal itself.Nathan:The#1thingforrestoringtheestuarinesystemistocutbackon nitrogen.Butyes,theremightbeunintendedconsequencesfromdoingthat.Butthe 24 bigpictureisthatifyoupullnitrogenout,theeelgrasscomesback,yougetmore carbonsequestrationinsoils,morehabitat,moreshellfish,morebait,andmorebig fishcomingin. • NarragansettBayCommissionislookingataproblemareaneartheSavetheBay facility.It’sanareawherethewaterjustpoolsup.Agyrepreventsitfromhaving exchangewiththetidalflow.Asaresult,it’sadeadarea.They’relookingatgreen restorationmethodslikehaving40or50solar-poweredupwellersgrowingoysters andclams.Thatwouldpullthenitrogenoutofthewater. • Shellfishrestorationhasabigconnectiontowaterquality.Inthosetwoyearswhen wehadtheoysterbloominthe1990s,theyhadthefewestbeachclosuresinyears. • RIShellfishermen’sAssociationispushingformoreshellfish-basedrestoration. We’rereallyexcitedaboutwhatNBCwantstodowithshellfishrestorationforwater quality. • ThestateisworkingonstartingaShellfishInitiativetosupportalotoftheseefforts. It’stheoutgrowthoftheShellfishManagementPlan.AzureCygleratSeaGranthas moreinfo.Weshouldallsupportthat.Itwillhavethreefocalpoints:resilient coastlines,shellfishrestoration,andfindingoutwhatkindofnitrogenandbacteria levelsaregoodforthebay. • Thereareprojectstoputemptyshellsintotheponds. • Oneproblemistheywon’tallowshellfishrestorationinclosedareas. • SavetheBayhasbeenplantingeelgrassfordecadesandit’snotsurviving.Youcan’t putitwhereitwon’tgrow.Isthatavisibilitything?Nathan:Iwouldhopethey’re plantingitintelligently.It’sapositivefeedback–oncethatgrassisthereitstarts pullingcarbondioxideoutofthewaterandshovingitunderground. • Alotofoystergrowersaretalkingaboutcarboncreditsforshellfish.Isittruethat themoreshellfishweputinthebay,themorecarbonwetakeout?Nathan:Butwhat happenstotheemptyshells–wepullouttonsofshellfishandallthatcalciumends upsomewhereelse,getsremovedfromtheestuary. • Therearerestorationprogramstocollectshellsandputthembackforreefbuilding andlarvalsettlementpromotion.Nathan:That’sanotherexampleofapositive feedbackloop.Youthrowinashell,andnotonlydoesitmakethewaterbetter,but itgivesalarvaloysteraplacetolive,whichthenfiltersthewater,whichmakesit better.Intheory,youcanjustkeepbuildingonit.Ithinkthatthrowingshellsinthe waterisbrilliant.Crushedshellisalsogood–theybufferthewater.Therearemany commonsensethingsthatcanwork. • Exceptthere’salawthatyoucan’tthrowshellsback–youneedanArmyCorp permit.Sotheregoesthecommonsense! • NewYorkjustdumpedahalfabillionoystersintheNewYorkHarbor.1Other placesaredoingcoolthingswecanemulate. Knowledgegapsandmonitoring: • Nathan:Youguysshouldkeeprecordsofyourobservations.Writedownwhat you’reseeing.There’ssomegoodscienceouttherebeingdonebasedon 1Findoutmorehere:https://www.billionoysterproject.org 25 • observationallogs.Oftenitsfishermen’sobservationthatkick-startscientific research.It’sreallyvaluableinformationthatcan’tbegottenanyotherway. Sometimespeoplesay‘areyouseeinganysignsofoceanacidification?’or‘thatmust beasignofoceanacidification’–butfromwhatIhearyousay,thisisaninvisible problemthat’srunninginthebackgroundbutwon’tbevisibleexceptbycomparing thingswayinthefuturewiththingswayinthepast.It’snotsomethingwewould actuallyseeinourfishingactivities,right?Nathan:Yeah,it’sgoingtoaffectgrowth andmortalityoverthelongrun,butit’snotgoingtoberealvisible.2%peryear– veryslow Afewproposedrecommendations: 26
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