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.
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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.
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Fig.1
ThisiscalledtheKeelingcurve(Figure2).It’safamouspicturethatshowsthecarbon
dioxidegoingfromabout320ppmin1960toabout410ppmrightnow.Soglobalcarbon
dioxideisincreasingintheatmosphere.
Fig.2
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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….
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Fig.4
Fig.5
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Fig.6
It’salotofstuff:erosion,factoryoutputs,stormwaterrunoff,fertilizerfromfarmfields,the
leavesthatcomeoffthetrees.Butthentheotherpartofitisiseutrophication(Figure7):
whenyougetexcessnutrientsinthewateranditcreatesphytoplanktonbloomsthatsink
anddie,andthebacteriaconsumealltheoxygen,andreleasecarbondioxide.Those
phytoplanktonbloomscanreallyconcentratecarbondioxideanddisruptthedistribution
ofwhereoxygenandcarbondioxideshouldbe.
Fig.7
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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.
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Fig.9
Themagnitudeofacidificationwillbedeterminedbythreethings:atmosphere,
decomposinglocalorganiccomponents(whichareveryimportantinbaysandestuaries),
andtheupwellingofacidifiedwaterfromdeepwaters.Andthisalloccursalongwith
temperatureandsalinitycycles,whichhaveaninfluenceonacidity.Likeanincreasein
watertemperaturemakeswatermoreacidic.Andregional-scalehydrography:GulfStream,
etc.Andthenthere’sinter-annualvariability.It’safairlycomplexsystem.It’sreally
importanttohavealotofdata.
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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%.
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Fig.10
Fig.11
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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.
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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
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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.
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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.
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Insum,therearemanyinteractingstressorsandmanyunknowns(Figure17).
Fig.17
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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.
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Fig.19
Fig.20
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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?
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Fig.22
Fig.23
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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.…
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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.
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Changeisinevitableinsomeform,andpeoplearegoingtoneedtoadapt.Gottobeflexible
tosustainfisheriesandfishermen.That’swhatwe’regoingtoneedtodomovingforward.
Moreinformation:
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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.
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•
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•
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
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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
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•
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:
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