2011update

DanBoganAlaskaNaturalHeritageProgramUniversityofAlaskaAnchorage

WhatisDidymo?  Freshwater,stalkeddiatomcommonlycalled“RockSnot”

 NativetoAlaska’scoldoligotrophicwaters

 Canformdensematsonstream/lakebottoms

 Tendstothriveinwaterswithabundantlight,stableflowregimes,highN:Pratios

Shouldwe(inAK)beconcerned? TheincidenceofdidymocoveredstreamshasincreasedinNorthAmericaoverthelast20years,notablyinwarmermoremesotrophicwaters

 Unsightlydensemats(“nuisanceblooms”)arenotwelldocumentedinAlaskastreams

 Anecdotally,matsareshowingupinstreamswheretheyhaven’tbeenseenbefore

 Potentialnegativeecologicalimpact(s)ofdidymomats

Poten<alroleoffishermen Bothwelletal.(2009)madeaconvincingcaseforincreasedfishingpressureinfluencingthespreadofdidymoinBCrivers.

  FirstappearanceofnusiancebloomsinBCriversintheearly1990scorrespondedwithincreasedfishingpressurefromnon‐Canadiansandtheadventoffelt‐soledwaders(1988).

 Manyofthebloomshavesincesubsided.

DidymohistoryinAlaska Pite,etal.(2009)lookedatdiatomsfromsedimentcorestakenfromNaknekLakein2003.

 Theyfounddidymovalvesthroughoutthecoredatingbackto1218,withnotrendsinabundancevariation

 Varianceinvalvemorphologymaybepromisingindistinguishingnuisancestrains.

DidymohistoryinAlaska  2007wasthefirstreportednuisancebloomontheBrooksRiver

 WeobtainedanothersedimentcorefromNaknekLakein2009

 AimedforBrooksRiverdepositionzone

2003

x 2009 coring site

DidymohistoryinAlaska Wealsofoundnosignificantvariationindidymoabundancethroughoutthecore

  IndexdiatomsfromBrooksRiverwerenotpresentinthecoreindicatingthatwemissedthetarget(BrooksR.depositionzone)

 WouldliketotryagainandalsodosomemorphometricworktocompareBrooksRiverdidymovalveswithothernuisancedidymo

  Geneticresearchison‐goingbySpaulding(percomm)attemptingtodetectdifferencesinnuisancestrains

beenattemptingtoverifyanddocumentaccountsofnuisancebloomsthroughoutthestate.

receivedsevenverifiedsamplesoverthepastfouryearsfromvariousagencypersonnel.

documentedseveralothernuisancebloomsinsouthcentral,interior,andsouthwestAlaska.

ReferencesBothwell,M.L.etal.2009.Onthebootsoffishermen:Thehistoryofdidymobloomson

VancouverIsland,BritishColumbia.Fisheries,vol.34,no.8:382‐388.Bothwell,M.L.etal.2008.DidbloomsofDidymospheniageminataaffectrunsof

anadromoussalmonidsonVancouverIsland?InBothwell,M.L.&S.A.Spaulding(eds),Proceedingsofthe2007InternationalWorkshoponDidymospheniageminata.CanadianTechnicalReportonFisheriesandAquaticSciences2795:50–53.

Pite,D.P.etal.2009.HistoricalabundanceandmorphologyofDidymospheniaspeciesinNaknekLake,Alaska.ActaBotanicaCroatica,Vol.68,No.2

Spaulding,S.&L.Elwell,2007.IncreaseinnuisancebloomsandgeographicexpansionofthefreshwaterdiatomDidymospheniageminata.Recommendationsforresponse.UnitedStatesGeologicalSurveyWhitePaperwebpublication,January2007:33pp.

Spaulding,S.A.etal.2008.ConfirmeddistributionofDidymosopheniageminata(Lyngbe)SchmidtinNorthAmerica.InBothwell,M.L.&S.A.Spaulding(eds),Proceedingsofthe2007InternationalWorkshoponDidymospheniageminata.CanadianTechnicalReportonFisheriesandAquaticSciences2795:26–29.

Sundareshwar,P.V.etal.2011.Didymospheniageminata:Algalbloomsinoligotrophicstreamsandrivers.GeophysicalResearchLetters,Vol.38

Whitton,B.A.etal.2009.BiologyofthefreshwaterdiatomDidymosphenia:areview.Hydrobiologia,630:1‐37.