The influence of hydrodynamic processes on

Francois Carlotti

Description

The influence of hydrodynamic processes on zooplankton transport and distributions in the North Western Mediterranean: estimates from a Lagrangian model Z.F.Qiu a,b, A.M.Doglioli a, Z.Y.Hu a, P.Marsaleix c, F.Carlotti a,? aLaboratoire d'Oceanographie Physique et Biogeochimie, Aix Marseille Universite, CNRS, UMR 6535, Marseille, France bKey Laboratory of Ocean Circulation and Waves, Institute of Oceanology, CAS, Qingdao, China cLaboratoire d'Aerologie, 14 Avenue Edouard Belin, Toulouse, France Abstract A Lagrangian module has been developed and coupled with the 3D circulation model Symphonie to study the influence of hydrodynamic processes on zooplankton trans- port and distributions in the North Western Mediterranean (NWM). Individuals are released every 3 days from March to August 2001 in two initial areas: around the DYFAMED sampling station in the central Ligurian Sea and in the Rhone river plume. Then the individuals are tracked for 40 days either as passive particles or with a simple diel vertical migration (DVM) pattern. The simulations suggest strong seasonal patterns in the distributions of the individuals released around the DY- FAMED sampling station. Individuals spread all over the NWM basin after 40 days Preprint submitted to Elsevier 23 May 2010

• necessarily passive


• hydrodynamic processes


• offshore circulation


• lagrangian model


• transport and69


• enables zooplankton


• shelf transport

Sujets

• Carlotti
• Rhône (département)
• Western Province

Informations

• Publié par: pefav
• Nombre de lectures: 25
• Langue: English
• Poids de l'ouvrage: 7 Mo

Extrait

Theinfluenceofhydrodynamicprocesseson zooplanktontransportanddistributionsinthe NorthWesternMediterranean:estimatesfrom aLagrangianmodel Z.F.Qiu a,b ,A.M.Doglioli a ,Z.Y.Hu a ,P.Marsaleix c , F.Carlotti a, ∗ a Laboratoired’Oce´anographiePhysiqueetBioge´ochimie,AixMarseilleUniversite´, CNRS,UMR6535,Marseille,France b KeyLaboratoryofOceanCirculationandWaves,InstituteofOceanology,CAS, Qingdao,China c Laboratoired’Ae´rologie,14AvenueEdouardBelin,Toulouse,France Abstract ALagrangianmodulehasbeendevelopedandcoupledwiththe3Dcirculationmodel Symphonietostudytheinfluenceofhydrodynamicprocessesonzooplanktontrans- portanddistributionsintheNorthWesternMediterranean(NWM).Individuals arereleasedevery3daysfromMarchtoAugust2001intwoinitialareas:around theDYFAMEDsamplingstationinthecentralLigurianSeaandintheRhoˆneriver plume.Thentheindividualsaretrackedfor40dayseitheraspassiveparticlesor withasimpledielverticalmigration(DVM)pattern.Thesimulationssuggeststrong seasonalpatternsinthedistributionsoftheindividualsreleasedaroundtheDY- FAMEDsamplingstation.IndividualsspreadallovertheNWMbasinafter40days PreprintsubmittedtoElsevier23May2010

butdifferentpatternsoccurdependingontheseason,theinitialdepthsofrelease andthecapacityofDVM.Offshore-shelftransportonlyoccursinAprilandMay withparticlesendingupintheGulfofLions(GoL)inlowconcentrations.Inother months,theNorthernCurrent(NC)canbeconsideredasabarrierforparticles enteringtheGoLfromtheoffshoresea.Aquartertoahalfofpassiveindividuals releasedintheRhoˆneriverplumeremainintheGoL.Therestistransportedby theNCtowardstheCatalanSea.ApplyingasimpleDVMschemedoesnotincrease theretentionofparticlesontheshelf. Keywords:Lagrangian,zooplankton,NorthWesternMediterranean,Gulfof snoiL 1 1Introduction 2 Overthepastfewdecades,ithasbecomeclearthatphysicalprocesses 3 areimportantdriversofpopulationdynamicsintheoceans(Milleretal., 4 1998;Batchelderetal.,2002).Zooplanktonorganismsarecriticallydependent 5 ontheirphysicalenvironmentsbuttheyarenotnecessarilypassiveparticles 6 (Batchelderetal.,2002;Cianellietal.,2007;SentchevandKorotenko,2007; 7 Carretal.,2008).Theyswimverticallywhichinfluencestheirspatio-temporal 8 distributions.Ateachphaseoftheirdevelopment,theyhavetofindprey 9 andavoidpredators.Attheadultstagetheywillseekmatesandreproduce. 10 Therefore,zooplanktontransportinavarietyofphysicalconditionscanbe 11 consideredasthecombinationoftwocloselylinkedprocesses.Thefirstis 12 zooplanktontransportbynon-stationaryflowfieldsandthesecondisthe ∗ Correspondingauthor. Emailaddress: [e-mail] (F.Carlotti). 2

13 behaviouralresponseofzooplankton,mainlybyswimming,tothechangesof 14 environmentalconditions. 15 Wheninvestigatingtherelationshipsbetweenparticledistributionandphys- 16 icalprocesses,researchersoftenusedbio-physicalmodels(e.g.Levyetal., 17 2000;Oschlies,2002).Lagrangianparticletrackingmodelscoupledwithhy- 18 drodynamicmodelsareparticularlyefficienttoolstoexaminetheroleplayed 19 byvariousphysicalprocesses,tostudytransportprocessesoveranentirebasin 20 andtosimulatecomplexandinteractiveprocessesactingatdifferentscales 21 (e.g.Milleretal.,1998;Blankeetal.,1999;Falcoetal.,2000;Guizienetal., 22 2006;Speirsetal.,2006;Lettetal.,2007). 23 RecentdevelopmentsofLagrangianmodelinghavehighlightedthelinks 24 betweenphysicalstructures,zooplanktonbehaviourandmarineproductivity 25 inregionssuchastheBenguelaecosystem(Mullonetal.,2003;Lettetal., 26 2007)ortheGeorgesBank(Milleretal.,1998).Cianellietal.(2007)simulated 27 theparticleexchangeintheGulfofLions(GoL)usingaLagrangianapproach 28 coupledwithathree-dimensional(3D)circulationmodel.Theyfoundthat 29 particledistributionsarestronglyrelatedtothemesoscaleandsub-mesoscale 30 hydrodynamicstructuresontheshelfandtotheoffshorecirculationassociated 31 withtheNorthernCurrent(NC). 32 Dielverticalmigration(DVM)isthemostcommonzooplanktonswimming 33 behaviourinwhichorganismsresideinsurfaceornear-surfacewatersatnight 34 andindeeperwatersduringtheday.Thisbehaviourenableszooplanktonto 35 feedinrelativelyproductivesurfacewatersatnightandavoidvisualpredators 36 duringtheday(Haney,1988).ThepotentialeffectofDVMonzooplankton 37 transporthasbeendemonstratedbyseveralresearchers(Batchelderetal., 3