The influence of hydrodynamic processes on zooplankton transport and distributions in the North Western Mediterranean: estimates from

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, Chinese Academic of Sciences, 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 zooplank- ton transport and distributions in the North Western Mediterranean (NWM). The individuals are released every 3 days from March to August 2001 and tracked for 40 days in two initial areas: the surrounding of the DYFAMED sampling station in the central Ligurian sea and the Rhone river plume, which are either considered as passive particles or able to perform diel vertical migrations (DVM) with a simple swimming pattern. The simulations suggest strong seasonal patterns in the distribu- tions of the individuals released at DYFAMED sampling station. Individuals could be spread all over the NWM basin after 40 days but different pattern s occurs fol- lowing the season, the initial released depth of the individuals, and the capacity of DVM or not.

• model domain


• transport processes


• shelf transport


• over time


• lagrangian particle-tracking


• using bio-physical models


• pelagics such

Sujets

• Carlotti
• Rhône (département)
• Western Province
• Overtime

Informations

• Publié par: pefav
• Nombre de lectures: 28
• Langue: English
• Poids de l'ouvrage: 2 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,ChineseAcademicofSciences, Qingdao,China c Laboratoired’Ae´rologie,14AvenueEdouardBelin,Toulouse,France Abstract ALagrangianmodulehasbeendevelopedandcoupledwiththe3Dcirculation modelSymphonietostudytheinfluenceofhydrodynamicprocessesonzooplank- tontransportanddistributionsintheNorthWesternMediterranean(NWM).The individualsarereleasedevery3daysfromMarchtoAugust2001andtrackedfor 40daysintwoinitialareas:thesurroundingoftheDYFAMEDsamplingstationin thecentralLigurianseaandtheRhoˆneriverplume,whichareeitherconsideredas passiveparticlesorabletoperformdielverticalmigrations(DVM)withasimple swimmingpattern.Thesimulationssuggeststrongseasonalpatternsinthedistribu- tionsoftheindividualsreleasedatDYFAMEDsamplingstation.Individualscould bespreadallovertheNWMbasinafter40daysbutdifferentpatternsoccursfol- lowingtheseason,theinitialreleaseddepthoftheindividuals,andthecapacityof DVMornot.Anoffshore-shelftransportonlyoccursinAprilandMaywithparticles endingintheGulfofLions(GoL)inlowconcentrations.Fortheothermonths,the northcurrentcanbeproperlyconsideredasabarrierforparticlesenteringintothe GoLfromtheoffshoresea.Attheendofthe40days,passiveindividualsreleasedin theRhoˆneriverplumearespreadontheGoLshelforintheCatalansea.Following theseasonbetweenaquartertoahalfoftheinitialreleasedindividualsstayinthe GoL.SimpleDVMbehaviordoesnotincreasetheretentionontheshelf. Keywords:Lagrangian,zooplankton,NorthWesternMediterranean,Gulfof snoiL PreprintsubmittedtoElsevier30September2008

1Introduction Inthelastdecades,itbecomesclearthatphysicalprocessesareimportant driversofpopulationdynamicsintheoceans(Milleretal.,1998;Robinson etal.,2005).Zooplanktonorganismsarecriticallydependentontheirphysi- calenvironmentsbuttheyarenotpassiveparticlesastheirdefinitionstates. Indeed,theyareableofverticalswimmingbehaviorwhichcouldinfluence theirspatio-temporaldistribution.Ateachphaseoftheirdevelopments,they havetofindpreyandavoidpredators,andattheadultstagetheyhavetofind mateandreproduce.Zooplanktontransportinavarietyofphysicalconditions canbeconsideredasthecombinationoftwocloselylinkedaspects.Thefirst involveszooplanktontransportbynon-stationaryflowfieldandthesecond involvesthebehavioralresponseofzooplanktonorganisms,mainlyswimming, tothechangesofenvironmentalconditions. Investigatingtherelationshipsbetweenparticledistributionandphysical processesusingbio-physicalmodelsprovidesarationaltounderstandthein- fluenceofsuchphysicalstructuresonthedynamicsoflocalecosystems(Levy etal.,2000;Oschlies,2002). Lagrangianparticle-trackingmodelscoupledwithhydrodynamicmodelsare particularlyefficienttoolstoexaminetheroleplayedbyvariousphysicalpro- cesses,tostudytransportprocessesoveranentirebasinandtosimulatecom- plexandinteractiveprocessesactingatdifferentscales(e.g.Milleretal.,1998; Blankeetal.,1999;Falcoetal.,2000;Guizienetal.,2006;Speirsetal.,2006; Lettetal.,2007).Recentdevelopmentsoflagrangianmodelinghavehigh- lightedthelinkagesbetweenphysicalstructures,zooplanktonbehaviorand marineproductivityinregionsuchastheBenguelaecosystem(Mullonetal., 2003;Lettetal.,2007)ortheGeorgesbank(Milleretal.,1998).Cianellietal. (2007)simulatedforparticleexchangeintheGulfofLions(hereinafterGoL) usingaLagrangianapproachcoupledwiththethree-dimensional(3D)circu- lationSymphoniemodel.Theyfoundthatparticledistributionsarestrongly relatedtothemesoscaleandsub-mesoscalehydrodynamicstructuresonthe shelfandtotheoffshorecirculationassociatedwiththeNorthCurrent(here- inafterNC). Withtheparticle-trackingapproach,onecanattaintrajectoriesanddis- tributionsofzooplanktonunderdifferentphysicalconditions,andaddthe zooplanktonbehaviortotransportincomparisonwiththesimpletransportof passivezooplanktonindividuals. Dielverticalmigration(hereinafterDVM)isthemostcommonswimming ∗ Correspondingauthor. Emailaddress: [e-mail] (F.Carlotti). 2