The identificationofbacterialcommunitystructurehasled,sincethebeginningofthe1990s,totheideathatbacterioplanktonpopulationsarestratifiedinthewatercolumnand thatdiverselineageswithmostlyunknownphenotypesdominatemarinemicrobialcommunities.Thediversityofdepth-relatedassemblagesisalsoreflectedintheirpatterns ofactivities,asbacteriaaffiliatedtodifferentgroupscanexpressdifferentactivities inagivenecosystem.Weanalysedbacterialassemblages(DGGEfingerprint-ing) andtheiractivities(prokaryoticcarbonproduction,protease,phosphatase,chitinase,beta-glucosidaseandlipaseactivities)intwoareasintheRossSea,differingmainlyintheirproductivityregime:twostationsarelocatedintheTerraNovaBaypolynyaarea(highlyproductiveduringsummer)andtwoclosetoCapeAdare(lowphytoplanktonbiomassandactivity).Ateverystationapronouncedstratificationofbacterial assemblageswasidentified,highlightingepipelagiccommunitiesdifferingsubstantiallyfromthemesopelagicandthebathypelagiccommunities.Multivariateanalysis suggestedthatpressureandindirectlylight-affectedvariables(i.e.oxygenandfluorescence)hadagreateffectonthebacterialcommunitiesoutcompetingthepossibleinfluencesoftemperatureanddissolvedorganiccarbonconcentration.Generallyactivities decreasedwithdeptheventhoughasignaloftheCircumpolarDeepWater(CDW)atoneofthenorthernstationscorrespondedtoanincreaseinsomeofthedegradativeactivities,generatingsome‘hotspots’intheprofile.Wealsofoundthatsimilarassemblagesexpresssimilarmetabolicrequirementsreflectedinanalogouspatterns ofactivity(similardegradativepotentialandleucineuptakerate).Furthermore,the presenceofeukaryoticchloroplasts’16SrDNAindeepsampleshighlightedhowinsomecasesthedensesurface-waterformation(inthiscaseHighSalinityShelfWater—HSSW) anddownwellingcanaffect,atleastforsomephylotypes,thebacterial(16SrDNAbased)communitystructureofthedarkocean.

Depth profiles of bacterioplankton assemblages and their activities in the Ross Sea

CELUSSI M;CATALETTO B;DEL NEGRO P
2009

Abstract

The identificationofbacterialcommunitystructurehasled,sincethebeginningofthe1990s,totheideathatbacterioplanktonpopulationsarestratifiedinthewatercolumnand thatdiverselineageswithmostlyunknownphenotypesdominatemarinemicrobialcommunities.Thediversityofdepth-relatedassemblagesisalsoreflectedintheirpatterns ofactivities,asbacteriaaffiliatedtodifferentgroupscanexpressdifferentactivities inagivenecosystem.Weanalysedbacterialassemblages(DGGEfingerprint-ing) andtheiractivities(prokaryoticcarbonproduction,protease,phosphatase,chitinase,beta-glucosidaseandlipaseactivities)intwoareasintheRossSea,differingmainlyintheirproductivityregime:twostationsarelocatedintheTerraNovaBaypolynyaarea(highlyproductiveduringsummer)andtwoclosetoCapeAdare(lowphytoplanktonbiomassandactivity).Ateverystationapronouncedstratificationofbacterial assemblageswasidentified,highlightingepipelagiccommunitiesdifferingsubstantiallyfromthemesopelagicandthebathypelagiccommunities.Multivariateanalysis suggestedthatpressureandindirectlylight-affectedvariables(i.e.oxygenandfluorescence)hadagreateffectonthebacterialcommunitiesoutcompetingthepossibleinfluencesoftemperatureanddissolvedorganiccarbonconcentration.Generallyactivities decreasedwithdeptheventhoughasignaloftheCircumpolarDeepWater(CDW)atoneofthenorthernstationscorrespondedtoanincreaseinsomeofthedegradativeactivities,generatingsome‘hotspots’intheprofile.Wealsofoundthatsimilarassemblagesexpresssimilarmetabolicrequirementsreflectedinanalogouspatterns ofactivity(similardegradativepotentialandleucineuptakerate).Furthermore,the presenceofeukaryoticchloroplasts’16SrDNAindeepsampleshighlightedhowinsomecasesthedensesurface-waterformation(inthiscaseHighSalinityShelfWater—HSSW) anddownwellingcanaffect,atleastforsomephylotypes,thebacterial(16SrDNAbased)communitystructureofthedarkocean.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.14083/2270
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