I-Eastern Tropical North Pacific (ETNP) iyindawo encane kakhulu, eqhubekayo, futhi eqinisa umoya-mpilo (OMZ) ehlanganisa cishe ingxenye yendawo yonke yama-OMZ omhlaba. Ngaphakathi kwe-OMZ core (~350–700 m ukujula), umoya-mpilo oncibilikisiwe ngokuvamile useduze noma ngaphansi komkhawulo wokuthola ukuhlaziya wezinzwa zesimanje (~10 nM). Ama-gradients e-oxygen aphezulu ngaphezulu nangaphansi kwe-OMZ core aholela ekwakhiweni okuqondile kwemiphakathi yamagciwane ehlukahluka phakathi kwama-particle-associated (PA) kanye nama-free-living (FL) size fractions. Lapha, sisebenzisa i-16S amplicon sequencing (iTags) ukuhlaziya ukuhlukahluka kanye nokusatshalaliswa kwezinhlobo ze-prokaryotic phakathi kwama-FL kanye nama-PA size fractions kanye naphakathi kwezimo ze-ambient redox. Izimo ze-hydrographic endaweni yethu yokutadisha zazihlukile kulezo ezibikwe ngaphambilini ku-ETNP nakwamanye ama-OMZ, njenge-ETSP. Ama-trace oxygen concentrations (~0.35 μM) ayekhona kulo lonke i-OMZ core endaweni yethu yokuthatha isampula. Ngenxa yalokho, ukuqongelela kwe-nitrite okuvame ukubikwa kuma-OMZ cores kwakungekho njengoba kwakunjalo ngokulandelana kwamagciwane e-anammox (uhlobo lwe-Brocadiales).I-CandidatusI-Scalindua), ezivame ukutholakala ngaphesheya kwemingcele ye-oxic-anoxic kwezinye izinhlelo. Kodwa-ke, ukusatshalaliswa kwamagciwane e-ammonia-oxidizing (AOB) kanye ne-archaea (AOA) kanye namazinga aphezulu okufakwa kwekhabhoni ye-autotrophic (1.4 μM C d–1) kwaqondana nokugcwala okukhulu kwe-ammonium eduze kwengxenye ephezulu ye-OMZ. Ngaphezu kwalokho, amalungu ohloboI-Nitrospina, kwakukhona i-dominant nitrite-oxidizing bacterial (NOB) clade ephakamisa ukuthi kokubili i-ammonia ne-nitrite oxidation zenzeka ekugxilweni kwe-trace oxygen. Ukuhlaziywa kokuhlolwa kokufana (ANOSIM) kanye ne-Non-metric Dimensional Scaling (nMDS) kwembule ukuthi ukumelwa kwe-bacterial kanye ne-archaeal phylogenetic kwakuhluke kakhulu phakathi kwama-size fractions. Ngokusekelwe kumaphrofayili e-ANOSIM kanye ne-iTag, ukwakheka kwama-PA assemblages kwakuthonywe kancane uhlelo lwe-biogeochemical oluncike ekujuleni olukhona kune-FL fraction. Ngokusekelwe ekubeni khona kwe-AOA, NOB kanye ne-trace oxygen enkabeni ye-OMZ siphakamisa ukuthi i-nitrification iyinqubo esebenzayo emjikelezweni we-nitrogen walesi sifunda se-ETNP OMZ.
Isingeniso
Ngenxa yokushintsha kwesimo sezulu okuqhubekayo kanye nemisebenzi yabantu yendawo, amazinga e-oxygen encibilikisiwe aye ehla olwandle oluvulekile nasezinhlelweni zasolwandle ezisogwini (UBreitburg nabanye, 2018). Ukulahlekelwa komoya-mpilo okulinganiselwa olwandle oluvulekile eminyakeni engama-60 edlule kudlula u-2% (USchmidtko nabanye, 2017), okudala ukukhathazeka ngemiphumela yokwanda kwendawo ephelelwe umoya-mpilo (UPaulmier noRuiz-Pino, 2009). Ama-OMZ olwandle avulekile akheka lapho ukukhiqizwa okuphezulu okuphezulu komhlaba kukhuthaza isidingo se-oxygen yezinto eziphilayo emanzini angaphansi komhlaba okudlula amazinga omoya-mpilo ongokoqobo ekujuleni. Ukuhlushwa kwe-oxygen kumakholomu amanzi e-OMZ kungaba ne-gradients ejulile (i-oxycline) ngaphezulu nangaphansi kwengqikithi ephelelwe yi-oxygen edala i-hypoxic (ngokuvamile phakathi kuka-2 no-90 μM), i-suboxic (<2 μM) kanye ne-anoxic (ngaphansi komkhawulo wokutholwa (∼10 nM) izendlalelo zobukhulu obuhlukahlukene (UBertagnolli noStewart, 2018). Ukwehla kwe-oxygen kuholela ekwakhiweni okuqondile kwemiphakathi ye-metazoan kanye ne-microbial kanye nezinqubo ze-biogeochemical kulezi zinhlobo ze-oxyclines ezibanzi (UBelmar nabanye, 2011).
Amanye amazinga aphezulu kakhulu okulahlekelwa yi-nitrogen aqoshwe kuma-OMZ ase-Eastern Tropical North Pacific (ETNP) kanye naseNingizimu Pacific (ETSP) (UCallbeck nabanye, 2017;UPenn nabanye, 2019), iCariaco Basin ehlukaniswe unomphela (UMontes nabanye, 2013), uLwandle lwase-Arabia (UWard nabanye, 2009), kanye ne-OMZ yesistimu yokukhulisa i-Benguela (UKuypers nabanye, 2005Kulezi zinhlelo, izinqubo ezincane ze-canonical denitrification (ukunciphisa i-nitrate nge-heterotrophic kuya kuma-nitrogen intermediates futhi ngokuvamile kuya kugesi ye-dinitrogen) kanye ne-anammox (i-anaerobic ammonium oxidation) kuholela ekulahlekelweni yi-nitrogen okungase kunciphise ukukhiqizwa okuyinhloko (UWard nabanye, 2007Ngaphezu kwalokho, ukukhishwa kwe-nitrous oxide olwandle (igesi enamandla yokushisa) okuvela ekususweni kwe-nitrification yamagciwane okwenzeka kuma-OMZ kulinganiselwa ukuthi kudala okungenani ingxenye yesithathu yokukhishwa kwe-nitrous oxide yemvelo emhlabeni jikelele (UNaqvi nabanye, 2010).
I-ETNP OMZ iyindawo encane kakhulu, eqhubekayo, futhi eqinisa umoya-mpilo ecishe ibe yisigamu sendawo yonke yama-OMZ omhlaba, itholakala phakathi kwe-latitude engu-0–25°N kanye ne-longitude engu-75 kanye no-180°W (UPaulmier noRuiz-Pino, 2009;USchmidtko nabanye, 2017Ngenxa yokubaluleka kwazo kwezemvelo, i-biogeochemistry kanye nokuhlukahluka kwamagciwane ezifundeni ezahlukene ze-ETNP OMZ kuye kwafundwa ngokujulile (isb.,UBeman noCarolan, 2013;UDuret nabanye, 2015;UGanesh nabanye, 2015;UChronopoulou nabanye, 2017;UPack nabanye, 2015;UPeng nabanye, 2015). Izifundo zangaphambilini zibika ukuthi umoya-mpilo oncibilikisiwe kule ngxenye ye-OMZ (ukujula okungu-∼250–750 m) ngokuvamile useduze noma ungaphansi kwemikhawulo yokuthola ukuhlaziya (∼10 nM) (UTiano nabanye, 2014;UGarcia-Robledo nabanye, 2017). Kodwa-ke, eceleni kwenyakatho ye-OMZ ye-ETNP (indawo yesayithi locwaningo ∼22°N) amazinga omoya-mpilo ku-500 m angafinyelela isilinganiso sonyaka esiphakathi kuka-10 no-20 μM (UPaulmier noRuiz-Pino, 2009; Idatha evela ku-World Ocean Atlas 2013)1Ngesikhathi somkhankaso wasensimini obikwe lapha, silinganise umoya-mpilo enkabeni ye-OMZ ngamanani anele (0.35 μM) ukusekela izinqubo zamagciwane e-aerobic, njenge-ammonium kanye ne-nitrite oxidation, futhi sivimbele kancane izinqubo ezibalulekile zamagciwane e-anaerobic. Izinqubo zamagciwane e-aerobic zitholakale ngaphambilini ezingqimbeni ezibonakala zingaphansi kwe-oxygen noma ze-anoxic ze-ETNP OMZ (UPeng nabanye, 2015;UGarcia-Robledo nabanye, 2017;UPenn nabanye, 2019Kodwa-ke, izici ezilawula ukusatshalaliswa kanye nemisebenzi yamaqembu athile asebenzayo ama-microorganisms kuma-OMZ azikaqondakali ngokugcwele.
Ukuba khona kwama-nitrifiers lapho umoya-mpilo ungabonakali khona ku-OMZ kungachazwa ukushintshashintsha kwamuva endaweni eqondile ye-oxycline ngenxa yokuphefumula kwe-oxygen okuqondile okwenzeka ngezikhathi ezithile, okungaholela emazingeni e-oxygen trace esikhashana ngaphakathi kwe-OMZ cores (UMuller-Karger nabanye, 2001;Ulloa nabanye, 2012;UGarcia-Robledo nabanye, 2017). Izimo ezinjalo zesikhashana zingasetshenziswa yi-aerobic noma i-microaerophilic populations, kufaka phakathi ama-nitrifiers. Ngaphezu kwalokho, izinhlayiya ezicwilayo ezivela ku-epipelagic (amaseli ahlanganisiwe, ama-pellets endle, nezinto eziphilayo eziyinkimbinkimbi) zingaqukatha amazinga amancane omoya-mpilo (UGanesh nabanye, 2014Ngakho-ke, umoya-mpilo kanye namagciwane e-aerobic angathuthwa aye emanzini angangcolisi, okuvumela okwesikhashana ukuthi i-metabolism ye-aerobic yenzeke ngokuhambisana nezinhlayiya. Izinhlayiya zaziwa njengezindawo ezishisayo zokujikeleza kwe-biogeochemical yamagciwane (USimon nabanye, 2002;UGanesh nabanye, 2014) futhi ingasekela izinqubo eziphikisanayo ze-anaerobic noma ze-aerobic microbial ezingabonwa esimweni sokuphila ngokukhululeka (U-Alldredge noCohen, ngo-1987;UWright nabanye, 2012;USuter nabanye, 2018).
Esifundweni samanje, sihlola imiphakathi ye-prokaryotic ehlala engxenyeni esenyakatho ye-OMZ ye-ETNP kanye nezici zemvelo ezingase zithonye ukusatshalaliswa kwayo okuqondile kusetshenziswa i-16S amplicon sequencing (iTags) ehlanganiswe nezibalo ze-multivariate. Sihlole izingxenyana ezimbili zosayizi; ingxenye ephilayo yamahhala (0.2–2.7 μm), kanye nengxenyana ehlobene nezinhlayiya (>2.7 μm, ebamba izinhlayiya kanye namaseli e-protistan) ekujuleni okuningi eceleni kwe-oxycline okuhambisana nezimo ezihlukile ze-redox.
Singahlinzeka ngezinzwa ze-oxygen ezincibilikisiwe ngamapharamitha ahlukene, ukuze ukuhlushwa kwama-molecule kuqashwe ngesikhathi sangempela. Siyakwamukela ukubonisana
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Isikhathi sokuthunyelwe: Julayi-05-2024