I-Eastern Tropical North Pacific (ETNP) iyindawo enkulu, eqhubekayo, futhi eqinisayo (OMZ) ehlanganisa cishe ingxenye yendawo yonke yama-OMZ omhlaba. Ngaphakathi kwe-OMZ core (~350–700 m ukujula), umoya-mpilo oncibilikisiwe useduze noma ungaphansi komkhawulo wokutholwa kohlaziyo wezinzwa zesimanje (∼10 nM). Imithamo yomoya-mpilo eqinile ngenhla nangaphansi kwengqikithi ye-OMZ iholela ekwakhiweni okuqondile kwemiphakathi yamagciwane aphinde ahluke phakathi kwamafrakshini kasayizi we-particle-associated (PA) kanye no-free-living (FL). Lapha, sisebenzisa i-16S amplicon sequencing (iTags) ukuze sihlaziye ukuhlukahluka nokusatshalaliswa kwezibalo ze-prokaryotic phakathi kwamafrakshini kasayizi we-FL kanye ne-PA kanye naphakathi kobubanzi bezimo ze-ambient redox. Izimo ze-hydrographic endaweni yethu yocwaningo bezihlukile kulezo ezibikwe ngaphambilini ku-ETNP nakwamanye ama-OMZ, njenge-ETSP. Landelela ukugxila komoyampilo (∼0.35 μM) bekukhona kuwo wonke umnyombo we-OMZ endaweni yethu yamasampula. Ngakho-ke, ukuqoqwa kwe-nitrite okuvame ukubikwa kuma-OMZ cores kwakungekho njengoba kwakungukulandelana kwamagciwane e-anammox (uhlobo lwe-Brocadiales).I-CandidatusScalindua), evame ukutholakala kumingcele ye-oxic-anoxic kwezinye izinhlelo. Kodwa-ke, amagciwane e-ammonia-oxidizing (AOB) kanye ne-archaea (AOA) ukusatshalaliswa kanye namazinga aphezulu e-autotrophic carbon assimilation rates (1.4 μM C d–1) kuhambisane nenani elikhulu le-ammonium elishiwo eduze kwaphezulu kwe-OMZ core. Ngaphezu kwalokho, amalungu ohloboI-Nitrospina, i-nitrite-oxidizing bacterial clade evelele (NOB) yayikhona ephakamisa ukuthi kokubili i-ammonia ne-nitrite oxidation kwenzeka ekugxilweni komoyampilo okulandela umkhondo. Ukuhlaziywa kokuhlolwa kokufana (ANOSIM) kanye ne-Non-metric Dimensional Scaling (nMDS) kwembula ukuthi izethulo zebhaktheriya ne-archaeal phylogenetic zazihluke kakhulu phakathi kwamafrakhishini osayizi. Ngokusekelwe kumaphrofayela e-ANOSIM ne-iTag, ukwakheka kwama-assemblages e-PA kwakuthonywe kancane umbuso we-biogeochemical oncike ekujuleni kunengxenye ye-FL. Ngokusekelwe ebukhoneni be-AOA, i-NOB kanye nokulandela umoya-mpilo kumongo we-OMZ siphakamisa ukuthi i-nitrification iyinqubo esebenzayo kumjikelezo we-nitrogen walesi sifunda se-ETNP OMZ.
Isingeniso
Ukusabela ekushintsheni kwesimo sezulu okuqhubekayo kanye nemisebenzi yabantu yendawo, ukugxila kwe-oxygen encibilikile kuye kwehla olwandle oluvulekile nasezinhlelweni zasolwandle zasogwini (Breitburg et al., 2018). Ukulahlekelwa komoyampilo okulinganiselwe olwandle oluvulekile phakathi neminyaka engama-60 edlule kudlula u-2% (Schmidtko et al., 2017), ukudala ukukhathazeka mayelana nemiphumela yokwandiswa kwendawo ephelelwe umoya-mpilo (U-Paulmier no-Ruiz-Pino, ngo-2009). Ama-OMZ olwandle avulekile akheka lapho ukukhiqizwa okuphezulu okungaphezulu komhlaba kubhebhezela isidingo somoya-mpilo webhayoloji emanzini angaphansi komhlaba adlula amazinga okungena komoya okubonakalayo ekujuleni. Ukugxiliswa komoyampilo kumakholomu amanzi e-OMZ kungaba nama-gradients aphakeme (i-oxycline) ngaphezulu nangaphansi kwe-oxygen-depleted core edala i-hypoxic (imvamisa phakathi kuka-2 no-∼∼90 μM), i-suboxic (<2 μM) ne-anoxic (ngaphansi komkhawulo wokutholwa (∼10 nM) izendlalelo zobukhulu obuhlukahlukene (U-Bertagnolli no-Stewart, ngo-2018). Ama-oxygen gradients aholela ekwakhiweni okuqondile kwemiphakathi ye-metazoan kanye ne-microbial kanye nezinqubo ze-biogeochemical kulezi zi-oxyclines ezibanzi (Belmar et al., 2011).
Amanye amanani aphezulu kakhulu okulahleka kwe-nitrogen arekhodiwe kuma-OMZ e-Eastern Tropical North Pacific (ETNP) naseNingizimu Pacific (ETSP) (U-Callbeck et al., 2017;U-Penn et al., 2019), i-Cariaco Basin ehlelwe unomphela (Montes et al., 2013), uLwandle lwase-Arabia (Ward et al., 2009), kanye ne-OMZ yohlelo lokukhuphula i-Benguela (Kuypers et al., 2005). Kulezi zinhlelo, izinqubo ze-microbial ze-canonical denitrification (ukunciphisa i-heterotrophic ye-nitrate ibe yi-nitrogen intermediate futhi ngokuvamile ibe yigesi ye-dinitrogen) kanye ne-anammox (i-anaerobic ammonium oxidation) iholela ekulahlekeni kwe-nitrogen okungase kube nomkhawulo ekukhiqizeni okuyinhloko (Ward et al., 2007). Ngaphezu kwalokho, ukukhishwa kwe-oceanic nitrous oxide (igesi ebamba ukushisa enamandla) evela ku-microbial denitrification okwenzeka kuma-OMZ kulinganiselwa ukuthi kubangele okungenani ingxenye eyodwa kwezintathu yokukhishwa kwe-nitrous oxide yemvelo emhlabeni jikelele (Naqvi et al., 2010).
I-ETNP OMZ iyindawo enkulu, eqhubekayo, futhi eqinisayo encane ye-oxygen encane ehlanganisa cishe uhhafu wendawo yonke yama-OMZ omhlaba, itholakala phakathi ko-0–25°N latitude kanye no-75 kanye no-180°W longitude (U-Paulmier no-Ruiz-Pino, ngo-2009;Schmidtko et al., 2017). Ngenxa yokubaluleka kwazo kwezemvelo, i-biogeochemistry kanye nokuhlukahluka kwe-microbial ezifundeni ezahlukene ze-ETNP OMZ kuye kwacutshungulwa kakhulu (isib.U-Beman no-Carolan, ngo-2013;Duret et al., 2015;Ganesh et al., 2015;Chronopoulou et al., 2017;Iphakethe et al., 2015;Peng et al., 2015). Ucwaningo lwangaphambilini lubika ukuthi umoya-mpilo oncibilikisiwe kulo mongo we-OMZ (~250–750 m ukujula) ngokuvamile useduze noma ungaphansi kwemikhawulo yokutholwa kohlaziyo (∼10 nM) (Tiano et al., 2014;U-Garcia-Robledo et al., 2017). Kodwa-ke, ngasemngceleni osenyakatho we-ETNP's OMZ (indawo yesayithi lokufunda ~22°N) ukugxila kwe-oxygen ku-500 m kungafinyelela isilinganiso sonyaka phakathi kuka-10 no-20 μM (U-Paulmier no-Ruiz-Pino, ngo-2009; Idatha evela ku-World Ocean Atlas 2013)1. Phakathi nomkhankaso wensimu obikwe lapha, silinganise umoya-mpilo kumgogodla we-OMZ ekugxilweni okwanele (0.35 μM) ukusekela izinqubo ze-aerobic microbial, ezifana ne-ammonium ne-nitrite oxidation, futhi sivimbele kancane izinqubo ezibalulekile ze-anaerobic microbial. Izinqubo ze-Aerobic microbial ziye zatholwa ngaphambili ezingqimbeni ezibonakala zincane noma ze-anoxic ze-ETNP OMZ (Peng et al., 2015;U-Garcia-Robledo et al., 2017;U-Penn et al., 2019). Kodwa-ke, izici ezilawula ukusatshalaliswa kanye nemisebenzi yamaqembu athile asebenzayo ama-microorganisms kuma-OMZ awakaqondwa ngokugcwele.
Ukuba khona kwama-nitrifiers lapho i-oxygen ingabonakali ku-OMZ ingachazwa ngamashifu akamuva endaweni eqondile ye-oxycline ngenxa ye-episodic vertical vertical oxygen ventilation, okungaholela emazingeni e-ephemeral trace oxygen ngaphakathi kwama-OMZ cores (U-Muller-Karger et al., 2001;Ulloa et al., 2012;U-Garcia-Robledo et al., 2017). Izimo zesikhashana ezinjalo zingasetshenziswa ngabantu be-aerobic noma ama-microaerophilic, kuhlanganise nama-nitrifiers. Ngaphezu kwalokho, izinhlayiya ezicwilayo ezivela ku-epipelagic (amangqamuzana ahlanganisiwe, ama-fecal pellets, nezinto eziphilayo eziyinkimbinkimbi) zingaqukatha amazinga okulandelana komoya-mpilo (Ganesh et al., 2014). Ngakho-ke, umoya-mpilo kanye nama-microbes e-aerobic angathuthwa aye emanzini angenayo i-anoxic, okuvumela okwesikhashana ukuguquguquka kwe-aerobic ukuthi kwenzeke ngokuhambisana nezinhlayiya. Izinhlayiya zaziwa njengezindawo ezishisa izikhotha ze-microbial biogeochemical cycling (USimon et al., 2002;Ganesh et al., 2014) futhi ingasekela izinqubo eziphikisanayo ze-anaerobic noma i-aerobic microbial ezingabonwa esimweni sokuphila mahhala (U-Alldredge noCohen, ngo-1987;Wright et al., 2012;USuter et al., 2018).
Ocwaningweni lwamanje, siphenya imiphakathi ye-prokaryotic ehlala emaphethelweni asenyakatho ye-ETNP's OMZ kanye nezici zemvelo okungenzeka zibe nomthelela ekusabalaliseni kwabo okuma mpo kusetshenziswa ukulandelana kwe-amplicon engu-16S (iTags) okuhlanganiswe nezibalo ezihlukahlukene. Sihlole amafrakhishini osayizi ababili; i-free-living (0.2-2.7 μm) ingxenyenazana, kanye nengxenye ehambisana nezinhlayiyana (>2.7 μm, ibamba izinhlayiya kanye namaseli e-protistan) ekujuleni okuningi eduze kwe-oxycline ehambisana nezimo ze-redox ezihlukile.
Singahlinzeka ngezinzwa zomoya-mpilo ezincibilikisiwe ngemingcele ehlukene, ukuze ukugxilwa kwamangqamuzana kuqashelwe ngesikhathi sangempela. Siyakwamukela ukubonisana
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Isikhathi sokuthumela: Jul-05-2024