I-Eastern Tropical North Pacific (ETNP) yindawo enkulu, ehlala ihleli, kwaye iqinisa i-oxygen minimum zone (OMZ) ethatha phantse isiqingatha sommandla wonke we-OMZ zehlabathi. Ngaphakathi kwe-OMZ core (∼350–700 m ubunzulu), i-oxygen enyibilikisiweyo idla ngokuba kufutshane okanye ngaphantsi komda wokufumanisa uhlalutyo lwee-sensors zanamhlanje (∼10 nM). Ii-gradients ze-oxygen ezithe tyaba ngaphezulu nangaphantsi kwe-OMZ core zikhokelela kwisakhiwo esithe nkqo see-microbial communities ezahluka phakathi kwee-particle-associated (PA) kunye nee-free-living (FL) size fractions. Apha, sisebenzisa i-16S amplicon sequencing (iTags) ukuhlalutya ukwahluka kunye nokusasazwa kwe-prokaryotic populations phakathi kwe-FL kunye ne-PA size fractions kunye noluhlu lweemeko ze-ambient redox. Iimeko ze-hydrographic kwindawo yethu yokufunda zahlukile kwezo zichazwe ngaphambili kwi-ETNP nakwezinye ii-OMZ, ezifana ne-ETSP. Ii-trace oxygen concentrations (∼0.35 μM) zazikho kuyo yonke i-OMZ core kwindawo yethu yokuthatha isampuli. Ngenxa yoko, ukuqokelelwa kwe-nitrite okuxelwa rhoqo kwi-OMZ cores bekungekho njengoko bekunjalo nakwiibhaktheriya ze-anammox (uhlobo lweBrocadiales).I-CandidatusI-Scalindua), ezifumaneka rhoqo kwimida ye-oxic-anoxic kwezinye iinkqubo. Nangona kunjalo, ukusasazwa kwebhaktheriya ye-ammonia-oxidizing (AOB) kunye ne-archaea (AOA) kunye namazinga aphezulu okuhlanganiswa kwekhabhoni ye-autotrophic (1.4 μM C d–1) ihambelane nomlinganiselo ophezulu we-ammonium kufutshane nomphezulu we-OMZ core. Ukongeza, amalungu ohloboI-Nitrospina, kukho i-dominant nitrite-oxidizing bacterial (NOB) clade ebonisa ukuba zombini i-ammonia kunye ne-nitrite oxidation zenzeka kwi-trace oxygen concentrations. Uhlalutyo lovavanyo lokufana (ANOSIM) kunye ne-Non-metric Dimensional Scaling (nMDS) lutyhile ukuba ii-bacterial kunye ne-archaeal phylogenetic representation zahluke kakhulu phakathi kwamaqhezu obungakanani. Ngokusekelwe kwiiprofayili ze-ANOSIM kunye ne-iTag, ukwakheka kwee-PA assemblages akuzange kuchaphazeleke kakhulu yi-previous deep-dependent biogeochemical regime exhomekeke kwi-FL fraction. Ngokusekelwe kubukho be-AOA, NOB kunye ne-trace oxygen kwi-OMZ core sicebisa ukuba i-nitrification yinkqubo esebenzayo kumjikelo we-nitrogen wale ndawo ye-ETNP OMZ.
Intshayelelo
Ukuphendula kutshintsho lwemozulu oluqhubekayo kunye nemisebenzi yabantu basekuhlaleni, ubuninzi beoksijini enyibilikisiweyo buyehla elwandle oluvulekileyo nakwiinkqubo zolwandle oluselunxwemeni (UBreitburg nabanye, ngo-2018). Ukulahleka kweoksijini okuqikelelweyo okuvela elwandle oluvulekileyo kwiminyaka engama-60 edlulileyo kudlula i-2% (USchmidtko nabanye, ngo-2017), nto leyo ebangela iinkxalabo malunga nemiphumo yokwanda kwendawo ephelelwe yioksijini (UPaulmier kunye noRuiz-Pino, ngo-2009). Ii-OMZ zolwandle oluvulekileyo zenzeka xa imveliso ephezulu ephezulu ivuselela imfuno ye-oksijini yebhayoloji emanzini angaphantsi komhlaba edlula amazinga omoya ophilayo kubunzulu. Uxinzelelo lwe-oksijini kwimiqolo yamanzi ye-OMZ lunokuba ne-gradients ende (i-oxycline) ngaphezulu nangaphantsi kombindi ophelelwe yi-oksijini odala i-hypoxic (ngesiqhelo phakathi kwe-2 kunye ne-90 μM), i-suboxic (<2 μM) kunye ne-anoxic (ngaphantsi komda wokufumanisa (∼10 nM) iileya zobukhulu obahlukeneyo (UBertagnolli kunye noStewart, 2018). Ukutshintsha kwe-oksijini kukhokelela kwisakhiwo esithe nkqo see-metazoan kunye nee-microbial communities kunye neenkqubo ze-biogeochemical kule mijelo mikhulu ye-oxyclines (UBelmar nabanye, ngo-2011).
Amanye amazinga aphezulu okulahleka kwe-nitrogen abhalwe kwi-OMZs zaseMpuma yeTropical North Pacific (ETNP) kunye neSouth Pacific (ETSP) (UCallbeck nabanye, ngo-2017;UPenn nabanye, ngo-2019), iCariaco Basin ehlala ihlukaniswe ngokwezigaba (UMontes nabanye, ngo-2013), uLwandle lwase-Arabia (UWard nabanye, ngo-2009), kunye ne-OMZ yenkqubo yokunyuka kweBenguela (UKuypers nabanye, ngo-2005). Kwezi nkqubo, iinkqubo ze-microbial ze-canonical denitrification (ukunciphisa i-nitrate kwi-nitrogen intermediates kwaye rhoqo kwi-dinitrogen gas) kunye ne-anammox (i-anaerobic ammonium oxidation) zikhokelela ekulahlekelweni yi-nitrogen okunokuthi kuthintele imveliso yokuqala (UWard nabanye, ngo-2007Ngaphezu koko, ukukhutshwa kwe-nitrous oxide yolwandle (igesi enamandla yokushisa) evela kwi-microbial disanitrification eyenzeka kwi-OMZs kuqikelelwa ukuba ibangela ubuncinane isithathu sesithathu sokukhutshwa kwe-nitrous oxide yendalo kwihlabathi liphela (UNaqvi nabanye, ngo-2010).
I-ETNP OMZ yindawo encinci ye-oxygen, ehlala ihleli, kwaye iqinisa amandla ethatha phantse isiqingatha sommandla uphela we-OMZs zehlabathi, ikwindawo ephakathi kwe-0–25°N latitude kunye ne-75 kunye ne-180°W longitude (UPaulmier kunye noRuiz-Pino, ngo-2009;USchmidtko nabanye, ngo-2017Ngenxa yokubaluleka kwazo kwindalo, i-biogeochemistry kunye nokwahlukahlukana kweentsholongwane kwiindawo ezahlukeneyo ze-ETNP OMZ kuye kwafundwa ngokunzulu (umz.,UBeman noCarolan, ngo-2013;UDuret nabanye, ngo-2015;UGanesh nabanye, ngo-2015;UChronopoulou nabanye, ngo-2017;UPack nabanye, ngo-2015;UPeng nabanye, ngo-2015Izifundo zangaphambili zibika ukuba ioksijini enyibilikisiweyo kule ngundoqo ye-OMZ (∼250–750 m ubunzulu) idla ngokuba kufutshane okanye ngaphantsi kwemida yokufumanisa uhlalutyo (∼10 nM) (UTiano nabanye, ngo-2014;UGarcia-Robledo nabanye, ngo-2017Nangona kunjalo, ecaleni komda ongasentla we-OMZ ye-ETNP (indawo yesifundo ∼22°N) amazinga eoksijini kwi-500 m anokufikelela kwi-avareji yonyaka phakathi kwe-10 kunye ne-20 μM (UPaulmier kunye noRuiz-Pino, ngo-2009Idatha evela kwi-World Ocean Atlas ka-2013)1Ngexesha lephulo lasentsimini elixelwe apha, silinganise ioksijini kwisiseko se-OMZ ngamaqondo aneleyo (0.35 μM) ukuxhasa iinkqubo ze-aerobic microbial, ezifana ne-ammonium kunye ne-nitrite oxidation, kwaye sithintele kancinci iinkqubo ezibalulekileyo ze-anaerobic microbial. Iinkqubo ze-aerobic microbial ziye zafunyanwa ngaphambili kwiindawo ezibonakala ngathi zingaphantsi okanye azinawo umoya we-ETNP OMZ (UPeng nabanye, ngo-2015;UGarcia-Robledo nabanye, ngo-2017;UPenn nabanye, ngo-2019Nangona kunjalo, izinto ezilawula ukusasazwa kunye nemisebenzi yamaqela athile asebenzayo eentsholongwane ezincinci kwi-OMZ azikaqondwa ngokupheleleyo.
Ubukho be-nitrifiers apho ioksijini ingafumanekiyo kwi-OMZ bunokuchazwa kukutshintsha kwamva nje kwindawo ethe nkqo ye-oxycline ngenxa yomoya we-oksijini othe nkqo, okunokukhokelela kumanqanaba e-oxygen trace engapheliyo ngaphakathi kwee-OMZ cores (UMuller-Karger nabanye, ngo-2001;Ulloa nabanye, ngo-2012;UGarcia-Robledo nabanye, ngo-2017Ezi meko zexeshana zingasetyenziswa zii-aerobic okanye ii-microaerophilic populations, kuquka ii-nitrifiers. Ngaphezu koko, amasuntswana atshonayo kwi-epipelagic (iiseli ezidibeneyo, ii-fecal pellets, kunye nezinto eziphilayo ezintsonkothileyo) anokuba namanqanaba amancinci eoksijini (UGanesh nabanye, ngo-2014). Ngoko ke, ioksijini kunye neentsholongwane ze-aerobic zinokuthuthwa ziye emanzini angenatyhefu, okwethutyana zivumele ukuba i-aerobic metabolisms yenzeke ngokunxulumene namasuntswana. Amasuntswana aziwa njengeendawo ezishushu zokujikeleza kwe-biogeochemical ye-microbial (USimon nabanye, ngo-2002;UGanesh nabanye, ngo-2014) kwaye inokuxhasa iinkqubo ezahlukeneyo ze-anaerobic okanye ze-aerobic microbial ezingabonwayo kwimeko yokuphila ngokukhululekileyo (U-Alldredge kunye noCohen, ngo-1987;UWright nabanye, ngo-2012;USuter nabanye, ngo-2018).
Kolu phononongo lwangoku, siphanda uluntu lwe-prokaryotic oluhlala kumda ongasentla we-ETNP's OMZ kunye nezinto ezingqongileyo ezinokuthi zichaphazele ukusasazwa kwazo ngokuthe nkqo kusetyenziswa i-16S amplicon sequencing (iTags) edibene nezibalo ze-multivariate. Sihlolisise amaqhezu amabini obungakanani; iqhezu elihlala likhululekile (0.2–2.7 μm), kunye neqhezu elinxulumene ne-particle (>2.7 μm, elibamba amaqhezu kunye neeseli ze-protistan) kubunzulu obuninzi ecaleni kwe-oxycline ehambelana neemeko ezahlukeneyo ze-redox.
Singabonelela ngee-sensors ze-oxygen ezinyibilikisiweyo ezineeparameter ezahlukeneyo, ukuze uxinzelelo lweemolekyuli lujongwe ngexesha langempela. Wamkelekile ukubonisana nathi
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Ixesha leposi: Julayi-05-2024