IMpuma yeTropiki kuMntla wePasifiki (ETNP) yindawo enkulu, eqhubekayo, kwaye iqinisa i-oksijini encinci yommandla (i-OMZ) eyenza phantse isiqingatha sommandla opheleleyo wee-OMZ zehlabathi. Ngaphakathi kwe-OMZ core (~350-700 m ubunzulu), i-oksijini echithiweyo iqhelekile kufutshane okanye ingaphantsi komda wokufumanisa uhlalutyo lwezinzwa zanamhlanje (∼10 nM). Imithamo yeoksijini engumnqantsa ngaphezulu nangaphantsi kondoqo we-OMZ ikhokelela kulwakhiwo oluthe nkqo lweendawo ezihlala iintsholongwane ezikwahluka phakathi kwamaqhekeza adityaniswe ngamasuntswana (PA) kunye nobukhulu obukhululekileyo (FL). Apha, sisebenzisa i-16S i-amplicon sequencing (iTags) ukuhlalutya ukuhlukahluka kunye nokusabalalisa kwabantu beprokaryotic phakathi kwe-FL kunye ne-PA ubukhulu beqhekeza kunye phakathi koluhlu lweemeko ze-ambient redox. Iimeko ze-hydrographic kwindawo yethu yokufunda zahlukile kwezo zichazwe ngaphambili kwi-ETNP kunye nezinye ii-OMZ, ezifana ne-ETSP. Ukulandelela i-oxygen concentrations (∼0.35 μM) yayikhona kuyo yonke ingundoqo ye-OMZ kwindawo yethu yesampuli. Ngenxa yoko, uqokelelo lwe-nitrite oluxelwe ngokuqhelekileyo kwii-OMZ cores belungekho njengoko belulandelelwano lwe-anammox bacteria (i-Brocadiales genusUmviwaScalindua), eziqhele ukufunyanwa kwimida yeoxic-anoxic kwezinye iinkqubo. Nangona kunjalo, iibhaktheriya ze-ammonia-oxidizing (AOB) kunye ne-archaea (AOA) yosasazo kunye namazinga aphezulu e-autotrophic carbon assimilation rates (1.4 μM C d–1) ingqamene noxinzelelo oluxeliweyo lweammonium kufutshane nomphezulu we-OMZ core. Ukongeza, amalungu ohloboNitrospina, i-bacterial nitrite-oxidizing bacterial (NOB) eyona nto yayikhona ibonisa ukuba zombini i-ammonia kunye ne-nitrite oxidation yenzeke ekulandeleni i-oxygen concentrations. Uhlalutyo lovavanyo lokufana (ANOSIM) kunye ne-Non-metric Dimensional Scaling (nMDS) lubonise ukuba ukubonakaliswa kwebhaktheriya kunye ne-archaeal phylogenetic kwahluke kakhulu phakathi kwamaqhezu obungakanani. Ngokusekwe kwiprofayili ye-ANOSIM kunye ne-iTag, ukubunjwa kwee-assemblages ze-PA akuchatshazelwa kangako bubunzulu obuxhomekeke kubunzulu be-biogeochemical regime kuneqhezu le-FL. Ngokusekelwe kubukho be-AOA, i-NOB kunye nokulandelela i-oksijini kwisiseko se-OMZ sicebisa ukuba i-nitrification yinkqubo esebenzayo kumjikelezo we-nitrogen walo mmandla we-ETNP OMZ.
Intshayelelo
Ukuphendula kutshintsho lwemozulu oluqhubekayo kunye nemisebenzi yabantu yendawo, ukugxininiswa kwe-oksijini echithiweyo kuye kwancipha kulwandle oluvulekileyo nakwiinkqubo zolwandle zaselwandle (Breitburg et al., 2018). Ilahleko yeoksijini eqikelelweyo evela kulwandlekazi oluvulekileyo kwiminyaka engama-60 edlulileyo idlula i-2% (Schmidtko et al., 2017), ukudala iinkxalabo malunga nemiphumo yokwandiswa kwendawo yokutshatyalaliswa kwe-oxygen (UPaulmier kunye noRuiz-Pino, ngo-2009). Ii-OMZ zolwandle ezivulekileyo zenza imveliso xa imveliso yebhayoloji yebhayoloji ifunxa imfuno yeoksijini kumanzi angaphantsi komhlaba adlula amanqanaba okungena komoya kubunzulu. Ugxininiso lwe-oksijeni kwiikholomu zamanzi ze-OMZ zinokuba ne-gradients (i-oxycline) ngaphezulu nangaphantsi kwe-oxygen-depleted core eyenza i-hypoxic (ngokuqhelekileyo phakathi kwe-2 kunye ne-90 μM), i-suboxic (<2 μM) kunye ne-anoxic (ngaphantsi komda wokufumanisa (∼10 nM) iileya zobukhulu obahlukeneyo (Bertagnolli kunye noStewart, ngo-2018). I-oxygen gradients ikhokelela kulwakhiwo oluthe nkqo lwemetazoan kunye ne-microbial community kunye neenkqubo ze-biogeochemical ecaleni kwezi oxyclines zibanzi.Belmar et al., 2011).
Ezinye zeereyithi eziphezulu zokulahleka kwe-nitrogen zirekhodwe kwi-OMZs ye-Eastern Tropical North Pacific (ETNP) kunye ne-South Pacific (ETSP) (Callbeck et al., 2017;UPenn et al., ngo-2019), iCariaco Basin esisigxina (Montes et al., 2013), uLwandle lwaseArabia (Ward et al., 2009), kunye ne-OMZ yenkqubo yokunyusa iBenguela (Kuypers et al., 2005). Kwezi nkqubo, iinkqubo ze-microbial ze-canonical denitrification (ukunciphisa i-heterotrophic ye-nitrate kwi-nitrogen intermediates kwaye ngokuphindaphindiweyo kwigesi ye-dinitrogen) kunye ne-anammox (i-anaerobic ammonium oxidation) ikhokelela kwilahleko ye-nitrogen enokuthi ithintele imveliso yokuqala.Ward et al., 2007). Ngaphezu koko, ukukhutshwa kwe-oceanic nitrous oxide ekhutshwayo (irhasi yegreenhouse enamandla) evela kwi-microbial denitrification eyenzeka kwi-OMZs kuqikelelwa ukuba ithatha isinye kwisithathu sezinto ezikhutshwayo zendalo zenitrous oxide zehlabathi.Naqvi et al., 2010).
I-ETNP OMZ yindawo enkulu, eqhubekayo, kwaye iqinisa i-oksijini encinci yommandla othatha phantse isiqingatha sendawo yonke yee-OMZ zehlabathi, iphakathi kwe-0-25 ° N ubude kunye ne-75 kunye ne-180 ° W ubude (UPaulmier kunye noRuiz-Pino, ngo-2009;Schmidtko et al., 2017). Ngenxa yokubaluleka kwazo kwendalo, i-biogeochemistry kunye ne-microbial diversity yemimandla eyahlukeneyo ye-ETNP OMZ iye yaphononongwa kakhulu (umz.,UBeman noCarolan, ngo-2013;Duret et al., 2015;Ganesh et al., 2015;Chronopoulou et al., 2017;Ipakethe et al., 2015;Peng et al., 2015). Izifundo zangaphambili zixela ukuba i-oksijini enyibilikileyo kule ngundoqo ye-OMZ (∼250-750 m ubunzulu) iqhelekile okanye ingaphantsi kwemida yokufumanisa uhlalutyo (~10 nM) (UTiano et al., ngo-2014;UGarcia-Robledo et al., ngo-2017). Nangona kunjalo, ecaleni komda ongasentla we-ETNP's OMZ (indawo yokufundela indawo ~22 ° N) i-oxygen concentrations kwi-500 m inokufikelela kumlinganiselo wonyaka phakathi kwe-10 kunye ne-20 μM (UPaulmier kunye noRuiz-Pino, ngo-2009; Idatha evela kwi-World Ocean Atlas 2013)1. Ngethuba lomkhankaso wentsimi ochazwe apha, silinganise i-oksijini kwi-OMZ engundoqo ekugxininiseni okwaneleyo (0.35 μM) ukuxhasa iinkqubo ze-aerobic microbial, ezifana ne-ammonium kunye ne-nitrite oxidation, kwaye inqanda ngokuyinxenye iinkqubo ezibalulekileyo ze-anaerobic microbial. Iinkqubo ze-Aerobic microbial ziye zafunyanwa ngaphambili kwiileya ezibonakala zincinci okanye ze-anoxic ze-ETNP OMZ (Peng et al., 2015;UGarcia-Robledo et al., ngo-2017;UPenn et al., ngo-2019). Nangona kunjalo, izinto ezilawula ukuhanjiswa kunye nemisebenzi yamaqela athile asebenzayo e-microorganisms kwi-OMZ ayikaqondwa ngokupheleleyo.
Ubukho be-nitrifiers apho i-oksijini ingabonakali kwi-OMZ inokuchazwa ngokutshintsha kwangoku kwisithuba esithe nkqo se-oxycline ngenxa ye-episodic vertical vertical oxygen ventilation, engakhokelela kumanqanaba e-oxygen ephemeral ngaphakathi kwe-OMZ cores.Muller-Karger et al., 2001;Ulloa et al., 2012;UGarcia-Robledo et al., ngo-2017). Iimeko ezinjalo ezidlulayo zinokusetyenziswa ngabantu be-aerobic okanye i-microaerophilic, kubandakanywa ne-nitrifiers. Ngaphezu koko, amasuntswana atshonayo asuka kwi-epipelagic (iiseli ezidityanisiweyo, iipellets zefecal, kunye nezinto ezintsonkothileyo zezinto eziphilayo) zinokuqulatha amanqanaba omkhondo weoksijini.Ganesh et al., 2014). Ke, ioksijini kunye ne-aerobic microbes zinokuthuthelwa kumanzi angenayo i-anoxic, okwethutyana ukuvumela i-aerobic metabolism ukuba yenzeke ngokubambisana namasuntswana. Amalungu aziwa njengezona ndawo ziphambili kwibhayisikile yebhayoloji yebhayoloji (USimon et al., ngo-2002;Ganesh et al., 2014) kwaye inokuxhasa ukuchasana kweenkqubo ze-anaerobic okanye ze-aerobic microbial ezingabonwayo kwimeko yokuphila ngokukhululekileyo (Alldredge kunye noCohen, ngo-1987;UWright et al., ngo-2012;Suter et al., 2018).
Kuphononongo lwangoku, siphanda uluntu lweprokaryotic oluhlala kumda osemantla we-ETNP's OMZ kunye nezinto zokusingqongileyo ezinokuchaphazela ukuhanjiswa kwazo ngokuthe nkqo zisebenzisa i-16S i-amplicon sequencing (iTags) edityaniswa nezibalo ezininzi. Sivavanye amaqhezu amabini obungakanani; i-free-living (0.2-2.7 μm) iqhezu, kunye neqhekeza elihambelana neqhekeza (> 2.7 μm, ukubamba amaqhekeza kunye neeseli zeprotistan) kwiindawo ezinzulu ezininzi kunye ne-oxycline ehambelana neemeko ze-redox ezahlukileyo.
Sinokubonelela ngeenzwa ze-oksijini ezinyibilikileyo kunye neeparitha ezahlukeneyo, ukwenzela ukuba i-molecular concentration ikwazi ukubeka iliso ngexesha langempela. Wamkelekile ukudibana
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Ixesha lokuposa: Jul-05-2024