Akarere k’Iburasirazuba bw’Amajyaruguru ya Pasifika (ETNP) ni agace kanini, gahoraho kandi gashyira imbaraga mu kirere (OMZ) gafite hafi kimwe cya kabiri cy’ubuso bwose bwa OMZ ku isi. Mu gice cy’imbere cya OMZ (~350–700 m), umwuka wa ogisijeni ushongeshejwe ubusanzwe uba uri hafi cyangwa munsi y’umupaka w’isesengura ry’ibikoresho bigezweho (~10 nM). Imiterere y’umwuka wa ogisijeni hejuru no munsi y’igice cy’imbere cya OMZ ituma habaho imiterere igororotse y’udukoko duto dutandukanye hagati y’uduce dufitanye isano n’udukoko (PA) n’uduce tw’ubunini bw’uturemangingo (FL). Aha, dukoresha uburyo bwa 16S amplicon sequencing (iTags) kugira ngo dusesengure ubudasa n’ikwirakwizwa ry’udukoko twa prokaryotic hagati y’uduce duto twa FL na PA no mu bwoko bw’imiterere ya redox iri mu gace k’ubushakashatsi bwacu. Imiterere y’amazi mu gace k’ubushakashatsi bwacu yari itandukanye n’iyavuzwe mbere muri ETNP no mu zindi OMZ, nka ETSP. Ingano ya ogisijeni (~0.35 μM) yari iri mu gice cy’imbere cya OMZ aho twatoranijwe. Kubera iyo mpamvu, ubwiyongere bwa nitrite bukunze kugaragara ku ngingo za OMZ ntibwari buhari nk'uko byari bimeze kuri bagiteri za anammox (ubwoko bwa Brocadiales).CandidatusScalindua), zikunze kuboneka ku mipaka ya okisike-anokisi mu zindi sisitemu. Ariko, bagiteri zigabanya ammonia (AOB) na archaea (AOA) zikwirakwira hamwe n'igipimo ntarengwa cyo kwinjizwa kwa karuboni mu buryo bwa autotrophic (1.4 μM C d–1) byahuriranye n'igipimo ntarengwa cya ammonium hafi y'igice cyo hejuru cy'inyuma cya OMZ. Byongeye kandi, abagize ubwokoNitrospina, hari ubwoko bwa bagiteri bukoresha nitrite oxidizing bagiteri (NOB) bugaragaza ko oxidation ya ammonia na nitrite bibaho ku rugero rwa ogisijeni. Isesengura ry’ikizamini cyo gusana (ANOSIM) na Non-metric Dimensional Scaling (nMDS) ryagaragaje ko imiterere ya bagiteri na phylogenetic ya kera yari itandukanye cyane hagati y’ibice by’ingano. Hashingiwe ku miterere ya ANOSIM na iTag, imiterere y’ibice bya PA ntiyagizweho ingaruka cyane n’uburyo bwa biogeochemical bushingiye ku bujyakuzimu busanzwe kurusha igice cya FL. Hashingiwe ku kuba hari AOA, NOB na ogisijeni yoroheje mu gice cy’imbere cya OMZ, dutanga igitekerezo cy’uko nitrification ari igikorwa gikora mu mizunguruko ya azote muri aka gace ka ETNP OMZ.
Intangiriro
Mu rwego rwo guhangana n’imihindagurikire y’ikirere ikomeje kubaho ndetse n’ibikorwa by’abantu mu gace runaka, ubwinshi bw’umwuka wa ogisijeni washongeshejwe bwagiye bugabanuka mu nyanja no mu nyanja zo ku nkombe z’inyanja (Breitburg n'abandi, 2018). Igipimo cy'uko umwuka wa ogisijeni watakaye mu nyanja mu myaka 60 ishize kirenze 2% (Schmidtko n'abandi, 2017), bitera impungenge ku ngaruka zo kwaguka k'agace kangiritse umwuka wa ogisijeni (Paulmier na Ruiz-Pino, 2009). OMZ zo mu nyanja zifunguye zibaho iyo umusaruro mwinshi w’ibanze utuma ogisijeni mu binyabuzima ikenerwa mu mazi yo munsi y’ubutaka irenga igipimo cy’umwuka uhumeka mu bujyakuzimu. Igipimo cya ogisijeni mu miyoboro y’amazi ya OMZ gishobora kugira imirasire miremire (okisijeni) hejuru no munsi y’inyuma y’umwuka wa ogisijeni ikora ogisijeni (ubusanzwe iri hagati ya 2 na ~ 90 μM), ogisijeni (<2 μM) na anogisi (munsi y’umupaka wo kumenyekana (∼10 nM) y’ibipimo bitandukanye (Bertagnolli na Stewart, 2018). Imiterere ya ogisijeni ituma habaho imiterere igororotse y'amatsinda ya metazoan na mikorobe ndetse n'imikorere ya biogeochemical kuri izi oksikelini nini (Belmar n'abandi, 2011).
Bimwe mu bipimo byo hejuru cyane by’igihombo cya azote byagaragaye muri OMZ zo mu Burasirazuba bwa Tropical North Pacific (ETNP) na South Pacific (ETSP) (Callbeck n'abandi, 2017;Penn n'abandi, 2019), ikibaya cya Cariaco gihora giherereye mu byiciro (Montes n'abandi, 2013), Inyanja ya Arabiya (Ward n'abandi, 2009), na OMZ ya sisitemu yo kuzamuka ya Benguela (Kuypers n'abandi, 2005). Muri ubu buryo, inzira za mikorobe zo kugabanya nitriti mu buryo bwa canonical (kugabanya nitriti mu buryo bwa heterotrophic mu buryo bwa azote, akenshi no mu mwuka wa dinitrojeni) na anamox (oxidation ya ammonium ya anaerobic) bitera igihombo cya azote gishobora kugabanya umusaruro w'ibanze (Ward n'abandi, 2007Byongeye kandi, imyuka ihumanya ikirere yo mu nyanja (ibyuka bihumanya ikirere) ituruka ku guhumanya ikirere kwa mikorobe biba muri OMZs, bivugwa ko itera nibura kimwe cya gatatu cy'ibyuka bihumanya ikirere ku isi (Naqvi n'abandi, 2010).
ETNP OMZ ni agace kanini, gahoraho kandi gashyira imbaraga nyinshi za ogisijeni gafite hafi kimwe cya kabiri cy'ubuso bwose bwa OMZ ku isi, gaherereye hagati ya latitude ya 0–25°N na longitude ya 75 na 180°W (Paulmier na Ruiz-Pino, 2009;Schmidtko n'abandi, 2017Bitewe n'akamaro kabyo mu bidukikije, imiterere y'ibinyabuzima n'ubuharike bw'udukoko two mu turere dutandukanye twa ETNP OMZ byigwa cyane (urugero:Beman na Carolan, 2013;Duret n'abandi, 2015;Ganesh n'abandi, 2015;Chronopoulou n'abandi, 2017;Pack n'abandi, 2015;Peng n'abandi, 2015). Ubushakashatsi bwakozwe mbere bwagaragaje ko ogisijeni yashongeshejwe muri iyi ngingo ya OMZ (ubujyakuzimu bwa metero 250–750) ubusanzwe iba iri hafi cyangwa munsi y’aho imipaka yo gupima isesengura igarukira (∼10 nM) (Tiano n'abandi, 2014;Garcia-Robledo n'abandi, 2017). Ariko, ku nkengero z'amajyaruguru ya OMZ ya ETNP (aho ubushakashatsi buherereye ~ 22°N) igipimo cya ogisijeni kuri metero 500 gishobora kugera ku mpuzandengo y'umwaka iri hagati ya 10 na 20 μM (Paulmier na Ruiz-Pino, 2009Amakuru yavuye muri Atlas y'inyanja y'Isi yo mu 2013)1Mu gihe cy'ubukangurambaga bwavuzwe hano, twapimye ogisijeni mu mutima wa OMZ ku gipimo gihagije (0.35 μM) kugira ngo dushyigikire ibikorwa bya mikorobe zo mu mwuka, nka ammonium na nitrite oxidation, kandi tubuza igice cy'imikorere y'ingenzi ya mikorobe zo mu mwuka. Ibikorwa bya mikorobe zo mu mwuka byagaragaye mbere mu bice bisa nkaho ari munsi ya ogisijeni cyangwa nta ogisijeni bya ETNP OMZ (Peng n'abandi, 2015;Garcia-Robledo n'abandi, 2017;Penn n'abandi, 2019). Ariko, ibintu bigenzura ikwirakwizwa n'imikorere y'amatsinda yihariye y'imikorere ya mikorobe muri OMZ ntibirasobanuka neza.
Kuba hari nitrifiye aho ogisijeni itagaragara muri OMZ bishobora gusobanurwa n'impinduka ziheruka mu mwanya uhagaze wa ogisijeni bitewe n'umwuka wa ogisijeni uhagaze, bishobora gutuma urugero rwa ogisijeni mu bice bya OMZ rugabanuka (Muller-Karger n'abandi, 2001;Ulloa n'abandi, 2012;Garcia-Robledo n'abandi, 2017). Ibyo bihe by'agateganyo bishobora gukoreshwa n'abantu bahumeka cyangwa bahumeka mu buryo butari bwo, harimo n'ibintu bitera umwuka mubi. Byongeye kandi, uduce twinjira mu mubiri duturuka mu gice cy'inyuma (uturemangingo twuzuyemo ibice, amacandwe, n'ibintu bito by'umwimerere) bishobora kuba birimo urugero ruto rwa ogisijeni (Ganesh n'abandi, 2014). Bityo, ogisijeni na mikorobe zo mu kirere zishobora kujyanwa mu mazi atarimo uburozi, bigatuma by'agateganyo imikorere y'umubiri ikorwa hamwe n'uduce duto. Uduce duto tuzwiho kuba ahantu hakunze kugaragara imikorere y'uturemangingo twa biogeochemical (Simon n'abandi, 2002;Ganesh n'abandi, 2014) kandi ishobora gushyigikira imikorere itandukanye ya mikorobe zidafite umwuka cyangwa aerobic zitagaragara mu buzima bworoshye (Alldredge na Cohen, 1987;Wright n'abandi, 2012;Suter n'abandi, 2018).
Muri ubu bushakashatsi, dukora ubushakashatsi ku miryango ya prokaryotic yiganje mu majyaruguru ya OMZ ya ETNP n'ibintu bidukikije bishobora kugira ingaruka ku miterere yabyo ihagaze hakoreshejwe uburyo bwa 16S amplicon sequencing (iTags) hamwe n'ibarurishamibare rya multivariate. Twasuzumye ibice bibiri by'ingano; igice cy'ubuzima bw'umuntu (0.2–2.7 μm), n'igice cy'uduce dufitanye isano (>2.7 μm, gifata uduce kimwe n'uturemangingo twa protistan) mu bujyakuzimu bwinshi ku ruhande rwa oxycline rujyanye n'imiterere itandukanye ya redox.
Dushobora gutanga ibikoresho byo gupima umwuka wa ogisijeni washongeshejwe bifite ibipimo bitandukanye, kugira ngo igipimo cya molekile gishobore gukurikiranwa mu gihe nyacyo. Murakaza neza kugisha inama.
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Igihe cyo kohereza: Nyakanga-05-2024