Ruwan murjani

**Coral bleaching** shine tsari lokacin da corals suka zama fari saboda asarar algae da pigments na photosynthetic. Wannan asarar pigment na iya haifar da damuwa daban-daban, kamar canje-canje a cikin zafin ruwa, haske, salinity, ko abubuwan gina jiki. Coral mai tsabta ba lallai bane ya mutu, kuma wasu corals na iya tsira. Koyaya, murjani mai launin shudi yana cikin damuwa, yana da haɗari ga yunwa da cututtuka, kuma yana cikin haɗarin mutuwa.   Babban dalilin murfin murjani shine hauhawar yanayin teku saboda Canjin yanayi.

Bleaching yana faruwa ne lokacin da coral polyps ke fitar da zooxanthellae (dinoflagellate da ake kira algae) waɗanda ke zaune a cikin ƙwayoyin su, suna sa murjani ya zama fari. Zooxanthellae sune photosynthetic, kuma yayin da zafin ruwa ya tashi, suna fara samar da nau'in iskar oxygen. Wannan yana da guba ga murjani, don haka murjani yana fitar da zooxanthellae. Tun da zooxanthellae ke samar da mafi yawan launi na murjani, kwayar murjani ta zama bayyananne, tana nuna kwarangwal na murjani da aka yi da calcium carbonate. Yawancin murjani masu haske suna bayyana fari mai haske, amma wasu suna da shuɗi, rawaya, ko ruwan hoda saboda sunadarai masu launi a cikin murjani.

Corals masu tsabta suna ci gaba da rayuwa, amma sun fi fuskantar cututtuka da yunwa. Zooxanthellae suna samar da har zuwa kashi 90 cikin dari na makamashi na murjani,  don haka ana hana murjani abinci mai gina jiki lokacin da aka fitar da zooxanthellaes.  Wasu murjani suna murmurewa  idan yanayi ya koma yadda ya kamata,  kuma wasu murjani na iya ciyar da kansu. Koyaya, yawancin murjani ba tare da zooxanthellae ba suna fama da yunwa.

Yawancin lokaci, coral polyps suna rayuwa a cikin dangantaka ta endosymbiotic tare da zooxanthellae .  Wannan dangantakar tana da mahimmanci ga lafiyar murjani da reef,  wanda ke ba da mafaka ga kusan kashi 25% na rayuwar ruwa.  A cikin wannan dangantakar, murjani yana ba da mafaka ga zooxanthellae. A sakamakon haka, zooxanthellae suna samar da mahadi waɗanda ke ba da makamashi ga murjani ta hanyar photosynthesis. Wannan dangantakar ta ba da damar murjani ya tsira aƙalla shekaru miliyan 210 a cikin yanayin da ba shi da abinci mai gina jiki. Rashin haske na coral ya haifar da rushewar wannan dangantakar.

Babban dalilin murfin murjani shine hauhawar yanayin teku saboda Canjin yanayi wanda Ayyukan ɗan adam suka haifar. Yawan zafin jiki game da 1 ° C (ko 2 ° F) sama da matsakaici na iya haifar da fari. Tekun yana ɗaukar babban ɓangare na hayakin carbon dioxide (CO2) wanda aikin ɗan adam ya samar. Kodayake wannan ɗaukar yana taimakawa wajen daidaita yanayin zafi na duniya, yana kuma canza sunadarai na teku a hanyoyin da ba a taɓa gani ba.  Acidification na teku (OA) shine raguwar pH na ruwan teku wanda ya haifar da shan carbon dioxide na mutum daga yanayi. Wannan raguwar pH na ruwan teku yana da tasiri sosai a kan yanayin halittu na ruwa.&nbsp;&nbsp;

Dangane da Shirin Muhalli na Majalisar Dinkin Duniya, tsakanin 2014 da 2016, abubuwan da suka fi tsayi a duniya sun kashe murjani a kan sikelin da ba a taɓa gani ba. A cikin 2016, furewar murjani a kan Babban Barrier Reef ya kashe kashi 29 zuwa 50 cikin dari na murjani na reef.    A cikin 2017, furewar ta kai ga yankin tsakiya na reef. Matsakaicin lokacin tsakanin abubuwan da suka faru ya ragu tsakanin 1980 da 2016. An yi rikodin abubuwan da suka faru a cikin 2020, 2021, da 2022 a kan Babban Barrier Reef da kuma a kan reefs a Yammacin Australia. Tsakanin 2023 da 2024, taron rikodin na huɗu ya faru, tare da damuwa mai zafi da aka samu a kowane babban tafkin teku na Arewacin Hemisphere da Kudancin Hemispher. Ana iya samun murjani masu haƙuri a duniya a kudancin Tekun Farisa. Wasu daga cikin wadannan murjani suna fure ne kawai lokacin da yanayin ruwa ya wuce ~35 ° C.  &nbsp;

Corals da ke samar da manyan yanayin halittu na teku na wurare masu zafi sun dogara da alaƙar symbiotic tare da algae-like single-cell flagellate protozoa da ake kira zooxanthellae waɗanda ke zaune a cikin ƙwayoyin su kuma suna ba da murjani launi. Zooxanthellae suna ba da murjani da abubuwan gina jiki ta hanyar photosynthesis, wani muhimmin abu a cikin ruwa mai tsabta da rashin abinci mai gina jiki. A musayar, murjani yana ba da zooxanthellae tare da carbon dioxide da ammonium da ake buƙata don photosynthesis. Yanayin muhalli mara kyau, kamar yanayin zafi ko sanyi, haske mai ƙarfi, har ma da wasu cututtukan ƙwayoyin cuta, na iya haifar da rushewar coral / zooxanthellae symbiosis. Don tabbatar da rayuwa ta ɗan gajeren lokaci, coral-polyp sannan ya cinye ko ya fitar da zooxanthellae. Wannan yana haifar da haske ko fari gaba ɗaya, saboda haka kalmar "mai tsabta". A karkashin yanayin damuwa mai sauƙi, wasu murjani na iya bayyana mai haske mai launin shudi, ruwan hoda, purple, ko rawaya maimakon fari, saboda ci gaba ko karuwar kasancewar kwayoyin sinadarin murjani na ƙwayoyin murjani, wani abu da aka sani da "launi mai launi". Kamar yadda zooxanthellae ke samar da har zuwa kashi 90 cikin 100 na bukatun makamashi na murjani ta hanyar samfuran photosynthesis, bayan fitarwa, murjani na iya fara fama da yunwa

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