Biyoloji blanchi koray

Tanperati dlo lanmè ki wo nan konbinezon ak limyè solèy la fò lakòz tèmik estrès nan koray. Sa a estrès ka lakòz dezòd nan pwosesis nòmal fotosentetik nan zooxanthella koray la ki mennen nan koray blanchi.

Lè yon koray blanchi, koloni a pral gen yon aparans blan klere kòm polip yo gratis nan zooxanthellae yo ak Se poutèt sa transparan. Yon koray blanchi vivan men fonksyone ak mwens pase 95% nan sous nitrisyonèl li. Koray yo ka siviv pandan plizyè jou oswa mwa san zooxanthellae yo, men kapasite yo pou yo siviv depann de nivo ak kalite estrès ak sansiblite koray la. Si estrès pèsiste, koray yo ka mouri grangou ak mouri. Si estrès pa pèsiste, Lè sa a, koray yo ka reprann zooxanthellae epi refè. Sepandan, menm si koray yo siviv blanchi, yo ka soufri sub-letal enpak tankou redwi pousantaj kwasans koray ak repwodiksyon ak ogmante sansiblite nan maladi.

Sous: Administrasyon Nasyonal Oseyan ak Atmosfè

Varyasyon nan Sifikiblite Blanchi

Corals differ widely in their susceptibility to bleaching. Historically, bleaching risk followed a fairly consistent pattern, with complex, branching corals tending to be more vulnerable and massive species, particularly those with fleshy polyps showing greater resistance. ref However, this pattern is no longer consistent. Susceptibility now varies across reef regions and is strongly influenced by prior bleaching history. ref For example, during the 2015-2017 bleaching event in the Mesoamerican Reef system, some branching species of Acropora were less susceptible to bleaching than several massive coral species. ref

Bleaching severity index across species in the Mesoamerican reef system during the 2015-2017 bleaching event. Source: Muniz-Castillo et al. 2024

Coral reefs’ susceptibility to bleaching may also vary based on the conditions to which a reef has adapted, its species composition, and reef zonation. ref Corals on reef flats, for example, will often be able to tolerate much higher water temperatures than colonies of the same species inhabiting reef slopes. Within reefs, bleaching susceptibility also varies depending on colony size and stress intensity, ref and two colonies from the same species may exhibit varied responses to stress.

The type of zooxanthellae can also influence bleaching susceptibility. Various species of zooxanthellae (from the genus Symbiodiniacea), previously referred to as “clades”, ref gen diferan sansiblite nan estrès. Pareyman yo ak lame-koray Se poutèt sa, enfliyanse kapasite koray la yo dwe pi rezistan a pi wo tanperati. Sepandan, koray ki gen senbyon ki reziste chalè yo gen tandans grandi pi dousman, ref which is perhaps one reason why slower-growing coral species can sometimes be more tolerant to thermal stress.