Reef-building corals (Scleractinia)

Assembled from 32 blocks · 2 evidence · 23 related

1. Story
2. Colonial cnidarians of the order Scleractinia whose individual polyps — soft, tentacled, a few millimetres across — secrete an external skeleton of aragonite, a crystalline form of calcium carbonate. The colony is the accumulation of thousands of such skeletons; the reef is the accumulation of colonies over centuries to millennia, cemented and bored and re-cemented. Only the zooxanthellate (hermatypic) scleractinians build reefs, and they do it under a narrow set of conditions: clear water, low nutrients, salinity near oceanic, temperatures broadly between about 18 and 30 degrees Celsius, and enough light to run photosynthesis in the tissue. That light requirement, not depth pressure, is why the reef-builders are concentrated in the top few tens of metres. Azooxanthellate scleractinians exist in cold and deep water down to thousands of metres, but they build slowly and are not the subject of this Journey.
3. Knowledge
4. Reef-building corals (Scleractinia)
5. Zooxanthellae (Symbiodiniaceae)
6. Marine heatwave
7. Connections
8. Marine heatwave
9. Zooxanthellae (Symbiodiniaceae)
10. Zooxanthellae (Symbiodiniaceae)
11. Coral bleaching
12. Crown-of-thorns starfish (Acanthaster)
13. Elkhorn coral (Acropora palmata)
14. Darwin publishes The Structure and Distribution of Coral Reefs
15. The first global mass bleaching event
16. A published projection that reefs would bleach faster than they could recover
17. Mass bleaching on the Great Barrier Reef
18. The interval between severe bleaching events is measured, and it has collapsed
19. Reef-building corals (Scleractinia)
20. Coral bleaching
21. Thermal refugia
22. Coral restoration methods
23. Mass bleaching on the Great Barrier Reef during a La Nina
24. Extreme water temperatures in the Florida Keys kill nursery and wild coral
25. Reef-building corals (Scleractinia)
26. Reef-building corals (Scleractinia)
27. Coral calcification
28. The first global mass bleaching event
29. The coral symbionts are reclassified into a family of genera
30. Evidence
31. Zooxanthellae translocate a large majority of fixed carbon to the coral host, which is what allows reef-building corals to thrive in nutrient-poor tropical water. V55 verification basis: not consulted in this session; the paper was identified and its central finding stated from the producing model's knowledge of the symbiosis literature. Page range not given rather than invented.
32. Global shallow coral reef area is on the order of a few hundred thousand square kilometres — under a tenth of one per cent of the ocean surface — while supporting a very large share of marine species. V55 verification basis: not consulted; the atlas's often-quoted global area figure (about 284,300 square kilometres) is stated from the producing model's knowledge. Later satellite mapping has produced substantially different totals on different definitions, and that discrepancy could not be reconciled here.