Crown-of-thorns starfish (Acanthaster)

Assembled from 41 blocks · 2 evidence · 31 related

1. Story
2. A large corallivorous sea star that everts its stomach over living coral and digests the tissue off the skeleton, leaving white scar. It is native and normally present at low densities; the problem is outbreaks, in which densities rise by orders of magnitude and a reef can lose most of its living coral within a few years. Genetic work published in 2008 showed that what had been treated as a single Indo-Pacific species, Acanthaster planci, is at least four species with distinct ranges, so accounts written before that date describe a composite. On the Great Barrier Reef, analysis of twenty-seven years of monitoring attributed forty-two per cent of the observed coral cover loss between 1985 and 2012 to crown-of-thorns predation — more than bleaching contributed over the same period, and second only to tropical cyclones. Why outbreaks happen is genuinely unresolved: the leading hypothesis is that nutrient runoff from agriculture boosts the phytoplankton that starfish larvae eat, raising larval survival; competing accounts invoke removal of predators, or natural population cycles that outbreak regardless.
3. Knowledge
4. Reef-building corals (Scleractinia)
5. Great Barrier Reef
6. Crown-of-thorns starfish (Acanthaster)
7. Connections
8. Great Barrier Reef
9. Reef-building corals (Scleractinia)
10. Twenty-seven years of monitoring show coral cover roughly halved
11. The 27-year decline of coral cover on the Great Barrier Reef and its causes
12. Coral Triangle
13. Mesoamerican Barrier Reef System
14. Crown-of-thorns starfish (Acanthaster)
15. Australian Institute of Marine Science
16. Great Barrier Reef Marine Park Authority
17. Great Barrier Reef Marine Park Act creates a single managing authority
18. The Great Barrier Reef is inscribed on the World Heritage List
19. Mass synchronous spawning described on the Great Barrier Reef
20. The Long-Term Monitoring Program begins annual reef surveys
21. A measured decline in Great Barrier Reef coral calcification is published
22. Twenty-seven years of monitoring show coral cover roughly halved
23. Mass bleaching on the Great Barrier Reef
24. A second consecutive year of mass bleaching on the Great Barrier Reef
25. Mass bleaching on the Great Barrier Reef during a La Nina
26. The fifth mass bleaching on the Great Barrier Reef since 2016
27. The current state of the fourth global bleaching event is not established in this package
28. Marine heatwave
29. Zooxanthellae (Symbiodiniaceae)
30. Zooxanthellae (Symbiodiniaceae)
31. Coral bleaching
32. Crown-of-thorns starfish (Acanthaster)
33. Elkhorn coral (Acropora palmata)
34. Darwin publishes The Structure and Distribution of Coral Reefs
35. The first global mass bleaching event
36. A published projection that reefs would bleach faster than they could recover
37. Mass bleaching on the Great Barrier Reef
38. The interval between severe bleaching events is measured, and it has collapsed
39. Evidence
40. What had been treated as the single Indo-Pacific species Acanthaster planci comprises at least four species with distinct geographic ranges. V55 verification basis: not consulted; the finding is stated from the producing model's knowledge of the taxonomy, and any revision published since could not be checked.
41. Mean hard coral cover on surveyed Great Barrier Reef sites fell from 28.0 per cent in 1985 to 13.8 per cent in 2012, with roughly forty-eight per cent of the loss attributed to tropical cyclones, forty-two per cent to crown-of-thorns starfish and ten per cent to bleaching. V55 verification basis: not consulted; the cover figures and the three attribution percentages are stated from the producing model's knowledge of this widely cited result.