The Coral Triangle (Philippines, Malaysia, Indonesia, PNG, Solomon Islands, Timor-Leste) holds 76% of all coral species and 37% of reef fish species. The "Amazon of the Sea" spans 5.7 million km² of tropical ocean.
Most reef species reproduce by broadcasting eggs and sperm into the water column. Larvae drift for days to weeks, transported by currents. The Triangle acts as a larval source replenishing reefs across the Indo-Pacific.
At temperatures 1–2°C above the seasonal maximum for 4+ weeks, corals expel their symbiotic zooxanthellae algae, turning white. Bleached corals can recover if temperatures drop, but prolonged bleaching causes mortality.
Oceanographic models reveal that Halmahera eddy and Mindanao Current are key larval highways. Protecting source reefs (those exporting larvae) provides asymmetric conservation benefit across connected networks.