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What Biodiversity Means on a Reef
'Biodiversity' on a coral reef refers to the number of species in multiple categories: corals, reef fish, invertebrates, molluscs, echinoderms, and crustaceans. The sites on this list represent the highest measured species counts in scientific surveys.
1. Raja Ampat, Indonesia
1,508 fish species; 537 coral species. The highest documented coral biodiversity on Earth. Located at the epicenter of the Coral Triangle in West Papua. Conservation International surveys between 2001 and 2010 established these numbers.
2. Tubbataha Reefs, Philippines
600+ fish species; 360 coral species. The central Philippines' contribution to the Coral Triangle's diversity. A UNESCO World Heritage Site entirely protected from fishing.
3. Milne Bay, Papua New Guinea
730+ fish species. Bob Halstead documented the marine life of Milne Bay over decades of diving; later scientific surveys have produced numbers that place it among the top five globally.
4. Kimbe Bay, Papua New Guinea
860 fish species. Kimbe Bay in West New Britain is one of the few sites that rivals Raja Ampat in recorded fish species density. The seamounts at its center concentrate pelagic life unusually well.
5. Coral Sea, Australia
1,600+ reef species across all taxonomic groups. The Coral Sea — the body of water between Australia and the outer reef systems of PNG, Solomon Islands, and Vanuatu — functions as a reservoir from which larvae disperse across the western Pacific.
6. Red Sea, Egypt/Saudi Arabia
1,000+ fish species; 250+ coral species. The Red Sea has an unusually high level of endemism — species found nowhere else — driven by its geological isolation as a semi-enclosed sea. Approximately 17% of its fish species are endemic.
7. Maluku Islands, Indonesia
The narrow seas around the Maluku (Molucca) Islands — historically famous as the Spice Islands — have some of the highest fish diversity in a small geographic area of any site within the Coral Triangle.
8. Great Barrier Reef, Australia
1,500+ fish species; 400 coral species. The sheer size of the GBR (344,400 km2) produces diversity at a scale no single site can match.
9. Maldives
1,100+ marine species recorded across the atoll system. The deep channel systems between atolls provide habitat corridors connecting shallow reef species with deep-water pelagic species.
10. Florida Keys, USA
6,000+ marine species of all types — the most comprehensive species count of any reef in the western Atlantic. The only living coral barrier reef in the continental United States.