[00:00.33]Tropical islands are an obvious magnet for life.
[00:04.08]But things are just as busy underwater.
[00:07.70]Deep currents collide with these islands,
[00:10.49]forcing small but vital amounts of nutrients up from the depths.
[00:14.61]At 50 metres deep, sea fans are amongst the first to benefit.
[00:19.63]Closer to the surface, corals have sunlight to help them grow.
[00:24.72]And thanks to the smallest trickle of nutrients,
[00:28.00]a barren desert can bloom into an underwater oasis,
[00:32.28]supporting a greater variety of life than any other ocean habitat.
[00:37.76]These coral reefs are a magnet for green turtles,
[00:42.66]offering a service not available in the open ocean -
[00:46.11]a good clean-up by a shoal of tangs.
[00:49.45]This work-over is far from cosmetic.
[00:51.97]As well as removing parasites,
[00:53.44]the cleaning stops the build-up of algae,
[00:55.43]so the turtle can swim freely.
[00:57.80]But it's also got to feel good.
[01:00.95]