Robot Tide Pools

The lagoon on Ofu is an important natural laboratory

In the reefs surrounding American Samoa, we’ve found dozens of species of corals – tabletop, mound, and branching corals – that, like many, rely on a fragile balance of conditions for life.  However, the Ofu reefs also house some of the strongest corals in the Pacific.  In ongoing studies begun in 2005, we have taken samples of these corals and tested them in ‘Robot Tidepools’ 

These devices run the corals through the equivalent of a treadmill test, exposing them to water set at precisely controlled water temperatures – normal and hotter.  The results show the Ofu corals to be tougher than almost any others. One idea is the that corals toughen up with their regular regime of heat exposure during Ofu’s midday summer low tides.  

Why study coral reefs?

Coral reefs, such as those surrounding Ofu, American Samoa, provide a home to at least 25% of marine species. Yet they are severely threatened by global climate change.  Now research shows that some resilient ‘supercorals’ in the Pacific can continue to grow and thrive in the face of increasing temperatures.  Studying these survivors may help us learn which are most likely to survive climate change – and thus, which to protect with our limited conservation dollars.

Learning why some reefs survive and some reefs die is important.

These reefs provide not only habitat for marine animals and food for us, they protect our coastlines from hurricanes and storms.  But when ocean water warms, algae stop producing sugars, depriving the corals of a crucial food source. 

Corals are also threatened by other conditions such as runoff from land, pollution and overfishing.  But the discovery of these temperature-resistant Ofu corals shows we may learn which corals are most likely to survive, if we protect them, in a warmer ocean, on a warmer planet.