In Hot Water


 

 

 

Editor’s note: Coral reefs have often been called the tropical rainforests of the sea for their beauty and abundance of wildlife. They are a critically important part of healthy oceans, and support entire marine ecosystems. They also provide jobs, food, and tourism valued at $375 billion per year. But they’re disappearing. Intensity and frequency of major bleaching events have been increasing around the world for decades. Half the coral in US Caribbean was lost to bleaching in 2005 alone. To further his work on the issue, Dr. Stephen Palumbi, director of Stanford’s Hopkins Marine Station, Pew Fellow in Marine Conservation, and OWOO Science Advisor is headed to American Samoa and the Cook Islands in search of the corals most likely to survive. This is the first in a series of special reports from the field that will continue throughout his team’s three-week expedition.

 

Part 2    Part 3    Part 4    Part 5    Part 6    Part 7

 

The back reefs of Ofu Island are a tropical paradise, rich green peaks rising around turquoise lagoons. The tides wash in and out slowly, making the water as warm and pleasant as any tourist of the tropics could ask for. But these warm waters are also an important training ground. The corals that live in these lagoons are periodically exposed to temperatures high enough to bleach and kill most reefs. Mass coral bleaching events across the globe, in response to rising ocean temperatures, have caused scientists to worry that coral reefs around the world may die out as the climate changes.

The back reef of Ofu, American Samoa, voted one of the ten most beautiful beaches in the world. Photo by Dan Griffin, Garthwait-Griffion Films.

 

Dr. Stephen Palumbi

On Ofu, in the remote islands of American Samoa, we have found corals resilient enough to live high above their normal bleaching temperature. We are trying to understand how these corals survive. But a bigger question looms: do these tough corals live elsewhere?

We study this with a coral stress tank – a computer-controlled aquarium that lets us heat seawater to a precise degree. We place tiny a fragment of coral from two different reef locations in these tanks, ramp the temperature up over the course of a day and record which of the corals bleach.

 

On March 18th, we will test run our newest tank in American Samoa, where we’ve already some of the toughest corals alive. From there we will travel to Rarotonga in the Cook Islands, a place where normal ocean temperatures are lower than in American Samoa. The final stop is the ‘almost-atoll’ of Aitutaki, a small island north of Rarotonga.

 

I hope you’ll follow our trip as we look for the toughest corals, the ones most likely to survive as the ocean heats up, in an effort to understand this important animal and how to preserve it.



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