Tuesday, October 21, 2014

Introducing the mystery.........

We are conducting our research on the corals bleaching in Kaneohe Bay, Oahu.

Corals are bleaching. Right now, in majestic Hawaii and throughout the northwestern Hawaiian Islands. Depending on the severity of bleaching, the corals may not recover. Coral bleaching is the loss of symbiotic algae that reside within the tissues of the coral. Elevated surface seawater temperature is to blame – at least in part. In actuality, it is an accomplice to the crime. Elevated temperature leads to the formation of the chemical weapon responsible for coral bleaching – superoxide – a reactive chemical that is an oxygen radical. High levels of this chemical lead to expulsion of the algae and subsequent bleaching and can initiate cell death of the coral host. But, who is wielding this weapon? And, why?

We have a long list of suspects – the coral host, the symbiotic algae Symbiodinium, or the other coral-hosted bacteria. The evidence thus far has pointed to Symbiodinium as the perpetrator. And in fact, coral bleaching is attributed to overproduction of superoxide by Symbiodinium in response to light and temperature stress. But, has Symbiodinium received a fair trial? To date, the evidence against Symbiodinium has been indirect. There are no actual measurements of superoxide production from corals or the algae during the bleaching process and the source of and triggers for superoxide formation are not actually clear.

We hope to unravel this mystery – at least in part – by conducting the first field-based (in situ) superoxide measurements from bleaching and non-bleaching corals during the natural bleaching event occurring in Kaneohe Bay, Oahu. But collecting this evidence is tricky. Superoxide only has a lifetime of a few minutes. It’s hard to catch. There are no instruments that we can put in the water to measure it. But, we may have a way – by setting up a boat-based laboratory with an optimized detector system. By doing so, we hope to obtain clues as to whom is making superoxide, how this varies with coral species, and how superoxide links to coral bleaching. Is Symbiodinium truly to blame? The jury’s still out…

Colleen Hansel

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