What was done
Photosynthesis was measured on three treatment groups of the coral Agaricia tenuifolia to assess the role of temperature-induced oxidative stress on photosynthesis and coral bleaching.  The three treatments consisted of corals exposed to (1) ambient seawater temperature, (2) seawater temperature 2-3°C above ambient, and (3) seawater temperature 2-3°C above ambient in the presence of antioxidants.

What was learned
Coral samples exposed to antioxidants and higher seawater temperatures exhibited photosynthetic rates comparable to coral samples under ambient conditions, while coral samples exposed to higher seawater temperatures alone experienced a decrease in photosynthetic rates.  The presence of antioxidants also prevented bleaching of the corals.

What it means
This study demonstrates that bleaching in the coral Agaricia tenuifolia may be prevented by the presence of certain antioxidants.  Consequently, the authors concluded that "temperature-induced bleaching appears to represent a short-term strategy to expel symbionts producing high concentrations of oxygen radicals."  In some cases, therefore, bleaching may actually be the method by which a more profound problem, i.e., oxidative stress, is treated.