Bonaire’s Divers Asked to Take Special Care with Corals During Abnormally High Sea Water Temperature

Recently, the Bonaire National Marine Park received a “Bleaching Warning” from NOAA.  When sea surface temperatures (SST) are one degree Celsius (or more) over the maximum monthly mean, the area is designated a “hot spot” and a bleaching watch is issued.

This happened for Bonaire on August 28, 2008 when the sea surface temperatures reached 29.3 degrees Celsius in the region, a degree above the maximum monthly mean of 28.3 degrees Celsius.

At these high temperatures, corals will bleach when experiencing anomalously high levels of a combination of light and water temperature. The stress level is measured in Degree Heating Week (DHW). For instance, if the water temperature is one degree Celsius above the maximum monthly mean for a week, this is equal to 1 Degree Heating Week.  (For example, 10 DHW could be 1 degree Celsius for ten weeks, 2 degrees Celsius for five weeks or 2.5 degrees Celsius for four weeks.) When the DHW is less than 4, the corals have accumulated enough thermal stress to lead to significant coral bleaching.

Last week, a survey showed that at this time only small colonies of Smooth Flower Coral (Eusmilia fastigiata), Boulder Brain Coral (Colpophyllia natans), and Boulder Star Coral (Montastrea annularis) were experiencing low levels of bleaching. Surveys will continue this week. All divers are asked to remember that during bleaching events affected coral colonies are under enormous stress and extreme care should be taken not to come in contact with the reef. (Source:  Bonaire National Marine Park)

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