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Bleaching on Hawaii’s Coral Reefs: What’s Going On?


Photo: Duke University

In the waters off the shore of Maui

something strange is happening. Perhaps quite fittingly for the month of October and Halloween, coral bleaching is giving Maui’s reefs a ghostly pallor that’s unsettling to people who snorkel here as well as scientists. This unprecedented bleaching is happening because of record high water temperatures. This isn’t the first time Hawaii has seen coral bleaching; 2009 saw bleaching occurring off the coast of Oahu.

According to The Seattle Times, a reef specialist with Hawaii’s Division of Aquatic Resources says that this bleaching – the worst Maui has seen – is expected to last into at least November and December. This phenomenon is disheartening because bleaching weakens coral and can even kill it. Global warming and El Nino are to blame for this most recent outbreak. Basically, when waters get too warm, the coral (a living thing, mind you) emits symbiotic algae that usually live within it, photosynthesizing the oxygen and sugars that feed coral polyps. When algae is no longer present, a whitish appearance occurs.

Olowalu in West Maui seems to be the hardest hit, as it’s the location of a 1000-acre reef with large old corals that act as reproductive stock for reefs around the area, particularly West Maui and Lanai. The good news is that with cooler water temps on their way, corals can bounce back from this bleaching effect. Still, the water is at 80 degrees, pretty balmy as we head into late fall.
How can you help?

As a visitor to Maui, there are some steps you can take to bring about positive change. Here are some tips:

• Employ proper reef etiquette. This means as a diver or snorkeler, you should keep you hands off the coral, whether it’s bleached or not.
• Don’t feed reef fish. This puts a wrench into the natural balance of the ecosystem that helps fish and sea urchins clean excess algae growth from coral.
• Apply reef-friendly sunscreens that contain titanium oxide or zinc oxide. You can find tubes of this lotion at dive shops all over the island. Stay away from sunscreens that have benzophenone-2, or BP-2, which is poisonous to coral.
• If you see bleached coral, report it to the proper authorities. Fill out a report form at Hawaii’s Eyes of the Reef website to help fund data into researching what can be done about coral bleaching.
• Adopt a coral head. Whenever you find yourself snorkeling or diving near your adopted coral head, check out its condition and report it to the website above.

A visit to Maui for snorkeling is always a great way to see the local marine life in action. Oahu has some beautiful snorkeling too, so come on over and see us during your Hawaiian vacation. Hoku Hawaii Tours has plenty of options for you to choose from when it comes to fun, educational excursions throughout Oahu.