The 2016 Worldwide Coral Bleaching Event: Update from Maui

By Kelly Montenero

Photo from XL Catlin Seaview Survey, 2015, American Samoa

If you’ve put a mask on your face and taken a quick look around in the waters around Maui in the last 4 months, you’ve surely noticed the event that all of the world is talking about: the world’s third, and worst, global coral bleaching event.

The strengthening 2015/ 2016 El Niño season, in conjunction with ocean warming due to climate change, led to record high ocean water temperatures in the Pacific, which had a very easily observed effect on our coral reef: many colonies of coral became snow white, or “bleached”. Coral gets its color, and food, from photosynthetic plant-like single celled organisms that live inside the coral animal’s tissue. These organisms, called zooxanthellae, use energy from the sun to photosynthesize, and they share some of the sugar they create with their coral hosts, like a renter pays a landlord. But when the coral animal gets stressed due to high water temperatures, the symbiotic zooxathellae are expelled into the water column, leaving only the clear coral tissue and the white skeleton of the coral behind. If the coral remains stressed for too long and the zooxanthellae can’t return to it’s tissue, the coral will likely starve or become diseased. In some cases, macroalgae grows over the bleached but still living coral, suffocating it from water flow, sunlight and oxygen.

The current coral bleaching event is expected to have impacted 38% of the world’s coral reefs by the end of this year. A group called XL Catlin Seaview, including Google, the University of Queensland, and the namesake insurance group interested in the effects of climate change, made it their mission to scientifically record the world’s coral reefs and reveal them to all in high-resolution, 360-degree panoramic vision. This group traveled out to Maui to document the bleaching event, as well as locations on Oahu and in the South Pacific. The images communicate the state of decline of our reefs, and the devastating effects of climate change.

On Maui, we have been glad to note that water temperatures are slowly dropping back down. In early February, the ocean temperature off the north shore was 77.9 degrees F- much lower than the 87 degrees F that we observed in late summer. However, average water temperature in February is 75 degrees F, and as the trend of global ocean warming is predicted to continue, our corals are not out of the woods yet.

Unfortunately, NOAA is predicting that bleaching will continue in the Southern Hemisphere’s late summer of February-May 2016. If temperatures and environmental stressors reduce, there is a chance that the bleached coral can recover before the algae takes over- this is why herbivorous fish like parrotfish are so important! It is important to realize that El Niño weather patterns are a regular occurrence that raise water temperature, but when this is paired with rising baseline sea temperatures (as the oceans have absorbed over 90% of the heating from climate change), it results in mass bleaching events.

So what can you do to help? Healthy reefs are more resilient to warming and have a better chance of recovery. We can help our reefs become more resilient by creating low stress conditions for them, including reducing overfishing, sedimentation, pollution and anchor damage pressures. On the larger scale, we can all do our part to think blue and reduce our carbon emission footprint. Everyone can make this effort in their own way, whether it means investing in solar panels, using biofuels, riding your bike to work, voting for legislation that increases conservation, or buying local products to decrease the energy cost in transporting your goods. Get involved, make your voice heard, and we can still make a difference to ensure that coral still surrounds Maui for generations to come.

All images courtesy of XL Catlin Seaview Survey.