In this era of global warming, the incessant stream of news articles citing vicious weather patterns and rising sea levels seems endlessly alarming, and perhaps even desensitising – since this has been a constant topic since the 1980’s. Two weeks ago, a short video demonstrating the visual effects of coral bleaching floated around the web, showing how once the waters around the coral become too warm, the coral explosively reject the tiny algae that live on their tissues. It served as a potent reminder of the unpredictable consequences of our daily habits and actions, but also of how little we know about the intricacies of the planet’s ecosystems. Today I hope to do a little more digging, and shed some much needed light on a salty little creature that rarely receives it.


Corals are marine invertebrates that largely rely on a symbiotic relationship with algae. The undersea kaleidoscopes we imagine actually reflect the colors of each type of photosynthetic algae that live in harmony with their hosts. Coral reefs, in turn, are the most diverse of all marine ecosystems with approximately a quarter of all sea creatures dependent on them for food and shelter.


Coral bleaching occurs when the corals’ symbiotic relationship with algae is stressed by either higher than average water temperatures, water pollution, or overfishing. The algae are rejected by coral, taking with them the corals’ deep colors and only source of sustenance, meaning that corals starve and die off if the bleaching persists. The phenomenon isn’t new, and actually the most devastating instance of coral bleaching happened during the 1998 El Nino.  Although the reefs can recover, rising background temperatures increasingly chip away at the chance of that opportunity, since the water temperature around the reefs must drop before the algae return. It can take hundreds of years for coral to develop such diverse algae compositions, but only a year of warm water to destroy the fragile ecosystems.

Today, The Guardian reports that 93% of Australia’s Great Barrier Reef has been affected by coral bleaching. In my home of Hong Kong, the natural coral reefs that used to surround the island have long been affected by nitrogen and phosphorus discharge in sewage waste, paving the way for other life forms to grow rapidly and destabilize the ecosystems. Life underneath the water is pale, monochromatic, and almost ghostly – a warning of what occur in other islands that humans perhaps naively believe to be immune to the effects of pollution.

It’s easy to feel helpless when you’re a thousand miles away, but being part of the global ecosystem means that the things we do don’t happen in a vacuum.  If you’re interested in conserving the reefs we have left, it helps to revisit how you use the resources around you. One way is to simply conserve water and use eco-friendly detergent to prevent pollution runoff. Another is to lessen fossil fuel emissions through energy conservation. Pessimists may claim these actions as futile, but the oft-quoted Edmund Burke comes to mind: “all that is necessary for the triumph of evil is that good [wo]men do nothing”. 


/ Words and photos by Anne Berry /