You might have seen that Hawaii has banned certain sunscreens that have been linked to coral bleaching. In particular, it’s the organic “chemical” sunscreen ingredients oxybenzone and octinoxate that have been banned. It sounds like a great victory for the environment, right?
But if you search a little past the headlines, you’ll find that there are actually a lot of coral experts and marine ecologists who aren’t happy with the decision. Why is that?
To find out, let’s look at the science behind sunscreen and its effects on coral.
Check out the video here – keep scrolling for the text version.
What Is Coral Bleaching?
The concerns about sunscreen’s effects on coral come from studies on isolated coral samples, and the main possible impact is coral bleaching.
Coral live in symbiosis with algae (zooxanthellae) that live inside them. The algae are important to the coral because they absorb sunlight and photosynthesise to create nutrients to feed the coral. The algae are also responsible for the beautiful colours in coral.
But when the coral is overly stressed, it expels the algae, leaving the coral bleached and pale, and without their main source of food (algae provide about 90% of the coral’s energy). Bleaching is sometimes reversible, and if the stress is only temporary, the algae can return to the coral. But if the stress is prolonged or too severe, then the bleaching continues and the coral will eventually starve and die.