Coral Reefs

I think it’s safe to say most divers love reef diving, seeing the colours, the abundance of fish, and searching for the cool critters hiding in nooks and crannies. But how much do most of us know about corals?

Marine conservation organizations and documentaries of late have done a good job educating the mass population that corals are in fact animals, not plants or rocks, and they are incredibly susceptible to human pressures.

What are Corals?

We’ve established that corals are animals, but more specifically they are actually colonies of thousands (or more) of tiny animals living and working together! Each individual animal is known as a polyp and they are closely related to jellyfish and anemones. Polyps can live alone as solitary corals, but most often, they group together to form colonies, and these are what form the basis of our reefs.

Corals come in many shapes and sizes. There are stony corals, which are the main building blocks of the coral reefs that so many of us love to dive in. There are also gorgonians and soft corals, which resemble more plant-like structures. A lot of divers don’t realize that the beautiful “plants” that they see on the reef, are actually animals, but they do have a special relationship with plants!

Corals and Zooxanthellae

Corals have a symbiotic relationship with a single-celled type of algae called zooxanthellae. Zooxanthellae live inside the tissue of coral polyps and help provide the majority of the nutrients corals need. They also contribute to the vibrant colours that many corals have! So zooxanthellae are also involved when the reefs experience an unfortunate event of coral bleaching.

Coral Bleaching and Ocean Acidification

Coral reefs develop over millions of years and require very specific ocean conditions to thrive. Water temperature, salinity, clarity, and current all affect their formation. If any of these conditions aren’t met, corals can become unhealthy and “stressed”. The stressed corals expel their zooxanthellae, losing the colour they provide. Hence, coral “bleaching”. Without their zooxanthellae, corals literally starve to death.

While many people know about coral bleaching, ocean acidification is also causing problems for corals across the globe. Ocean acidification happens because the ocean is a massive carbon sink – it absorbs carbon dioxide from the atmosphere. Because of rising emissions in the last hundred or so years, the ocean has absorbed so much carbon dioxide that it has become more acidic. This is detrimental to many corals and shellfish, as the acidity of the water dissolves the minerals in the water which they require to build their skeletons. This causes them to grow more slowly and have weaker skeletons.

How Can We Help?

Education! The biggest thing we can do as divers is continue to learn as much about the ocean as we can! The more we understand, the more we can share with our friends and families.

We can also all make small shifts in the way we live and dive to be more sustainable. Go diving with shops who are passionate about conservation efforts, practice good buoyancy skills to prevent accidently touching the reef, and save power and water while you are at home and traveling! Everyone working together can make a difference.

By Holly & Kaila