25 October 2018

This is Why We Celebrate Our Reefs

Arthur's Rock, Mabini, Batangas (Photo by Maria Lourdes Palomares)

This year, 2018, marks the third celebration of the International Year of the Reef (IYOR).  It was first conceived in 1997 by the International Coral Reef Initiative (ICRI) to address the rising threats to our coral reefs and its associated ecosystems—mangroves and seagrass beds. Because caring for our coral reefs becomes ever more critical today, this celebration aims to inspire people to come together and help improve the conditions of our reefs for the long-term.

But first, what actually is a coral?

For centuries, taxonomists have been baffled about corals. Yes, they’re like plants—immobile, photosynthetic, home to many creatures. In contrast, like animals, they can be insidious: to capture a nearby prey, they fire their toxic nematocysts from their stinging cells (cnidocytes). Quite a character, right?

Thankfully, with the invention of the microscope, corals have landed their spot: they are clearly animals, but "flower animals" to be exact [2].

What makes corals as we know them today? 

What clads them with hunting colors?

And what enables them to build colonies underwater?

It's the zooxanthellae. They're single-celled dinoflagellates.

Zooxanthellae and corals are inextricably linked to one another. These symbiotic algae live within the corals’ tiny polyps, channeling almost 90% of the food it makes—glucose and amino acids—which enables the growth of calcium-laden structures [6]. Specifically, these reef-building corals (Scleractinia) need light and thus restricted to shallow sunlit waters. However, not all  Scleractinia have zooxanthellae. In fact, half of all Scleractinia do not have symbiotic algae (azooxanthellate species) and thus are not limited by light, temperature and depth. This eases competition for space, allowing them to live in different ocean depths, relying on plankton for food [7].

So we know now that zooxanthellae breathe life to reef-building corals, while corals provide a home to the algae. It's a partnership that has long stood time.

And why is this partnership so special, especially now? A recent study reveals this relationship dates back to 160 M years ago, during Middle Jurassic, well before the days that wiped out dinosaurs. This is particularly interesting to scientists because it opens possibilities on the coral algae's resilience against rising temperatures [4].

The Earth has warmed 1°C since the 19th century. Although it sounds no big deal, even half a degree increase in global temperature is a step away from coral mass mortality (what we experience today) to a world where corals become 'rare' [5].

When corals experience stress from severe pollution, increased temperatures and acidic waters, they excrete their algae, their very life, and thus become bleached [2]. This wildly impacts marine life, which highly depends on these ecosystems for food, shelter, and breeding [3]. On the bright side, there are more tools available now to increase public awareness on coral bleaching. A great tool, NOAA Coral Reef Watch uses a daily global 5km satellite (based on sea surface temperature monitoring) to depict areas where coral bleaching heat stress currently reaches various levels. 

According to the World Wildlife Fund (WWF), healthy reefs and other ecosystem services amount to more than $29.8 B yearly. But beyond the huge economic value we get from reefs—food security, coastal protection, tourism, medicines, among countless benefits—the presence of corals reminds us that there is so much in nature that's difficult to put a value on. 

Reefs are too precious. They leave us in awe. A world without them is just difficult to imagine. 

Conservation International produced a great film series called Nature Is Speaking, where known figures literally embody the Earth. In the video below, Ian Somerhalder is the CORAL REEF. And he's not just a rock. He does way more than we could imagine.

Protecting our oceans can be a lot to take in and these days we can be easily flooded with reminders to do our part as ocean stewards. Sure, incredible movements spur here and there and they’re truly commendable. But how can we, as ordinary citizens, not only contribute this year but also commit long-term?
Luckily, there’s a number of small things we can do—things that we're probably doing now—which we can improve upon and anchor to a more meaningful purpose.

One way is to reduce our plastic use by bringing our own recyclable shopping bags. We can also participate in coastal clean-ups. It might also be a good idea to make our time online worth it by creating and sharing meaningful content. Nowadays, if we're keen to put our curiosity to good use, we can become a citizen scientist and participate in real data gathering. We can also know more about corals online—SeaLifeBase, a database of all non-fish species in the world, can be a good place to start.  Happy learning!

[1] International Year of the Reef. Retrieved from https://bit.ly/2qkNjGi
[2] Amorina, K. 1 Sep 2016. Coral, Explained. Hakai Magazine. Retrieved from https://bit.ly/2Aoq5T0
[3] Murali. 16 Sep 2018. Why Coral Reefs are Important for Earth. City Today.  Retrieved from https://bit.ly/2ERfS5R
[4] Halton, M. 10 Aug 2018. Coral Reefs 'Weathered Dinosaur Extinction."  BBC News. Retrieved from https://bbc.in/2Pcg2Zp
[5] Plumer and Popovich N. 7 Oct 2018. Why Half a Degree of Global Warming is a Big Deal. The New York Times. Retrieved from https://nyti.ms/2QPjRAR
[6] NOAA. Corals. Retrieved from https://bit.ly/2ReIlUl
[7] Veron, JEN. 2000. Corals of the World, Vol. 1,2,3. Australian Institute of Marine Science.