By now you have probably heard the news that coral reefs all over the world are currently in danger of bleaching. A perfect storm of already increasing sea surface temperatures paired with one of the largest El Nino events in recorded history have left many coral reefs in literal hot water. In March 2015, NOAA announced the arrival of the what would turn out to be one of the largest El Nino events in history, and warned of the consequences to coral reef ecosystems around the globe. As the year went on the El Nino event has continued to get stronger and stronger and is now predicted to last well into 2016. What this means for coral reefs could be devastating.
First, let’s dig deeper into what coral bleaching is. Corals are animals that create colonies out of thousands of identical, yet individual, coral polyps. In order to create these colonies the polyps produce a calcium carbonate skeleton. Producing such an elaborate skeleton requires a large amount of energy, much more energy than the coral is able to produce. This is where zooxanthellae comes into play. Zooxanthellae is a small plant-like dinoflagellate. The zooxanthellae actually inhabits the tissues of coral in perhaps the natural worlds best example of symbiosis. This is also responsible for giving the corals the spectacular range of colors so notorious on coral reefs. The catch, is that both the coral and its symbiotic zooxanthellae are very sensitive temperature change. As the surrounding water temperatures increase these little dinoflagellates get stressed out and begin producing reactive oxygen species (ROS). These ROS actually harm the coral and can even lead to programmed cell death (PCD). In order to protect themselves, corals begin to expel the zooxanthellae in a last second effort to save themselves. This expulsion of zooxanthellae is what we refer to as coral reef bleaching. As the zooxanthellae leaves so does the color, leaving only the transparent tissue and a bleach-white skeleton underneath. Though bleaching is not a good thing and is commonly affiliated with environmental disaster, it is actually the corals way of survival during thermal stress. That’s not to say that all is okay during a bleaching event. The coral will die if the temperature does not decrease within a couple weeks.
We are currently seeing significant bleaching in the Hawaiian Islands, which I personally witnessed in Kāneʻohe Bay on Oahu and in the Kapoho tide pools on the Big Island in late August. The corals in the Caribbean are also suffering. Bleaching in Southern Florida and the Keys have already been documented and the outlook for reefs south of Florida are only getting worse. Reefs in Haiti, The British Virgin Islands, The Dominican Republic and the Lesser Antilles are likely to have bleaching events in the coming months. In fact, this morning I was tipped off by a viewer asking if the corals at T4O’s Grand Cayman research site were bleaching. I immediately checked our live underwater camera and was shocked to see the large coral heads of Montastrea annularis beginning to bleach. Now this is obviously bad news, but even worse, this is just the beginning. Summer has just ended in the northern hemisphere. And although El Nino will continue in theCaribbean and Hawaiian islands for the next month or so, the southern hemisphere is heading to summer and reefs throughout the Southern Pacific and Indian Oceans could be facing a catastrophic bleaching event. The current consensus is The Great Barrier Reef will get hit hard with coral reef bleaching in 2016. And although the great Barrier Reef is the most well known reef on the planet, it is far from the only ecosystem in the region. The Great Barrier Reef is part of the coral triangle, a region spanning Australia, Indonesia, Philippines, and Malaysia. This entire region, which supports hundreds of coral species, is projected to be hit with extremely warm water. And that doesn’t even include most of the Indian Ocean which will also get hit with high SSTs. There is a very real possibility that we are witnessing the 3rd Global Bleaching Event on record, (1998 & 2010 previously).
So why does this matter? Coral reefs are like forests, they need time to grow back and become healthy. Since the 1980’s bleaching events have become more and more frequent. Global coral coverage is said to have decreased nearly 30% in just a few decades and the current pace of change is quite simply to fast for the corals to keep up. Coral bleaching can not only cause mortality, but also has a continued effect on those that do survive. Corals that do make through the hot times tend to become more prone to disease and other stressors. We are talking about about an ecosystem estimated to be worth around 30 billion dollars per year and supporting over 500 million people who depend on it. That’s 30 billion dollars that live in less than 1% of our ocean and that number continues to decrease. 25% of all marine life makes the coral reef home at some point in their lives and without the reef, life in our oceans would become much different. Scientists all over the world have warned that within 40-50 years coral reef ecosystems may not even exist, a drastic prediction that actually could be correct. In the end corals provide:
- Habitat: Home to over 1 million diverse aquatic species, including thousands of fish species
- Income: Billions of dollars and millions of jobs in over 100 countries around the world
- Food: For people living near coral reefs, especially on small islands
- Protection: A natural barrier protecting coastal cities, communities and beaches
- Medicine: The potential for treatments for many of the world’s most prevalent and dangerous illnesses and diseases.
Are we really willing to sit back and watch one of the most essential ecosystems on this planet dwindle away? El Nino or not, it is about time we did something to protect our natural world that provides us with life. When it comes down to it, it may be those divers, surfers, and scientists who point it out and raise a fuss, but they are not ‘tree huggers’ and environmentalists. They are just like the rest of us, but they’ve watched our coral reefs change over the years and they’ve seen their demise first hand. Just because you do not have a personal connection with our oceans does not mean it does not affect you. We are all inextricably tied to the sea and it is our responsibility, as a species, to protect the ecosystems that have enabled us to thrive.