THE TIDES, CORAL BLEACHING

So what is coral?

For those who have gone deep sea diving or just swam in the shallow parts of the ocean, I am sure you have seen corals. For the rest of you who haven’t seen it first hand then national geographic or marine documentaries may have educated you on that.

At a glance corals look like large rock. That couldn’t be any further from the truth. Unlike plants, corals do not make their own food. Corals are in fact animals. The branch or mound that we often call “a coral” is actually made up of thousands of tiny animals called polyps. A coral polyp is an invertebrate that can be no bigger than a pinhead to up to a foot in diameter. Each polyp has a saclike body and a mouth that is encircled by stinging tentacles. The polyp uses calcium carbonate (limestone) from seawater to build a hard, cup-shaped skeleton. This skeleton protects the soft, delicate body of the polyp.

What is coral bleaching?

Coral bleaching is when corals lose their vibrant colours and turn white. This happens when there is an increase in temperature and the coral sheds of the algae that grow on it. The coral and algae have a symbiotic relationship (a relationship where both parties benefit from each other). The coral provides carbon dioxide and ammonium for the algae allowing it to photosynthesis while the algae provides nutrients as food for the coral. In addition, the algae gives the coral its colour. Increase in temperature therefore causes the coral to expel algae and in so doing it loses its colour and it will eventually die.

What causes coral bleaching?

Increase in ocean temperatures due to climate change is killing corals around the world. A slight increase in temperature even by 1-degree Celsius can cause corals to die.

A global mass coral bleaching has been occurring since 2014 because of the highest recorded temperatures plaguing oceans. These temperatures have caused the most severe and widespread coral bleaching ever recorded in the Great Barrier reef.

The most severe bleaching in 2016 occurred near Port Douglas. In late November 2016 surveys of 62 reefs showed that long term heat stress from climate change caused a 29% loss of shallow water coral. between 2014 and 2017 around 75% of the world’s tropical coral reefs experienced heat-stress severe enough to trigger bleaching. The highest coral death and reef habitat loss was inshore and mid-shelf reefs around Cape Grenville and Princess Charlotte Bay.

How does coral bleaching impact wildlife? Coral reefs support some of the most biodiverse ecosystems on the planet. Thousands of marine animals depend on coral reefs for survival, including some species of sea turtles, fish, crabs, shrimp, jellyfish, sea birds, starfish, and more. Coral reefs provide shelter, spawning grounds, and protection from predators. They also support organisms at the base of ocean food chains. As reef ecosystems collapse, already at-risk species may face extinction.

How does coral bleaching impact humans? Coral bleaching impacts peoples’ livelihoods, food security, and safety. Coral reefs are natural barriers that absorb the force of waves and storm surges, keeping coastal communities safe. Without them, we must rely on manmade seawalls that are expensive, less effective, and environmentally damaging to construct. Bleached coral also compounds the overfishing crisis by removing links in the food web and depriving some fish and crustacean species of a place to spawn and develop. Anyone relying on these animals as a primary source of income or protein will be in trouble. Finally, reef tourism brings in billions of dollars each year and supports thousands of jobs. Bleached coral reefs, devoid of magnificent marine species, jeopardize it all.

Watch the short video on coral bleaching.

https://www.youtube.com/watch?v=fA6mpexcyN4