Coral Bleaching

Coral Bleaching
Posted on 10/08/2019

Sea Turtles, different species of fish, starfish, small sharks, crabs, shrimp and many more marine animals inhabit one home: coral reefs. Supporting 25% of the oceans marine life, many coral reefs are facing weakness and destruction. The weakness is due to coral “bleaching”. Coral has a symbiotic relationship with zooxanthellae—a type of algae that lives on the polyps of coral— in which they both rely on each other for survival. This algae is what gives the coral its color and provides food for the coral, thus giving the coral its much-needed energy to keep building itself. Corals have hard skeletons that are a white color, those skeletons are covered with zooxanthellae algae living on the coral. The polyps—the mouth like structures for the coral— take minerals from the water and use them to add to their structures. Part of the reason coral bleaching is so significant and detrimental is because coral is a very slow-growing organism, taking a long time to grow, reproduce, and regenerate. It needs help to come back from these mass bleachings. Zooxanthellae doesn’t survive well when it interacts with high heat. When the water temperature rises the zooxanthellae will stop producing food for the coral, which will expel the algae, leaving the coral a bright white color. This doesn’t completely kill the coral: it just makes it vulnerable, but at this stage if the algae doesn’t come back then the coral is essentially left to die. Since corals reproduce as such a low speed it makes it very hard for a coral reef to come back after a mass bleaching. While global warming and heat is a strong contributor for coral bleaching, landfill pollution also contributes to coral bleaching by suffocating the coral.

Therefore, coral bleaching causes thousands of species living in the reefs to lose their homes, nurseries, and protection. Fish, crabs and jellyfish are just a few of the different animals that use coral reefs as protection from predators. Coral bleaching causes instability in the food chain due to the reefs being the support and sense of foundation for the animals at the base of the food chain. Coral reef tourism brings in millions of dollars and with less coral reefs there would be less money and fewer jobs. The reefs also protect as a barrier for big waves. If we had more coral reefs, then not as many sand dunes would be necessary. It would save money and time, while helping the ocean’s ecosystem. Organization funding, studies, rehabilitation, movements, and conservation are many of the ways people are helping the coral reefs stay alive. In the past 40 years, coral bleaching has become five times more frequent. Between 2014–2017, 75% of the tropical coral reefs experienced high temperatures and for 30% of it was deadly. While reefs can come back from bleaching events, each time they are bleached it makes them weaker and gives a less chance of being able to recover if another bleaching were to hit them. The great barrier reef is the largest coral reef in the world. It is located off shore of north-eastern Australia. 30% of the Great Barrier reefs died due to coral bleaching in 2016, and another 20% died in 2017.

Evelyn Buehren, Social Media Coordinator

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