LOSING THEIR COLOR AND LOSING THEIR COOL
Coral Bleaching and Global Warming
What Are Coral Reefs?
Contrary to popular belief, coral reefs are not plants but actually a system of many living animals.
They consist of limestone structures made by small sea animals called coral polyps. These polyps pull calcium and carbonate out of the water and combine them to make colorless calcium carbonate structures. However, if the calcium carbonate polyps are completely white, where does the color come from?
They come from tiny algae that live inside the polyps called Zooxanthellae (zoh-uh-zan-theh-lai). These algae have a symbiotic relationship with the coral, meaning that their interactions benefit both species. The corals give the algae a protected environment and the compounds (carbon dioxide, water, and sunlight ) they need to perform photosynthesis.
In return, the zooxanthellae produce food (simple sugars and amino acids) and oxygen for the coral to survive. These algae, when they're alive, produce vibrant pigments that are what you see when you look at a piece of coral.
So What Causes Coral Bleaching?
Coral, like reptiles and other marine creatures, is cold-blooded, which means they can’t make their own body heat and relies on their surroundings' temperature. Coral can only live in temperatures in the range of 73-84 degrees Fahrenheit, or 23-29 degrees Celsius.
However, due to global warming, the oceans act as a massive sponge and absorb the excess heat trapped in the Earth's atmosphere by greenhouse gases, causing the temperature of the ocean to rise. The rising water temperatures cause the coral to become stressed and expel the zooxanthellae living inside them, and as a result, they lose their color and their source of food.
This often leads to the coral dying completely.
Ocean Acidification
Another cause of coral death is ocean acidification. The excess carbon dioxide in the atmosphere due to pollution from things such as cars has to go somewhere. Some of it dissolves into the ocean, increasing the acidification levels ever so slightly. However, this is enough for the limestone structures the coral polyps built to become weaker and begin to collapse and dissolve, also killing the coral.
What Are Scientists Doing And What Can You Do?
These corals are the backbone of an entire ecosystem, and when these corals collapse, every marine animal that relies on them suddenly has no way of life. However, all hope is not lost, and there are ways to revive coral from their stressed state.
Scientists have been identifying corals that naturally survive the increased temperatures without bleaching and have been selectively breeding them to create a type of “super coral” that isn’t affected by heat. They have also been trying to bring baby corals and algae via specialized chemicals, such as scented gels that mimic the smell of healthy reefs, to bleached areas to restore the reefs.
Because coral bleaching is typically caused by pollution, the best way to protect these corals is by reducing our footprints. If you live near a beach, make sure to support your local beaches and organizations by participating in beach cleanups and events. Using less water, skipping fertilizers or weed killers that seep into local waterways, and properly disposing of trash are also better ways to reduce your impact from home.
You can also support, join, or donate to organizations like the Coral Reef Alliance, an international nonprofit working globally to reduce local threats like overfishing and water pollution while helping reefs adapt to climate change, or Reef Check, a global citizen-science network with volunteer teams across 90 countries that monitor reef health and educate communities.
If you're located in New Jersey, check out the NJDEP Fish and Wildlife Artificial Reef Program, which is helping maintain major marine artificial reef sites along the coast, or the Jersey Shore-based nonprofit Save Coastal Wildlife, which is dedicated to coastal wildlife restoration, education, and habitat protection.
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