The beautiful underwater habitat that is the coral reef can be found all over the world’s oceans. Coral reefs are large structures composed of the skeletons of coral, which are marine invertebrate (no backbone) animals. Hermatypic, or “hard” corals, are the species that build up the coral reefs due to their ability to extract calcium carbonate from seawater to create a hard exoskeleton covering their soft bodies. An individual coral is called a polyp, and new polyps live on their ancestral exoskeletons, adding on one exoskeleton at a time to make the reef a prominent part of the environment around it. The largest coral reefs are found in the clear, shallow waters of the tropics; they can grow quickly in these environments. However, in the present day, coral reefs all over the world are threatened with extinction, and it all goes back to how these organisms feed.
Some corals feed by catching small sea life such as fish by using stinging tentacles they have on the outer part of their bodies. However, most corals throughout the world get their sustenance through their symbiotic relationship with an alga called zooxanthellae, per the U.S. Environmental Protection Agency. These algae live inside the coral polyp’s body and produce food for both themselves and the coral surrounding it through photosynthesis. They also provide the vibrant color for the corals, which are usually clear and colorless. In turn, the corals provide a home and carbon dioxide (to initiate photosynthesis) for the algae.
The issue in the present day is that corals are dying in reefs all around the world due to coral bleaching, which is linked to rising temperatures in the ocean. Coral bleaching occurs when warm ocean water stresses corals to the point where they expel zooxanthellae, which normally live inside their tissues. This leaves the coral without a direct food source and depleted of its lively colors. The most recent issue with the die-off of the corals in our world is in the Great Barrier Reef, located in Australia; it is the largest coral system on the planet and is more than 1,500 miles long. According to Russell Reichelt, chairman of the Great Barrier Reef Park Authority, “the corals in the far remote north of the reef experienced extremely hot, still conditions over the past summer, and were bathed in warm water for months.” This created heat stress that the corals could not overcome. At the same time, ocean acidification is inhibiting the corals’ ability to construct their hard exoskeletons. Due to emissions of fossil fuels, more carbon dioxide gas is dissolved into the ocean water; this lowers the pH of the ocean water (making it more acidic). Furthermore, the reefs are threatened by the runoff of industrial chemicals from farms and lawns and by overfishing of the wildlife that inhabit the reefs.
The destruction of our coral reefs is an event that is bound to happen as the industrialization of human beings on Earth continues every year. However, there are ways in which we can help protect these habitats from further damage. According to the Nature Conservancy, we can help save coral reefs and the wildlife that depend on them by conserving water, helping to reduce pollution, planting trees, and disposing of trash properly. It is our duty as inhabitants of this Earth to protect all that makes it up, and that includes saving the diverse ecosystem of underwater coral reefs in our oceans.